DogAndPanda: compute_c64_unf.htm

compute_c64_unf.htm

COMPUTEI's FIRST BOOK OF

COMMODORE

64 GAMES

\ XI 3-UU "^M "³1 J

COMPUTE! Publications,!^

One of the ABC Publishing Companies

Greensboro, North Carolina

Commodore 64 is a trademark of Commodore Electronics Limited.

COMPUTE! Publications, Inc.:

"Writing an Arcade Game" (February),

"Minefield" Qune),

"The Hawkmen Of Dindrin" Qune),

"Goblin" (July),

"Rats" (July),

"Writing a Simulation Game" (July),

"Blockhead" (August),

"Diamond Drop" (September),

"Mystery Spell" (September),

"High Speed Mazer" (October),

"Mosaic Puzzle" (October).

The following articles were originally published in COMPUTE's Gazette Magazine,

"Adding Joysticks To Your Games" (July),

"Snake Escape" Only),

"Cylon Zap" (August),

"The Viper" (August),

"States & Capitals Tutor" (September),

"Oil Tycoon" (October).

Reproduction or translation of any part of this work beyond that permitted by Sections 107 and 108 of the United States Copyright Act without the permission of the copyright owner is unlawful.

Printed in the United States of America

ISBN 0-942386-34-5

10 9876543

COMPUTE! Publications, Inc., Post Office Box 5406, Greensboro, NC 27403, (919) 275-9809, is a subsidiary of American Broadcasting Companies, Inc., and is not associated with any manufacturer of personal computers. Commodore 64 is a trademark of Commodore Electronics Limited.

Contents

Foreword

Chapter 1. The 64 as a Game Machine........... l

Why the Commodore 64 Is a Great Game Machine

Eric Brandon...................................... 3

Writing Your First Game

Richard Mansfield..................................

Writing a Simulation Game

Richard Mansfield................................... 11

Writing an Arcade Game

Richard Mansfield................................... 16

Adding Joysticks to Your Games

Charles Brannon.................................... 20

Chapter 2. Maze Games.......................... 27

Rats!

Mike Steed (64 Translation by Gregg Peele)................ 29

Goblin

Dan Goff (64 Translation by Patrick Parrish).............. 36

Snake Escape

Daryl Biberdorf (64 Translation by Patrick Parrish)......... 39

The Viper

Dave and Casey Gardner

(64 Translation by Charles Brannon).................... 44

Chapter 3, Thinking Games..................... 49

States & Capitals Tutor

Enoch L. Moser.................................... 51

Mystery Spell

Doug Hapeman (64 Translation by Eric Brandon).......... 58

Oil Tycoon

Gordon F. Wheat (64 Translation by Chris Metcalf)......... 68

Mosaic Puzzle

Bruce Jordan (64 Translation by Chris Metcalf)............. 76

Chapter 4. Dexterity.............................. 81

Blockhead Matt Giwer (64 Translation by Gregg Peele)............... 83

Diamond Drop

Matt Gizver (64 Translation by Eric Brandon)............. 90

Laser Bounce

Frank L. Broadnax.................................. 95

Chapter 5. Arcade-Style Games..................103

The Hawkmen of Dindrin

Esteban V Aguilar, Jr. (64 Version by Charles Brannon)......105

Minefield

Sean Igo (64 Translation by Gregg Peele)..................113

Cylon Zap

Mark Dudley (64 Translation by Gregg Peele)..............119

Laser Gunner

GaryR. Lecompte (64 Translation by Philip I. Nelson).......129

Chapter 6. Machine Language Games...........135

Using the Machine Language Editor: MLX

Charles Brannon....................................137

Munchmaze

Gary E. Marsa (64 Translation by Gregg Peele).............144

Richthofen's Revenge

Chris Metcalfand Marc Sugiyama......................151

Zuider Zee

Marc Sugiyama.....................................168

Appendix A. Beginner's Guide to Typing

In Programs........................193

Appendix B. How to Type In Programs.........197

Appendix C. Maze Generator................... 199

Charles Bond (Translated to machine language by

Gary E. Marsa and for the 64 by Gregg Peele)..............201

Appendix D. Do You Want to Write Your Own Games?

Orson Scott Card....................................211

Index..............................................217

Foreword

COMPUTEl's First Book of Commodore 64 Games is packed full of great games. But this book serves a double purpose.

First, it provides you with a variety of games, which you can merely type into the computer, save on disk or tape, and then play again and again.

Second, because the full program is here in print, you can see exactly how the game's creator brought off the effects you like.

In fact, to make this book as useful as possible, many of the games are accompanied by explanations of how the program works. Chapters at the beginning and end of the book will also help you learn how to write your own games.

In order to make typing in the programs as easy as possible, we have included three aids. Be sure to read over the article in Appendix A "Beginner's Guide to Typing in Programs." Also, review Appendix B "How to Type in Programs."

A number of the programs are written completely or partially in machine language. If you have ever typed in a machine language program with its hundreds of DATA statements, you will appreciate the "Machine Language Editor (MLX)" in Chapter 6. MLX is a BASIC program that will help you type in machine language programs perfectly the first time.

Why the

Commodore 64 Is a Great Game Machine________

Eric Brandon

One of the first things a new programmer wants to do is write a game. The programmer soon discovers that there is no "move alien around" command; rather, the computer must be told what to do in hundreds of tiny little steps.

Fortunately, the Commodore 64 is loaded with features that make this arduous task much easier and reduce the number of steps that have to be programmed into the computer. The games in this book try to exploit these features as much as possible, to save the programmer time, and to save you typing.

Parlez-vous BASIC?

What language to program the game in is the first decision the programmer must make. On the Commodore 64 the choice is between BASIC and machine language.

The native language of the computer is machine language. This means that programs written in BASIC have to be translated into machine language while they are running. That translation takes time, so BASIC programs run much slower than programs written in machine language.

Although machine language is much faster, it is also a more difficult language to use; so to speed up writing the game, many programmers opt for BASIC, or some combination of BASIC and machine language. The choice ultimately depends on how critical speed is to the game. Witness the incredible speed of "Munch-maze" or "The Viper," both written in machine language. Other

I The Commodore 64 As A Game Machine

games where speed is not so important, such as "Mystery Spell/' use no machine language at all.

The 64 makes machine language programming easier because it has a popular, easy-to-use microprocessor chip, and it has areas of memory where machine language programs can be conveniently tucked away.

Make Your Own Alphabet

Whenever you see a letter or graphic character on the screen, you are looking at one member of a character set. The character set is where the computer goes to see what a character such as A looks like, before it can put it on the screen.

By holding down the SHIFT and Commodore keys, you can switch between two character sets. In one of them, character number one looks like this: A; in the other, it looks like this: a.

This is very important to the game programmer, because with the 64 he can create his own character set. For example, the programmer can tell the computer that character one is a happy face. From then on, moving a happy face around on the screen is just as easy as moving any other character. Here is a short program that changes the A character into a happy face:

5 REM DISABLE INTERRUPTS AND REVEAL CHARACTER ROM

10 POKE 56334,PEEK(56334)AND254

20 POKE 1,PEEK(1)AND251

25 REM COPY CHARACTER SET DOWN TO RAM

29 PRINT "PLEASE WAIT 30 SECONDS"

30 FOR 1=0 TO 2048

40 POKE 12288+1,PEEK(53248+1)

50 NEXT I

55 REM COVER UP CHARACTER ROM AND REENABLE INTERRU

PTS 60 POKE l,PEEK(l)OR4 70 POKE 56334,PEEK(56334)ORl 75 REM ENABLE NEW CHARACTER SET 80 POKE 53272,28

85 REM POKE IN HAPPY FACE OVER "A" 90 FOR 1=0 TO 7 100 READ A 110 POKE 12296+1,A 120 NEXT 130 END 195 REM EACH NUMBER IS ONE ROW OF THE DOTS THAT MA

KE UP THE FACE 200 DATA 60,66,165,129,165,153,66,60

The Commodore 64 As A Game Machine

Even more powerful is the technique of telling the computer that character one looks like the left half of a spaceship, and character two like the right half. By combining redefined characters, you can create large shapes. This technique is used in "The Hawkmen of Dindrin."

Another Way of Making a Spaceship

Sometimes a game needs objects on the screen that can go through or over other objects, like a spaceship moving over a star-field. Not only can the 64 do this, but also it will automatically detect a collision between objects.

These objects, called sprites, have a number of other useful features. Each of the 504 dots can be assigned a color independent of its neighbor, and the whole sprite can double in size either vertically or horizontally. Although only eight sprites can usually be displayed at a time, most games do not require that many.

Sprites can also be used for animation. The bird in Mystery Spell is a sprite. To make the bird's wings flap, several versions of the bird were drawn, with the wings up, midway, and down. By telling the bird to look like one shape after another, the illusion of flapping wings is achieved.

Small Is Beautiful

Sometimes, instead of large objects, a game needs to work with pixels, the individual dots that make the image on your screen. High-resolution mode allows control over each individual dot on the screen.

With high-resolution graphics it is possible to make very detailed backgrounds on the screen, over which you can move the sprites that play the game. None of the games in this book use this technique because it would require the typing in of 8000 numbers that describe each of the dots on the high-resolution screen.

Color Me 64

Every good game-playing computer has the ability to put color on the screen. Some have as many as 256 different shades of colors, and some have as few as six.

Just as important as how many colors a computer has is how many colors it can display at once. The 64 is very good at multicolor graphics. Any character or dot can be any one of 16 colors. Furthermore, each dot within a character or a sprite can have its own color.

T The Commodore 64 As A Game Machine

Breaking the Sound Barrier

One of the most important features of a good game is sound effects for explosions, fanfares, and other sundry noises.

The Commodore 64 incorporates a minisynthesizer called the SID chip. The SID chip can make three different tones at once, so that harmony and chords are possible. You can hear this in the short songs played by "Richthofen's Revenge/'

Furthermore, the SID gives you control over attack, decay, sustain, and release, sophisticated sound characteristics that can make the same note sound like it came from anything from a drum to an underwater oboe.

Join the Party

This book is more than a book of games. The Commodore 64 is a great machine with features that allow arcade-quality games. Some of these features take practice to learn.

Many of the articles include explanations of how the game was designed and how the features of the 64 were exploited. By typing in the games and reading the articles, not only will you have hours of fun playing the games, but you will also be learning many of the techniques needed to design your own games.

Writing Your First Game

Richard Mansfield

Richard Mansfield, senior editor of COMPUTE! Publications, explains the details of a simple game. A beginning programmer can learn a great deal studying this short program.

If you are tempted to write your own games, go ahead. It's a good way to learn to program. Games are basically the same as any other kind of programming.

Computer games fall into two broad categories: 1. imitations of old standards (checkers, Othello) and 2. games which could not be played without a computer (Space Invaders, Pac-Man). This second category is more difficult to program for several reasons. For one thing, you've got to think up a whole new, and entertaining, concept and then adjust the action until it is just hard enough to be challenging but not so difficult that people want to give up.

This category (basically arcade games) is especially hard to program precisely because a good computer-only game exploits all of the computer's special attributes: speed, color, and sound. To do this well, to make things look and respond just the way you imagine them, requires a good bit of programming experience. Usually, too, several things are happening at once in an arcade game. This often means that such a program must be written in machine language, which is far faster than BASIC.

High Card Slice

Old standards, on the other hand, can often be the best way to get started programming games. You already know the game concept, and cards or dice or game boards are fairly easily constructed and manipulated on your computer screen. To illustrate, let's take a look at a simple simulation of one of the oldest card games, "High Card." The rules are simple: you place a bet,

I The Commodore 64 As A Game Machine

and then you draw a card from the deck. The computer, your opponent, draws a card too, and the highest card wins the money

One simplification here is that there is no attempt to represent the cards on the screen. The entire game relies simply on words (Ace of Spades, for example) when cards are drawn.

Like most computer programs, the program can be visualized as having four distinct zones: initialization, main loop, subroutines, and data tables. We can go through the steps in programming this game by looking at each zone separately.

Initialization

From lines 10 through 80 we are teaching the computer some basics about this game. Initialization is the activity which must take place before any of the action can begin. Computers are so fast that they will zip up through these lines and start things off in the main loop at line 100 in a flash. However, as programmers, we are aware that several preliminary events took place inside before anything else.

In line 20, the computer discovers that there is a variable called DOLLARS which is set equal to 500. It sets aside a section (like a small box) in its memory which it labels DOLLARS. When the game is running, it will add or subtract from this box (lines 230-240) to keep a running total of how much money you have left to bet. From time to time (line 110), it will check the box and report to the player how much he has. The box labeled DOLLARS is called a variable because during the game the amount in it will vary

Lines 30 through 60 are simple enough—they ask the player to give his or her name. The computer memorizes it in another box called NAME$ and can now speak more personally to the player in lines 140 and 230. Also, the computer prints the rules of the game in line 60.

Line 70 READs four names (the face cards) from the data tables in lines 510 on. It also makes a mental note that it already READ four items. So, when it's asked to READ again (line 80), it will start with the next unread item of data which will be CLUBS. By now, the computer has memorized a variety of important facts: the player's name, the amount of his or her betting purse, the names of the face cards, and the suits of a standard deck. In less than a second, the computer has grasped and filed away the necessary facts to go on to the main loop where all the action takes place.

The Commodore 64 As A Game Machine

The Main Loop

After checking that the player has money to bet, the computer asks for the bet, checks again that the bet is possible, and then runs through one cycle of the game starting in line 160. At this point, a programmer might find it worthwhile to visualize the steps involved in the game: draw a card for the player; draw for the computer; decide who won; adjust the player's purse.

Since both draws are essentially identical actions (the only difference will be that we say "Bob draws a . . ." instead of "The computer draws"), we don't need to program the draw twice. This is where subroutines come in handy.

The Subroutine

Twice in the main loop, we GOSUB 300. First the player, then the computer, draws. Line 310 randomly picks two numbers, the card and the suit. If line 320 finds that this selection matches the one drawn just before by the player, it goes back for another draw. Line 330 makes the name of the card be the number if it is less than 11 (a face card).

Then line 340 announces the draw using three variables. The first variable (PLAYER$) is set up in either line 160 or 190 as appropriate. Then the CARD$ and SUIT$ variables are selected from the lists that were memorized back in the initialization phase (lines 70-80). The subroutine then RETURNS to the main loop.

Lines 210-240 decide and announce the winner of this round. First, if the variable CARD (the computer's card) is greater than (>) YOURCARD, the computer is declared the winner in line 240, the purse is adjusted, and the main loop is restarted (GOTO 100). If the cards are equal, nothing happens to the purse and the next round begins. Notice that we don't need to say IF YOURCARD > CARD at the start of line 230 to test if the player has won. It's the only possible thing if the computer has gotten this far.

Once you've solved a particular problem, you'll find you can use the solution in many future games. This subroutine which draws cards, for instance, would work just as well for Poker, or Blackjack, or dozens of other games. Subroutines are handy not only because they can be used repeatedly within a program, but because they can also be saved and used repeatedly in future programs. So think up a simple, traditional game and teach it to your computer. There is probably no more pleasurable way to learn programming than to write a game.

T The Commodore 64 As A Game Machine

High Card

10 REM*NECESSARY INITIAL INFORMATION*

20 DOLLARS=500

30 PRINT " WITH WHOM DO I HAVE THE PLEASURE"

40 PRINT " OF PLAYING HIGH CARD SLICE?"

50 INPUT NAME$

60 PRINT " HIGH CARD WINS IN THIS GAME!"

70 DIM SUIT$(4),CARD?(14):FOR 1=11 TO 14: READ CAR

D$(I):NEXT I 80 FOR 1=1 TO 4: READ SUIT?(I): NEXT I 90 REM

100 REM*MAIN PROGRAM LOOP* 110 PRINT:PRINT" YOU HAVE $" DOLLARS 120 IF DOLLARS<=0 THEN PRINT" THE GAME IS OVER. YO

U ARE OUT OF CASH.":END 130 PRINT"WHAT IS YOUR BET";:INPUT BET 140 IF DOLLARS<BET THEN PRINT" YOU ONLY HAVE $"DOL

LARS" TO BET,"NAME?:GOTO 130 150 YOURCARD=0:YURSUIT=0 160 PLAYER?=NAME? 170 GOSUB300

180 YOURCARD=CARD:YURSUIT=SUIT 190 PLAYER?=" THE COMPUTER" 200 GOSUB300

210 IF CARD>YOURCARD THEN GOTO 240

220 IF CARD=YOURCARD THEN PRINT " A TIEi":GOTO 100 230 PRINT NAME? " WINS": DOLLARS = DOLLARS + BET:G

OTO 100 240 PRINT " THE COMPUTER WINS": DOLLARS= DOLLARS-B

ET:GOTO 100 290 REM

300 REM*SUBROUTINE TO DRAW THE CARDS* 310 CARD=INT(RND(5)* 13)+2:SUIT=INT(RND(5)*4)+1 320 IF CARD=YOURCARD AND SUIT=YURSUIT THEN 300:REM

NO IDENTICAL DRAWS 330 IF CARD<11 THEN CARD?(CARD)=STR?(CARD) 340 PRINT PLAYER? " DRAWS THE " CARD?(CARD) " OF "

SUIT?(SUIT) 350 RETURN 490 REM

500 REM* DATA TABLE* 510 DATA JACK,QUEEN,KING,ACE 520 DATA CLUBS,DIAMONDS,HEARTS,SPADES

Writing a Simulation Game

Richard Mansfield

A simulation is an imitation of life. It can be the most difficult type of game to create. Thought, rather than fast action, is important. Try the short simulation offered here, then see if you can write one of your own.

There are three basic types of computer games: arcade, adventure, and simulation games. Let's briefly look at the characteristics of arcade and adventure games and then write a simulation.

Realtime Action

Arcade games feature what's called realtime action. Unlike chess or bridge, things happen fast. You can't sit back and plan your next move; you must react immediately to the space invaders. In other words, events take place at the same speed as they would in reality: realtime.

Arcade games also have a strong appeal to the eye and ear. There is much animation, color, and sound. In fact, your ability to respond quickly and effectively depends in part on all the clues you get from the graphics and sound effects. Strategy, while often an aspect of arcade play, is clearly secondary. These games are a new kind of athletics: the fun of man versus machine. Like auto racing, arcade games are essentially isometric exercises—you don't run around; you just stay in one place flexing and unflexing your muscles, tensing and relaxing.

Story and Strategy

Strategy however, is more important in "adventure" games. The emphasis is on planning ahead and solving riddles. It can be like living inside an adventure novel. There is drama, characterization, and plot. You might start out, for example, in a forest with a shovel and a trusty; if enigmatic, companion parrot. As you try to figure out what to do next, the parrot keeps saying "piny dells, piny dells." After wandering aimlessly through the trees, it

T The Commodore 64 As A Game Machine

suddenly comes to you that the bird is saying "pine needles" and you dig through them and find a treasure map.

Your "character" will travel, meet friends and enemies, and have the opportunity to pick up or ignore potentially useful items such as food, magic wands, and medicine. It's customary that you cannot haul tons of provisions. You'd have to decide whether or not to leave the shovel in the forest. Yet you might be sorry that you'd dropped it if you're involved in a cave-in later in the game.

In any case, adventure games are fundamentally verbal. The computer displays the words:

YOU ARE IN A BOAT ON A LAKE. NIGHT IS

FALLING, to which you can respond in any number of ways. You might type:

DIVE OFF BOAT, and the computer would reply that you now see an underwater cave or whatever. You move through the scenes the way a character moves through a novel. There is generally no penalty if you take time to plan your next move. It's not realtime.

Imitations of Life

The third category, simulation, is the least common kind of computer game. This is because to really imitate something, to simulate it effectively, you need lots of computer memory to hold lots of variables. However, memory has recently become far less expensive so we can expect to see increasingly effective simulation games. Star Trek and Hammurabi, both simulations, have long been popular home computer games. Although they are similar to adventure games, simulations are random. That is, there is no secret to discover, no puzzle to solve, no plot. Like real life, things happen with unpredictable, complex results.

Here's a program which simulates investing. The key to simulating is to arrange realistic interactions between variables. Look at line 600. If there is "international unrest," the price of gold (PGLD) goes up and the price of Bundtfund stock (PB) goes down. This relationship between gold, stock, and an international crisis is true to life. Alternatively, stock goes up and gold goes down on line 700 during a "market rally."

The game allows you to make investment decisions, and then

a "month" passes during which the value of your investments will go up or down. In line 510, three variables are given random values. Stock can gain or lose up to 10 points (variable X), and

The Commodore 64 As A Game Machine

gold can change by $20 an ounce (Y). Variable Z will be used to simulate flipping a coin. Also notice lines 520 and 525. In 520, we determine whether or not there will be unrest. The variable CH is just a counter. Each "month," CH is raised by one. Two conditions are required for unrest to happen: in a given month, CH must be greater than 4 and it must be less than whatever X turns out to be. If both these conditions are met, CH is reset to zero and we've got international unrest. This has the effect of creating unrest roughly every four to six months. Likewise, another rhythm is set up in line 525 to cause market rallies. In both cases, however, you cannot be certain exactly when to invest in gold or in stocks.

The decision to raise or lower stock prices is made in line 530 and based on the coin toss variable, Z. Again, stocks move in opposition to gold. Prices will rise about 50 percent of the time, but you can never know what will happen in a given month.

Suggested Complications

This is the core, a rough sketch, of an investment simulation game. There is much you can do to make it a more effective simulation and thereby a more enjoyable game. The more variables in a simulation, the better. For example, add leverage and additional "incidents" which affect prices, improve the randomizing, and include other types of investments. You could even use a separate counter which, every five years, causes the X and Y variables to swing more widely to reflect recession/recovery cycles.

As you can see, a simulation should be lifelike. It has interdependent cycles and a degree of unpredictability. Its realism derives from including a sufficient number of variables. And those variables must interact in plausible ways and with just the right amount of randomness. A simulation is a little world you create. You can define cause and effect and then fine-tune the whole thing until it seems well-balanced. Adventure and arcade games are certainly enjoyable, but this investment simulation can be built up to the point where it's just as much fun as any other kind of game.

Mixing Styles

Of course, these three categories—arcade, adventure, and simulation—are somewhat arbitrary. Some of the best games contain elements of each, There are adventure games with graphics—you see the forest, the shovel, the pine needles. After you say DIVE, your character jumps into a lake and the screen transforms into an

T The Commodore 64 As A Game Machine

underwater scene. Likewise, arcade games can include the different "settings" so characteristic of adventure games. Popular arcade games such as Tron and Donkey Kong change the playfield as you earn more points.

There are several ways to add to the appeal of our investment simulation, beyond just making it a more complex, more accurate simulation. You could add the visuals and sound of arcade games. Try creating a ticker tape across the top of the screen to show price changes and news events. Maybe add a bell sound to indicate the end of further transactions. And from adventure games you could borrow two elements: riddles and the necessity of planning ahead. One easy way to incorporate these two elements would be to make paying taxes a part of the game. After all, the closer it is to real life, the better the simulation.

Investment Simulation

5 PRINT"{CLR}" 10 CASH=100000:PGLD=400

15 POKE 53272,23:REM SHIFT TO LOWER CASE 20 PB=80

31 PRINT: PRINT"BUNDTFUND IS $"PB" PER SHARE.YOU H AVE "B"{4 SPACES}SHARES. — $"PB*B

33 PRINT" GOLD IS{4 SPACES}$"PGLD" PER OUNCE.

{2 SPACES}YOU HAVE "GLS" OUNCES. — $"GLD*PGLD

34 T=PB*B+GLD*PGLD

35 PRINT:PRINT" TOTAL INVESTMENTS — $"T

36 PRINT:PRINT" YOU HAVE $"CASH" TO SPEND."

40 PRINT:PRINT"GRAND TOTAL":PRINT"(INVESTMENTS + C

ASH){4 SPACES}$"T+CASH 45 IFCK=1THEN500 50 PRINT: PRINT"1.BUY{2 SPACES}2.SELL{2 SPACES}3.D

ONE" 60 INPUTA:IFA=3THENCK=1:G0T031 100 PRINT"WHICH?{3 SPACES}1.GOLD{4 SPACES}OR

{4 SPACES}2.STOCK" 110 INPUTF 120 PRINT"HOW MANY (SHARES{3 SPACES}0R{3 SPACES}OU

NCES)?" 130 INPUTN 140 IFF=1THEN160 150 PRINCE=PB*N:IFA=1THENCASH=CASH-PRICE:B=B+N:G0T

0400 155 CASH=CASH+PRICE:B=B-N:GOTO 400 160 PRICE=PGLD*N:IFA=1THENCASH=CASH-PRICE:GLD=GLD+

N:GOTO400 170 CASH=CASH+PRICE:GLD=GLD-N

The Commodore 64 As A Game Machine

400 GOTO50

500 PRINT"PRESS ANY KEY TO CONT" ;

503 GET C$:IF C$=""THEN 503

505 CK=0:PRINT:PRINT"{CLR}ONE MONTH LATER ...":FOR

T=1TO700:NEXTT:PRINT 510 X=INT((RND(1)*100)/10):Y=INT((RND(1)*200)/10):

Z=RND(1) 520 CH=CH+1:IFCH>4ANDCH<XTHENCH=0:GOTO600 525 IFCH=2GOTO600

530 IF Z>.5 THENPB=PB+X:PGLD=PGLD-Y:GOT031 540 PB=PB-X:PGLD=PGLD+Y:GOT031 600 PRINT"INTERNATIONAL UNREST...":PGLD=PGLD+2*Y:P

B=PB-2*X:GOT031 700 PRINT"MARKET RALLY ...{2 SPACES}":PGLD=PGLD~2*

Y:PB=PB+3*X:GOT031

Writing an Arcade Game

Richard Mansfield

Using the memory-mapped video could help you create faster moving games. The sample program here will assist you in designing your own fast-moving game.

When you bring home your computer, usually the first thing everyone expects you to do is to write an arcade game. Who's "everyone"? It could be your children, your friends, even you— anybody who is tired of spending lots of money and wants you to program a game to play at home for free.

The best defense is to politely point out that:

1. Arcade games are among the hardest types of software to write.

2. Professionals, working in teams, can take a year to write one.

However, it is well worth trying to write action games. You might not be able to duplicate the speed or complexity of professional games, but you can create very entertaining games of your own. After you've spent a few weeks getting familiar with BASIC and have typed in a few games, you are ready to take up the challenge. This is one of the best ways to learn some important programming techniques and to explore the graphics and sound capabilities of your computer.

Ten Million IF/THENs

Your main problem is going to be speed. BASIC, though fast enough for most jobs, is pretty slow when it has to keep track of ten aliens, two mother ships, torpedoes, stars, and the player's position. All these things are in motion at once. You need to have a way to control players, to detect collisions, to score points, etc. We at COMPUTE! received a letter from reader John Anderson which touches on these problems:

The Commodore 64 As A Game Machine

In order to make a fast, effective "arcade-style" game, I would like to know how to let my computer know where a large number of things are on the screen (like walls in a maze) without 10,000,000 IF/THEN statements. I would also like to know how to keep things, like the little figures racing around during a game, from plowing through walls and wiping them out or coming hack onto the other side of the screen.

As Anderson points out, the first solution that comes to mind is to use an IF/THEN test for every possible event in the game. IF the ball hits the target, THEN raise the score. IF the ball misses the target, THEN let it move one more space. And on and on. This quickly slows the action down to a crawl.

POKE Ping-Pong

One of the simpler arcade games is a simulation of Ping-Pong. You need to keep track of only three things: two paddles and one ball. Let's start off by solving the hardest problem. How can we bounce a ball around the screen both quickly and accurately?

The key to the problem is the fact that many computers have an area set aside in RAM which is an image of what you see on screen. This is called memory-mapped video and most computers have it. It means that if you POKE into that area of RAM, a character will appear on the screen. The next RAM byte address is the next space on screen, and so on. You can use this built-in "map" to tell what is where by using the fast PEEK command, and you can move things quickly with POKEs.

The example program will work on all VICs.

SCR = The address where screen RAM memory starts.

LN = The length of one screen line.

WALL = A solid square that appears when this number is

POKEd anywhere into SCR.

BLANK = A blank space character that returns the screen

to normal if POKEd into SCR on top of a WALL or

FIGURE.

FIGURE = A character that, when POKEd into SCR, looks

like a ball.

The memory cells holding the screen image are located in different places. The VIC determines where it starts by using the formula in line 100. First, draw a border around your screen like a picture frame. Perhaps print reversed spaces all around. (See lines 250-310.) This border is very useful. It will let you know when your ball has hit the edge.

J The Commodore 64 As A Game Machine

LOC is a variable in the program that's always changing whenever the ball changes. It keeps track of the current location of the ball. What you do is keep another variable (VECTR, in this example) which holds the direction and distance of the ball's current motion. When VECTR is added to LOC, we know where to move the ball next.

There are four possible directions to go in the simplest kind of animated games. Traveling up, VECTR = -LN since you subtract the number of spaces in one screen line to move the ball to the line above. Going down is + LN, right is +1, left is -1.

Notice line 180. That is how the computer tells if the ball has reached a border. The next position the figure is supposed to be POKEd into is checked to see if the WALL variable is sitting there. If not, the figure is moved (lines 200-220). If there is a wall, line 190 reverses the figure's direction.

If you type in the example program, you'll be on your way to making a Ping-Pong game that will be as fast as you could want. What's left is to play around with VECTR to get different angles of bounce off walls so the ball can go anywhere. Then add two movable pieces of wall (paddles) and scorekeeping.

Ping-Pong

SCR=1024:COL=55296:POKE53281_/0

WALL=160:REM WALL CHARACTER, SOLID SQUARE.TRY

{SPACE}OTHER CHARACTERS.

LN=40

GOSUB 260:REM DRAW BORDER

LOC=SCR+LN*10+LN/2:CLOC=COL+LN*10+LN/2:REM SCR EEN AND COLOR LOCATION

VECTR=LN:REM ALSO TRY -1,+1,LN-1,LN+1,ETC.

BLANK=32

FIGURE=81:REM "BALL"CHARACTER.

IF PEEK(LOC+VECTR)<>WALL THEN 200

VECTR=-VECTR:REM REVERSE DIRECTION

POKE LOC,BLANK:REM ERASE OLD BALL

LOC=LOC+VECTR:CLOC=CLOC+VECTR:REM CALCULATE NE

W POSITION

POKELOC+54272,1:POKELOC,81:REM PLACE BALL

GOTO180

END

REM BORDER SUBROUTINE

PRINT"(CLR}^h;:REM CLEAR SCREEN.

FOR 1=0 TO LN-1:POKE SCR+I,WALL:POKE COL+I,2:N

EXTI:REM TOP

100

110

120 130 140

150 160 170 180 190 200

210

220 230 240 250 260 270

The Commodore 64 As A Game Machine

280 FOR 1=0 TO LN-l:POKE SCR+LN*24+I,WALL:POKECOL+

LN*24+I,2:NEXT I:REM BOTTOM 290 FOR 1=0 TO 24: POKESCR+I*LN,WALL:POKECOL+I*LN,

2:NEXTI:REM LEFT 300 FOR 1=0 TO 24:POKE SCR+LN-1+I*LN,WALL:POKECOL+

LN-1+I*LN,2:NEXTI:REM RIGHT 310 RETURN

Adding Joysticks to Your Games

Charles Brannon

Taking advantage of the Commodore 64's fascinating capabilities often involves PEEKs and POKEs which can be confusing at first. This article explains the essentials of using joysticks in your own BASIC programs.

First of all, if you don't yet own a Commodore joystick, you can use the readily available Atari joysticks, or any Atari-compatible joystick—which gives you quite a choice. A number of custom sticks are available from outside companies.

The Inside Story

To really understand joysticks, you have to know how they work. Don't worry; joysticks are no more complicated than a light switch. In fact, inside the base of the joystick are five switches that act like push buttons. When you press the joystick north (up), south (down), east (right), or west (left), or press the joybutton, a switch is closed.

You can also move the stick diagonally (NE, SE, SW, NW). How can four buttons give you eight directions? Simple. The joystick is designed so that diagonal movement closes two switches simultaneously.

Joy Bit

Each switch controls one part of a memory location inside your computer. These are called bits. A bit can hold only two values— either zero or one. Zero normally means nothing, false, empty, off. One means positive, true, on. Although it may seem confusing at first, the joystick bits are reversed. When the joystick is centered (not deflected in any direction), all the bits are on. They are all ones. But if you move the joystick up, the north bit will become a zero. If you move the joystick diagonally to the lower right, both the south and east bits will become zeros.

The Commodore 64 As A Game Machine

Siliconomics

Joysticks would be easier to use if each direction had its own separate memory location. That way, you could check the north, south, east, west, and joybutton bits separately. But to economize (and you always do when designing microchips, where the cost is more than proportional to the amount of silicon used), all the bits are grouped together into a single memory byte (eight bits = one byte). The bits are ordered like this:

Value When Off

Direction (Zero When On)

North: 1

South: 2

West: 4

East: 8

Button: 16

As we'll explain shortly, your program will detect which way the joystick is deflected by looking at this byte. The number in the byte will be the sum of all these values. Here's how it works.

Let's ignore the joybutton for a moment. If the stick is not moved, the summed value in the byte would be 15 (1 + 2 + 4 + 8 = 15). If the stick were moved up (north), the north value would become zero, and the remaining numbers would add up to 14. If the joystick were moved left (west), the west value would become zero, and the remaining numbers would add up toll.

The easiest way to use the joystick is to read the memory location with the BASIC command PEEK and use IF/THEN statements to take appropriate actions for each direction. Refer to this diagram:

14 A

11 <*----------------- 15

T The Commodore 64 As A Game Machine

A series of IF/THEN statements might look like this:

10 V=PEEK(56321)AND15

20 IF V=14 THEN PRINT "NORTH"

30 IF V=13 THEN PRINT "SOUTH"

40 IF V=7 THEN PRINT "EAST"

50 IF V=ll THEN PRINT "WEST"

60 IF V=6 THEN PRINT "NORTHEAST"

70 IF V=5 THEN PRINT "SOUTHEAST"

80 IF V=9 THEN PRINT "SOUTHWEST"

90 IF V=10 THEN PRINT "NORTHWEST"

100 IF V=15 THEN PRINT "CENTER"

110 GOTO 10

Line 10 reads the value of the joystick byte and keeps it in a variable, V The number 56321 is the memory location for joystick port #1. PEEK reads this location, but you won't get just values from 0-15. Other functions are also read here, such as the joybutton. The AND15 isolates the values we're looking for by turning off all the other unwanted bits. I won't explain here why this works—just take my word for it.

Who's on First?

You can read the second joystick (port #2) by substituting the number 56320 for 56321 in line 10. It might seem logical that the joystick which is read by PEEKing location 56320 should be the first joystick, since it has the lower number, but that's not the way it works. You can't argue with the lettering on the side of your Commodore 64 which clearly shows which is first and which is second.

Also, you'll notice that the first joystick will seem to press certain keys on your keyboard. This is a hardware anomaly, but you can play some joystick games by pressing keys in the upper-left part of your keyboard. It is not a reliable method, however.

Another Way

Although the sample program above will read the joystick, it's not necessarily the best way. IF/THEN statements are among the slowest statements in BASIC, so if speed is important (as in games), there are better ways to go. Here's a faster method. Change line 10 to:

10 V=15-(PEEK(56321)AND 15)

The Commodore 64 As A Game Machine

Now the values returned will be:

Notice that the range is smaller here. You can now use the values as the index to an array. Watch how it works. Let's shorten the example program:

10 FOR 1=0 TO 10:READ A$:MESSAGE$(I)=A$:NEXT I

20 DATA CENTER,NORTH,SOUTH,,WEST,NORTHWEST,SOUTHWE

ST,,EAST,NORTHEAST,SOUTHEAST 30 V=15-(PEEK(56321)AND15) 40 PRINT MESSAGE?(V):GOTO 30

MESSAGES (pronounced message-string) is a string array. A string array is a single variable name that holds a whole list of strings (a string is any series of characters). Each string has its own box or place in the array. We address the item in the list by calling its number. The READ loop on line 10 fills the MESSAGES array with the ten strings. If we say PRINT MESSAGE$(0) we'll get CENTER. PRINT MESSAGE$(5) gives NORTHWEST.

Some of the DATA items are followed by two commas, which are separators. The computer interprets this to mean that between the commas there is a null (empty) string. It saves us from having to include items we don't need (since some of the numbers in the range 0-10 don't correspond to any joystick direction).

Table Look-Up for Speed

Printing the messages indirectly by using the joystick number is a form of table look-up. Instead of having the computer go through a bunch of IF/THENS; or searching a list for an answer, table lookup is direct and fast. All the answers are already determined. This is especially useful for games, where speed is important. For

T The Commodore 64 As A Game Machine

example, you could use a different character for any direction the player is facing, and put them into an array to be selected by the joystick number.

Tricky Techniques

You can also read the joystick by masking (isolating) the bits you are looking for. Remember that each direction has a number associated with it. If we want to check for north, we just check to see if the north bit has turned to zero. If we're checking for north this way, we'll capture northeast and northwest as well, which we wouldn't have caught with a mere IF/THEN statement. Here we'll mask out the north bit:

V=(15-PEEK(56321)AND15) AND 1

If V = 0, the joystick is not deflected north. If V = 1, the joystick is being moved north, northeast, or northwest. To check for left (west):

V=(15-PEEK(56321)AND15) AND 4

If V = 0, there is no movement to the left. If V = 4 (yes, 4, not 1), the stick is being pressed left, northwest, or southwest. See how you can separate the original four directions from the eight possible ones?

So, to check for any direction, use:

V=PEEK(15-PEEK(56321)AND15) AND number

V (or whatever variable you use) will be either zero (not deflected) or nonzero (deflected). Substitute 1, 2, 4, or 8 for number (1 = up, 2 = down, 4 = left, 8 = right).

The Joybutton

You can check for the joybutton, also called the fire button or trigger, with:

B1=PEEK(56321)AND16 (for port #1) B2=PEEK(56320)AND16 (for port #2)

A zero value means the button is pushed. A nonzero value (16) means the button is not pushed. For example, if you are waiting for the user to press the button to begin a game, you could use a loop:

500 IF (PEEK(56321)AND16)<>0 THEN 500

The Commodore 64 As A Game Machine

It's a Natural

Using a joystick in your next game will make it easier to play, since joysticks seem more natural than pressing keys on the keyboard. But remember that a joystick is just a tool. It will not move objects around for you — it will just tell you how the user is deflecting the joystick.

There are other uses for joysticks besides games. Unlike the keyboard, with its 50-odd keys to deal with, the joystick limits input to just nine possibilities (the eight directions and the joybutton). The joystick can be used to select menu options, answer simple questions (left = no, right = yes), and even enter text (as you do with arcade games when you set the high score). Study the following example program for more ideas.

Program Explanation

This program contains three subroutines you can use in your own programs. Lines 10-70 just test the subroutines and show you how to use them. The subroutine at 500 will accept a yes or no answer (left = no, right = yes) and return it in A$.

Lines 700-770 let the user enter a number by counting it up and down with the joystick. The number can be found in the variable C. C will not exceed the limits of MN (minimum) and MX (maximum). The user presses the joybutton to exit. Notice the POKE 198,0. Since the first joystick interferes with the keyboard, this POKE is used to clear it out.

You can use the subroutine at 800 to accept a letter of the alphabet. The letter is returned as a number from 1-26 in the variable C. In the sample program (line 20), it is used to accept a three-digit string of initials.

Joystick Example

10 PRINT"ENTER YOUR INITIALS:";

20 GOSUB800:N$=N$+CHR$(C+64):IFLEN(N$)OTHEN20

30 PRINT: PRINT"HOW OLD ARE YOU? ";:GOSUB700:AGE=C

40 PRINT:PRINTN$;", YOU CLAIM TO BE";AGE;"YEARS OL

D." 50 PRINT .-PRINT "IS THAT TRUE? " ; :GOSUB500 60 PRINTA$:IFA$="YES"THENPRINT"GOOD FOR YOU":END 70 PRINT"SO WHAT IS THE TRUTH?":GOTO 30 500 REM SUBROUTINE FOR YES/NO 505 A$=^,,u

510 V=15-(PEEK(56321)AND15) 520 IF (VAND4)>0 THEN A$="NO"

T The Commodore 64 As A Game Machine

530 IF (VAND8)>0 THEN A$="YES"

540 IFA$ = ^M,,THEN510

550 POKE 198,0:REM GET RID OF ANY EXTRA KEYS

560 RETURN

600 REM COUNTING SUBROUTINE

610 REM C WILL CONTAIN THE COUNT

620 REM VARIABLE MX AND MN CONTROL

630 REM THE MAXIMUM AND MINIMUM

640 REM VALUES ALLOWED.{2 SPACES}USE

650 REM GOSUB 700 FOR THE DEFAULT

660 REM (1 AND 10), OR GOSUB 710

670 REM IF YOU ALTER MX AND MN

700 MN=1:MX=99

710 C=MN

720 PRINTRIGHT$("{2 SPACES}"+STR$(C),2);"{2 LEFT}"

730 V=15-(PEEK(56321)AND15)

740 C=C+((VAND8)=8)*(C<MX)-((VAND4)=4)*(C>MN)

750 REM IF FIRE BUTTON PRESSED, EXIT

760 IF(PEEK(56321)AND16)=0THENPOKE198,0:PRINT"

{2 RIGHT}";:RETURN 770 GOTO 720 800 REM TEXT ENTRY:SIMILAR TO NUMBER COUNTING ROUT

INE 810 C=l

820 PRINT CHR$(64+C);"{LEFT}"; 830 V=15-(PEEK(56321)AND15)

840 C=C+((VAND8)=8)*(C<26)-((VAND4)=4)*(C>1) 850 IF(PEEK(56321)AND16)=0THENPOKE198,0:PRINT"

{RIGHT}";:RETURN 860 GOTO820

Rats!

Mike Steed 64 Translation by Gregg Peele

This impressive game makes you feel that you are inside a maze, not just seeing it from above. Three-dimensional views appear as hallways, doors, and corners as you struggle to find the way out.

You must find your way through a maze displayed from a rat's eye view. After you have solved the maze, the program displays the top view and traces your steps.

First, you are asked what maze size you want, up to 15 by 15 (you may wish to change the DIM statement in line 49—add two to the largest dimension you want — and line 43). Line 45 checks to see if the machine code has been POKEd in, so you have to wait for that only the first time.

The space bar is used to move forward, and the J and L keys are used to turn left and right, respectively (turning doesn't change your location; it just gives you the view in another direction). The M key will display the top view of the maze, mark your position, and tell you in which direction you are headed.

There are five machine language routines in "Rats!" LINE, as its name implies, draws a line; this routine is similar to Applesoft's HPLOT TO or Atari BASIC'S DRAWTO command. PLOT sets the hi-res cursor to the position from which the next line is to be drawn, and plots that point on the screen. The COLOR routine fills the screen with color.

INIT removes everything that is not a letter or number from the screen (thus the quarter-square graphics are erased, but not the MOVE XX at the bottom of the screen), and sets all the variables used by the other routines (locations 826-837) to zero.

SCR either loads or saves something to or from the screen. This routine is used to save the screen to memory after the top view of the maze has been displayed the first time, and from then on is used to display the maze almost instantly, so you have to wait only once.

[T13V ?s|0

\f Maze Games

Typing in the Programs

Whenever you run Rats!, you must prepare the computer by first running Program 1. Tape users should not enter line 180; likewise, disk users should not enter line 190.

Program 1 will automatically LOAD and RUN Program 2. Therefore, it is necessary for tape users to SAVE Program 2 immediately following Program 1, and disk users should SAVE Program 2 on the same disk as Program 1, using the filename Rats.

Program 1. Rats! Parti

100 POKE16384,0:POKE16385,0

110 POKE56578_/PEEK(56578)OR3

120 POKE56576,(PEEK(56576)AND252)0R1

130 POKE53272,4:POKE648,128

140 POKE53280,12:POKE53281,12

145 POKE641,0:POKE642,64

150 P0KE43,1:P0KE44,64:P0KE55,0:P0KE56,128:P0KE646

,1:PRINT^M{CLR}" 160 REM DISK USERS ENTER LINE 180 170 REM CASSETTE USERS ENTER LINE 190 180 LOAD"RATS",8:RUN:END:REM DISK USERS ONLY 190 POKE 198,1:POKE 631,131:END:REM CASSETTE USERS ONLY

Program 2. Rats! Part 2

2 REM DISK USERS SAVE WITH THE FILENAME RATS

3 PRINT CHR$(142):GX=49152:GOTO 38

4 REM DRAW 3-D VIEW

5 N=2:A=H:B=V:FF=2t(F-l):SYS IN

6 Z=M%(A,B)*FF:IF ((Z/l6) AND 1)=1 THEN RL=-1:G0SU B 25:GOTO 8

7 W=M%(A+S,B-R)*FF:IF ((W/l28) AND 1)=1 THEN RL=-1 :GOSUB 21

8 IF ((Z/64) AND 1)=1 THEN RL=1:G0SUB 25:G0T0 10

9 W=M%(A-S,B+R)*FF:IF ((w/128) AND 1)=1 THEN RL=1: GOSUB 21

10 IF ((Z/128) AND 1)=1 THEN 14

11 N=N+1:IF N>8 THEN 15

12 A=A+R:B=B+S:IF B<2 THEN 15

13 GOTO 6

14 GOSUB 17

15 RETURN

16 REM DRAW CENTER BACK

17 POKE HX,VX+DX(N) : POKE HY,YU(N):SYS PL.-POKE HY,Y D(N):SYS LI

Maze Games

18 POKE HX,VX-DX(N):SYS LI:POKE HY,YU(N):SYS LI:PO KE HX,VX+DX(N):SYS LI

19 RETURN

20 REM DRAW BACK SIDE

21 POKE HX,VX+RL*DX(N-l):POKE HY,YU(N):SYS PL:POKE

HX,VX+RL*DX(N):SYS LI

22 POKE HY,YD(N):SYS LI .-POKE HX, VX+RL*DX(N-1) : SYS {SPACE}LI

23 RETURN

24 REM DRAW RIGHT OR LEFT SIDE

25 POKE HX,VX+RL*DX(N-1):POKE HY,YU(N-l):SYS PL:PO KE HX,VX+RL*DX(N)

26 POKE HY,YU(N):SYS LI:POKE HY,YD(N):SYS LI:POKE {SPACE}HX,VX+RL*DX(N-l)

27 POKE HY,YD(N-1):SYS LI:POKE HY,YU(N-l):IF N>2 T HEN SYS LI

28 RETURN

29 REM GET KEYBOARD CHARACTER

30 GET A$:IF A$=^M" THEN 30

31 RETURN

37 REM INITIALIZE

38 HX=828:HY=829:LINE=12288:PLOT=12665:INIT=12685: SCR=12725

39 FL=12726:FH=12730:TL=12734:TH=12738

40 PRINT " {CLR}{5 DOWN} {17 RIGHT}RATSi

41 PRINT "{2 DOWN}{3 RIGHTjSOLVE A MAZE FROM A RAT 'S EYE VIEW

42 INPUT "{3 DOWN}{7 RIGHTjMAZE SIZE (H,V) {3 SPACES}3,3{5 LEFT}";H,V

43 IF H<3 OR H>15 OR V<3 OR V>15 THEN 40

44 PRINT "(CLR}(DOWN}PLEASE WAIT...

45 IF PEEK(LI)=32 AND PEEK(LI+1)=33 AND PEEK(LI+2) =48 THEN 48

46 CK=0:FOR L=12288 TO 12761:READ A:POKE L_/A:CK=CK +A:NEXT:FORK=GXTOGX+2 3:READGX

47 POKEK,GX:NEXT:IF CK<>50144 THEN PRINT " {DOWN}ER ROR IN DATA STATEMENTS":STOP

48 N=H*V-1:H=H+1:V=V+1:D=1

49 DIM M%(17,17),WALK(100),CUT(5),DX(8),YU(8),YD(8 )

50 FOR J=l TO V+1:M%(1,J)=4:M%(H+1,J)=1:NEXT

51 MX=79:MY=49:VX=39:VY=24:X=VX

52 FOR J=l TO 8:DX(J)=X:YU(J)=INT(VY-X*VY/VX):YD(J )=INT(VY+X*(MY-VY)/VX)

53 X=INT(X*7/10):NEXT

54 FOR 1=2 TO H:M%(I,V+l)=8:M%(I,1)=2:FOR J=2 TO V :M%(l_#j)=15:NEXT:NEXT

55 R=INT(H/2)+l:S=INT(V/2)+l:M%(R_#S)=15

56 PRINT "{CLR}{DOWN}GENERATING MAZE...";:GOSUB 20 00

Maze Games

58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90

91 92 93

I=I+l:CUT(l)=4

REM GENERATE RANDOM MAZE (ALGORITHM FROM ROGERS

AND STRASSBERGER) FOR IWALK=1 TO N I=Z

IF M%(R-l_fS)>14 THEN 1=1+1:CUT(I)=1 IF M%(R,S-1)>14 THEN 1=1+1:CUT(I)=2 IF M%(R+1,S)>14 THEN 1=1+1:CUT(I)=3 IF M%(R,S+1)>14 THEN IF 1=0 THEN 75

IF I<>1 THEN I=INT(RND(1)*I)+1 ON CUT(I) GOTO 67,69,71,73 M%(R,S)=M%(R,S)-(M%(R,S) AND M%(R,S)=M%(R,S)-((M%(R,S)/4) M%(R,S)=M%(R,S)-((M%(R,S)/8) M%(R,S)=M%(R,S)-((M%(R,S)/2) M%(R,S)=M%( R, S ) - ( (M% ( R, S ) /4 ) M%(R,S)=M%(R,S)-(M%(R,S) AND M%(R,S)=M%(R,S)-((M%(R,S)/2) M%(R,S)=M%(R,S)-((M%(R,S)/8) IF D=-l THEN 79

1):R=R-1 AND 1)*4:

GOTO 86 S=S-1 GOTO 86 R=R+1 1):GOTO 86 AND 1)*2:S=S+1 AND l)*8:GOTO 86

AND AND AND

1)*8: 1)*2: 1)*4:

IF R<>H THEN

IF S<>V THEN

R=2:S=2:GOTO

IF R<>2 THEN

IF S<>V THEN

R=H:S=2:GOTO

S=S+l:D=-D:GOTO 84

R=R+D

IF M%(R,S)=15 THEN 75

GOTO 59

NEXT IWALK

MH=H:MV=V:I=INT(RND(1)*(MH-1))+2

M%(I,1)=0:M%(I,2)=M%(I,2)-((M%(I,2)/8)

H=INT(RND(1)*(MH-1))+2:Hl=H:V1=V

PRINT "{CLR}{DOWN}MAZE COMPLETED.

OTO 105

REM DISPLAY TOP VIEW OF MAZE

HZ=INT(79/MH):VZ=INT(49/MV)

SYS IN:POKE 214,24:PRINT TAB(25);

{9 SPACES}{HOME}";

POKE HX,l+HZ:POKE HY,1+VZ:SYS PL:

1:SYS LI

FOR J=l TO MV:FOR 1=2 TO MH:N=M%(I,J):X=I*HZ+1:

Y=J*VZ+1

IF ((N/2) AND 1)=1 THEN POKE HX,X:POKE HY,Y:SYS

PL:POKE HX,X-HZ:SYS LI IF ((N/4) AND 1)=1 THEN POKE HX,X:POKE HY,Y:SYS

PL:POKE HY,Y-VZ:SYS LI NEXT:NEXT

AND 1)*8 ":GOSUB 2000:G

"{UP} :POKE HY,MV*VZ+

JVIaze Games

99 RETURN

100 REM MARK PLAYER'S POSITION

101 X=H*HZ-l:Y=V*VZ-l:POKE HX,X+l:POKE HY,Y+1:SYS {SPACE}PL

102 POKE HX,X-HZ+2:POKE HY,Y-VZ+2:SYS LI:POKE HY,Y +2:SYS PL

103 POKE HX,X+2:POKE HY,Y-VZ+2:SYS LI

104 RETURN

105 FOR X=l TO MH:FOR Y=l TO MV:M%(X,Y)=M%(X,Y)+M% (X_/Y)*16:NEXT:NEXT

106 REM PLAY

107 F=INT(RND(l)*4)+l:ON F GOTO 108,109,110,111

108 R=0:S=-1:GOTO 112

109 R=+1:S=0:GOTO 112

110 R=0:S=+1:GOTO 112

111 R=-1:S=0

112 PRINT "(CLR}(DOWN}PRESS {RVS}j{OFF} TO TURN LE FT

113 PRINT "{DOWN}PRESS {RVS}l{OFF} TO TURN RIGHT

114 PRINT "{DOWN}PRESS {RVS}SPACE{OFF} TO GO FORWA RD

115 PRINT "{DOWN}PRESS {RVS}m{OFF} TO DISPLAY TOP {SPACE}VIEW OF MAZE

116 PRINT "{3 DOWNHRVS} PRESS ANY KEY TO CONTINUE

117 GOSUB 30:PRINT "{CLR}";:SYS49152:GOSUB 5

118 REM GET KEYSTROKE

119 GOSUB 30

120 ON -(A$="J")-2*(A$="L")-3*(A$=" ")-4*(A$="M") {SPACE}GOTO 122,124,131,136

121 GOSUB2000:GOTO 112

122 F=F-1:IF F<1 THEN F=4

123 GOTO 125

124 F=F+1:IF F>4 THEN F=l

125 ON F GOTO 126,127,128,129

126 R=0:S=-1:GOTO 130

127 R=+1:S=0:GOTO 130

128 R=0:S=+1:GOTO 130

129 R=-1:S=0

130 GOTO 135

131 Z=M%(H,V):T=Z*2t(F-l):T=(T/128) AND 1:IF T=l T HEN GOSUB 2000:GOTO 119

132 NM=NM+l:POKE 214,24:PRINT TAB(25);"{UPjMOVE";N M;"{HOME}";

133 IF NM<100 THEN WALK(NM)=F

134 H=H4-R:V=V+S:IF V<2 THEN 147

135 GOSUB 5:GOTO 119

136 IF NOT MS THEN 138

J Maze Games

137 POKE FL,218:POKE FH,49:POKE TL,0:POKE TH,128:S YS SC:GOTO 139

138 GOSUB 92:POKE FL,0:POKE FH,128:POKE TL,218:POK E TH,49:SYS SC:MS=-1

139 GOSUB 101:PRINT "{HOME}YOU ARE FACING ";: ON F

GOTO 140,141,142,143

140 PRINT "NORTH";:GOTO 144

141 PRINT "EAST";:GOTO 144

142 PRINT "SOUTH"; .-GOTO 144

143 PRINT "WEST";

144 PRINT ".{2 SPACES}PRESS ANY KEY TO":PRINT "CON TINUE":GOSUB 30

145 PRINT "{HOME}{39 SPACES}":PRINT "{8 SPACES}"

146 GOSUB 5 .-GOTO 119

147 GOSUB2000:V=V1:H=H1:IF MS THEN POKE FL,218:POK E FH,49:POKE TL,0:POKE TH,128

148 IF MS THEN SYS SC:GOTO 150

149 GOSUB 92

150 GOSUB 101

151 PRINT "{HOME}{DOWN}CONGRATULATIONS-YOU'RE OUT {SPACE}IN";NM;"STEP!{LEFT}{INST}S"

152 REM DRAW PATH WALKED

153 POKE HX,H*HZ-HZ/2+l:POKE HY,V*VZ-VZ/2+l:SYS PL

154 FOR N=l TO NM:IF N>100 THEN 158

155 F=WALK(N):V=V+(F=1)-(F=3):H=H+(F=4)-(F=2)

156 POKE HX,H*HZ-HZ/2+l:POKE HY,V*VZ-VZ/2+l:SYS LI

157 NEXT

158 PRINT:END

160 DATA 32, 33, 48, 173, 58, 3, 133, 2 170 DATA 173, 59, 3, 133, 195, 32, 0, 49 180 DATA 173, 62, 3, 205, 63, 3, 16, 8 190 DATA 240, 6, 32, 173, 48, 76, 3, 48 200 DATA 96, 169, 128, 24, 109, 60, 3, 56 210 DATA 237, 58, 3, 141, 63, 3, 169, 128 220 DATA 24, 109, 61, 3, 56, 237, 59, 3 230 DATA 141, 64, 3, 162, 128, 142, 66, 3 240 DATA 142, 69, 3, 232, 142, 67, 3, 142 250 DATA 68, 3, 173, 63, 3, 201, 128, 176 260 DATA 11, 169, 127, 141, 68, 3, 169, 0 270 DATA 56, 237, 63, 3, 41, 127, 141, 63 280 DATA 3, 173, 64, 3, 201, 128, 176, 11 290 DATA 169, 127, 141, 67, 3, 169, 0, 56 300 DATA 237, 64, 3, 41, 127, 141, 64, 3 310 DATA 173, 63, 3, 205, 64, 3, 176, 32 320 DATA 174, 63, 3, 172, 64, 3, 142, 64 330 DATA 3, 140, 63, 3, 173, 68, 3, 141 340 DATA 66, 3, 173, 67, 3, 141, 69, 3 350 DATA 169, 128, 141, 67, 3, 141, 68, 3 360 DATA 173, 63, 3, 74, 141, 65, 3, 169

Maze Games

370 DATA 0, 141, 62, 3, 96, 173, 68, 3

380 DATA 56, 233, 128, 24, 109, 58, 3, 141

390 DATA 58, 3, 173, 69, 3, 56, 233, 128

400 DATA 24, 109, 59, 3, 141, 59, 3, 173

410 DATA 65, 3, 24, 109, 64, 3, 141, 65

420 DATA 3, 238, 62, 3, 173, 65, 3, 205

430 DATA 63, 3, 48, 35, 240, 33, 56, 237

440 DATA 63, 3, 141, 65, 3, 173, 66, 3

450 DATA 56, 233, 128, 24, 109, 58, 3, 141

460 DATA 58, 3, 173, 67, 3, 56, 233, 128

470 DATA 24, 109, 59, 3, 141, 59, 3, 96

480 DATA 169, 0, 133, 168, 169, 32, 133, 196

490 DATA 165, 2, 201, 80, 176, 56, 165, 195

500 DATA 201, 50, 176, 50, 234, 234, 234, 234

510 DATA 70, 2, 38, 168, 106, 38, 168, 133

520 DATA 195, 10, 10, 101, 195, 10, 10, 38

530 DATA 196, 10, 38, 196, 234, 234, 234, 133

540 DATA 195, 166, 168, 189, 99, 49, 133, 168

550 DATA 164, 2, 177, 195, 162, 15, 221, 103

560 DATA 49, 240, 4, 202, 16, 248, 96, 173

570 DATA 98, 49, 240, 6, 138, 5, 168, 170

580 DATA 208, 8, 138, 73, 255, 5, 168, 73

590 DATA 255, 170, 189, 103, 49, 164, 2, 145

600 DATA 195, 96, 1, 1, 2, 4, 8, 32

610 DATA 126, 123, 97, 124, 226, 255, 236, 108

620 DATA 127, 98, 252, 225, 251, 254, 160, 234

630 DATA 0, 173, 60, 3, 141, 58, 3, 133

640 DATA 2, 173, 61, 3, 141, 59, 3, 133

650 DATA 195, 32, 0, 49, 96, 162, 128, 160

660 DATA 0, 134, 254, 132, 253, 177, 253, 41

670 DATA 127, 201, 64, 48, 2, 169, 32, 145

680 DATA 253, 200, 208, 241, 232, 224, 132, 208

690 DATA 232, 169, 0, 170, 157, 58, 3, 232

700 DATA 224, 12, 208, 248, 96, 169, 218, 133

710 DATA 251, 169, 49, 133, 252, 169, 0, 133

720 DATA 253, 169, 128, 133, 254, 162, 4, 160

730 DATA 0, 177, 251, 145, 253, 136, 208, 249

740 DATA 230, 252, 230, 254, 202, 48, 2, 208

750 DATA 240, 96

1000 DATA 162, 0, 169, 1, 157, 0, 216, 157

1010 DATA 0, 217, 157, 0, 218, 157, 0, 219

1020 DATA 232, 208, 241, 96, 234, 234, 234, 0

2000 S0=54272:FORE=S0TOS0+28:POKEE,0:NEXT

2010 POKE54296, 15 :POKE54277, 51 :POKE54278, 211

2020 POKE 54276, 33 :POKE 54273, 63 :POKE54272, 75

2030 F0RT=1T0 200 :NEXT;PQKE54276, 32,F0RT=1T0 100

:NEXT 2040 FORE=S0TOS0+28:POKEE,0:NEXT 2050 RETURN

Goblin

Dan Goff 64 Translation by Patrick Parrish

In "Goblin," custom characters are used to create a simple yet entertaining game. The object is to capture the scowling creatures with your goblin while avoiding the many block-shaped obstacles that lie in your path.

After obstacles and sad faces have been positioned, "Goblin" begins when the main character appears at the bottom of the screen. As the game progresses, the goblin moves continually upward and the player controls only its horizontal movement. The O and P keys, in conjunction with the GET command in line 260, enable the player to move the goblin left and right, respectively. Children especially like the cumulative effect of the GET statement; they make rapid key punches and then wait for the delayed effects.

As each sad face is captured by the goblin, the score is updated and printed at the upper left. If the goblin successfully clears the screen of all the faces, an entirely new playfield will be provided. A game lasts as long as you wish.

A single round ends when the goblin crashes into an obstacle. At this point, the remaining sad faces smile, and you are asked if you wish to play again.

If you play again, your previous highest score will be posted as the new game begins. The incentive to exceed a record score makes any game more fun.

Goblin

80 POKE 53280,2:POKE 53281,1

90 PRINT"{CLR}{7 DOWN}{4 RIGHTjPLEASE WAIT...DEFIN

ING CHARACTERS"; 100 POKE 52,48:POKE 56,48:CLR:P0KE56334,PEEK(56334

)AND254 105 P0KE1,PEEK(1)AND251

108 FORN=0TO2047:POKEN+12288,PEEK(N+53248):NEXTN

109 FOR N=0 TO 7:POKEN+12320,PEEK(N+54064):NEXT N

110 IFS>HSTHENHS=S

112 RESTORE:B=4:Z=1964:Zl=Z+54272:W=0:S=J:G=0

Maze Games

115 VS=54296:AD=54277:SR=54278:WF=54276:LB=54272:H

B=54273 120 FOR X=0TO31:READ A:PQKEX+12288,A:NEXT 123 POKE l,PEEK(l)OR4:POKE56334,PEEK(56334)ORl 125 POKE 53272,(PEEK(53272)AND240)+12 130 PRINT" {CLRHGRN} {14 RIGHT} {RVS}G O B L I N" 140 PRINT"{HOME}{RED}{2 DOWN}{RVS}"SPC(17)"HS="HS 145 PRINT"{HOME}{BLK}{22 DOWN}{RVS}0=LEFT";SPC(27)

;"P=RIGHT" 150 FOR 1=1 TO 118 160 X=INT(RND(l)*680)+1144 170 IFPEEK(X)=BTHEN 160 180 POKEX,B:POKEX+54272,0:NEXTI 190 F0RI=1T036 195 G1=0

200 X=INT(RND(l)*680)+1144

210 IF PEEK(X)=BORPEEK(X)=10RPEEK(X)=3THEN 200 220 IFPEEK(X+39)=BANDPEEK(X+40)=BANDPEEK(X+41)=BTH

ENPOKEX, 3:POKEX+54272,0:Gl=l 225 IF Gl=l THEN G=G+l:GOTO 240 230 POKEX,l:POKEX+54272,0 240 NEXT I 250 POKEZ,32:Z=Z-40:Zl=Zl-40:IF Z<1144 THEN Z=Z+76

0:Zl=Zl+760 260 GET A$:IFA$="0"THENZ=Z-1:Z1=Z1-1 270 IFA$="P"THENZ=Z+1:Z1=Z1+1 280 IFPEEK(Z)=B THEN 410 290 IFPEEK(Z)=1 THEN GOSUB 330 300 POKEZ,0:POKEZ1,0:FORT=1TO220:NEXT 310 IFW=36-G THEN J=S:GOSUB350:GOTO110 320 GOTO 250 330 W=W+l:S=S+25:PRINT"{HOME}{BLU}{2 DOWN}"S:POKE

{SPACEJVS,15:POKE AD_#30:POKE SR,200:POKE WF,17 340 POKEHB,71:POKELB,12:FORT=1TO90:NEXTT:POKEVS,0:

POKEHB,0:POKELB,0:RETURN 350 PRINT^m{HOMEHRED}{18 DOWN} {8 RIGHT} {RVS} ******

ALL RIGHT1******" 355 FORI=1TO10:GETC$:NEXTI:REM COLLECT GARBAGE 360 POKE VS,15:POKE AD_/30:POKE SR,200:POKE WF_#17:F

OR 1=1 TO 17 370 H=INT(RND(0)*10)+21:L=INT(RND(0)*45)+210:POKE

{SPACE}HB,H:POKE LB_#L 380 FOR T=l TO 80:NEXT T:NEXTI:POKE VS_#0:POKE HB_f0

:POKE LB_#0 400 RETURN 410 POKEZ,2:POKEVS,15:POKEAD,30:POKESR,200:POKEWF,

129:POKE HB_#2:POKE LB,125 415 FOR 1=1 TO 400:NEXT I:POKE VS,15:POKE HB_#0:POK E LB,0

J Maze Games

420 FORX=1144T01823:IF PEEK(X)<>1THEN NEXTX

430 IFPEEK(X)=1THEN POKEX,3:NEXTX

440 J=0

445 FORI=1TO10:GET C?:NEXTI

450 PRINT"{HOME}{BLU}{20 DOWN}{RVS}PLAY AGAIN? (Y/

N)^M:POKE 646,14 465 GET C$:IF C$="^u THEN 465 470 IFC$="Y"THEN 110 490 POKE53272,21:POKE53280,14:POKE53281,6:POKE 52,

50:POKE56,50:PRINT"{CLR}SEE YA1" 500 DATA126,219,219,255,165,90,90,165,60,66,165,12

9,153,165,66,60 510 DATA 170,85,170,85,126,219,255,189,60,66,165,1

29,165,153,66,60 520 DATA 0,0,0,0,0,0,0,0

Snake Escape

Daryl Biberdorf 64 Translation by Patrick Parrish______________________

You'll have to watch out for poisonous mushrooms as you race against the clock towards your goal in "Snake Escape."

In "Snake Escape," your goal is to move a snake out of a poisonous garden. There are approximately 150 poisonous plants on the screen after you enter your skill level. The snake appears in the upper-left corner after all poisonous plants have been placed. You then attempt to get the snake to the escape hole within the time limit you chose earlier.

The snake must reach the hole without hitting a poisonous plant, running into itself, or running out of time. If it reaches the escape hole safely, you will receive a bonus in addition to your score. The snake grows as it moves along; you receive one point for each body segment it adds while moving. If it runs into itself or a poisonous plant, a cross will appear in the center of the screen with your score and the number of remaining snakes. You may stop the snake if you wish by simply releasing all keys, but remember this costs you time.

Strategy

If you are running your snake near the left or right edges of the screen, remember that the 64 has horizontal screen wraparound. You may end up hitting a poisonous plant on the other side of the screen, so be careful! Occasionally, the snake will be cornered between plants and itself due to a miscalculation in maneuvering. Try to fill up all the spaces you can in the cornered-off area. You may lose a snake, but you will still receive a few extra points. Also, try to keep moving at all times. And watch where you're going.

The direction in which the snake moves is determined in lines 200 through 230. As written, keys I (up), J (left), K (right), and M (down) move the snake. If you aren't comfortable controlling the snake with these keys, you can easily change the program to accept other key commands.

Maze Games

For instance, suppose you want to use the Z key rather than the J key to move the snake left. Since location 197 reads the keyboard, you must first determine the number which is POKEd into this location when Z is pressed. Type the following line:

1 PRINT PEEK(197):FOR 1=1 TO 400:NEXT I:GOTO 1

and then RUN the program. Next press the Z key, and the number in location 197 corresponding to the Z key (12) will print repeatedly on the screen. Try some other keys, noting their values, then hit the RUN/STOP key

You are now ready to make the modification in line 200: substitute 12 for 34. RUN the program (after deleting line 1, of course); you can move the snake left with the Z key

Snake Escape

5 GOTO100

10 POKE54296, 15 :POKE54277_/ 17 :POKE54278, 17

15 POKE 54276, 17 :POKE 54273, 28 :POKE54272, 49

20 POKE542 76,0:POKE54273,0:POKE54272,0

30 RETURN

100 SO=0:SR=3

110 GOSUB30000:GOSUB29000

120 PRINT"{CLR}"

130 GOSUB28000:GOSUB8000:GOSUB9000:GOSUB28000

140 TI$="000000"

150 CL=INT(RND(1)*7)+1:IFCL=5ORCL=3THEN150

160 IFTI$=L$THENGOSUB7000:GOTO130

170 IFDH=0THENPOKEB,HC

180 POKEB,HC:POKECO,CL

190 K=PEEK(197)

200 IFK=34THENDR=-1:GOTO250:REM LEFT

210 IFK=37THENDR=1:GOTO250:REM RIGHT

220 IFK=33THENDR=-40:GOTO250:REM UP

230 IFK=36THENDR=40:GOTO250:REM DOWN

240 GOTO160

250 POKEB_/BC:B=B+DR:CO=CO+DR:SO=SO+l

260 IFPEEK(B)=88THENDH=0:GOTO9500

270 IFPEEK(B)=160THENGOSUB5000:GOTO120

280 IFPEEK(B)=81THENGOTO9500

300 IFB<1024ORB>2023THENB=B-DR:CO=CO-DR

310 GOSUB10:GOTO150

4000 REM PRINT INSTRUCTIONS

4010 PRINT"{CLR}{DOWN}{BLU}{5 RIGHT}YOUR GOAL IS T

0 MOVE THE SNAKE OUT OF THE{2 SPACES}POISON P

ATCH." 4020 PRINT"{DOWN}{GRN}{5 RIGHTjTRY TO AVOID ALL PO

ISON ({BLK}X{CYN})."

Maze Games

4030 PRINT"{3 DOWN}{RED}CONTROLS:":PRINT"{PUR} J=

{RVS}LEFT":PRINT"{GRN} K={RVS}RIGHT" 4040 PRINT"{CYN} I={RVS}UP":PRINT"{RED} M={RVS}DOW

N" 4050 PRINT"{DOWN}{RED}POINT VALUES:" 4060 PRINT"{BLU}BODY SEGMENT={RVS}1{OFF} POINT" 4070 PRINT"{2 DOWN}{RED}YOU WILL RECEIVE A BONUS F

OR ESCAPING." 4080 PRINT"{3 DOWN}{PUR}{RVS}{8 RIGHT}HIT A KEY TO

START " 4090 GETA§:IFA$=""THEN4090 4100 RETURN

5000 VB=0:POKE53280,3:POKE53281,1 5010 IFS=1THENVB=20 5020 IFS=2THENVB=30 5030 IFS=3THENVB=40 5035 IFS=4THENVB=50 5040 BN=FNSC(VB) 5050 PRINT"{CLR}{6 DOWN}{8 RIGHT}{BLU}...YOU HAVE

{SPACE}ESCAPED! I 1" 5060 SO=SO+BN

5070 print"{2 down}{15 right}{red}{rvs}bonus{off}:

{rvs}{blu}"bn"{off}" 5080 print"{2 down}{15 right}{rvs}{pur}score{off}:

{rvs}{grn}"so 5090 print"{2 down}{8 right}{blu}"sr" {redjsnakes

{space}remaining" 5100 poke54296, 15 :poke54277, 83 :poke54278, 50

5102 forhi=33to 57step2:lo=int(rnd(0)*50)+180

5103 poke 54276,17:forj=1to60:nextj:poke 54273,hi: poke54272,lo:next

5106 fort=lto 200 :next:poke54276,0:poke54273,0:po

KE54272,0 5120 DH=2:RETURN 6000 PRINT" {CLR} {10 DOWN} {12 RIGHT} {BLU}WVWWVVV

VVV"

6003 print"{12 right}{blu}v{rvs}{cyn}{11 right}

{off}{blu}v" 6005 print" {12 right}vwvvwwww" 6010 print"{home}{11 down]i13 right}{rvs}{blk} gam

6020 POKE54296, 15 :POKE54277, 53 :POKE54278, 69

6021 POKE 54276, 33 :POKE 54273, 3 :POKE54272, 244

6022 FORT=lTO 900 :NEXT:POKE54276,0:POKE54273,0:PO KE54272,0

6025 POKE36874,150:PRINT"{HOME}{11 D0WN}{18 RIGHT} {RVS}{BLK} OVER "

6026 POKE54296, 15 :POKE54277_f 53 :POKE54278_# 69

6027 POKE 54276, 33 :POKE 54273, 2 :POKE54272, 163

\J Maze Games

6028 F0RT=1T0 900 :NEXT:POKE54276,0:POKE54273,0:PO

KE54272,0 6040 PRINT"{3 DOWN}{12 RIGHT}{RED}PLAY AGAIN ?" 6050 GETP$:IFP$=""THEN6050 6060 IFP$="Y"THENSO=0:SR=3:LK=0:GOTO120 6070 IFP$<>"N"THEN6050

6080 PRINT"{3 DOWN}{17 RIGHT}BYE!{HOME}":END 7000 SR=SR-1:POKE53280,3:POKE53281,1 7010 PRINT"{CLR}{6 DOWN} {REDJwHEW! YOU HAVE JUST

{SPACE}DIED OF EXAUSTIONI" 7020 PRINTSPC(14)"{4 DOWN}{GRN}^{PUR}SCORE{OFF}:

{RVS}{GRN}"SO 7030 PRINTSPC(9)"{5 DOWN}{RED}"SR"{BLU}SNAKES REMA

INING" 7040 POKE54296, 10 :POKE54277, 31 :POKE54278, 17

7042 POKE 54276, 33 :POKE 54273, 5 :POKE54272, 71

7043 FORV0=15T05STEP-.5:POKE54296,V0:FORT=1TO100:N EXT:NEXT

7045 POKE54276,0:POKE54273,0:POKE542 72,0:POKE54296

,0 7050 FORT=1TO2000:NEXT 7060 IFSR=0THEN6000 7070 RETURN 8000 POKE53280,4:POKE53281,1:PRINT"{CLR}{3 DOWN}"S

PC(42)"{RED}CHOOSE YOUR SKILL:" 8005 PRINT"{2 SPACES}gl7 T3 "

8010 PRINTSPC(51)"{DOWN}{BLU}LEVEL 1=60 SECONDS" 8020 PRINTSPC(51)"{RED}LEVEL 2=45 SECONDS" 8030 PRINTSPC(51)"{GRN}LEVEL 3=30 SECONDS" 8040 PRINTSPC(51)"{PURjLEVEL 4=15 SECONDS" 8045 PRINT"{3 DOWN]I {7 RIGHT}{YEL}l{BLU}e{GRN}V

{pur}e{cyn}l {red}?" 8050 gets$:ifs$=""then8050

8060 S=VAL(S$)

8070 IFS=1THENL$="000100":RETURN

8080 IFS=2THENL$="000045":RETURN

8090 IFS=3THENL$="000030":RETURN

8100 IFS=4THENL$="000015" .-RETURN

8110 GOTO8050

9000 POKE53280,4:POKE53281,8:PRINT"{CLR}"

9010 FORF=1TO150:D=INT(RND(1)*966)+1058

9020 POKED_/88:POKED+54272,l:FORJ=l TO20:NEXTJ:POKE

D+54272_#0:NEXTF 9030 POKE2023,160:POKE202 2,160:POKE1983,160:POKE19

82,160 9040 POKE56295,6:POKE56294_/6:POKE56255,6:POKE56254

,6 9050 POKE1943,32:POKE2021,32 9060 RETURN

Maze Games

9500 POKE54296, 15 :POKE54277, 53 :POKE54278, 69 9505 POKE 54276, 33 : POKE 54273, 5 :POKE54272, 71 9510 FORT=lTO 900 :NEXT:POKE54276,0:POKE54273,0:PO

KE54272,0 9515 POKE54296, 15 :POKE54277, 53 :POKE54278, 69 9520 POKE 54276, 33 :POKE 54273, 3 :POKE54272, 244 9525 FORT=lTO 900 :NEXT:POKE54276,0:POKE54273,0:PO

KE54272,0 9530 POKE54296, 15 :POKE54277, 53 :POKE54278, 69 9533 POKE 54276, 33 :POKE 54273, 2 :POKE54272, 163 9536 FORT=lTO 900 :NEXT:POKE54276,0:POKE54273,0:PO

KE54272,0 9540 SR=SR-1

9550 print"{home}{10 down}"spc(18)"{rvs}{wht}

{right} {right}"spc(37)"rip"spc(37)"{right} {right}"spc(3 7)"{right} {right}{off}"

9560 fort=1to1000:nextt

9570 poke53280,3:poke53281,1:print"{clr}{5 down}"

9580 printspc(14)"{red}too bad!!"

9590 print"{4 down]i {14 right}{rvs}{blu}score{off}: {rvs}{pur}"so"{off}"

9600 printspc(8)"{4 down}{grn}"sr"{blu}snakes rema

INING" 9610 FORT=1TO2000:NEXTT:IFSR=0THEN6000 9620 GOTO120 10000 POKEV,15:POKES3,217:POKES3,217:POKEV,0:POKES

3,0:RETURN 28000 BC=81:HC=87:B=1024:S3=36876:CO=55296:LK=0:RE

TURN 29000 DEFFNA(L)=INT(RND(l)*L)+1064 29010 DEFFNSC(L) = INT(RND(1)*L)+5:RETURN 30000 POKE53280,3:POKE53281,1 30010 PRINT"{CLR}{8 DOWN}{11 RIGHT}{RVS}{RED]

{17 SPACES}" 30020 PRINT"{11 RIGHT}{RVS}{RED} {GRN}{15 SPACES}

{RED} " 30030 PRINT"{11 RIGHT}{RVS}{RED} {GRN} SNAKE ESCAP

Ei {RED} " 30040 PRINT"{11 RIGHT}{RVS}{RED} {GRN}{15 SPACES}

{RED} " 30050 PRINT"{11 RIGHT}{RVS}{RED}{17 SPACES}" 30070 PRINT"{2 DOWN}{12 RIGHT}{BLU}INSTRUCTIONS ?" 30080 GETI?:IFI$=""THEN30080 30090 IFI$="Y"THENGOSUB4000:GOTO30120 30100 IFI$="N"THEN30120 30110 GOTO30080 30120 RETURN

The Viper

Dave and Casey Gardner 64 Version by Charles Brannon

'The Viper" is a fast-action game with 60 difficulty levels. A joystick is required.

The Viper is a fast, furious, hungry snake. It races about, devouring its favorite food — asterisks! And the more it eats, the bigger it gets. Since snakes have a hard time growing wider, the Viper simply gets longer. Since the Viper has such sharp, venomous teeth, it must not in its haste accidentally run into its own lengthening body. To make things especially interesting, the Viper must maneuver through a maze with electric walls. One false move means certain doom.

With a joystick you can experience the perils of the Viper. The program is easy to set up and play. Just follow the screen instructions. Maneuver the Viper with a joystick plugged into port one.

You can choose from various difficulty levels to control the Viper's speed. You also select one of three courses — no maze, the easy maze, or the hard maze. Your score is the number of those delicious asterisks eaten multiplied by the skill level you selected, so the harder the game, the more possible points. You get twice as many points for the easy maze, and five times as many for the hard maze.

A Word to Programmers

In order to get the game to run fast enough, the entire main loop of the program was written in machine language. The resulting speed was so fast that delay loops had to be inserted just to slow it down to a barely playable level. If you're brave enough, try level 20 — you'll never be able to play it. If anyone can score any points on level 20 with the hard maze, it will be truly miraculous.

Another feature is the word VIPER that moves about on the title screen. No, it's not high-resolution graphics, and it's not made of sprites, but rather from simple character graphics found on the keyboard. The movement works with programmable INSerts and DELetes. Again, look it over. You may be able to use the technique foranimation in your next game.

Maze Games

The Viper

100 DT=60:DIM MA(DT),Q(100),1%(15)

110 I%(14)=-40:I%(13)=40:I%(11)=-1:I%(7)=1

120 I%(10)=-41:I%(6)=-39:I%(9)=39:I%(5)=41:JOY=563

21 130 F0RJ=1T0DT:READMA(J):NEXT 140 PRINT"{WHT}{CLR}"CHR$(142):C=54272:SC=1024:POK

E53281,2:POKE53280,8 150 MZ=0:P=0:DR=0 160 CURR=2 51:SPEED=493 52:INDEX=SPEED+1:LNGTH=INDEX

+1:RTN=LN+1 170 SID=542 72:V=SID+24:S1=SID:S2=SID:S3=S2:A=2:N=2

:MM=0:S4=SID+4 180 FORI=0TO24:POKESID+I,0:NEXT:POKESID+1, 25 :POKES

ID+5_f6:POKESID+6,0 190 POKESID+24,15

200 GOSUB410:POKESID+5,6:POKESPEED,19-SK 210 FORJ=1024TO1063:POKEJ+C,7:POKEJ,160:NEXT 220 FORJ=1064TO2024STEP40: POKEJ+C, 7.-POKEJ, 160:NEXT 230 FORJ=2023T01984STEP-1:POKEJ+C,7:POKEJ,160:NEXT 240 FORJ=1983TO1063STEP-40:POKEJ+C,7:POKEJ,160:NEX

T 250 M=INT(RND(1)*1000)+SC 260 IFPEEK(M)<>32THEN250 270 POKEM,42:POKEM+C,l 280 S=INT(RND(1)*1000)+SC 290 IFPEEK(S)<>32THEN280 300 POKE S,90:POKES+C,16*RND(1):IF(PEEK(56321)AND1

5)=15THEN300 310 S%=S/256:POKECURR,S-S%*256:POKECURR+1,S%:POKEI

NDEX,0 320 POKELNGTH,N:SYS49152+5:REM MAIN LOOP GOTO 170 330 HIT=PEEK(RTN)

340 IFHIT<>160ANDHIT<>214THEN360 350 S=PEEK(CU)+256*PEEK(CU+1):POKES,42:POKES+C,7:G

OTO770 360 IFHIT<>42THEN320 370 POKESID,0:POKESID+5,9:POKES4,128:POKES4,129:P=

P+l:N=N+2:FORT=1TO50:NEXT 380 POKES4,128:POKESID,0:POKESID+5,6:POKESID+24,0:

POKESID+24,15 390 GOSUB880:POKEM,42:POKEM+C,1:POKESID+24,0:POKES

ID+24,15 400 GOTO320

410 IFTR=1THENPRINT"{CLR}":GOTO470 420 GOSUB950 430 PRINT"{2 DOWN}{3 SPACES}GET THE '♦'S BUT":PRIN

T"{3 SPACES}DON'T HIT ANYTHING ELSE"

J Maze Games

440 PRINT"{2 DOWN}{3 SPACES}USE JOYSTICK IN CONTRO

L PORT ONE." 450 FORJ=1TO45:POKESID,230:POKES4,33:FORT=1TO2:NEX

T:POKES4,32:POKESID,0 460 POKESID+5,2

470 PRINT"{3 DOWN}"TAB(11)"ENTER SKILL LEVEL:" 480 PRINTTAB(10)^Mg83{RVS}{9 SPACES}11111111112":

SK=10 490 PRINT" {YEL}SLOW{WHT} {2 SPACES} <- fc83{RVS}l2

345678901234567890{OFF}{WHT} ->{2 SPACES}g63

FAST" 500 PRINTTAB(10)"{RVS}{WHT} ^{CYN} -{PUR} -{GRN}

{YEL} -gl3 -E63 -E7§ _Z{BLU} -g3l-":PR

INT 510 PRINT"{UP}"TAB(10+SK);"{WHT}T{LEFT}"; 520 J=15-(PEEK(56321)AND15):SK=SK+((JAND8)=8)*(SK<

19)-((JAND4)=4)*(SK > 0) 530 IF(PEEK(56321)AND16)=0 THEN560 540 IF TKT THEN530 550 T=TI+5:PRINT" ":GOTO510 560 IFTR=1THENPRINT"{CLR}":GOTO610 570 PRINT CHR$(14)"{CLR}{DOWN}YOU WILL GET 2 TIMES

":PRINT" AS MANY POINTS WITH" 580 PRINT" AN EASY MAZE. 590 PRINT"{2 DOWN} YOU WILL GET 5 TIMES":PRINT" AS

MANY POINTS WITH" 600 PRINT" A HARD MAZE. 610 PRINT CHR$(14)"{2 DOWN}g83 PRESS {WHTjLEFT

£8J_ FOR HARD MAZE" 620 PRINT"{DOWN} PRESS {WHT}RIGHTg83 FOR EASY MA

ZE" 630 PRINT"{DOWN} PRESS {WHT}JOYBUTTONg83 FOR NO

{SPACE}MAZE" 640 IFPEEK(56321)<>255 THEN640 650 MZ=0:J=PEEK(56321):IF(JAND16)=0THENPRINT"{CLR}

"CHR$(142); .-RETURN 660 IF(JAND15)=15 THEN650

670 PRINT"{CLR}"CHR$(142):IF(JAND4) THEN720 680 I=-1:PRINT"{HOME}{RVS}HARD MAZE" 690 FORJ=lTODT:POKESC+80+I*320+MA(J)+C_/3:POKESC+MA

(J)+80+I*320_#160:NEXTJ 700 1=1+1:IFI<2 THEN690 710 MZ=1:RETURN 720 IF(JAND8)THEN570

730 I=-1:PRINT"{HOME}{RVS}EASY MAZE" 740 F0RJ=1T032:POKESC+MA(J)+C+80+320*I,3:POKESC+MA

(J)+80+320*I,160:NEXT 750 1=1+1 :IFK2THEN740 760 MZ=2:RETURN

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770 POKESID,0:POKESID+5,15:POKES4,129:FORJ=15T04ST

EP-.1:POKESID+24,J:NEXT 780 POKESID+24,15:FORT=1TO500:NEXT:P0KES4,128:FORT

=1TO200:NEXT:POKESID+5,6 790 IFMZ=1THENP=P*5 800 IFMZ=2THENP=P*2 810 R=P*(SK+1)

820 PRINT"{CLR}{2 DOWN}{YEL} YOUR SCORE:"R 830 IFR>HSTHENHS=R

840 PRINT"{2 DOWN} {CYN}HIGH SCORE:"HS 850 PRINT:PRINT"{WHT}PRESS g33{RVS}JOYBUTTON

{OFF} {WHT}TO PLAY AGAIN." 860 IF(PEEK(56321)AND16)THEN860 870 GOTO140

880 M=INT(RND(1)*1000)+SC:MM=0 890 IFPEEK(M)<>32THEN880 900 RETURN 910 DATA 259,260,336,337,338,341,342,343,376,383,4

11,412,413,414,415,416 920 DATA 423,424,425,426,427,428,456,463,496,497,4

98,501,502,503,579,580 930 DATA 258,259,330,331,332,333,334,345,346,347,3

48,349,418,419,420,421 940 DATA 490,491,492,493,494,505,506,507,508,509,5

78,581 950 PRINT"{CLR}{WHT} "CHR$(142);:FORI=2T039:PRINT"

j^"; :NEXT: PRINT: PRINT" {4 DOWN}" 960 PRINT" ";:FORI=2T039:PRINT"^";:NEXT 970 PRINT"{HOME}{DOWN}B3 @3 E@3 l@l §3 @3

[SPACE}g2 @ij g3 @>j" 980 PRINT"{2 SPACES}{RVS} £{OFF}£{RVS}£{OFF}£

{ RVS } £{ OFF } £{ RVS } £{OFFT£{ RVST£{ OFF"J"£

{RVS}£{OFF}£{RVS} £{OFF}£ 990 PRINT" gTStRVS} {OFF}£{RVS}£{OFF}£{RVS}£

{off}£B2 t3{rvs}£{offT£Et31rvs}£{off}

£g*3lRVS}g*§" 1000 PRINT" 12 T3 £t3 12 T^{2 SPACES}&2 T^

12 T3 E3 T3{3 SPACES}":IFZZ=1THEN1070 1010 IFPEEK(900)O232THENGOSUB1130 1020 FOR CO=3 TO 7:POKE894,CO:SYS893 1030 FORI=1TO20:PRINT"{HOME}{DOWN}"CHR$(148)"

{DOWN}{LEFT}"CHR$(148)" {DOWN}{LEFT}"CHR$(148

)" {DOWN}{LEFT}"CHR$(148)" {DOWN}{LEFT}" 1040 POKESID+1,CO*2+I:P0KES4,33:POKES4,32:NEXT 1050 FORI=1TO20:PRINT"{HOME}{DOWN} "CHR$(20)^M

{DOWN} "CHR$(20)"{DOWN} "CHR$(20)"{DOWN} "CHR

$(20)"{DOWN} " 1060 POKESID+1,CO*2+20-I:POKES4,33:POKES4,32:NEXT:

J Maze Games

1070 FORI=1TO10:PRINT"{HOME}{DOWN}"CHR$(148)"

{DOWN}{LEFT}"CHR$(148)" {DOWN}{LEFT}^mCHR$(148 )" {DOWN}{LEFT}"CHR$(148)" {DOWN}{LEFT}"

1080 NEXT

1090 POKESID+1,60

1100 FORJ=l5T01STEP-1:POKE894,J:POKESID,J*10:POKES 4,33

1110 SYS893:POKES4,32:POKESID+24,J:NEXT:POKESID+l, 15:POKESID+24,15

1120 ZZ=1:RETURN

1130 FORI=893TO905:READA:POKEI,A:NEXT

1140 PRINT"{HOME}{8 DOWN}{RVS}READY TO PLAY IN 5 S ECONDS..."

1150 DATA 169, 1, 162, 0, 157, 40, 216, 232

1160 DATA 224, 160, 208, 248, 96

1170 FORI=49152TO493 50:READA:CK=CK+A:POKEI,A:NEXT

1180 PRINT"{HOME}{8 DOWN}{30 SPACES}"

1190 IF CK<>29203 THEN PRINT"ERROR IN DATA STATEME NTS 1":POKE900,0:END

1200 RETURN

1210 DATA169,0,141,199,192,173,1,220

1220 DATA41,15,170,189,183,192,240,3

1230 DATA141,199,192,173,201,192,10,170

1240 DATA165,251,157,205,192,165, 252,157

1250 DATA206,192,56,173,201,192,237,202

1260 DATA192,16,3,24,105,128,10,170

1270 DATA189,205,192,133,253,189,206,192

1280 DATA133,254,169,32,145,253,238, 201

1290 DATA192,173,201,192,16,5,169,0

1300 DATA141,201,192,169,230,141,0,212

1310 DATA169,32,141,4,212,169,33,141

1320 DATA4,212,169,214,145,251, 24,165

1330 DATA251,133,253,165,252,105,212,133

1340 DATA254,169,5,145,253,24,173,199

1350 DATA192,16,13,101,251,133,251,165

1360 DATA252,233,0,133,252,76,138,192

1370 DATA101,251,133,251,165,252,105,0

1380 DATA133,252,24,165,251,133,253,165

1390 DATA252,105,212,133,254,177,251,201

1400 DATA32,208,24,169,81,145,251,169

1410 DATA4,145,253,173,200,192,240,8

1420 DATA162,0,134,162,197,162,208,252

1430 DATA76,5,192,141,203,192,96,0

1440 DATA0,0,0,0,41,217,1,0

1450 DATA39,215,255,0,40,216,0,0

kj ^^J 1

States & Capitals Tutor

Enoch L. Moser

"States & Capitals Tutor" in addition to being a useful tool for students who are learning the American states and capitals, also demonstrates the use of arrays in programs and the storage and retrieval of data on cassette. Both of these concepts are important to programmers, but nonprogram-mers may use States & Capitals Tutor without delving into the working details.

"States & Capitals Tutor" asks a student the name of either a state or a capital, and keeps track of correct and incorrect responses. The program randomly decides whether to quiz the student on either states or capitals and also chooses the questions randomly.

Questions answered correctly are not repeated. However, the program will repeat questions that are missed. And like any good teacher, States & Capitals Tutor will help students who ask for it. Students who are stumped can simply type HELE The program gives the correct answer and comes back to the troublesome question later. It also keeps track of how many times the student asks for help.

When all 50 states have been correctly matched with their capitals, and if the student has not asked for help or missed any questions, he or she is rewarded with a perfect score message.

A Two-Part Program

The program reads the states and capitals from a disk or tape file which is generated by Program 2, "File Maker." To use these programs, follow this procedure:

1. Type in Program 1. Line 5 for tape users should be

5 OPEN 1,1,0, "STATES" Line 5 for disk users should be

5 OPEN 1,8,0, "STATES"

2. SAVE Program 1 to disk or tape. Tape users should leave the tape at its position after the SAVE.

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3. Type in Program 2 (File Maker). Line 40 for tape users should be

40 OPEN 1,1,1, "STATES" Line 40 for disk users should be

40 OPEN 1,8,1, "STATES"

4. RUN the program. The states and capitals will be on the tape or disk under the filename STATES. (Tape users should leave the tape in its position.)

5. SAVE Program 2.

6. Rewind the tape.

7. LOAD Program 1; leave the PLAY button pressed and the tape in position when loading is complete.

8. RUN Program 1.

How the Programs Work

As mentioned, the File Maker program stores the states and capitals on tape or disk under the filename STATES. The main program, States & Capitals Tutor, reads this file and stores the data in ST$ (I,J), a two-dimensional array (more on this in a moment). When a right answer is given, the range of the random number generator (line 100) is decreased by one (line 205), and that state/capital is moved to the top part of the list (lines 180-200), out of the range of selection. Otherwise, the program is fairly straightforward.

The definitions of the variables are: ST$ (49,1) States and capitals array. K Number of elements moved to top of list.

Rl% State pointer.

R2% State or capital selector.

AN$ Answer.

RT% Number right.

WR% Number wrong.

HE% Number of helps.

1$ Temporary string for exchanging data.

Arrays

An array is simply an ordered set of data. It may have one or more dimensions. A one-dimensional array is merely a list whose data elements are numbered starting with 0. For example, a grocery list of 20 items, numbered 0 to 19, would be a one-dimensional array with 20 data elements.

To define an array, you must use a special type of variable called a subscripted variable. This takes the form AN(I), where AN

Thinking Games

is the Array Name and I is the number (subscript) of the desired element. In our grocery list example, if I = 19, then AN(I) would be the last item on the list.

The array name may be any legal variable name, with $ (string variable) or % (integer variable) appended if appropriate. (This would indicate that the data contained in the array are strings or integers.)

Let's say you want a one-dimensional array with four elements. The four elements are integers (whole numbers): 21, 23, 25, and 27. The array would be represented by AN%(I). That is to say, AN% (0) = 21, AN% (1) = 23, AN% (2) = 25, and AN% (3) = 27.

A two-dimensional array is also an ordered list, but one whose elements are each an ordered list themselves. It's easier to understand if you picture it as a chart. For example, a two-dimensional array might look like this:

	1 = 0	1 = 1	1 = 2	1 = 3
J = 0	21	23	25	27
J=l	43	45	47	49
J = 2	51	53	58	59

A proper name for this array could be AN% and its elements identified as AN%(I,J). If I = 0 and J = 0, then AN%(I,J) = 21. If 1 = 3 and J = 2, then AN% (I,J) = 59. The advantage of arrays is that they let you store lots of numbers or other data without using lots of variables, and you can access any data element with a simple mathematical calculation. But be careful: arrays also consume big chunks of memory.

Arrays can become very complicated. It's easy to picture one-and two-dimensional arrays, but how about arrays of three or even four dimensions? Elements of three-and four-dimensional arrays are identified in the form AN%(I,J,K) and AN%(I,J,K,L), respectively.

Creating Arrays

Typically arrays are created with nested FOR/NEXT loops, each containing a READ from a DATA statement or an INPUT from a storage device. Each FOR/NEXT level creates one ordered list. For example, the following program could be used to define the contents of the two-dimensional array shown above:

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10 DIM AN%(3,2)

20 FOR 1=0 TO 3

30 FOR J=0 TO 2

40 READ AN%(I,J)

50 NEXT J

60 NEXT I

70 DATA 21,43,51,23,45,53,25,47,58,27,49,59

The inner (or nested) FOR/NEXT loop (lines 30-50) creates the ordered list of elements in the J-dimension within each element of the I-dimension. Compare the above chart to the DATA statement in line 70 to see how the array is set up.

The DIMension statement (line 10) is required to tell the computer how much memory to set aside for the array. Note that dimension sizes in a DIMension statement are one less than the number of elements in the dimension. The numbers of dimensions and the number of elements in each dimension are limited only by the amount of memory available.

Remember that an array can hold other types of data besides numbers. States & Capitals Tutor uses a two-dimensional string array ST$(IJ), to store the 50 states and 50 capitals. See lines 10-35 in Program 2.

Storing Data

Data can be added to a program by using DATA statements or keyboard inputs, or from data files stored on tape or disk. Tape or disk files work best when several programs must have access to the same data, or when a program needs several different data files, or when the amount of data you need to store exceeds memory capacity. Note that when arrays are filled from DATA statements, twice as much memory is required as when they are filled from tape or disk.

Storing and retrieving data is quite simple if you adhere to a few rules. First, before information can be written to or read from a file, a communications channel between the computer and recorder must be opened with the OPEN command. This tells the computer which file is involved and in which direction the information will flow (input from the recorder into the computer, or output from the computer to the recorder). If a write is indicated in the OPEN command, the computer will write a filename. If a read is indicated, the computer will search for the requested filename and then read the file.

Second, the file must be closed, after use, by the CLOSE command. This is especially important when creating a new file.

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The third rule to watch when storing information on tape or disk is that variable types must be consistent. That is to say data stored as numeric, integer, or string variables must be read back into variables of the same type. The variable names themselves are not stored, so they can be read back into entirely different variables, as long as you don't mismatch types.

Fourth, data is read back in the same order in which it was written. Therefore, the program must expect the data in exactly the same order in which it will be received.

Program 1. States & Capitals Tutor

5 OPEN 1,1,0,"STATES":REM FOR DISK OPEN 1,8,0,"STA

TES" 10 DIM ST$(49,1) 15 FOR 1=0 TO 49 20 FOR J=0 TO 1 25 INPUT#1,ST$(I,J) 30 NEXT J 35 NEXT I 40 CLOSE 1

45 K=0:RT%=0:WR%=0:HE%=0 48 PRINTCHR$(147) 50 PRINT"STATES TUTOR" 55 PRINT:PRINT"THIS PROGRAM TUTORS THE STUDENT IN

{6 SPACES}STATES AND CAPITALS" 60 PRINT:PRINT"IF YOU DON'T KNOW AN{2 SPACES}ANSWE

R,TYPE 'HELP'" 65 PRINT:PRINT"PRESS ANY KEY TO CONTINUE" 70 GET A$:IF A$=""THEN70 100 R1%=INT((50-K)*RND(-RND(0))) 105 R2%=INT(2*RND(1)) 110 PRINTCHR$(147) 115 IF R2%=0 THEN 130

120 PRINT"THE CAPITAL OF ":PRINTST?(Rl%,0) ; " IS" 125 GOTO 140 130 PRINTST$(R1%,1):PRINT:PRINT"IS THE CAPITAL OF

{SPACE}WHAT STATE?" 140 INPUT AN$

145 IF AN$=ST$(R1%,R2%)THEN170 150 IF AN$="HELP"THEN220 155 GOTO 250 170 RT%=RT%+1 175 PRINT"THAT'S RIGHTi" 180 FOR I=0TO1 185 I$=ST$((49-K),I) 190 ST$((49-K),I)=ST$(R1%,I) 195 ST$(R1%,I)=I$

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200 NEXTI

205 K=K+1

210 GOTO 300

220 HE%=HE%+1

225 PRINT:PRINT"THE ANSWER IS..."

230 PRINTSPC(5)ST$(R1%,R2%)

235 GOTO 300

250 WR%=WR%+1

255 PRINT:PRINT"SORRY.THE CORRECT ANSWER IS '

260 PRINT:PRINTSPC(5)ST$(Rl%,R2%)

300 PRINT:PRINT:PRINT:PRINT

305 PRINT"YOUR SCORE IS:"

310 PRINTSPC(5)RT%;" RIGHT"

315 PRINTSPC(5)WR%;" WRONG"

320 PRINTSPC(5)HE%;" HELPS"

325 IF RT%=50THEN400

330 PRINT:PRINT"PRESS ANY KEY TO CONTINUE "

335 GET A$:IF A$=""THEN 335

340 GO TO 100

400 IF WR%+HE%=0THEN430

405 PRINT"THAT'S ALL. BUT NOT ALL YOUR ANSWERS"

406 PRINT"WERE CORRECT OR I HAD TO HELP YOU." 408 PRINT"PRESS ANY KEY TO START OVER"

410 GET A$:IF A$=""THEN410

415 GOT045

430 PRINT:PRINT"YOU DID ITIiiil"

435 PRINT"A PERFECT SCORE AND I DIDN'T HELP"

440 PRINT:PRINT"PRESS ANY KEY TO START OVER"

445 GET A$:IF A$=""THEN 445

450 GOTO 45

Program 2. File Maker (Data File)

10 DIM ST$(49,1)

15 FOR 1=0 TO 49

20 FOR J=0 TO 1

25 READ ST?(I,J)

30 NEXTJ

35 NEXTI

40 OPEN 1,1,1,"STATES":REM FOR DISK OPEN 1,8,1,"ST

ATES" 45 FOR 1=0 TO 49 50 FOR J=0 TO 1 55 PRINT#1,ST$(I,J) 60 NEXT J 65 NEXT I 70 CLOSE 1 75 DATA ALABAMA,MONTGOMERY,ALASKA,JUNEAU,ARIZONA,?

HOENIX,ARKANSAS,LITTLE ROCK

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80 DATA CALIFORNIA,SACRAMENTO,COLORADO,DENVER,CONN

ECTICUT,HARTFORD,DELAWARE 82 DATA DOVER 85 DATA FLORIDA,TALLAHASSEE,GEORGIA,ATLANTA,HAWAII

,HONOLULU,IDAHO,BOISE 90 DATA ILLINOIS,SPRINGFIELD,INDIANA,INDIANAPOLIS,

IOWA,DES MOINES,KANSAS,TOPEKA 95 DATA KENTUCKY,FRANKFORT,LOUISIANA,BATON ROUGE,M

AINE,AUGUSTA,MARYLAND 97 DATA ANNAPOLIS 100 DATA MASSACHUSETTS,BOSTON,MICHIGAN,LANSING,MIN

NESOTA,SAINT PAUL,MISSISSPPI 102 DATA JACKSON 110 DATA MISSOURI,JEFFERSON CITY,MONTANA,HELENA,NE

BRASKA,LINCOLN,NEVADA 112 DATA CARSON CITY 115 DATA NEW HAMPSHIRE,CONCORD,NEW JERSEY,TRENTON,

NEW MEXICO,SANTA FE,NEW YORK 117 DATA ALBANY 120 DATA NORTH CAROLINA,RALEIGH,NORTH DAKOTA,BISMA

RCK,OHIO,COLUMBUS 125 DATA OKLAHOMA,OKLAHOMA CITY,OREGON,SALEM,PENNS

YLVANIA,HARRISBURG 130 DATA RHODE ISLAND,PROVIDENCE,SOUTH CAROLINA,CO

LUMBIA,SOUTH DAKOTA,PIERRE 135 DATA TENNESSEE,NASHVILLE,TEXAS,AUSTIN,UTAH,SAL

T LAKE CITY,VERMONT 13 7 DATA MONTPELIER 140 DATA VIRGINIA,RICHMOND,WASHINGTON,OLYMPIA,WEST

VIRGINIA,CHARLESTON 142 DATA WISCONSIN,MADISON 145 DATA WYOMING,CHEYENNE

Mystery Spell

Doug Hapeman 64 Version by Eric Brandon_________

This spelling game features lively graphics and sprites. It's also a clever teaching aid for parents, teachers, and students in which spelling lessons can be reviewed and then practiced.

If you've ever played Hangman, you won't have any trouble learning "Mystery Spell." Although it's similar in concept, there's a twist. Instead of a gallows you see flying blackbirds.

When the game begins, the letters of the alphabet appear near the bottom of the screen, and blank spaces representing the secret word appear near the top. When you select a letter, the bird moves to the selected letter if it's a correct choice. For each incorrect choice, a blackbird descends and lands on a perch. Too many blackbirds disallow any more guesses, and the word will be spelled correctly for you.

The program has 53 preselected words. You can change the words or add to the word list simply by creating your own DATA statements beginning at line 2780. The only restriction is that the last DATA entry must be an asterisk (*).

Animation

The most interesting feature of Mystery Spell is the animated bird. The bird flies around the top of the screen, swooping down to pick up letters or to sit on its perch, depending on whether your guesses are right or wrong.

As the bird moves around, it seems to flap its wings, creating an illusion of flight. This is achieved by rapidly displaying different poses. In films, this is done by passing many frames through a projector every second. To achieve the illusion of flapping wings, we too must create a few frames of a bird in motion.

Using a sprite editor program, we first drew the bird you see in Figure 1. Then, using that sprite, we designed two more birds, one with the wing up (Figure 2) and one with the wing down

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(Figure 3). Using those shapes, we designed three more birds identical to the first three, but without legs. This gave us three frames for the bird carrying a letter, and three frames for the bird flying freely We then set up the DATA statements in the program as if we were going to display six different sprites.

Immediately after the screen RAM are eight memory locations that tell the 64 where in memory to find the shapes of the eight sprites. Usually these locations are at 2040 to 2047 ($0ZF8 to $07FF). By rapidly POKEing 2040 with the pointer to each frame, the bird seems to flap its wings. To see how this is done, look at lines 2000-2060. This is the routine which flies the bird around the top of the screen until you press a key. Line 2050 steps through the frame numbers. The actual POKEing is done at the end of line 2000.

Another interesting feature of the game is that when you guess correctly, the bird swoops down to pick up a letter, and then carries it up to the word. How is that letter incorporated into the bird sprite?

In the character set ROM at 53248 ($D000), the shape of each character is contained in eight bytes. Each byte is one row, and each bit is a column within that row. Depending on whether the value of that bit is 0 or 1, the pixel will be clear or set inside the character. The sprite is 24 bits wide, which is as wide as three characters. This means that by putting character shape data into every third byte within a sprite, we can make character shapes inside sprites. This technique could be used in any program which moves letters or text around smoothly. To see how this is done, look at lines 2180-2260.

Lines 2180 and 2190 make the character ROM available to be PEEKed. They also turn off the keyboard. Lines 2200 to 2240 take the character data and put it in the sprites. Finally, lines 2250 and 2260 cover up the character ROM and reenable the keyboard.

^U-

Thinking Games

Figure 2. Bird with Wing Up

Figure 3. Bird with Wing Down

Figure 1. Sprite-Created Bird

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Mystery Spell

100 GOSUB 2660

110 X=RND(-TI)

120 DIM W(20),W$(500)

130 GOSUB 1190 :REM DRAW HOUSE

140 PRINT"{HOME}{BLU}PLEASE WAIT...

150 GOSUB 1380 :REM POKE IN SPRITES

160 GOSUB 1970 :REM GET WORDS

170 GOSUB 690{2 SPACES}:REM SET UP SPRITES

180 PRINT"{HOME}{14 SPACES}"

190 W?=W?(RND(1)*N+1)

200 GOSUB 650

210 L$=" ABCDEFGHIJKLMNOPQRSTUVWXYZ"

220 PRINT"{HOME}{17 DOWN}{8 RIGHT}";

230 FOR 1=2 TO 14

240 PRINTMID?(L?,I,1)"{RIGHT}";

250 NEXT

260 PRINT:PRINT"{DOWN}{8 RIGHT}";

270 FOR I=15TO 27

280 PRINTMID?(L?,I,1)"{RIGHT}";

290 NEXT

300 PRINT"{HOME}{4 DOWN}"SPC(18-LEN(G?));

310 FOR I=1T0 LEN(G$)

320 PRINTMID?(G?,1,1)"{RIGHT}";

330 NEXT

340 IF COUNT<>LEN(W$) THEN420

350 POKE 198,0

360 FOR DL=1TO100:NEXTDL:CL=CL+1:IFCL=3THENCL=1

370 PRINTMID?("{BLK}{CYN}",CL,1);

380 PRINT"{HOME}{14 SPACES}YOU WIN 1111"

390 GETA?:IFA?=""THEN 360

400 GOTO 2610

410 GOSUB 2000

420 GETA?:IFA? <"A"ORA?>"Z"ANDA? <>"<"THEN410

430 IF A?="<-"THEN 760

440 P=ASC(A?)-64

450 IF MID?(L?,P+1,1)<>" "THEN540

460 PRINT"{HOME}{4 DOWN}{8 SPACES}LETTER ALREADY C

HOSEN{10 SPACES}" 470 FOR 1=1 TO 800:NEXTI 480 PRINT"{HOME}{4 DOWN}{38 SPACES}" 490 PRINT"{HOME}{4 DOWN}"SPC(18-LEN(G?)); 500 FOR I=1T0 LEN(G?) 510 PRINTMID?(G?,I,1)"{RIGHT}"; 520 NEXT 530 GOTO 420

540 L?=LEFT?(L?,P)+" "+MID?(L?,P+2) 550 RF=0 :REM FLAG FOR CORRECT GUESS

^C Thinking Games

560 FOR 1=1 TO LEN(W§)

570 IF MID$(W$,I,1)<>A$ THEN 610

580 G$=LEFT?(G$,l)+MID$(W$_#I,1)+MID?(G$,1+2)

590 RF=RF+1

600 COUNT=COUNT+l

610 NEXT I

620 IF RF=0 THEN GOSUB 1030

630 IF RF THEN GOSUB 2070

640 GOTO 220

650 G$ = " "

660 FOR 1=1 TO LEN(W§) :G?=G?+^,,-^M :W(l)=0:NEXT

670 RETURN

680 1=1+1:GOTO1980

690 REM SET UP SPRITES

700 V=53248

710 FOR 1=0 TO 15:POKE V+I,0:NEXT

720 POKE V+21,255

730 FOR I=V+39 TO V+46.-POKE I,0:NEXT

740 X=0:Y=60:S=251

750 RETURN

760 PRINT"{HOME}{BLU}ENTER YOUR GUESS:

770 POKE V+21_/PEEK(V+21)AND254

780 FOR 1=1 TO LEN(W$):PRINT"g@3";:NEXT

790 PRINT"{HOMEJ{18 RIGHT}";GU$;

800 IF LEN(GU§)<LEN(W$)THENPRINT"g+aⁿ;

810 IF LEN(GU$)<LEN(W$)-1 THEN FOR 1=2 TO LEN(W$)~

LEN(GU$):PRINT"£@ %"; 820 GET K$:IF K$=""THEN 820 830 IF K$=CHR?(20) AND LEN(GU§)>0 THEN GU$=LEFT$(G

U$,LEN(GU$)-1):GOTO790 840 IF K$=CHR$(13) AND LEN(GU$)=LEN(W$) THEN 870 850 IF K$>="A" AND K$<="Z" AND LEN(GU$)<LEN(W$) TH

EN GU$=GU$+K$ 860 GOTO 790 870 IF GU$<>W$ THEN 930 880 PRINT"{HOME}{38 SPACES}"

890 PRINT"{HOME}{4 DOWN}"SPC(18-LEN(" "+W$)); 900 FOR I=1T0 LEN(" "+W$) 910 PRINTMID$(" "+W$_/I_/1)^M{RIGHT}"; 920 NEXT:GOTO350 930 PRINT"{H0ME}{BLK}{13 SPACES}SORRY... YOU LOSE

{5 SPACES}" 940 PRINT"{BLK}THE WORD WAS ..." 950 PRINT"{HOME}{4 DOWN}"SPC(18-LEN(" "+W?)); 960 FOR I=1T0 LEN(" "+W$) 970 PRINTMID$(" "+W$,I,1)"{RIGHT}"; 980 FOR D=l TO 200:NEXT 990 NEXT 1000 POKE 198_#0

Thinking Games

1010 GETA$:IFA$="^MTHEN1010

1020 GOTO 2610

1030 DB=DB+l:S=S-3

1040 DX=32*DB+16:DY=225

1050 IF DB=8 THEN DB=0

1060 POKEV,XAND255:POKEV+16,PEEK(V+16)AND2540R-(X>

255):POKE V+l,Y:POKE2040,S 1070 IF X=0 THEN POKE V+21,PEEK(V+21)ORl 1080 FLAG=0 1090 IFABS(X-DX)>1THENX=X+3:FLAG=1:IFX>344THEN X=0

:POKEV+21,PEEK(V+21)AND254 1100 IF Y<DY THEN Y=Y+2:FLAG=1 1110 S=S+1:IFS=251THENS=248 1120 IF FLAG THEN 1060 1130 X=DX:Y=DY 1140 POKEV+2*DB,XAND255:POKEV+16,PEEK(V+16)OR(2TDB

)*(-(X>255)) 1150 POKEV+2*DB+1,Y:POKE2040+DB,254 1160 IF DB<>0 THEN POKE V+21,PEEK(V+21)AND254 1170 X=0:Y=60:IF DB=0 THEN 930 1180 RETURN

1190 POKE 53281, 3 .-POKE 53280, 4 1200 PRINT"{CYN}{CLR} 1210 PRINT"{4 DOWN} 1220 PRINT 1230 PRINT"{5 SPACES}{GRN}{3 SPACES}{RVS}

[2 SPACES}{OFF}[10 SPACES}{WHT}Bd3{UP}{RVS}

£b31off}{down}{6 spaces}{grn}

1240 PRINT"{6 SPACES}{RVS}&k|{4 SPACES}{OFF} gJ3{6 SPACES}{RVS}{YEL}£E*3{BLK}{OFF}

g2 g3{3 spaces}{grn} {rvs}&j3 El3{off}

1250 print" {6 spaces }{rvs }&j>|{ 4 spaces} &l3 {off}{5 spaces}{rvs}{yel}£{2 spaces}b*l {off}{blk}gg3{3 spaces}{grn} {rvs} {3 spaces}{off}

1260 print"{6 spaces} {rvs }gg3{ 4 spaces}^ {off}{4 spaces}{rvs}{yel}£{4 spaces}b*§ {off}{grn}{3 spaces}{rvs}ij3{3 spaces}^l3 {off}

1270 print"{6 spaces}{rvs}{6 spaces}{off} {4 spaces}{rvs}{red}{4 spaces}fu3 {off} {grn}{3 spaces}{rvs}{5 spaces}{off}

1280 print"{6 spaces}g53{2 spaces}{rvs}

{2 spaces}{off}{6 spaces}{rvs}{red} ^£3

{4 spaces}{off}{2 spaces}{grn}{3 spaces}{rvs}

B53 {off}

1290 PRINT"{RVS}E63{8 SPACES}g53{2 SPACES} E63{6 SPACES} {RED} {2 SPACES} El3f<F3 E£3E6§{5 SPACESJE53 g63{l2 SPACES}"?

(V-

Thinking Games

1300

1310 1320 1330

1340

1350 1360 1370 1380

1390 1400 1410

1420 1430 1440 1450 1460 1470 1480 1490 1500 1510 1520 1530 1540 1550 1560 1570 1580 1590 1600 1610 1620 1630 1640 1650 1660 1670 1680 1690 1700 1710

PRINT"{8 SPACES}§53(2 SPACES}£63

[6 SPACES} {RED} {2 SPACES} {OFF} {RVS}§K3

{2 SPACES}§63{5 SPACES}§53 §63

{12 SPACES}";

PRINT"§6 3{RVS}";

FOR 1=0 TO 8:PRINT"{40 SPACES}";:NEXT

FOR 1=1 TO 8 : L=1024+23*40+I*4 .-POKE L,114:P

OKEL+54272_/0:NEXT

FOR 1=0 TO 39:POKE 1024+24*40+1,160:POKE 5529

6+24*40+1,13:NEXT

PRINT"{HOME}

PRINT"{BLK}

RETURN

1=15872:IFPEEK(1+1)=96THENFORI=lT064*6+2:READ

A:NEXT:RETURN

READ A:IF A=256 THEN 1410

POKE I,A:I=I+l:GOTO 1390

FOR 1=0 TO 63:POKE 254*64+1,PEEK(249*64+1):NE

XT:RETURN

DATA 0,96,0,0,113,224,0

DATA 121,176,0,125,252,117,193

DATA 192,127,255,192,113,255,128

DATA 0,252,0,0,24,0,0

DATA 24,0,0,102,0,0,102

DATA 0,0,0,0,0,0,0

DATA 0,0,0,0,0,1,224

DATA 0,1,176,0,127,252,117

DATA 193,192,127,255,192,113,255

DATA 128,0,252,0,0,24,0

DATA 0,24,0,0,102,0,0

DATA 102,0,0,0,0,0,0

DATA 0,0,0,0,0,0,0

DATA 0,0,0,0,0,0,1

DATA 224,0,1,176,112,127,252

DATA 127,221,192,115,185,192,1

DATA 179,128,0,172,0,0,24

DATA 0,0,24,0,0,102,0

DATA 0,102,0,0,0,0,0

DATA 0,0,0,0,0,0,0

DATA 0,0,0,0,96,0,0

DATA 113,224,0,121,176,0,125

DATA 252,117,193,192,127,255,192

Thinking Games

1720 1730 1740 1750 1760 1770 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

2010 2020

2030 2040 2050 2060 2070 2080 2090

2100 2110 2120

2130 2140 2150 2160

DATA 113,255 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,1,224 DATA 127,252 DATA 192,113 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,0,0,0 DATA 0,0,0,0

,128,0,252,0,0

,0,0,0

,0,1,176,0

,117,193,192,127,255

,255,128,0,252,0

,0,0,0

,0,0,0 DATA 0,0,1,224,0,1,176 DATA 112,127,252,127,221,192,115 DATA 185,192,1,179,128,0,172 DATA 0,0,112,0,0,0,0 DATA 0,0,0,0,0,0,0 DATA 0,0,0,0,0,0,0 DATA 0,0,0,0,0,0,0 DATA 0,0,0,0,0,0,0 DATA 0,0,0,0,0,0,0,256 1=1

READ W$ (I) : IFW$ (I) = " * "THENN=I-1 : RETURN 1=1+1:GOTO1980

POKEV,XAND255:POKEV+16,PEEK(V+16)AND2540R-(X> 255):POKE V+l,Y:POKE2040,S IF X=0 THEN POKE V+21,PEEK(V+21)ORl X=X+3:IFX>344 THEN X=0:POKEV+21,PEEK(V+21)AND 254

Y=Y-1+RND(1)*2:IFY>100THENY=99 IF Y<50 THEN Y=50 S=S+1:IFS=254THENS=251 RETURN

DX=INT(P+13*(P>13))*16+24+40 DY=173+INT(P/14)*24:IF S>250 THEN S=S-3 POKEV,XAND255:POKEV+16,PEEK(V+16)AND2540R-(X> 255):POKEV+1,Y:POKE2040,S IF X=0 THEN POKE V+21,PEEK(V+21)ORl FLAG=0

IFABS(X-DX)>2THENX=X+3:FLAG=1:IFX>344THENX=0: POKEV+21,PEEK(V+21)AND254 IF Y<DY THEN Y=Y+2:FLAG=1 S=S+1:IFS=251THENS=248 IF FLAG THEN 2090 X=DX:Y=DY

■C Thinking Games

2170 POKEV,XAND255:POKEV+16,PEEK(V+16)AND2540R-(X>

255):POKEV+1,Y:POKE2040,249 2180 POKE 56334_/PEEK(56334)AND254 2190 POKE 1,PEEK(1)AND251 2200 FOR 1=0 TO 7 2210 B=PEEK(53248+8*P+I) 2220 FOR J=248 TO 250 2230 POKE J*64+40+I*3,B 2240 NEXT J,I 2250 POKE l,PEEK(l)OR4 2260 POKE 56334,PEEK(56334)ORl 2270 PRINT"{HOME}{17 DOWN}{8 RIGHT}"; 2280 FOR 1=2 TO 14 2290 PRINTMID$(L$,I,1)"{RIGHT}"; 2300 NEXT

2310 PRINT:PRINT"{DOWN}{8 RIGHT}"; 2320 FOR I=15TO 27 2330 PRINTMID$(L?,I,1)"{RIGHT} 2340 NEXT

2350 DX=160-8*LEN(G$):DY=69 2360 POKEV,XAND255:POKEV+16,PEEK(V+l6)AND2540R-(X>

255):POKEV+1,Y:POKE2040,S 2370 IF X=0 THEN POKE V+21,PEEK(V+21)ORl 2380 FLAG=0 2390 IFABS(X-DX)>2THENX=X+3:FLAG=1:IFX>344THEN X=0

:POKEV+21,PEEK(V+21)AND254 2400 IF Y>DY THEN Y=Y-2:FLAG=1 2410 S=S+1:IFS=251THENS=248 2420 IF FLAG THEN 2360 2430 X=DX:Y=DY 2440 POKEV,XAND255:POKEV+16,PEEK(V+16)AND2540R-(X>

255):POKEV+1,Y:POKE2040,249 2450 PRINT"{HOME}{4 DOWN}"SPC(18-LEN(G$)); 2460 FOR I=1T0 LEN(G$) 2470 IF MID$(G$,I,1)=A$ THEN PRINT A$;:RF=RF-1:IFR

F=0 THEN GOSUB 2560 2480 IF MID$(G$,I,1)<>A$ THEN PRINT"{RIGHT}"; 2490 PRINT"{RIGHT}"; 2500 IF RF=0 THEN 1=100:GOTO2540

2510 FOR J=0 TO 15:X=X+1:S=S+1:IFS=251THENS=248 2520 POKEV.XAND255:POKEV+16,PEEK(V+16)AND2540R-(X>

255):POKE2040_/S 2530 NEXT J 2540 NEXT I 2550 RETURN 2560 FOR K=0 TO 7 2570 FOR J=248 TO 250 2580 POKE J*64+40+K*3,0 2590 NEXT J,K

Thinking Games

:,,

2600 RETURN

2610 PRINT"{CLR}{7 DOWN}{BLK}DO YOU WISH TO PLAY A

GAIN (Y/N) ?" 2615 POKE V+21,PEEK(V+21)AND254 2620 PRINT"{10 DOWNJYOU MISSED THIS MANY :" 2630 GETA$:IFA$<>"N"AND A?<>"Y"THEN2630 2640 IF A$="Y"THENPOKE V+21,0:RUN110 2650 END

2660 POKE 53281,0:POKE 53280,0

2670 PRINT"{CLR}{YEL}{13 SPACES}INSTRUCTIONS 2680 PRINT"{2 DOWN}{WHT}{4 SPACES}CHOOSE LETTERS T

O GUESS THE WORD. 2690 PRINT"{DOWN}IF YOU CHOOSE A WRONG LETTER, THE

BIRD 2700 PRINT"{DOWN}WILL LAND ON ITS PERCH. 2710 PRINT"{DOWN}{4 SPACES}WHEN ALL THE PERCHES AR

E FULL, OR 2720 PRINT"{DOWN}YOU GUESSED THE WORD, THE GAME IS

OVER 2730 PRINT"{2 DOWN}{4 SPACES}YOU CAN HIT THE "CHR$

(34)^I,<-"CHR$(34)" KEY ANYTIME TO 2740 PRINT"{DOWN}GUESS THE WORD. IF YOU GET IT WRO

NG,{DOWN}{4 SPACESjYOU LOSE. 2750 PRINT"{3 DOWN}{9 RIGHT}{YEL}HIT A KEY TO BEGI

N" 2760 GETA$:IFA?=""THEN2760 2770 RETURN

2780 DATA HAPPY,BRIDGE,FAMILY,CHILDREN 2790 DATA WINDOW,TRAIN,DWARF,BIRDS 2800 DATA SUPERMAN,CONCERT,PEOPLE,MAGIC 2810 DATA SPACE,SCIENCE,PLANETS,GALAXY,STARS 2820 DATA ROOMS,TEACHER,CHALK,BLACKBOARD 2830 DATA SCREEN,COMPUTER,KEYBOARD,PROGRAM 2840 DATA SPELLING,WORDS,COLORS,LETTERS 2850 DATA MARKET,STREETS,SQUARE,TRIANGLE 2860 DATA MOVIE,SPACESHIP,LASER,AIRPLANE,BOAT 2870 DATA STICK,ROCK,PAPER,WIN,PLACE,SHOW 2880 DATA CHANNEL,EXECUTIVE,MONEY,SHIRT 2890 DATA QUIET,LOUD,BILLBOARD,YACHT,MOTORCYCLE,*

Oil Tycoon

Gordon F. Wheat 64 Translation by Chris Metcalf

You are P J. Uing and you are about to make big money in the petroleum business, but drilling for oil is not as easy as it sounds. There are obstacles you must overcome in order to make a profit. There are shale formations that grind away your pipe. You can blast through them, but your dynamite is limited. Pockets of natural gas sometimes collect where you have previously pumped out the oil. Hit one of these and your oil rig goes up with a bang. There are also "devils" that live in the oil. They take a dim view of your draining their caverns. But you won't give up—because you are the Oil Tycoon.

I designed "Oil Tycoon" to be as much fun for parents as it will be for children. Since the game is not based on reaction time but rather on strategy, it helps even the score for the arcade dropouts. Your strategy will slowly build, and before long you will be rolling in cash or attaining high scores, however you wish to look at it.

Difficulty Levels

The screen will display the high scores attained for each of the eight difficulty levels. The program will return to this screen after each game. Your score and the difficulty level of the game you have just completed are displayed at the top of the screen.

At the bottom of the screen you will see "DIFF . LEVEL 12345678." Choose the difficulty level by moving the joystick left and right and pressing the fire button when the number of the difficulty level you want is blinking. Level one is primarily for small children. I would recommend that seasoned gamers begin with level two. The higher the difficulty level, the more difficult the game becomes. The various conditions for the eight difficulty levels are shown in the table.

Thinking Games

Difficulty Levels

Sticks of

Dynamite per Pieces Invisible

Level Oil Rig of Shale Shale

1 3 20 No

2 2 20 No

3 3 30 No

4 2 30 No

5 4 20 Yes

6 3 20 Yes

7 4 30 Yes

8 3 30 Yes

Playing Oil Tycoon

After you choose the level, the oil field is drawn on the screen. It will be different for each game; you should never see the same screen twice. For each game, you receive five oil rigs, each of which has 20 lengths of pipe and a number of sticks of dynamite, depending on the difficulty level you choose.

In the upper-left corner of the screen are the oil rigs you have remaining. In the upper-right corner is your score. Between these are the sticks of dynamite you have remaining for the oil rig now in play. The second line displays the unused lengths of pipe for the oil rig now in play As you drill, this pipe will be used one length at a time and will be replaced as you withdraw your drill. The lower portion of the screen is the playing field. Yellow squares are dirt, black squares are oil, and the irregular squares are shale.

Move the joystick left and right to position your oil rig over the column you want to drill through. To drill, pull the joystick down. To withdraw the drill, push the joystick up. You cannot move the oil rig while there is drilling pipe in the ground. You cannot bore through shale, through devils, or off the bottom of the screen. If you try your drill wSl be ground up, and you will lose that length of pipe for the oil rig in play This becomes very important in difficulty levels above four, for the shale is invisible and looks like dirt. At these levels, it is very easy to lose most of your drilling pipe before you realize that you are trying to drill through shale. Also try to avoid drilling through empty spaces from which you have previously pumped oil. Natural gas can collect in these empty spaces and may cause an explosion when you try to drill through them again.

■C Thinking Games

Controlling the fire button takes some getting used to, because it does three things. As you bore, if the end of the drilling pipe is in oil or an empty space, pressing the fire button causes your oil rig to start pumping. If the end of the pipe is in dirt, pressing fire drops a stick of dynamite down the pipe. If you are not drilling, or if you have fully withdrawn the pipe, pressing fire replaces your current oil rig with one of your remaining rigs. Be careful—it is easy to lose valuable rigs. Replacing your oil rig with a new one is useful mainly when you have used up your allotted dynamite for the rig in play, or if you do not have enough pipe remaining to reach pools of oil near the bottom of the screen.

Use your dynamite to blow up shale, devils, or dirt. When you drop dynamite down the pipe, it will continue to fall until it hits one of these three obstacles. This means that if there is oil or empty space directly below the tip of the drill, the dynamite will fall out of the bottom of the pipe and through this space until it hits shale, a devil, or dirt.

Pumping Oil

When you pump, all of the oil in adjacent spaces to the sides and above the level of the drill bit will be pumped out. In other words, all squares of oil connected to the one you are pumping will also be pumped out only if they lie directly above or to the sides of the oil being pumped. Any squares of oil below those which are being pumped out will remain where they are.

If you uncover a devil while pumping, it will blow up your oil rig. If you try to pump a pool of oil which is at or below the level of an uncovered devil, and which is directly connected to the devil's space, it will also blow up your rig.

The deeper the oil, the more it is worth when you pump it out. An extra oil rig is awarded for each $100,000 you acquire. In addition, if you pump out all the oil on the screen and then retract your pipe, you will be awarded an extra oil rig and a new screen is drawn.

Oil Tycoon

100 PRINT" {CLR} g 7 §":IFPEEK (14336 )==2ANDPEEK( 14805

)=24THEN195 105 POKE53280_/6:POKE53281,6:POKE53270,8 110 PRINTTAB(14)"INSTRUCTIONS"SPC(28)"§12 T3":PR

INT"{DOWN}JOYSTICK:" 115 PRINT"{DOWN} RIGHT AND LEFT = MOVE RIG" 120 PRINT" DOWN - DRILL":PRINT" UP = RETRACT PIPE"

Thinking Games

125 PRINT"{2 DOWN}{2 SPACESjWHEN YOU PUSH THE FIRE

BUTTON AND THE 130 PRINT"PIPE IS DOWN IN OIL OR IN SPACE, THE" 135 PRINT"PUMP IS TRIGGERED.{2 SPACESjlF THE PIPE

{SPACE}IS DOWN" 140 PRINT"IN DIRT, DYNAMITE IS DROPPED. 145 PRINT"{2 DOWNjWATCH OUT FOR SHALE AND GAS IN E

MPTY","SPACES AND DEVILS IN OIL. 150 PRINT"{2 DOWNjPLEASE {CYN}WAITg73 FOR FURTHE

R INSTRUCTIONS." 155 POKE52,56:POKE56,56:CLR:AD=14336 160 FORA=ADTOAD+207:READB:POKEA,B:NEXT:POKE56334,P

EEK(56334)AND254:POKEl,51 165 FORA=AD+2 56TOAD+471:POKEA,PEEK(38912+A):NEXT:P

0KE1,55 170 POKE56334,PEEK(56334)ORl 175 PRINT"{UP}{2 SPACES}PRESS ANY KEY WHEN READY T

O BEGIN. " 180 IFPEEK(197)=64ANDPEEK(653)=0ANDPEEK(56320)=127

THEN180 185 : 190 : 195 PRINT"{CLR}":POKE53280,6:POKE54296,15:DIMA%(40

):W=1184:JS=56320 200 POKE53282,6:POKE53283,0:POKE53270,24:POKE54291

,0:POKE54292,240 205 FORI=0TO2:POKE54276 + 1*7,8:NEXT:POKE53281,3 210 POKE54284,0:POKE54285,240:POKE542 77,0:POKE5427

8,240:IFZ > B%(T)THENB%(T) =Z 215 POKE53272,21:PRINT"{CLR}{DOWN}{RED}",T_#"

{2 SPACES}$"MID?(STR?(Z*100),2)".00{BLU}" 220 PRINTTAB(8)"{DOWN} LEVEL{6 SPACES}HIGH SCORE

{DOWN}" 225 F0RA=1T08:PRINT,A,"{2 SPACES}?"MID?(STR?(B%(A)

*100),2)".00":PRINT:NEXT 230 PRINT"{DOWN} DIFFICULTY LEVEL? 12345678{GRN}":

T=l 235 POKE56194+T,0:T1=T:T=T+(PEEK(JS)AND4)/4-(PEEK(

JS)AND8)/8:T=(7ANDT-1)+1 240 IFT<>T1THENP0KE56194+T1,6 245 POKE56194+T,l:L=3:IFT/2=INT(T/2)THENL=2 250 S=20:IFT=3ORT=4ORT>6THENS=30 255 N=24:IFT>4THENN=25:L=L+1 260 GETA?:IF(PEEK(56320)AND16)=16ANDA?<>CHR?(13)TH

EN235 265 POKE53272,31:PRINT"{CLR}":POKE53280_f9;POKE5328

1,1:M=4:Z=0:K=0:GOSUB5 90 270 POKEW+X,14:X=20:P=20:Y=L:R=1:GOSUB705:GOSUB645

:POKE198,0

"^ Thinking Games

275 :

280 :

285 REM MAIN LOOP OF PROGRAM

290 A=PEEK(JS):IF(AAND4)=0ANDR=1THENPOKEW+X,14:X=X

+(X>0) 295 IF(AAND8)=0ANDR=1THENPOKEW+X,14:X=X-(X<39) 300 POKEW+X,2:IF(AAND2)=0ANDP>0THEN340 305 IF(AAND1)=0ANDR>1THEN400 310 IFR>1AND(AAND16)=0THEN435 315 IFR=1AND(AAND16)=0 THEN375 320 GOTO290 325 : 330 :

335 REM DRILLING AND GAS EXPLOSIONS 340 A=R*40+W+X:C=PEEK(A):P=P-1:GOSUB675 345 IFC=NORC=3ORA>2023THENFORA=1TO3:GOSUB730:NEXT:

GOTO290 350 IFRND(1)>.06ORC < >14THENF0RB=1T03:POKEA,C+B:GOS

UB730:NEXT:R=R+1:GOTO290 355 F0RB=1T02: POKEA, C+B .-GOSUB730 :NEXT:GOSUB735 : B=0 360 R=R-1:POKE54296,4:IFR<1THENP0KE54296,15:POKEW+

X,23:GOSUB715:GOT0375 365 POKE54273_/B:POKE54276_r129;A=R*40+W+X:C=PEEK(A)

:PK=PEEK(A+54272):POKEA,C+l 370 POKEA+54272,15:FORD=0TO200:NEXT:POKEA,C-3sPOKE

A+54272,PK:B=B+10:GOTO360 375 POKEW+X,14:X=20:M=M-1:P=20:Y=L:R=1:GOSUB705:IF

M<0THEN205 380 GOSUB645:GOTO290 385 : 390 :

395 REM DRILLING UP 400 R=R-1:B=R*40+W+X:C=PEEK(B):F0RA=1T03:POKEB,C-A

:GOSUB730:NEXT 405 P=P+1:GOSUB675:IFR<>1THEN290 410 FORA=W+80TO2023:IFPEEK(A)=9THEN290 415 NEXT:M=M+1:FORC=1TO3:GOSUB705:NEXT:GOSUB590:GO

SUB645:GOTO290 420 :

425 :

430 REM DYNAMITE, GUSHERS, DEVILS

435 J=Z:Q=R-1:FORA=0TO21:A%(A)=0:NEXT:B=Q*40+W+X:A

=PEEK(B):IFA<> 7THEN480 440 A=W+X:B=40:IFY<1THEN290 445 A=A+40:C=PEEK(A):POKEA,C+l:1FC=140RC=9THENP0KE

A,C+4

450 POKE54273,B:POKE54276,33:FORD=0TO200:NEXT:D=PE

EK(A+40) 455 IFD<>4ANDD<>NANDD<>3ANDA<1984THENB=B-2:POKEA,C

:GOT0445

Thinking Games

460 POKE54276,8:GOSUB735:POKEA+54312,15

465 IFC<>14ANDC<>9THENR=R-1

470 Y=Y-1:GOSUB665:GOTO290

475 :

480 A%(X)=1:POKE54273,40:POKE54276,129:POKE54296,4

:V=W+X-40 485 IFA=12THENP0KEB,17:Z=Z+Q:POKEV,0 490 E=0:F=38:D=1:G=1:1=1:GOSUB530:POKEV,1:E=39:F=1

:D=-l:G=D:I=D:GOSUB530 495 E=0:F=39:D=l:G=-40:1=0:G0SUB530:POKEV,0:IFC<>6

THEN515 500 Z=J:POKEB,3:POKEB+542 72,2:POKEV,14:FORA=0TO40:

POKE54280,88:POKE54283,17 505 POKE53283,14:POKE54296,6:F0RB=1T05:NEXT 510 POKE54296,0:POKE53283,0:FORB=1TO5:NEXTB,A:POKE

54283,0:B=0:GOTO360 515 IFHTHENQ=Q-1:GOT04 90 520 POKEV,14:POKE54276,8:POKE54296, 15:POKE54283,2:

GOSUB705:GOSUB645:GOTO290 525 :

530 IFC=6THENRETURN

535 H=0:FORA=ETOFSTEPD:IFA%(A)=0THEN570 540 B=Q*40+W+A+G:C=PEEK(B) 545 IFC=90RC=12THENPOKEB,C+5:H=l:Z=Z+Q+ABS(I)-1:A%

(A+I)=1:G0T0565 550 IFC=140RC=17THENA%(A+I)=1:H=l:GOT0570 555 IFC=3THENC=6:RETURN 560 A%(A+I)=0:GOTO570

565 IFRND(1)<.02ANDCO12THENC=6:RETURN 570 NEXT:RETURN 575 : 580 :

585 REM INITIALIZE THE DISPLAY 590 PRINT" {HOME} {5 DOWN} g8§ " ; :F0RA=1T099 .-PRINT"D

DDDDDDD";:NEXT:PRINT"DDDDDDD"; 595 POKE2023,4:POKE56295_/15:B=400:C=1264:FORA=1TO2

:FORD=1TO40 600 E=INT(RND(0)*B/2)*2+C:IFPEEK(E)=90RPEEK(E+l)=9

THEN600 605 POKEE,9:POKEE+1,9:NEXT:B=360:C=l665:NEXT:FORA=

1TOS 610 B=INT(RND(1)*340)*2+l264:C=PEEK(B):IFC=90RC=NT

HEN610 615 POKEB_/N:POKEB+54272,10:NEXT:FORA=0TO199:POKE55

296+A,0:NEXT:FORA=0TO39 620 POKE55376+A, 3 :POKE1104+A, 20 .-NEXT 625 FORA=0TO3:POKE55337+A,2:NEXT:RETURN 630 : 635 :

^C Thinking Games

640 REM UPDATE SCREEN INFORMATION

645 PRINT"{HOME}{CRN}"SPC(23)"$"MID?(STR$(Z*100),2

)".00" 650 A=INT(Z/1000):IFA=K+1THENK=K+1:GOSUB705:GOSUB7

05:M=M+1 655 IFM<1THENPOKE1024,14:POKE55296,14:GOT0665 660 FORA=1024TO1023+M:POKEA,2:POKEA+54272,0:NEXT:P

OKEA,14:POKEA+54272,0 665 IFY=0THENPOKE1031,14:POKE55303,0:GOTO675 670 FORA=1031TO1030+Y:POKEA,19:POKEA+54272,0:NEXT:

POKEA,14:POKEA+54272,0 675 IFP<1THENPOKE1064,14:POKE55336,0:RETURN 680 FORB=1064TO1063+P:POKEB,17:POKEB+54272,0:NEXT:

POKEB,14:POKEB+54272,0 685 RETURN 690 : 695 :

700 REM MUSIC AND OTHER SUBROUTINES 705 POKE54276,17:FORA=15TO0STEP-1:POKE54296,A:POKE

54273,86:F0RB=1T025:NEXTB,A 710 POKE54276,8:POKE54296,15:RETURN 715 POKE54276,8:POKE54276,129:POKE54273,91:FORD=15

TO0STEP-1:POKE54296,D 720 POKE53281,1:POKE53280,2:FORE=1TO70:NEXT:POKE53

280,6:NEXT 725 POKE54276,8:POKE54296,15:POKE53280,9:RETURN 730 POKE54287,20:POKE54290,8:POKE54290,129:POKE542

90,128:RETURN 735 POKEA,21:POKEA+40,22:GOSUB715:POKEA,14:POKEA+4

0,14:RETURN 740 : 745 :

750 REM CHARACTER DATA 755 DATA2,138,164,73,74,52,20,8,64,81,37,146,82,44

,40,16,24,24,36 760 DATA60,90,102,231,153,20,42,42,20,62,73,20,20,

136,34,136,34,136,34,136,34 765 DATA148,22,148,34,136,34,136,34,148,22,148,22,

148,34,136,34,148,22,148 770 DATA22,148,22,148,22,136,62,188,62,188,62,188,

22,170,170,170,170,170 775 DATA170,170,170,150,150,150,170,170,170,170,17

0,150,150,150,150,150,170,170 780 DATA170,150,150,150,150,150,150,150,150,150,19

0,190,190,190,190,190,150,0,0 785 DATA0,0,0,0,0,0,20,20,20,0,0,0,0,0,20,20,20,20

,20,0,0,0,20,20,20,20,20,20 790 DATA20,20,20,60,60,60,60,60,60,20,0,60,60,60,6

0,60,60,0,0,0,0,255,255,0,0,0

Thinking Games

795 DATA218,118,181,153,110,93,197,65,65,82,150,85

,121,181,150,173,2,106,129,20 800 DATA64,162,129,2,169,128,141,19,145,169,0,133,

136,34,136,34,136,34,136,34

7*<

Mosaic Puzzle

Bruce Jordan 64 Translation by Chris Metcalf_________

This adaptation of an old favorite will challenge your reasoning powers,

"Mosaic Puzzle" is a computer version of those sliding-squares puzzles that used to drive people nuts before the advent of Rubik's Cube. The object of the game is to arrange the 15 squares into some predetermined order by sliding them around in their frame. The first few moves are easy, but as the game progresses, it gets a lot more complicated. You'll find yourself rearranging everything just to get the last few squares in place.

The game has a timer for up to 23 hours, 59 minutes, 59 seconds, and a chicken switch. It also automatically checks for the winning order and allows you to go back to the puzzle the way you left it or reset it to the beginning arrangement.

When you start the game, you're asked if you wish to set a time limit. If you answer Y for yes, enter the time limit in one line with no spaces or punctuation between the values. For example, for a 1-hour, 23-minute limit, enter 012300.

Next, enter the goal order. This will be the order that you will try to match to win the game. When this is done, the upper half of the screen will clear, and the puzzle will appear.

Either the RETURN key or the fire button allows you to pause momentarily before resuming the game, restarting the program, or stopping play entirely. Breaking off and resuming has no effect on the time clock (displayed at the top of the screen along with the time limit).

As an aid to the user, various keys for up, down, right, and left can be selected at the beginning of the game. A joystick can also be used, as long as it is plugged into control port two. The time limit is an option in this version; if no time limit is selected, the screen will display elapsed time and TIME LIMIT: NONE.

If you succeed in getting the squares in the goal order, the message YOU WIN! appears on the screen, accompanied by a short tune and the elapsed time. If the time runs out before you are finished, you'll hear an unpleasant sound.

Thinking Games

Mosaic Puzzle

100 POKE53280,14:POKE53281,6:POKE55,176:POKE56,29:

CLR:POKE54276,8:POKE54283, 8 110 POKE54277,0:POKE54278,255:POKE54284,0:POKE5428

5_/255:POKE54296_/15 120 S=1355:SC=S+54272:DIMA$(16) 130 PRINT"{CLR}":G=1632:X=0:DX=1:P=55904:Sl=54276:

S2=54283:AD=1232:R=14 140 PRINT"{CLR}{DOWN}"TAB(ll)" MOSAIC PUZZLE"TAB(5

0)"E17 Y^lDOWN}" 150 : 160 :

170 REM FIND TIME LIMIT, MOVE KEYS 180 PRINT"g73 DO YOU WANT A TIME LIMIT? ";:GOSUB

270 190 IFIN$o"Y"THEN240 200 H=l:INPUT"{HOME}{6 DOWN} HOURS MINS SECS (6 DI

GITS)";T$:IFLEN(T$)<>6THEN200 210 IFLEFT$(T$,2)>"23"ORLEFT$(T$,2)<"0"THEN200 220 IFMID$(T$,3,2)>"59"ORMID$(T$,3,2)<"0"THEN200 230 IFRIGHT$(T$,2)>"59"ORRIGHT$(T$,2)<"0"THEN200 240 PRINT"{DOWN} KEY FOR UP: ";:GOSUB270:U$=IN$:PR

INT"{DOWN} FOR DOWN: ";:GOSUB270:D$=IN$ 250 PRINT"{DOWN} FOR LEFT: ";:GOSUB270:L$=IN$:PRIN

T"{DOWN} FOR RIGHT: ";:GOSUB270:R$=IN$ 260 GOTO310 270 PRINT"i+3";:WAIT198,255:GETIN$:PRINT"{LEFT}"

;:POKE216,1:PRINTIN?:RETURN 280 : 290 :

300 REM FIND GOAL ORDER

310 PRINT"{CLR}"TAB(43)"ENTER GOAL SETUP" 320 PRINT"{DOWN}{3 SPACES}1 2 3 4 5 6 7 8 9"SPC(23

)"A B C D E F {RVS}SPACE" 330 PRINTTAB(5)"{DOWN}lN ANY ORDER":PRINTTAB(248)"

GOAL 340 FORK=0TO3:POKE1592+K,100:POKE1792+K,99:POKE558

64+K,R:POKE56064+K,R 350 POKE1631+K*40,103:POKE1636+K*40,101:POKE55903+

K*40_/R:POKE55908+K*40_/R:NEXT 360 F0RI=1T016:POKEG+X,63:POKEP+X,1 370 WAIT198,255:GETA$(I):FORL=I-1TO0STEP-1:IFA$(I)

=A$(L)THEN370 380 NEXT:IFA$(I)=" "THENFORK=0TO4:POKE55471+K,15:N

EXT:B2=32:GOTO420 390 IF(A$(I)<^,,1"0RA$(I)>^,,F^,,)0R(A$(I)>^,,9^,,ANDA$(I)<"

A")THEN370 400 B=VAL(A$(I)):B2=B+48:IFBTHENPOKE55417+2*B,15:G

OTO420

■^ Thinking Games

410 B=ASC(A?(l))-64:B2=B:POKE55457+2*B,15

420 POKEG+X,B2:X=X+DX:IFX=4THENG=G+40:P=P+40:X=0

430 NEXT

440 :

450 :

460 REM SET UP WORK AREA

470 PRINT"{HOME}":FORI=0TO64:PRINT"{4 SPACES}";:NE

XT:PRINT"{HOME}"TAB(127)"PUZZLE" 480 FORK=0TO3:POKE1192+K,100:POKE55464+K,R:POKE139

2+K,99:POKE55664+K,R 490 POKE1231+K*40,103:POKE55503+K*40,R:POKE1236+K*

40,101:POKE55508+K*40,R:NEXT 500 READA,B,C:IFA>=0THENPOKEAD+A,Bs POKE55504+A,C:G

OTO500 510 FORI=1TO500:NEXT:POKES1-3,80:POKES1,33:PRINT"

{HOME}"TAB(28)"{10 DOWN}{RED}{WHT}1GOIg73" 520 FORT=1TO300:NEXT:PRINT"{HOME}"TAB(28)"

{10 DOWN}{4 SPACES}":POKES1,8:TI?="000000^H530 PRINT"{HOME}"TAB(25)"LIMIT:{CYN}";:IFT?=""THEN

PRINT"NONE":GOTO580 540 PRINTLEFT?(T$,2)":"MID?(T$,3,2)":"RIGHT?(T?,2)

"g73" 550 : 560 :

570 REM LOOP MAIN CONTROL 580 PRINT"{HOME}TIME ELAPSED:{WHT}"LEFT?(TI§,2)":"

MID?(TI?,3,2)":"RIGHT?(TI? , 2)"g 7 V' 590 IFH=1ANDT?<=TI?THEN750 600 GETB?:J=31-PEEK(56320)AND31:IFB?=""ANDJ=0THEN5

80 610 IFB?=CHR?(13)ORJ=16THENWN=0:GOTO780 620 IFB?=D?OR(JAND2)THENDR=-40:CK=100:GOTO660 630 IFB?=L?OR(JAND4)THENDR=1:CK=101:GOTO660 640 IFB?=R?OR(JAND8)THENDR=-1:CK=103:GOTO660 650 DR=40:CK=99:IFB?< >U?AND(JAND1)=0THEN580 660 IFPEEK(S+DR)=CKTHEN580 670 POKES,PEEK(S+DR):POKESC,PEEK(SC+DR):POKES+DR_#3

2:S=S+DR:SC=SC+DR 680 FORM=0TO120STEP40:FORN=0TO3:W=PEEK(AD+M+N)AND1

27:IFW<>PEEK(1632+M+N)THEN580 690 NEXT:NEXT:PRINT"{HOME}"TAB(24)"{5 D0WN}{CYN}

{RVS}YOU WINlg7i":POKESl-3_/0:POKESl,33:WN=l 700 READN1,N2,D:IFN1=-1THENP0KES1,8:GOTO780 710 POKESl-4_/Nl:POKESl-3_/N2:FORT=lTOD:NEXT:GOTO700 720 : 730 :

740 REM END OF GAME 750 PRINT"{HOME}"TAB(23)"{5 DOWN}{WHT}{RVS}1 YOU LO

SElg73":POKESl-3,10:POKESl,17:WN=l

Thinking Games

760 POKES2-3,60:P0KES2,129:FORT=1TO300:NEXT:P0KES2

,8:P0KES1,8 770 :

780 TM$=TI$:PRINT"{HOME}"TAB(21)"{9 D0WN}(1) RESET 790 PRINTTAB(21)"{D0WN}(2) QUIT":IFWN=0THENPRINTTA

B(21)"{DOWN}(3) AS YOU LEFT IT" 800 GETV$:IFV$ <"1"ORV$ >"3"THEN800 810 IFV$="1"THENRUN 820 IFV$="2"THENEND 830 IFWNTHEN800 840 PRINT"{HOME}{8 DOWN}":FORI=1T06:PRINTTAB(21)"

{18 SPACES} ".-NEXT 850 TI$=TM$:GOTO580 860 : 870 :

880 REM SETUP AND MUSIC DATA 890 DATA0,49,1,1,178,3,2,51,1,3,180,3 900 DATA40,53,1,41,182,3,42,55,1,43 910 DATA184,3,80,57,1,81,129,3,82,2,1 920 DATA83,131,3,120,4,1,121,133,3,122 930 DATA6,1,123,32,3,-1,-1,-1 940 DATA 96,22,150,0,0,50,96,22,75,0,0,50,96,22,75

,49,28,175,96,22,115,49,28 950 DATA175,135,33,250,0,0,0,-1,-1,-1

Blockhead_______

Matt Giwer 64 Version by Gregg Peele_____________________________

Here is a challenging game for the whole family. See how many balloons the blockhead can pop in the allotted time. Requires game paddles.

"Blockhead" is a colorful game similar to some of the early arcade games. It is simple to play, and will especially appeal to young children, who will like the clever use of sound and color in the game. The program makes good use of the Commodore 64's graphic capabilities, for it utilizes the eight available sprites and even includes a machine language routine. This interrupt-driven routine provides optimal motion in the game, as well as monitors the position of the sprites.

Once you have the program typed in, SAVEd, and LOADed, you can see that the machine language routine still operates, even if the BASIC part of the program does not. LOAD and RUN Blockhead, then press RUN-STOE This breaks the BASIC program, but the blockhead can still be moved with the paddle control.

Blockhead uses the collision register to detect when one sprite touches another. Since the collision register is changed only temporarily when sprites collide, the contents representing the collision must be saved until an event occurs which may again make the sprite collide. The register is then cleared, and the sprite is ready for collision. Collision detection between the blockhead and balloons is handled through BASIC.

The game is played with a set of paddles, which must be plugged into Control Port 1. Since Blockhead is a one-player game, only one paddle will work. The paddle moves the blockhead's home base from side to side, with the blockhead standing on it. You use the fire button on the paddle to make the blockhead leap.

The original version of this game is written to be used with Atari-style paddles. If you have Commodore paddles, you must change lines 1070 and 1080 to read as follows;

1070 DATA 216,24,173,164,194,105,28,141 1080 DATA 161,194,56,173,164,194,233,217

This alteration leaves a slight glitch in the paddle movement around the seam but provides for optimal range for movement around the screen.

Playing the Game

This game works using a timer. The object of the game is to pop the balloons as they float across the sky. The more balloons you pop in the time limit of two minutes, the more points you'll receive. Not only must you pop the balloons, but you must also catch the blockhead before he falls below his home base. If you miss catching him, points are deducted until you bring him to the surface by pressing the fire button. He'll then leap back into the air.

For each balloon that you pop, you receive 10 points. Each time you drop the blockhead, your score is reduced by 15 points.

When you LOAD and RUN the program for Blockhead, a tune plays and the screen sets up. This takes a few moments, so be patient. Finally, the blockhead appears, and the balloons begin to float across the sky. At first, they are close to the ground and easy to pop. Simply press the fire button and the blockhead leaps into the air. If he touches a balloon, it disappears, and you'll hear a soft popping sound. You've just received ten points. The balloons will continue to float at this level until all six of them are popped by the blockhead.

As soon as the first level of balloons has been popped, the tune plays again, then another level, slightly higher, appears from the left side of the screen. There are six levels of balloons altogether. If you pop all the balloons, 36 in all, the game stops, even if there is time remaining. At this point, you're asked if you want to play another game.

Of course, popping the balloons is only half the fun. You also have to catch the blockhead as he drops to the ground. If you miss him with the paddle-controlled base, he will vanish. To make him reappear, you need to press the fire button to make him leap back up.

Going for the High Score

After playing Blockhead a few times, you'll notice some things that can increase your score, or reduce the time it takes you to pop all the balloons.

If you time the blockhead's leap, you can pop two balloons at once. This must be precise. The blockhead has his hands out-

Dexterity

stretched, and if both come in contact with a balloon at the same time, the balloon on either side will pop. Sometimes this works, and other times it doesn't.

You can also receive points if the blockhead comes very close to a balloon. The balloon won't pop, but you'll hear the popping sound, and another ten points will be added to your score. Just as with trying to pop two balloons at once, this will not work all the time.

If you keep the blockhead's home base stationary, most of the time he will fall back to it. Not always, so you have to keep your eye on him.

Remember that the blockhead is not able to pop a balloon on the way down, only on the way up.

Blockhead

100 POKE49152,0

110 DIM HA(12),HB(12),HC(12),LA(12),LB(12),LC(12)

120 F0RQ=1T011:READHA(Q),LA(Q),HB(Q),LB(Q),HC(Q),L

C(Q):NEXT 130 S=54272:F0RE=ST0S+28:POKEE,0:NEXT 140 POKE54296,15 :POKE54277,56 :POKE54278,212 150 POKE54284,56 :POKE54286,212 160 POKE54291,56 :POKE54292,212 170 POKE S+4,17:POKES+16,17:POKES+18,17 180 F0RD=1T011

190 P0KES+1,HA(D):POKES,LA(D):POKES+8,HB(D) 200 P0KES+9,LB(D):POKES+15,HC(D):POKES+14,LC(D) 210 FORT=1TO100:NEXT

220 IFHC(D) =7THENFORT=1TO100:NEXT 230 NEXT

240 F0RT=1T0 450 :NEXT:F0RE=ST0S+28:POKEE,0:NEXT 250 IFPEEK(49152)=173ANDTH=1THENRETURN 260 DATA33,135,21,31,8,97,31,165,21,31,8,225,29, 22

3,22,96,9,104 270 DATA 28 ,49,22,96,9,247,26,156,21,31,10,143 280 DATA28,49,21,31,9,247,29,223,22,96,9,104,31,16

5,22,96,8,225 290 DATA33,135,21,31,8,97,25,30,22,96,7,233,33,135

,21,31,8,97 300 GOTO330 310 S=54272 320 POKES+24,15:POKE54276,65:POKE5427 5,10:POKE5427

4,10:P0KES+24,0:RETURN 330 POKE53281,7:HI=134:GOSUB930 340 DATA1,255,0,7,255,192,15,239,224,31,1,240,63,1

09,248,63,111,248,63,1,248,63

£jk Dexterity

350 DATA237,248,63,109,248,31,1,240,31,239,240,15,

239,224,15,255,224,7,255,192,3 360 DATA255,128,1,255,0,0,254,0,0,124,0,0,56,0,0,1

6,0,0,56,0 370 V=53248

380 FOR J=960TO1022:READ WQ:POKE J,WQ:NEXT 390 POKEV+21,0 400 POKEV+41,6:POKEV+42,0:POKEV+43,1:POKEV+44,2;PO

KEV+4,70 410 POKE53264,0 420 POKEV+45,4:POKEV+46,8

430 FORT=2042TO2047:POKET,15:NEXT:POKEV+21,255 440 IFPEEK(V+2)< 50AND(PEEK(V+16)AND2)=0THENPOKEV+2

,254 450 DATA0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

0,0,0,0,0,0,255,255,255,255,255 460 DATA255,255,255,255,255,255,255,255,255,255,25

5,25 5,255,255,255,255,255,255 470 DATA255,255,255,255,255,255,255,255,255, 255 480 V=53248

490 FORI=832T0894:READJ:POKEI,J:NEXT 500 FORK=834+64T0892+66:READL:POKEK,L:NEXT:POKE204

l,14:POKEV+40,6 510 POKE2040,13:POKEV+39,2:POKEV,150:POKEV+l,200 520 IFPEEK(49152)<>173THENGOSUB1050 530 POKEV+3,191 540 IFHK70THENHI=59 550 TH=1:GOSUB130

560 POKEV+2,PEEK(V) .-POKEV+21, 255 570 FORG=V+5TO V+15STEP2:POKEG,HI:NEXT 580 SYS49658 590 DATA0 600 DATA0,0,0,0,0,0,3,255,240,3,63,48,3,51,48,3,24

3,240,3,63,48,3,204,240,3,243 610 DATA240,3,255,240,0,127,128,127,243,255,127,25

5,255,255,255,255,128,115 620 DATA128,0,127,128,0,127,128,0,251,192,1,241,22

4,3,224,240,7,192,120 630 IF(PEEK(56321)AND4)<>0THEN790 640 X2=0:POKE49829,0

650 FORT=(PEEK(V+3))TO50STEP-4:POKEV+3,T 660 IFPEEK(V+30)>3THENPOKEV+21,(PEEK(V+21)ANDNOT(P

EEK(V+30))):SC=SC+10:GOSUB310 670 POKE(V+21),(PEEK(V+21)OR3) 680 NEXT:GOTO700 690 GOTO790 700 POKE49829,0 710 FORJ=(PEEK(V+3))TO255STEP20:POKEV+3,J:IFPEEK(4

9829)=3THENX2=1:GOTO790

Dexterity

720 PI=INT(RND(0)*20)-10:IF(PEEK(53250)+Pl)<60AND(

PEEK(53264)AND2)=0THENPI=0 730 IF(PEEK(V+2)+Pl)<50AND(PEEK(V+16)AND2)=0ORPEEK

(V+2)>254THENPI=0 740 IF(PEEK(53264)AND2)<>0AND(PEEK(53250)+Pl)>20TH

ENPI=0 750 IF PEEK(53250)+PK245AND PEEK(53250)+PI>10THEN

POKE53250,PEEK(53250)+PI 760 IFPEEK(V+3)<201THEN780 770 PRINT"{HOME}{3 DOWN}{7 RIGHT}{BLK}OOPS 1":SC=SC

-5:FORT=1TO100:NEXT:PRINT"{HOME}{7 RIGHT}

{3 DOWN}{5 SPACES}" 780 NEXT 790 IF PEEK(V+21)=3THEN:HI=HI-15:POKEV+3,190:GOTO5

30 800 IFX2=1ANDPEEK(V+3)>180THENPOKEV+3,190

810 P=INT(RND(0)*20)-10:IFPEEK(53250)+P<15THENP=0 820 PRINT"{HOME}{15 RIGHT}{BLK}SCORE";"{5 SPACES}"

830 PRINT"{HOME}{15 RIGHT}{BLK}SCORE";SC

840 IFVAL(TI$)>5900THENTI$="000000"

850 IFTI$>="000200"THEN870

860 PRINT"{HOME}{DOWN}{3 RIGHT}TIME ";RIGHT$(TI$,4

);"{HOME}{DOWN}{3 RIGHTjTIME ";:GOTO630 870 PRINT"{HOME}{15 RIGHT}{8 DOWN}GAME OVER":POKEl

98,0 880 PRINT"{HOME}{DOWN}{3 RIGHT}TIME ";RIGHT?(TI$,4

);"{HOME}{DOWN}{3 RIGHTjTIME "; 890 PRINT"{HOME}{10 RIGHT}{10 DOWN}PLAY AGAIN? Y O

R N "

900 IFPEEK(197)=25THENCLR:RESTORE:GOTO110

910 IFPEEK(197)=39THENSYS2048

920 GOTO890

930 PRINT"{CLR}";: FORBO=1024TO1984STEP40 .-POKEBO, 22

4:POKEBO+39,224 940 POKEBO+54272,2:POKEBO+54311,2 950 POKEBO+l_/224:POKEBO+38,224 960 POKEBO+1+54272,4:POKEBO+54310,4 970 POKEBO+2,224:POKEBO+37,224 980 POKEBO+2+54272_/15:POKEBO+54309_/15 990 NEXT

1000 FORFL=1864TO2023:POKEFL,224:POKEFL+54272,8:NE

XT 1010 TI$="235952" 1020 FORTE=1025TO1062!POKETE_# 224:POKETE+54272,3:NE

XT 1030 POKE53280,1 1040 RETURN

1050 POKEV+21,0:F0RV1=49152T0496 73:READJ2:P0KEV1,J 2:CK=CK+J2:NEXT

1051 IF CKO65960 THEN PRINT "DATA ERROR IN LINES {SPACE}1060-1710":STOP

1052 RETURN

1060 DATA 173, 25, 212, 73, 255, 141, 164, 194 1070 DATA 216, 24, 173, 164, 194, 105, 40, 141 1080 DATA 161, 194, 56, 173, 164, 194, 233, 215 1090 DATA 141, 162, 194, 173, 164, 194, 201, 216 1100 DATA 176, 17, 173, 161, 194, 141, 163, 194 1110 DATA 173, 16, 208, 41, 254, 141, 16, 208 1120 DATA 76, 65, 192, 173, 16, 208, 9, 1 1130 DATA 141, 16, 208, 173, 162, 194, 141, 163 1140 DATA 194, 173, 163, 194, 141, 0, 208, 173 1150 DATA 30, 208, 141, 160, 194, 240, 3, 141 1160 DATA 165, 194, 173, 160, 194, 41, 1, 240 1170 DATA 23, 169, 190, 173, 163_# 194, 141, 2 1180 DATA 208, 173, 16, 208, 41, 1, 141, 6 1190 DATA 202, 10, 13, 6, 202, 141, 16, 208 1200 DATA 173, 16, 202, 56, 233, 210, 141, 17 1210 DATA 202, 173, 16, 202, 24, 105, 45, 141 1220 DATA 18, 202, 173, 16, 202, 201, 210, 176 1230 DATA 17, 173, 16, 208, 41, 251, 141, 16 1240 DATA 208, 173, 18, 202, 141, 4, 208, 76 1250 DATA 168, 192, 173, 16, 208, 9, 4, 141 1260 DATA 16, 208, 173, 17, 202, 141, 4, 208 1270 DATA 173, 19, 202, 56, 233, 210, 141, 20 1280 DATA 202, 173, 19, 202, 24, 105, 45, 141 1290 DATA 21, 202, 173, 19, 202, 201, 210, 176 1300 DATA 17, 173, 16, 208, 41, 247, 141, 16 1310 DATA 208, 173, 21, 202, 141, 6, 208, 76 1320 DATA 224, 192, 173, 16, 208, 9, 8, 141 1330 DATA 16, 208, 173, 20, 202, 141, 6, 208 1340 DATA 173, 22, 202, 56, 233, 210, 141, 23 1350 DATA 202, 173, 22, 202, 24, 105, 45, 141 1360 DATA 24, 202, 173, 22, 202, 201, 210, 176 1370 DATA 17, 173, 16, 208, 41, 239, 141, 16 1380 DATA 208, 173, 24, 202, 141, 8, 208, 76 1390 DATA 24, 193, 173, 16, 208, 9, 16, 141 1400 DATA 16, 208, 173, 23, 202, 141, 8, 208 1410 DATA 173, 25, 202, 56, 233, 210, 141, 26 1420 DATA 202, 173, 25, 202, 24, 105, 45, 141 1430 DATA 27, 202, 173, 25, 202, 201, 210, 176 1440 DATA 17, 173, 16, 208, 41, 223, 141, 16 1450 DATA 208, 173, 27, 202, 141, 10, 208, 76 1460 DATA 80, 193, 173, 16, 208, 9, 32, 141 1470 DATA 16, 208, 173, 26, 202, 141, 10, 208 1480 DATA 173, 28, 202, 56, 233, 210, 141, 29 1490 DATA 202, 173, 28, 202, 24, 105, 45, 141

Dexterity

1500 DATA 30, 202, 173, 28, 202, 201, 210, 176 1510 DATA 17, 173, 16, 208, 41, 191, 141, 16 1520 DATA 208, 173, 30, 202, 141, 12, 208, 76 1530 DATA 136, 193, 173, 16, 208, 9, 64, 141 1540 DATA 16, 208, 173, 29, 202, 141, 12, 208 1550 DATA 173, 31, 202, 56, 233, 210, 141, 32 1560 DATA 202, 173, 31, 202, 24, 105, 45, 141 1570 DATA 33, 202, 173, 31, 202, 201, 210, 176 1580 DATA 17, 173, 16, 208, 41, 127, 141, 16 1590 DATA 208, 173, 33, 202, 141, 14, 208, 76 1600 DATA 192, 193, 173, 16, 208, 9, 128, 141 1610 DATA 16, 208, 173, 32, 202, 141, 14, 208 1620 DATA 238, 16, 202, 238, 16, 202, 24, 173 1630 DATA 16, 202, 105, 43, 141, 19, 202, 173 1640 DATA 19, 202, 105, 43, 141, 22, 202, 173 1650 DATA 22, 202, 105, 43, 141, 25, 202, 173 1660 DATA 25, 202, 105, 43, 141, 28, 202, 173 1670 DATA 28, 202, 105, 43, 141, 31, 202, 173 1680 DATA 30, 208, 240, 3, 141, 160, 194, 76 1690 DATA 49, 234, 120, 169, 0, 141, 20, 3 1700 DATA 169, 192, 141, 21, 3, 88, 96, 0 1710 DATA 255, 255, 0, 0, 255, 255, 0, 0

Diamond Drop

Matt Giwer 64 Version by Eric Brandon_________________

Catch the falling diamonds—if you can. This fast-action game is easy to play.

"Diamond Drop" is a game that requires good judgment and quick reflexes. It's fast and easy to play To insure fast action, it is written predominantly in machine language. BASIC is used only to print instructions, set up the display, select the skill level, and initiate the drop.

The game display starts with six rows of objects at the top of the screen and a stack of six catching trays at the bottom. As the objects begin to drop, you must use the L and; keys to maneuver the trays and catch the objects. To make play more challenging, one tray disappears whenever the last ball drops from a row. Thus, you have only one tray with which to catch objects from the last row. When all the objects have dropped, you start again with six rows of objects and six trays. Play continues until a total of five objects hit the ground.

Since the DATA statements comprise the machine language program for the game, it is essential that they be typed correctly. Be sure to SAVE a copy of the program before you attempt to RUN it, since an error in typing may cause your computer to lock up, forcing you to turn the power off to recover. If Diamond Drop fails to RUN properly, the problem will most likely be a mistyped number somewhere in the DATA statements, so check carefully

Diamond Drop

5 POKE 53280,12:POKE53281,0

7 IF PEEK(49152)<>120THENGOSUB49000

9 SYS 49745

10 PRINT" {CLRHWHT}"TAB(13)"DIAMOND DROP"

20 PRINT"{5 D0WN]{YEL}{5 SPACES}CATCH THE DIAMONDS BEFORE THEY

30 PRINT"{DOWN}{5 SPACES}T0UCH THE GROUND. YOU HAV

E FIVE 40 PRINT"{DOWN}{5 SPACES}CHANCES.

Dexterity

ROW( 4) =207 : ROW( 3 ) =207 : ROW( 2 F0RI=1T038:PRINT"Z^M;:NEXT:P

F0RI=1T038:PRINT"P";:NEXT:P F0RI=1T038:PRINT"P";:NEXT:P

45 PRINT"{2 DOWN}{WHT}{13 SPACES}L - MOVE LEFT

46 PRINT"{13 SPACES}; - MOVE RIGHT{YEL}"

50 PRINT"{5 DOWN}g63{9 SPACES}{RVS}HIT ANY KEY T

O BEGIN" 60 GETA$:IFA$=""THEN60 65 GOSUB 1000

70 PRINT"{CLR}{WHT}SCORE 00000{4 SPACES}CHANCES: Q QQQ "

71 SPEED = 53241

72 PADDLES=12*4096+4095

73 FLAG=12*4096+4094 : POKE FLAG,0

74 WIDTH = 12*4096+15*256+15*16+11

75 POKE PADDLES,6 : POKE WIDTH,W : POKE SPEED,10-S 78 ROW(6)=81:ROW(5)=81;

)=90:ROW(1)=90 80 PRINT" {YEL}{RVS}"

RINT"{OFF} "; 85 PRINT" {YEL}{RVS}";:F0RI=1T038:PRINT"^";:NEXT:P

RINT"{OFF} "; 90 PRINT" {CYN}{RVS}"

RINT"{OFF} "; 95 PRINT" {CYNHRVS}"

RINT"{OFF} "; 100 PRINT" {OFF}g73"; :F0RI=1T038:PRINT"W" ; :NEXT:

PRINT" "; 102 PRINT" {OFF}g73";:F0RI=1T038:PRINT"W";:NEXT:

PRINT" 105 PRINT"{WHT}"7

109 REM 40 SPACES IN NEXT LINE

110 FORI=1TO17:PRINT"{40 SPACES}";:NEXT 120 PRINT"{HOME}";

130 FOR 1=1984 TO 2023 : POKE I,248:POKE 1+54272,1

0:NEXT 140 IF PEEK(789)<>12*16THENSYS 12*4096 150 FOR ROW = 6 TO 1STEP-1:F0R CHAR=1 TO 38 155 FOR K=l TO 600-CHAR*10+(6-ROW)*20-50*(9~PEEK(S

PEED)):NEXT 157 IF PEEK(FLAG) THEN 2000 160 P=RND(1)*38+1

170 IF PEEK(1024+ROW*40+P)=32THEN160 180 POKE 1024+ROW*40+P,ROW(ROW)

190 NEXTCHAR

191 SYS 49745

192 FORQ=1TO2:POKE54296,05 :POKE5427 7,5:POKE54278,

218

193 POKE 54273,150 :POKE54272,139:POKE54276,17

194 FORT=1TO50:NEXT:POKE54276,16:FORT=1TO10:NEXT

195 NEXTQ

197 IF ROW >1 THENSYS 49691

200 NEXTROW

201 FOR K=l TO 300:NEXTK

205 POKE PADDLE,6

206 IF PEEK(SPEED)=2 AND PEEK(WIDTH)>1 THEN POKE W IDTH,PEEK(WIDTH)-1

207 IF PEEK(SPEED)>2 THEN POKE SPEED,PEEK(SPEED)-1 210 PRINT"{HOME}{DOWN}";

220 GOTO 80

999 END

1000 PRINT"{CLR}{7 SPACES}DIFFICULTY{4 SPACES} {5 DOWN}"

1010 INPUT"{WHT}SPEED (1-9){YEL}{3 RIGHT}5{3 LEFT}

^M;S

1015 IF S>9 OR S<1 THEN 1010

1020 INPUT"{3 DOWN}{WHT}WIDTH OF PADDLES (1-9)

{YEL}{3 RIGHT}4{3 LEFT}";W 1030 IF W>9 OR W<1 THEN 1020 1040 RETURN 2000 PRINT"{HOME}{10 DOWN}{2 SPACES}{YEL}GAME OVER

- HIT SPACE TO CONTINUE" 2010 POKE 198,0 2020 GETA$:IFA$<>" "THEN2020 2030 RUN 65 49000 PRINT"{WHT}{CLR}{2 DOWNLOADING MACHINE LANG

UAGE...{3 DOWN}":TI$="000000" 49005 1=49152 49007 PRINT"READY IN"STR$(31-VAL(TI$))" SECONDS

{UP}" 49010 READ A:CK=CK+A:IF A=256 THEN 49030 49020 POKE I,A:I=I+l:GOTO 49007 49030 IFCK<>89323 THEN PRINT "ERROR IN LINES 49152

TO 49840":STOP 49040 RETURN

49152 DATA 120,169,192,141,21,3,169 49160 DATA 29,141,20,3,88,169,18 49168 DATA 141,253,207,169,0,141,250 49176 DATA 207,141,247,207,141,248,207 49184 DATA 96,173,255,207,141,252,207 49192 DATA 172,253,207,169,32,153,151 49200 DATA 7,200,169,160,174,251,207 49208 DATA 153,151,7,200,202,208,249 49216 DATA 169,32,153,151,7,206,252 49224 DATA 207,208,3,76,3,193,172 49232 DATA 253,207,169,32,153,71,7 49240 DATA 200,169,160,174,251,207,153 49248 DATA 71,7,200,202,208,249,169 49256 DATA 32,153,71,7,200,206,252 49264 DATA 207,208,3,76,3,193,172 49272 DATA 253,207,169,32,153,247,6

49280 DATA 200,169,160,174,251,207,153 49288 DATA 247,6,200,202,208,249,169 49296 DATA 32,153,247,6,200,206,252 49304 DATA 207,240,123,172,253,207,169 49312 DATA 32,153,167,6,200,169,160 49320 DATA 174,251,207,153,167,6,200 49328 DATA 202,208,249,169,32,153,167 49336 DATA 6,200,206,252,207,240,91 49344 DATA 172,253,207,169,32,153,87 49352 DATA 6,200,169,160,174,251,207 49360 DATA 153,87,6,200,202,208,249 49368 DATA 169,32,153,87,6,200,206 49376 DATA 252,207,240,59,172,253,207 49384 DATA 169,32,153,7,6,200,169 49392 DATA 160,174,251,207,153,7,6 49400 DATA 200,202,208,249,169,32,153 49408 DATA 7,6,200,206,252,207,240 49416 DATA 27,172,253,207,169,32,153 49424 DATA 183,5,200,169,160,174,251 49432 DATA 207,153,183,5,200,202,208 49440 DATA 249,169,32,153,183,5,200 49448 DATA 165,197,201,42,208,13,173 49456 DATA 253,207,201,1,240,24,206 49464 DATA 253,207,76,40,193,201,50 49472 DATA 208,14,173,253,207,24,109 49480 DATA 251,207,201,39,240,3,238 49488 DATA 253,207,238,250,207,173,250 49496 DATA 207,205,249,207,240,3,76 49504 DATA 49,234,169,0,141,250,207 49512 DATA 169,112,133,251,169,7,133 49520 DATA 252,160,0,185,152,7,41 49528 DATA 127,201,32,208,74,200,192 49536 DATA 39,208,242,160,0,177,251 49544 DATA 201,81,240,37,201,207,240 49552 DATA 33,201,90,240,29,200,192 49560 DATA 40,208,237,56,165,251,233 49568 DATA 40,133,251,176,2,198,252 49576 DATA 166,251,208,220,166,252,224 49584 DATA 4,208,214,76,49,234,170 49592 DATA 152,24,105,40,168,138,145 49600 DATA 251,152,56,233,40,168,169 49608 DATA 32,145,251,32,251,193,76 49616 DATA 99,193,169,32,153,152,7 49624 DATA 32,81,194,169,15,141,24 49632 DATA 212,169,17,141,5,212,169 49640 DATA 213,141,6,212,169,2,141 49648 DATA 3,212,169,100,141,2,212 49656 DATA 169,5,141,1,212,169,135 49664 DATA 141,0,212,169,65,141,4

49672 DATA 212,160,0,162,0,142,32 49680 DATA 208,232,208,250,200,208,247 49688 DATA 169,12,141,32,208,169,64 49696 DATA 141,4,212,160,39,185,0 49704 DATA 4,201,81,240,11,136,208 49712 DATA 246,169,1,141,254,207,76 49720 DATA 49,234,169,32,153,0,4 49728 DATA 76,49,234,152,72,160,10 49736 DATA 185,0,4,201,57,208,9 49744 DATA 169,48,153,0,4,136,76 49752 DATA 255,193,185,0,4,24,105 49760 DATA 1,153,0,4,104,168,96 49768 DATA 174,255,207,202,142,255,207 49776 DATA 232,169,152,133,251,169,7 49784 DATA 133,252,56,165,251,233,80 49792 DATA 133,251,176,2,198,252,202 49800 DATA 208,242,160,0,177,251,201 49808 DATA 160,240,4,200,76,59,194 49816 DATA 174,251,207,169,32,145,251 49824 DATA 200,202,208,250,96,160,0 49832 DATA 152,153,0,212,200,192,9 49840 DATA 208,248,96,256

Laser Bounce

Frank L. Broadnax

Don't let the ball get by you. The longer you can chip away at the bricks, the higher your score.

"Laser Bounce" is a game of movement and trajectory similar to some of the earlier videogames. Using only the character set provided with the Commodore 64, it displays a spaceship, the laser balls which rebound from the ship, and the walls of energy you are trying to break through.

Played with a joystick plugged into Control Port 2, the game begins with a simple title screen and a short musical introduction. At that point you're asked if you want to read the instructions before the game. If this is your first game, you would press Y, and the instructions appear. Once you've played the game, however, you can press N and go directly to the screen setup.

The screen sets up quickly, with the present and high scores displayed at the top, your spaceship in the middle, and the six colored energy walls below. The number of spaceships remaining is indicated by the small circles near the top-right-hand corner of the display.

As soon as the screen is completed, the game begins. Your spaceship fires its laser, and the ball appears. The ball will travel in one of four directions to start the game. It will move up and to the right, up and to the left, down and to the right, or down and to the left. Be especially watchful for the ball to move up, toward your spaceship, for you won't have much time to intercept it.

Intercepting the laser ball makes it rebound and move toward the energy walls or the side of the screen. It will bounce off both, but you'll receive points only if it hits the wall and eliminates a brick. Ten points are awarded for each gap created.

Although it doesn't matter which part of the ship the ball touches, it's best to use its center. Sometimes you may think you're in the right position, but the ball misses one wing of the ship and gets by you. Unlike other games of trajectory, the ball will not bounce at a different angle depending on where it strikes

the ship. No matter where the ball touches the spaceship, it will simply rebound.

The ship moves rather slowly, so it's a good idea to keep track of the ball, especially when it gets trapped in the wall and is busy eliminating bricks. You should be able to tell when the ball will escape from the wall and head back toward you. Anticipating it is important: if your spaceship is out of position, it will be hard to recover in time to intercept. Because the spaceship moves three columns at a time, its movement is sometimes jerky, and can make it seem like the spaceship is changing position faster than it actually is.

The laser ball is also hard to keep track of at times. Because it is drawn and erased each time it moves, it blinks off and on. However, when it erases bricks from the energy wall, it seems to disappear for a moment. If it is eliminating bricks rapidly, the best way to keep track of it is to watch the pattern of erasing bricks. Plotting where it will return toward your ship, you can move to that position.

If you miss intercepting the ball, and it gets by you, your spaceship will reappear in the middle of the screen, fire its laser, and another round begins. You have a total of five spaceships during a game, the number remaining indicated by the display.

If you erase all five energy walls, the game isn't over. Another five walls are drawn when you reach 4800 points, the total you should have after eliminating all the bricks. Each time all five walls are erased, another five appear to take their place. You receive no additional spaceships, however.

As the game ends, a message appears asking if you want to play another game. Pressing Y sets up another screen after you've indicated whether you need to read the instructions again. The score will return to 0, but the previous high score remains as long as the computer is left on. The high score only prints once a ball is missed. You can quit playing simply by entering N when the prompt appears at the end of a game.

Laser Bounce Variations

It's easy to create several variations of this game simply by altering a few of the program lines.

An interesting variation can be created by changing line 400. Instead of the value DY = - DY, insert DX = - DX. This will make the laser ball wind its way down through the energy walls, reappearing and moving toward the spaceship only after it's erased its way free.

Another change can be made in lines 460 and 470. Insert GOTO 310 instead of GOTO 320. After a ball is missed, the energy screens will be redrawn, in effect making you start over. Your score will not return to 0, however.

Changing the value of DX in line 335 will also create another variation of Laser Bounce. DX = 2 will alter the angle at which the ball rebounds. This can make the ball difficult to intercept, especially as the game begins and the ball moves up and to one side. You'll have to be fast to intercept it before it gets by you.

Programmer's Notes

It may be useful to outline some of the major subroutines of this game program so you can see how it all fits together.

Lines 5-170

180-220

230-335 330

335

336-337

400

420-450

10100

12000-12130

15000-15160

20000-20080

25000-25020

Function

Set up the title screen and send the program to the

subroutine which plays the opening music.

Begin the setup of the game instructions, and send the

program to the subroutine at 35000, which contains the

rest of the game description.

Set variables and the screen.

Ball movement loop begins. This is the main loop of the

program.

Ball starts from the end of the laser.

Alter the direction of the ball each time it appears.

Check to see if the ball touches a brick in the energy wall.

Check to see if the ball is in contact with the spaceship.

Subroutine to create the firing laser using only standard

graphic characters.

POKE in the graphic character and colors to create the

energy walls. The reversed space with screen code value

of 160 was used to make the walls.

Create the spaceship using the graphic characters with

screen code values of 73, 81, and 83, and two characters

with the value of 67.

Subroutine to move the spaceship. The ship moves three

columns at a time by erasing its previous position and

POKEing in the new location. The value is read from the

joystick (PEEK 56320). This subroutine also keeps the

spaceship on the screen.

Scoring subroutine which starts in line 400, then moves

to this section of the program. The score is printed to the

screen, changing by 10 each time a brick is erased. Lines

25011 to 25019 redraw the bricks once the screen is

cleared, depending on the score displayed.

27000-27040 Sound subroutine for the effect as the ball hits and erases the bricks. Values are POKEd into sound memory locations for attack (A), waveform (W), high sound register (HF), and low sound register (LO). The sound variables are set in line 260, at the opening of the program.

30000-30070 Subroutine to handle a missed ball and the high score. The spare spaceships are controlled here as well. Line 30030 increases PL by 1 each time a ball is missed. If PL exceeds 1098, then the game ends; otherwise, line 30070 POKEs a value of 102 in location PL, erasing one spare spaceship.

35000-35100 Remainder of the screen and game instructions.

40000-40240 Set values and the DATA statements for the music which plays at the opening of the game

45000-45030 Subroutine which asks the player whether another game is wanted.

Laser Bounce

5 PRINT"{CLR}"

10 PRINT

20 PRINT

30 PRINT

40 PRINT

50 PRINTSPC(8)

60 PRINTSPC(8)

70 PRINTSPC(8)"*{4

{4 SPACES}*" 80 PRINTSPC(8)"*{21 160 PRINTSPC(8) 170 GOSUB40010

180 PRINTTABU28)^HDO YOU WISH INSTRUCTIONS" 190 PRINTTAB(96)"Y OR N" 200 GETA$:IFA$=""THEN200

210 IFA$="Y"THENPRINT"{CLR}":GOSUB35010 220 IFA$<>"Y"THEN230

230 PRINT"{CLR}":POKE53280,11:POKE53281,0 240 P1=1094:SC=0:CO=54272 250 FORR=54272T054296:POKER 260 L=54296:W=54276:A=54277 270 POKEL,15

302 FORU1=1024TO1063:POKEU1 304 FORU2=1064TO1103:POKEU2

306 FORU3=1095TO1098:POKEU3,87:POKEU3+CO,1:NEXT

307 PRINTTAB(6)^,,{UP}{WHT}SC0RE=ⁿ

308 PRINTSPC(23)"{3 UP}{WHT}HI=" 310 GOSUB12010

•I***********************"

"*{21 SPACES}*¹¹

SPACES}LASER{2 SPACES}BOUNCE

SPACES}*"

_r0:NEXT :HF=54273:LF=54272

,160:POKEUl+CO,11:NEXT _r102:POKEU2+CO,11:NEXT

Dexterity ^E,

320 GOSUB15010

3 25 C=1161:V=1162 2B=1163:N=1164:M=1165

330 REM BALL

335 X=19:Y=9:DX=1:DY=1

336 IFRND(1)<.5THENDY=-DY

337 IFRND(1)<.5THENDX=-DX

340 POKE1024+X+40*Y,81:POKE55296+X+40*Y,1

370 POKE1024+X+40*Y,32

380 X=X+DX:IFX=0ORX=39THENDX=-DX

390 Y=Y+DY:IFY=24THENDY=-DY

395 BL=1024+X+40*Y:C1=160

400 IFPEEK(BL)=C1THENDY=-DY:SC=SC+10:GOSUB25010:GO

SUB27010 420 IFPEEK(BL)=67THENDY=-DY:GOTO390 430 IFPEEK(BL)=81THENDY=-DY:GOTO390 440 IFPEEK(BL)=85THENDY=-DY:GOTO390 450 IFPEEK(BL)=73THENDY=-DY:GOTO390 460 IFPEEK(BL)=102THENGOSUB30010:GOTO320 470 IFPEEK(BL)=87THENGOSUB30010:GOTO320 480 GOSUB20020:GOTO340 10000 REM LASER DELAY 10100 FORT=1TO100:NEXT:RETURN 12000 REM DRAW BRICKS

12010 FORQ1=1504TO1583:POKEQl,160:POKEQ1+CO,7:NEXT 12030 FORQ2=1584TO1663:POKEQ2,160 2POKEQ2+CO,6:NEXT 12050 FORQ3=1664T01743:POKEQ3,160:POKEQ3+CO,8:NEXT 12070 FORQ4=1744TO1823:POKEQ4,160:POKEQ4+CO,5:NEXT 12090 FORQ5=1824TO1903:POKEQ5,160:POKEQ5+CO,2:NEXT 12110 FORQ6=1904TO1983:POKEQ6,160:POKEQ6+CO,4:NEXT 12130 RETURN

15000 REM LASER SHIP & LASER FIRE 15010 FORZ=1144TOH83:POKEZ_#32:NEXT 15020 POKE1161,85:POKE1162,67:POKE1163,81:POKE1164

_#672POKE1165_#73 15030 FORZl=55416T055455:POKEZ1,1:NEXT 15040 POKE1203,66:POKE55475,2:GOSUB10100 15050 POKE1243,66:POKE55515,2:GOSUB10100 15060 POKE1283,66:POKE55555,2:GOSUB10100 15070 POKE1323,66:POKE55595,2:GOSUB10100 15080 POKE1363,66:POKE55635,2:GOSUB10100 15090 POKE1403,81:POKE55675,1:GOSUB10100 15100 POKE1203,32:GOSUB10100 15110 POKE1243,32:GOSUB10100 15120 POKE1283,32:GOSUB10100 15130 POKE1323_/32:GOSUB10100 15140 POKE1363,32:GOSUB10100 15150 POKE1403,32:GOSUB10100 15160 RETURN 20000 REM SHIP MOVEMENT

20020 IFPEEK(56320)<>119THEN 20030

20025 POKEC,32:POKEV,32:POKEB,32:M=M+3:N=N+3:B=B+3

:V=V+3:C=C+3 20030 IFPEEK(1183)=73THENM=1183:N=1182:B=1181:V=11

80:C=1179 20040 POKEM,73:POKEN,67:POKEB,81:POKEV,67:POKEC,85 20050 IFPEEK(56320)<>123THEN 20060 20055 POKEM,32:POKEN, 32:POKEB,32:C=C-3:V=V-3:B=B-3

:N=N-3:M=M-3 20060 IFPEEK(1144)=67THENC=1143:V=1144;B=1145:N=11

46:M=1147 20070 POKEC,85:POKEV,67:POKEB,81:POKEN, 67:POKEM,73 20080 RETURN 25000 REM PRINT SCORE

25010 PRINTTAB(12)"{UP}{WHT}"SC

25011 IFSC=4800THENGOSUB12010

25012 IFSC=9590THENGOSUB12010

25013 IFSC=14380THENGOSUB12010

25014 IFSC=19170THENGOSUB12010

25015 IFSC=23960THENGOSUB12010

25016 IFSC=28750THENGOSUB12010

25017 IFSC=33540THENGOSUB12010

25018 IFSC=38330THENGOSUB12010

25019 IFSC=43120THENGOSUB12010

25020 RETURN 27000 REM SOUND

27010 POKEA,9:POKEW,17:POKEHF,67:POKELF,15

27030 POKEW,0

27040 RETURN

30000 REM MISSED BALL & HI SCORE

30010 IFSOHITHENHI=SC

30020 PRINTSPC(26)"{3 UP}{WHT}"HI

30030 P1=P1+1:IFP1>1098THENPRINTTAB(254)"{WHT}GAME

{3 SPACES}OVER":GOTO45000 30070 POKEP1,102:POKEPl+CO,11:RETURN 35000 REM INSTRUCTIONS

35010 PRINTTAB(88)"WELCOME TO LASER BOUNCE" 35020 PRINTTAB(40)"THE OBJECT OF LASER BOUNCE IS T

O REFLECT" 35030 PRINT"THE BALL BACK TO THE BRICKS WITH YOUR" 35040 PRINTTAB(40)"SPACE SHIP." 35050 PRINTTAB(40)"TO MOVE YOUR SHIP USE A JOY STI

CK" 35060 PRINTTAB(40)"PLUGGED INTO CONTROL PORT #2." 35070 PRINTTAB(126)"PRESS SPACE BAR TO PROCEED" 35080 GETP$:IFP$=""THEN35080 35090 IFP$<>CHR$(32)THEN35080 35100 IFP$=CHR$(32)THENRETURN 40000 REM SONG AT BEGINING

100

Dexterity £M

40010 SO=54272

40020 FORL=SOTOSO+24:POKEL,0

40030 POKESO+5,9:POKESO+6,40

40040 POKESO+24,15

40050 READHF,LF,DR

40060 IFHF<0THENRETURN

40070 P0KES0+1,HF:P0KES0,LF

40080 POKESO+4,33

40090 F0RT=1T0DR:NEXT

40100 P0KES0+4,32:FORT=1TO50:NEXT

40110 GOTO40050

40120 DATA14,24,250,11,48,125,12,143,125,14,24,125

40130 DATA11,48,125,12,143,125,14,24,125,15,210,25

0 40140 DATA12,143,125,14,24,125,15,210,125,12,143,1

25 40150 DATA14,24,125,15,210,125,16,195,250,18,209,2

50 40160 DATA14,24,125,15,210,125,11,48,125,12,143,12

5 40170 DATA14,24,250,12,143,125,11,48,125,16,195,25

0 40180 DATA16,195,250,14,24,250,11,48,125,12,143,12

5 40190 DATA14,24,125,11,48,125,12,143,125,14,24,125 40200 DATA15,210,250,12,143,125,14,24,125,15,210,1

25 40210 DATA12,143,125,14,24,125,15,210,125,16,195,2

50 40220 DATA18,209,250,14,24,125,15,210,125,11,48,12

5 40230 DATA12,143,125,14,24,125,16,195,125,14,24,12

5 40240 DATA12,143,125,11,48,500,-1,-1,-1 45000 PRINTTAB(44)"{WHTjDO YOU WISH ANOTHER GAME Y

OR N" 45010 GETA$:IFA$=^,,MTHEN45010 45020 IFA$="Y^MTHENPRINT^M{CLR}":GOTO180 45030 IFA$="N^MTHENPRINT^M{CLR}":END

101

The Hawkmen of Dindrin

Esteban V. Aguilar, Jr. 64 Version by Charles Brannon_________________

Fly down through the dangerous skies of the planet Dindrin to collect stones. Retrieve enough of them and win the game, but beware of the floaters and lizards. Several special techniques are used in this game, including animation, multicolor sprites, and sound effects, each of which is explained in the article.

There's a strange planet named Dindrin where multicolor floaters and a giant sky skimmer drift through the daytime skies. On the surface of the planet, vicious land hunters come up from the ground and set polished golden stones in the sun. It's a form of worship too obscure, too alien to describe.

Suddenly a strange-looking hawk-like creature dives down and snatches a stone. You are the hawkman. Your objective is to pick up the golden stones.

Several special programming tricks went into this game. When you have the game running, watch the screen carefully. A patrol snake sweeps across the bottom of the screen. Airborne floaters pop up all over the screen. The hawkman's wings flap. The luminous stones at the bottom of the screen are protected by menacing lizards whose tongues wiggle venomously at you.

To play the game, use a joystick plugged into the first port. Maneuvering is accomplished by pulling left on the joystick to go backward. Whenever you want to dive or fly upward, you must pull down or up (respectively) on the stick. One thing to keep in mind when ascending or descending is that you will move diagonally rather than straight up or down.

The joystick response will be strange and difficult to master, but predictable. Once in a while, an obstacle such as a floater will get in your way; press the fire button to safely bump into the obstacle (and get points for it).

There are a couple of things to consider before playing the

105

^% Arcade-Style Games

game. As time passes, you will lose energy. If your energy runs out, you will lose a life. Second, when you're flying, don't run into anything or you'll lose one of your lives. When all your lives are lost, the game is over.

How It's Done

Multicolored characters are used for the stones and the lizards. The patrol snake is a multicolored sprite.

The animation (wing flapping, tongue wiggling) is done by switching between two custom character sets. Every object to be animated has two alternate views. The same image is copied into both character sets for shapes that should not move, such as the stones or the score line.

A machine language routine is used for smooth, even horizontal motion for the patrol snake. Instead of being called when needed by BASIC, the machine language routine runs continuously in the background. The machine language routine also flips the character set.

Interrupting the Commodore 64

We used the hardware interrupt request (IRQ). To place a machine language routine so that it automatically executes every 1/60 second, you change the IRQ vector at $0314 (it normally points to the ROM interrupt routines) to point to your machine language routine. After your routine executes, it exits with a JMP to the normal ROM routine.

The setup is a little tricky While you're storing the new IRQ value, you have to use SEI (SEt Interrupt disable bit) to prevent any interrupts from happening. If you don't, an interrupt could occur after you had stored the first byte of the vector value but before you changed the second. The interrupt would then vector through a "half-baked" value, and end up in limbo.

After you've changed the IRQ vector, you clear the interrupt disable bit (CLI) and return with RTS to BASIC. The machine language routine will then be running continuously in the background, flipping the character set and moving the sprite.

Multicolor

Multicolor graphics are important for good arcade effects. A few years ago, graphic objects (such as a tank or plane) were always a single color, But increasing realism has been a feature of arcade graphics, and multicolored objects are an important aspect of this realism.

106

Arcade-Style Games

Normally, when you define a custom character set, you create eight rows of pixels (picture elements, dots). Each row is eight dots (or bits) wide. With multicolor, each row is divided up into four two-bit pairs. Each pair of bits can hold a number from 0-3: 00, 01,10,11. You use a different number for each color. This reduces the resolution to four multicolor pixels per row, so the lizards and stones are composed of two characters each. You also have to tell the VIC-II chip that you are using multicolor. Do this with:

POKE 53270, PEEK (53270) OR 16

Disable multicolor with:

POKE 53270, PEEK (53270) AND 239

Here is a sample multicolor shape:

rrrr r = red (arbitrary colors)

rbbb b = blue

rbgg g = green *bgg

Let's say the binary codes for red, green, and blue are (respectively) 01,10, and 11. Substituting gives:

01 01 01 01 01010101

01 10 10 10 01101010

01 10 11 11 01101111

You can change the colors according to this key:

00 Background #0 color register - 53281

01 Background #1 color register - 53282

10 Background #2 color register - 53283

11 Color in lower 3 bits in color memory.

That last line needs explaining. You know that to get variously colored characters, you POKE a number from 0-15 into the corresponding color memory location. However, colors 8-15 (accessed by the Commodore key) are really multicolors. Multicolor characters always are displayed with a color from 8-15. You won't get the eight alternate colors (such as gray), but the normal color on the key (15 = yellow). Just add eight to the normal color number. So, a bit value of 11 will take on the value in color memory. The other colors will come from the color registers (00 is transparent).

107

Arcade-Style Games

Multicolored sprites are similar. Instead of the normal 24-bit resolution, the bits are grouped into 12-bit pairs. The colors come from:

00 - Transparent, screen color

01 - Sprite multicolor register #0 53285

10 - Normal sprite color register

11 - Sprite multicolor register #153286

You tell the VIC-II chip that you are using a multicolored sprite by:

POKE 53276, PEEK (53276) OR (2 T X)

X is the sprite number, from 0 to 7. You can mix multicolored and regular sprites on the same screen. But all multicolored sprites will share the same two multicolor registers.

Simple SID Chip Sound

The "thrumming" noise is made by playing a low-pitched tone through the SID using the variable pulse wave and a fairly long (one-second) decay Another sound effect (I can't really describe it) is made with white noise and a medium decay. The high byte of the pitch is changed as the note is played. There is also another sound effect created by the sawtooth waveform affecting the low byte of the pitch.

Hawkmen of Dindrin

100 REM HAWKMEN OF DINDRIN

110 REM COMMODORE 64 VERSION

120 P0KE52,48:P0KE56,48:CLR:GOSUB500:EN=500:GOT016

0 130 PRINT^,,{HOME}{RVS}{RED}^,,;TAB(9)^m{LEFT}";EN; "

{BLU}";TAB(26-LEN(STR$(SC)));SC; 140 IF EN<=0THEN410 150 RETURN 160 IF(PEEK(56321)AND15)<>15THENJS=PEEK(56321)AND1

5 170 IFRND(1)>.9THENQ=LL*RND(1) + (15 *RND(1)+2)*LL:PO

KET+Q,FOOL:POKEC+Q,6 *RND(1)+2 180 IFRND(1)<-7THEN200 190 Q=920+INT(20*RND(1))*2:Z=3 3-2 *(RND(1)>.7):POKE

T+Q,Z:POKET+Q+1,Z+l 200 IFPEEK(V+31)THEN410 210 Q=PX+LL*PY:POKET+Q,PC:POKEC+Q,6:EN=EN-l-9*(1-(

PEEK(56321)AND16)/16) 215 PRINT"{HOME}{RVS}{RED}"TAB(9);"{LEFT}";-EN*(EN

>0);"{LEFT} ";:IFEN<=0THEN410

108

Arcade-Style Games

220 NX=PX+1+2*(JS=11):NY=PY+(NX<0)-(NX>39):NX=-NX*

(NX<40)-40*(NX<0) 230 NY=NY-(JS=13)+(JS=14):IFNY<20RNY>23THENJS=2 7-J

S:NY=PY 240 WHATSIT=PEEK(T+NX+LL*NY) 250 IF NY>22 THEN 300 260 IFWHATSIT=32THENPOKET+PX+LL*PY,32:PX=NX:PY=NY:

GOTO160 270 IFPEEK( 56321 )AND16THEN410 \j

280 POKET+PX+LL*PY,32:POKES+24,15:POKES+5,9:POKES+ 6,0:POKES+1,10

281 FORI=0TO10:POKES,1*20:POKES+4,32:POKES+4,33:NE XT:POKES+24,0

290 WHATSIT=32:SC=SC+10:EN=EN-50:GOSUB130:GOTO250

300 JS=27-JS:IFWHATSIT<33ORWHATSIT>34THEN330

305 Q=(NXAND254)+LL*NY:POKET+Q,32:POKET+Q+l,32:EN=

EN+50 310 GOTO320 320 POKET+PX+LL*PY,32:PX=NX:SC=SC+50:GOSUB130:GOTO

160 330 IFWH=32THEN160 340 REM GRAB'EM AND EAT 'EM UP! 350 POKET+PX+LL*PY,32:Q=LL*NY+(NXAND254):POKET+Q,3

7:POKET+Q+1, 38:POKET+Q-LL,42 360 POKET+Q-LL+1,36:POKEC+Q-LL,13:POKEC+Q-LL+1,13 370 POKES+24,15:POKES+1,0:POKES,255:POKES+3,8:POKE

S+2,0:POKES+5,12:POKES+6,0 375 POKES+4,64:POKES+4,65:F0RW=1T01500:NEXT:POKES+

4,64:FORL=STOS+24:POKEL,0:NEXT 380 POKE T+Q,33:POKET+Q+l,34:POKET+Q-LL,32:POKET+Q

-LL+1_#32 390 GOTO 430

400 REM PLAYER MEETS HIS DEMISE

410 POKES+24,15:POKES+5,9:POKES+6,0:POKES,200 420 FORI=0TO90STEP6:Q=PX+LL*PY:POKET+Q,44+1/30:POK

EC+Q,8*RND(1) 425 POKE53280,16*RND(1):POKES+1,I:POKES+4,128:POKE

S+4,129:NEXT 427 FORL=STOS+24:POKEL,0:NEXT 430 POKE53280,0:IFLK3THENPOKET+35+LI*2,32 440 POKET+PX+LL*PY,32:Z=PEEK(V+31):LI=LI+1:IFLI<4T

HENEN=500:GOSUB720:GOTO160 450 SYS52992:REM TURN OFF ML

460 PRINT"{HOME}{3 DOWN}{RVS}";TAB(15);"{BLK}G {RED}A{CYN}M{PUR}E{RIGHT}{GRN}0{BLU}V{YEL}E

{red}r{blu}^m

470 PRINTTAB(7)"{DOWN}{RVS}PRESS {RED}FIRE{BLU} TO

PLAY AGAIN" 480 IF(PEEK(56321)AND16)THEN480

109

Arcade-Style Games

490 RUN

500 REM INITIALIZATION

510 POKE53280,0:POKE53281,1

515 T=1024:C=55296:S=542 72:LL=40

520 CHSET=12288:IFPEEK(CHSET+264)=2 THEN 570

530 PRINT"{CLR}":C$="{BLK}{RED}{CYN}{PUR}{CRN}

{YEL}{BLU}":F0RI=1T07:PRINT"{HOME}{DOWN}";MID$

(C$,1,1);:GOSUB2000:NEXT 550 PRINTTAB(10)"{3 DOWN}{2 RIGHT}{BLK}READY IN

{RED}22{BLK} SECONDS"; 560 GOSUB750:GOSUB 840 570 PRINT"{CLR}";:FOOL=41 575 FORL=STOS+24:POKEL,0:NEXT 580 PC=43:POKE53282,10:POKE53283 , 2 590 POKE 53272,(PEEK(53272)AND240)OR12:REM ENABLE

{SPACE}NEW CHARACTER SET 600 POKE 53270,PEEK(53270)OR16 :REM SET MULTICOLOR MODE

610 print"{home}{red}{rvs}{2 spaces}energy 500 {2 spaces}{blu}{2 spaces}score{4 spaces}0 {grn}{2 spacesJlives {off}{pur}+ + +" 630 fori=0to39step2:q=24*ll+i:poket+q,39:poket+q+1

,40:pokec+q,7:pokec+q+1,7:next 640 fori=0to39step2:q=23*ll+i:poket+q,33:poket+q+l

,34:pokec+q,13:pokec+q+1,13:next 650 q=10+23*ll:poket+q,35:poket+q+1,36 660 v=53248:rem start of vic-ii chip registers 670 pokev,220:pokev+1,194:pokev+21,1:pokev+39,7:po

KE2040,13

680 POKEV+23,1:POKEV+29,1:POKE53285,3:POKE53286,4: POKE53276,PEEK(53276)ORl

681 FORI=0TO63:POKE83 2+1,0:NEXT:RESTORE 685 FORI=0TO18:READA:POKE832+8+I,A:NEXT

690 DATA192,0,3,240,0,15,124,85,95,255,0,12,8,0,3,

0,0,0,240 700 FORI=1TO5:Q=40*RND(1)+(10*RND(1)+3)*LL:POKET+Q

,FOOL:POKEC+Q,6*RND(1)+2:NEXT 710 SYS52992:REM START ML ROUTINE 720 PX=5:PY=5:PC=43:POKET+PX+LL*PY,PC:POKEC+PX+LL*

PY,6 730 IF(PEEK(56321)AND15)=15THEN730 740 RETURN 750 RESTORE:FORI=0TO18:READA:NEXT:FORI=0TO96:READA

:POKE52992+I,A:NEXT:RETURN 760 DATA 120,173,21,3,201,234,208,19 770 DATA 169,39,141,20,3,169,207,141 780 DATA 21,3,169,0,133,251,133,252 790 DATA 76,37,207,169,49,141,20,3 802 DATA 169,234,141,21,3,88,96,165

110

Arcade-Style Games ^%

804 DATA 251,141,0,208,173,16,208,41 806 DATA 254,5,252,141,16,208,24,165 808 DATA 251,105,4,133,251,165,252,105 810 DATA 0,133,252,240,12,165,251,201 812 DATA 91,144,6,169,0,133,251,133 814 DATA 252,165,162,74,144,8,173,24 816 DATA 208,73,2,141,24,208,76,49 818 DATA 234

840 POKE56334,PEEK(56334)AND254:POKEl,PEEK(l)AND251

841 FORI=0TO511*POKE13312+I,PEEK(54272+l):POKE1536 0+1,PEEK(54272+1):NEXT

842 P0KE1,PEEK(1)OR4:POKE56334,PEEK(56334)ORl 860 READA:IFA=-1THENRETURN

870 FORJ=0TO7:READB:POKECHSET+A*8+J,B:NEXTJ:GOTO860

880 DATA 32,0,0,0,0,0,0,0,0

890 DATA 33,2,9,9,9,9,9,2,0

900 DATA 34,160,88,88,88,88,88,160,0

910 DATA 35,12,3,16,196,195,63,3,3

920 DATA 36,0,192,252,236,252,240,192,192

930 DATA 37,3,35,131,139,139,171,35,3

940 DATA 38,192,192,224,232,202,194,194,200

950 DATA 39,64,80,84,85,85,85,85,85

960 DATA 40,1,5,21,85,85,85,85,85

970 DATA 41,0,102,219,36,126,137,66,60

980 DATA 42,0,15,0,51,63,15,15,3

990 DATA{2 SPACES}288,0,0,0,0,0,0,0,0

1000 DATA 289,2,9,9,9,9,9,2,0

1010 DATA 290,160,88,88,88,88,88,160,0

1020 DATA 291,12,3,0,192,195,63,3,3

1030 DATA 292,0,192,252,204,252,240,192,192

1040 DATA 293,3,3,35,171,139,139,131,35

1050 DATA 294,192,200,194,194,202,232,224,192

1060 DATA 295,64,80,84,85,85,85,85,85

1070 DATA 296,1,5,21,85,85,85,85,85

1080 DATA 297,129,102,90,36,126,82,36,24

1090 DATA 298,0,15,0,48,63,3,15,15

1100 DATA 43,153,219,231,255,90,24,36,66

1110 DATA 299,24,90,231,255,219,153,36,66

1120 DATA 44,217,219,231,75,2,24,36,66

1130 DATA 45,216,225,235,69,7,2,40,66

1140 DATA 46,192,192,145,3,67,1,72,130

1150 DATA 47,192,128,8,1,1,0,16,128

1160 DATA 300,217,219,247,99,22,24,36,68

1170 DATA 301,216,225,227,71,23,130,32,66 1180 DATA 302,192,200,129,3,131,1,64,130 1190 DATA 303,192,144,0,1,1,0,8,128

1200 DATA -1

111

Arcade-Style Games

"{RVS} {2 RIGHT} {2 RIGHT} "{RVS} {2 RIGHT} {2 RIGHT}

2000 PRINT" {RVS} {2 RIGHT} {2 RIGHT}{2 SPACES}

{2 RIGHT} {3 RIGHT} {RIGHT} {2 RIGHT} {RIGHT} {3 RIGHT} {RIGHT}{3 SPACES}{RIGHT} {3 RIGHT}

2010 PRINT" {RVS} {2 RIGHT} {RIGHT} {2 RIGHT}

{RIGHT} {3 RIGHT} {RIGHT} {RIGHT} {2 RIGHT} {2 SPACES}{RIGHT}{2 SPACES}{RIGHT} {3 RIGHT} {2 SPACES}{2 RIGHT} "

2020 PRINT" {RVS}{4 SPACES}{RIGHT}{4 SPACES}

{RIGHT} {RIGHT} {RIGHT} {RIGHT}{2 SPACES} {3 RIGHT} {RIGHT} {RIGHT} {RIGHT}{2 SPACES} {2 RIGHT} {RIGHT} {RIGHT} "

2030 PRINT" {RVS} {2 RIGHT} {RIGHT} {2 RIGHT} {RIGHT} {RIGHT} {RIGHT} {RIGHT} {RIGHT} {2 RIGHT} {3 RIGHT} {RIGHT} {3 RIGHT} {2 RIGHT}{2 SPACES}"

2040 PRINT" {RVS} {2 RIGHT} {RIGHT} {2 RIGHT}

{2 RIGHT} {RIGHT} {2 RIGHT} {2 RIGHT} {RIGHT} {3 RIGHT} {RIGHT}{3 SPACES}{RIGHT} {3 RIGHT} {3 DOWN}"

2060 PRINTSPC(15);"{RVS}£{2 SPACES}g*i{2 RIGHT} {3 SPACES}"

2070 PRINTSPC(15)

2080 PRINTSPC(15) {3 SPACES}"

2090 PRINTSPC(15);"{RVS} {2 RIGHT} {2 RIGHT}

2100 PRINTSPC(15);"g*3{RVS}{2 SPACES}{OFF}£ {2 SPACES}{RVS} {2 DOWN}"

2110 PRINT"{3 SPACES}{RVS}{3 SPACES}{2 RIGHT}

{3 SPACES}{RIGHT} {3 RIGHT} {RIGHT}{3 SPACES} {2 RIGHT}{3 SPACES}{2 RIGHT}{3 SPACES}{RIGHT} {3 RIGHT} "

2120 PRINT"{3 SPACES}{RVS} {2 RIGHT} {2 RIGHT} {2 RIGHT}{2 SPACES}{2 RIGHT} {RIGHT} {2 RIGHT} {RIGHT} {2 RIGHT} [2 RIGHT} {2 RIGHT}{2 SPACES}{2 RIGHT} "

2130 PRINT"{3 SPACES}{RVS} {2 RIGHT} {2 RIGHT}

{2 RIGHT} {RIGHT} {RIGHT} {RIGHT} {2 RIGHT} {RIGHT}{3 SPACES}{3 RIGHT} {2 RIGHT} {RIGHT} {SPACE}{RIGHT} "

2140 PRINT"{3 SPACES}{RVS} {2 RIGHT} {2 RIGHT} {2 RIGHT} {2 RIGHT}{2 SPACES}{RIGHT} {2 RIGHT} {RIGHT} {2 RIGHT} {2 RIGHT} {2 RIGHT} {2 RIGHT}{2 SPACES}"

2150 PRINT"{3 SPACES}{RVS}{3 SPACES}{2 RIGHT}

{3 SPACES}{RIGHT} {3 RIGHT} {RIGHT}{3 SPACES} {2 RIGHT} {2 RIGHT} {RIGHT}{3 SPACES}{RIGHT} {SPACE}{3 RIGHT} "

2160 RETURN

112

Minefield

Sean Igo 64 Translation by Gregg Peele______________________________

Your job is to get your trucks in quickly, defuse the bombs (especially the flashing ones which are about to go off), and get out as fast as you can. This game has four skill levels.

In this game, you drive a truck around to gather and defuse time bombs before they explode—all the while avoiding mines and bomb craters.

Playing the Game

You find yourself in the center of a small minefield with several bombs, represented by circles, and a generous number of mines, shown as X's. Your truck is a diamond. To defuse the bombs, just run over them with the truck.

When the bombs first appear, they are innocent-looking little circles. After a short time—the rate varies from bomb to bomb— they turn reverse-field. This means watch it. Soon they begin to blink, and you have only a few blinks to defuse them before they explode. Any mines (or heroic defusing teams) caught in the explosion will be instantly lost. Bombs caught in the explosion will explode, whether they were ready to or not.

Your truck can move in only four directions. It can wrap around all four edges of the screen. Don't run it into the mines or the craters (*) left by the bombs or your truck will be destroyed. Once you begin moving, your truck cannot stop until it is blown up or until the current minefield is cleared of bombs.

Skill Levels and Scoring

"Minefield" has four skill levels. Skill levels differ only in the number of trucks you get. Level 0, the easiest, has four trucks. Level 1 has three. Level 2 has two, and level 3 has one.

Scoring: 10 points for a normal bomb

20 points for a reverse-field bomb

30 points for a blinking bomb

-10 points at the end of an explosion for every bomb that

went off. This is incentive to defuse more than one or two

bombs in the later explosions.

113

^% Arcade-Style Games

Minefield

30 REM MINEFIELD FOR C-64 45 POKE53280,0:POKE53281,0 50 GOSUB 1130

60 REM ---INITIALIZE VARIABLES---

70 DIM BT(37),B3(37),B4(37),BP(37),BS(37),XM(4),YM

(4),BC(25) 80 DEF FNY(X)=INT((X-1024)/40) 90 DEF FNX(X)=(X-40*FNY(X))-1024 100 DEF FNS(X)=1024+PX+40*PY 110 DEF FNP(X)=1307+INT(34*RND(l))+40*INT(15*RND(l

)) 120 DEF FNN(X)=PEEK(FNS(X)) 130 FORJ=l TO 4:READ XM(J),YM(J):NEXT 140 DATA 0,-1,0,1,-1,0,1,0 150 SC=0:BT=1680:NB=4:NW=0:D=542 72 160 PRINT"{CLR}";:POKE 53272,21 170 PRINT"{RVSHWHT}MINE****- SCORE: 0" 180 PRINT" {RVS}{WHT}********-_:{RIGHT}HI SCORE: " ; HS 190 PRINT ^,,{RVS}{WHT}***FIELD_::{ RIGHT} WAVE: 1" 200 PRINT"{RVS}{WHT}{8 SPACESJ_z{RIGHT}";:IF NL<>1

{SPACE}THEN FORJ=l TO NL-1:PRINT"Z";:NEXT 210 FORJ=1024 TO 1183:IFPEEK(J)=32 THEN POKE J,160

:POKEJ+D,l 220 NEXT 230 XP$="{RED}U-l{DOWN}{4 LEFTJUU-II{DOWN}{6 LEFT}

UUU-IIl{DOWN]{7 LEFT}*******{DOWN}

[7 LEFTJJJJ-KKK" 235 XP$=XP$+"I RED}{DOWN}{6 LEFT}JJ-KK{DOWN}

{4 LEFT}J-K" 240 S$="{HOME}{24 DOWN}" 250 Q$="{WHT}{40 RIGHT}" 260 XR$="{WHT}{3 SPACES}{DOWN}{4 LEFT}{5 SPACES}

{DOWN}{6 LEFT}{7 SPACES}{DOWN}{7 LEFT}

{3 SPACES}*{3 SPACES}{DOWN}{7 LEFT}{7 SPACES}" 265 XR$=XR$+"{DOWN}{6 LEFT}{5 SPACES}{DOWN}

{4 LEFT}{3 SPACES}"

270 REM ---SET UP NEXT WAVE---

280 BG=0:NW=NW+1:IF NW>11 THEN 310

290 NB=NB+1.5:IF NW=1 THEN 330

300 IF NW<6 THEN BT=BT-180

310 PRINT"{HOME}{2 DOWN}{RVS}";TAB(15);NW

320 POKE FNS(l),32:FORJ=l TO NB:POKEBP(J),32:NEXT

325 FORJ=l TO 25:POKE BC(J),32:NEXT

330 BN=INT(NB):FORJ=l TO NB:BS(J)=1:NEXT

340 FORJ=l TO NB

350 BT(J)=(.4+INT(61*RND(l))/l00)*BT

360 B3(J)=BT(J)+.5*BT(J):B4(J)=B3(J)+.25*BT(J)

3 70 NEXT

Arcade-Style Games

380 PX=19:PY=15:POKE FNS(1),90:POKEFNS(1)+D,1 390 FORJ=l TO NB

400 BP(J)=FNP(1):IF PEEK(BP(J))<>32 THEN 400 410 POKE BP(J),87:POKEBP(J)+D,8:NEXT:NN=0

415 FORJ=l TO 25

416 BC(J)=FNP(1):IF PEEK(BC(J))<>32 THEN 416

417 IF PEEK(BC(J)+l)=87 THEN 416

419 POKEBC(J),86:POKEBC(J)+D,5:NEXT

420 GET R$:IF R$<>"" THEN 420 430 DR=0:TX=TI

440 REM ---GET COMMANDS---

450 R=(15-(PEEK(56321)AND15))*2

460 IFR<>0THENDR=LOG(R)/LOG(2){41 SPACES}

470 IFR=0THEN490

480 REM ---MOVE TRUCK---

490 IF DR=0 THEN 600

500 POKE FNS(l),32:PX=PX+XM(DR):PY=PY+YM(DR)

510 IF PX<0 THEN PX=39

520 IF PX>39 THEN PX=0

530 IF PY<4 THEN PY=24

540 IF PY>24 THEN PY=4

550 X=FNN(1)

560 IF X=32 THEN POKE FNS(1),90:POKEFNS(1)+D,1:GOT

O 600 570 IF X=42 OR X=86 THEN 960 580 GOTO 890

590 REM ---UPDATE BOMBS---

600 NN=NN+1:IF NN>INT(NB)THEN NN=1

610 IF BS(NN)=0 THEN 600

620 TG=TI-TX

630 IF TG>B4(NN) THEN Nl=NN:GOTO 720

640 IF BS(NN)>2 THEN 690

650 IF TG>BT(NN) THEN BS(NN)=2

660 IF TG>B3(NN) THEN BS(NN)=3

670 IF BS(NN)=1 THEN 450

680 IF BS(NN)=2 THEN POKE BP(NN),215:POKEBP(NN)+D,

l:GOTO 450 690 IF BS(NN)=3 THEN POKE BP(NN),87:POKEBP(NN)+D,1

:BS(NN)=4:G0T0 450 700 IF BS(NN)=4 THEN POKE BP(NN),215:POKEBP(NN)+D,

l:BS(NN)=3:GOTO 450

710 REM ---BOMB EXPLODES---

720 TQ=TI:PD=0

725 X$=^,,{OFF}^m+LEFT$(S$,FNY(BP(N1) )-2)+LEFT$(Q$,FN

X(BP(N1))-1) 730 BS(N1)=0:N2=0:PRINTX$;XP$;

740 FORJ=l TO NB:X=PEEK(BP(j)):IF BS(j)=0 THEN 760 750 IF X<>87 AND X<>215 AND X<>218 THEN N2=J 760 NEXT:IF FNN(1)<>90 AND FNN(1)<>218 THEN PD=1

115

Arcade-Style Games

770 PRINTX$;XR$;:GR=129{4 SPACES}:GOSUB2000

780 F0RJ=1T0NB:IF PEEK(BP(J))=32 AND BS(J)<>0 THEN

POKE BP(J),87-128*(BS(J)>1) 790 NEXT:BN=BN-1 800 IF PD=1 THEN 960 810 IF BN=0 THEN 840

820 IF N2=0 THEN TX=TX+(TI-TQ):GOTO 450 830 Nl=N2:GOTO 725

840 PRINT"{HOME}{2 DOWN}{RVS}";TAB(20); 850 FORJ=l TO 20:PRINT"{RVS}COMPLETED{9 LEFT}";:FO

RK=1 TO 100:NEXT 860 PRINT"{RVS}{9 SPACES}{9 LEFT}";:FORK=l TO 100:

NEXT:NEXT 870 SC=SC-10*(INT(NB)-BG):IF SC<0 THEN SC=0 880 PRINT"{4 LEFT}{3 UP}{10 SPACES}{10 LEFT}";SC:G

OTO 280

885 REM ---BOMB GATHERED---

890 BG=BG+l:TQ=TI:POKE FNS(1),218

895 FORJ=l TO NB:IF PEEK(BP(J))=218 THEN AJ=BS(J):

BS(J)=0 900 NEXT

910 IF AJ=4 THEN AJ=3

920 SC=SC+10*AJ:PRINT"{HOME}{RVS}";TAB(16);SC 930 GR=33:GOSUB2000:BN=BN-1:IF BN=0 THEN 840 940 TX=TX+(TI-TQ):GOTO 450 950 REM ---PLAYER DESTROYED---

960 GR=129:GOSUB2000

961 TQ=TI:FORJ=l TO 20:POKE FNS(1),42:FORK=l TO 25 :NEXT:POKE FNS(1),170

970 FORK=l TO 25 .-NEXT:NEXT: POKE FNS (1) , 32 :NL=NL-1

{19 SPACES} 980 POKE 1153+NL_/160:DR=0:PX=19:PY=15 990 IF NL=0 THEN 1045 1000 IF BN=0 THEN 840 1010 GET R$:IF R$<> " " THEN 1010 1020 FORJ=lTONB:IF PEEK(BP(J))=32 AND BS(J)<>0 THE

N POKE BP(J),87-128*(BS(J)>1) 1030 NEXT

1040 POKE FNS(1)_/90:TX=TX+(TI-TQ):GOTO 450 1045 IF SOHS THEN HS=SC: PRINT" {HOME} {DOWN} {RVS }" ;

TAB(19);HS 1050 FORJ=l TO 1500:NEXT:PRINT"{HOME}{WHT}{2 DOWN}

{RVS}";TAB(20);"GAME OVER{DOWN}{WHT}{9 LEFT}P

LAY AGAIN?"; 1060 PRINT"(Y/N){4 LEFT}";

1080 PRINT"{RVS}Y/{OFF}N{3 LEFT}";

1081 F0RJ=1 TO 99-.NEXT

1082 PRINT"{OFF}Y{RVS}/N{3 LEFT}";

1083 FORJ=l TO 99:NEXT

116

Arcade-Style Games

1084 GET R$:IF R$="Y" THEN 1110 1090 IF R$<>"N" THEN 1080 1100 PRINT"{CLR}{WHT}LATER ONI":END 1110 GOSUB 1130:GOTO 150

1120 REM ---INSTRUCTIONS---

1130 PRINT"{CLR}{RVS}{WHT}M{SHIFT-SPACE}l_

{SHIFT-SPACE}n{SHIFT-SPACE}e{SHIFT-SPACE}F

{ SHIFT-SPACE } I. { SHIFT-SPACE } E { SHIFT-SPACE } L

{SHIFT-SPACE}D":POKE 53272,23 1140 PRINT"{WHT}DO YOU NEED INSTRUCTIONS (Y/N)" 1150 GET R$:IF R$="N" THEN 1410 1160 IF R$<>"Y" THEN 1150 1180 PRINT"{CLR}{WHT}{DOWN}THE OBJECT OF THIS GAME

IS TO PICK UP" 1190 PRINT"{WHT}AS MANY BOMBS AS YOU CAN BEFORE TH

EY" 1200 PRINT"{WHT}EXPLODE. TO PICK UP A BOMB, JUST R

UN" 1210 PRINT"{WHT}OVER IT WITH YOUR TRUCK." 1220 PRINT"{WHT}BOMBS WILL EXPLODE AFTER A SHORT T

IME." 1230 PRINT" {WHT}JLF A BOMB TURNS REVERSE-FIELD, BE

{SPACE}CARE-" 1240 PRINT"{WHT}FUL WITH IT. IF IT STARTS TO BLINK

, IT" 1250 PRINT"{WHT}WILL VERY SHORTLY EXPLODE-WATCH OU

Til"

1260 PRINT"{WHT}BOMBS WILL CHAIN-REACT; ONE BOMB C

AUGHT" 1270 PRINT"{WHT}IN ANOTHER'S EXPLOSION WILL ALSO B

LOW" 1280 PRINT" {WHT} UP. I_F YOU ARE CAUGHT IN A BOMB'S

{SPACE}"

1290 PRINT"{WHT}EXPLOSION, YOU WILL BE BLOWN UP."

1300 PRINT"{WHT}ALSO, DO NOT RUN INTO BOMB CRATERS

(*)"

1310 PRINT"{WHT}OR MINES (X) OR YOU'LL BE TOTALLED ii

1320 PRINT"{WHT}THE CONTOLS ARE: 1 TO GO UP"

1330 PRINT"{WHT}Tl7 SPACES}CTRL TO GO LEFT"

1340 PRINT"{WHT}{17 SPACES}2 TO GO RIGHT"

1350 PRINT"{WHT}{17 SPACES}* TO GO DOWN"

1355 PRINT"{WHTjOR YOU CAN USE A JOYSTICK IN PORT

{SPACE}1." 1360 PRINT"{WHT}YOUR TRUCK CANNOT STOP ONCE YOU BE

GIN" 1370 PRINT"{WHT}MOVING. FT CAN WRAP-AROUND BOTH TH

E" 1380 PRINT"{WHT}THE TOP AND SIDES OF THE SCREEN."

117

^% Arcade-Style Games

1390 PRINT"{DOWN}{WHT}P{WHT}RESS RETURN TO CONTINU

E";

1400 GET R$:IF R$<>CHR?(13) THEN 1400

1410 PRINT"{CLR}s{WHT}ELECT SKILL SETTING (0-3)"

1420 GET R$:IF R$<"0" OR R$>"3" THEN 1420

1430 NL=4-VAL(R$):RETURN

1900 END

2000 REM SOUND OF EXPLOSION

2010 QW=54272

2020 FORS=QWTOQW+24: POKES,0 .-NEXT

2025 POKEQW+24,47

2030 POKEQW+5,64+7 :POKEQW+6_#240

2050 POKEQW+4,GR :POKEQW+l,36:POKEQW_#85

2060 FORT=1TO250:NEXT

2070 FORT=15TO0STEP-1 :POKEQW+24,INT(T):NEXT

2080 RETURN

Cylon Zap_______

Mark Dudley 64 Translation by Gregg Peele__________________________

Quick reflexes are what you'll need for this fast-action game.

"Cylon Zap" is an arcade-style game. A space station in the center of the screen, which you must defend at all costs, is attacked continually by Cylon ships. You must shoot them before they dive (kamikaze style) into the space station.

To defend against the Cylons, you have two weapons. First, the joystick is moved up, down, right, or left to fire lasers in any of these four directions. Second, the fire button detonates a smart bomb, which immediately clears the screen of all visible attackers. Smart bombs should be used sparingly, for only three are available at the beginning of play.

The score and the number of remaining bombs are continually updated at the upper-left corner of the screen. When the score reaches 30, the flank attackers begin to increase speed. When your score reaches 50, the attackers from the top and bottom increase their speed. If your score exceeds 60, you win bonus smart bombs.

If your point total is a high score since the program was first loaded, you enter your initials with the joystick. Moving the stick right or left lets you step through the alphabet forward or backward. When you find the correct letter, select it with the fire button. Be sure not to hold the fire button down too long when selecting your initials, or you may inadvertently choose the wrong letters.

Cylon Zap

100 POKE52,48:POKE56,48:CLR

125 DATA28,149,100,25,30,100,33,135,100,37,162,50,

50,60,50 130 DATA42,62,100,37,162,50,50,60,50,42,62,100,33,

135,100 140 DATA28,49,100,25,30,100 145 F0RX=1T036:READRT:NEXT 150 PRINT"{CLR}":POKE53281,0:POKE53280,0:PRINTCHR?

(14)

119

Arcade-Style Games

160 GOSUB590

170 PRINT"{3 DOWN}{11 SPACES}{RVS}LOADING

{SHIFT-SPACE}CHARACTERS" 180 POKE56334,(PEEK(56334)AND254):POKEl,PEEK(1)AND

251 190 FORA=0TO2047:POKE(A+12288),PEEK(A+53248):NEXT 200 FORA=12552T012672 210 READD

220 IFD<>-1THENP0KEA,D:NEXT 230 FORA=12288T014335: READD: IFDO-1THENPOKEA, PEEK (

A):NEXT 240 F0RA=12504TO12527:READD:POKEA,D:NEXT 250 POKEl,55 260 POKE56334,PEEK(56334)ORl

270 gosub750:print"{up}{10 spaces}instructions

{off} {rvs}y{off} or {rvs}n{off} " 280 geta$:ifa$=""thenpoke56079,int(rnd(1)*7+l):pok

E56084,INT(RND(l)*7+l) :GOTO280 290 IFA$="Y"THENPOKE53272,(PEEK(53272)AND240)+12:G

OSUB380 300 GOTO1000 310 DATA24,24,60,126,24,24,126,255,1,19,51,255,255

,51,19,1,128 315 DATA200,204,255,255,204,200 320 DATA128,255,126,24,24,126,60,24,24,24,24,60,24

,60,126,219,195 325 DATA3,7,44,254,254,44,7,3 330 DATA192,224,52,127,127,52,224,192,195,219,126,

60,24,60 3 35 DATA24,24,16,8,16,8,16,8,16,8 340 DATA145,74,44,113,142,52,82,137,0,0,0,170,85,0

,0,0,-1 350 DATA0,0,0,119,68,116,20,119,0,0,0,119,85,87,86

,117,0,0,0,112,64,96,64,112 360 DATA0,0,0,206,170,206,170,202,0,0,0,238,136,23

6,40,238,0,0,0 365 DATA224,128,224,32,224,-1 370 DATA0,0,0,206,170,202,170,206,0,0,0,139,218,17

1,138,139,0,0,0 375 DATA56,160,56,136,56

380 PRINT"{CLR}{RED}WELCOME TO CYLON ZAP" 390 PRINT"YOU HAVE A BASE NAMED ALPHA"{10 SPACES}:

PRINT 400 PRINT"{CYN}YOUR MISSION IS TO{2 SPACES}PROTECT

THE":PRINT"NUCLEAR REACTOR" 410 PRINT"{PUR}FROM THE KAMIKAZE STAR ":PRINT" FIG

HTERS" 420 PRINT"{DOWN}{GRN}YOU HAVE 4 LASERS{2 SPACES}CO

NTROLLED BY THE{4 SPACES}JOYSTICK"

120

Arcade-Style Games

430 PRINT"{BLU}YOU ALSO HAVE SMART BOMBS LAUNCHED

{SPACE}BY THE FIRE BUTTON" 440 PRINT"{DOWN}{YEL}ALL YOU DO IS POINT THE GUN A

ND THE{6 SPACES}LASER FIRES AUTOMATICALLY" 450 GOSUB500 460 PRINT"{CLR}{PUR}{DOWN}THE FIGHTERS WILL FLY FA

STER THE MORE{3 SPACES}OF THEM YOU DESTROY " 470 PRINT"{DOWN}{YEL}BONUS BASE AND BOMB AT 60 POI

NTS" 480 PRINT"{BLU}{DOWN}{9 SPACES}{RVS}GOOD LUCK":GOS

UB500:RETURN

500 A$="{RVS}"

510 FORL=1TO1000

520 PRINT"{HOME}"

530 PRINTTAB(2)A$;"{CYN}{20 DOWN}HIT RETURN TO CON

mil

540 GETR$:IFR?=CHR$(13)THENRETURN 550 F0RI=1T0333:NEXT

560 IFA$="{RVS}"THENA$="{OFF}":GOTO580 570 IFA$="{OFF}"THENA$="{RVS}":GOTO580 580 NEXTL

590 A$="{RED}*** *{3 SPACES}* *{4 SPACES}***

{2 SPACES}*{2 SPACES}*":X=LEN(A$):Z$="{DOWN}":

GOSUB710 600 A$="*{4 SPACES}* *{2 SPACES}*{4 SPACES}* *

{2 SPACES}** *":X=LEN(A?):Z$="{2 DOWN}":GOSUB7

610 A$="*{5 SPACES}*{3 SPACES}*{4 SPACES}* *

{2 SPACES}* **":X=LEN(A$):Z$="{3 DOWN}":GOSUB7 10

611 A$="*{5 SPACES}*{3 SPACES}*{4 SPACES}* *

{2 SPACES}* **":X=LEN(A$):Z$="{4 DOWN}":GOSUB7

10 620 A$="***{3 SPACES}*{3 SPACES}***{2 SPACES}***

{2 SPACES}*{2 SPACES}* ":X=LEN(A$):Z$="

{5 DOWN}":GOSUB710 630 A$="{YEL}{2 SPACES}***{2 SPACES}***{2 SPACES}*

**{2 SPACES}* *{2 SPACES}":X=LEN(A?):Z$="

{8 DOWN}":GOSUB710 640 A$="{4 SPACES}*{2 SPACES}* *{2 SPACES}* *

{2 SPACES}* *{3 SPACES}":X=LEN(A$):Z$="

{9 DOWN}":GOSUB710 650 A$="{3 SPACES}*{3 SPACES}***{2 SPACES}***

{2 SPACES}* *{3 SPACES}":X=LEN(A§):Z$="

{10 DOWN}":GOSUB710 660 A$="{2 SPACES}*{4 SPACES}* *{2 SPACES}*

{10 SPACES}":X=LEN(A$):Z$="{11 DOWN}":GOSUB710

121

Arcade-Style Games

670 A$="{2 SPACES}***{2 SPACES}* *{2 SPACES}* {4 SPACES}* *{2 SPACES}":X=LEN(A$):Z$=" {12 DOWN}":GOSUB710

680 PRINT:PRINT

700 GOTO170

710 S=54272

711 POKE54296,15 :POKE54277,18:POKE54278,240

712 POKE 54276,33

720 FORI=lTOLEN(A$):POKE54273,I+40

721 PRINT"{HOME}{DOWN}{8 RIGHT}"Z$;SPC(X)LEFT$(A$, I):POKE54272,(l*2)+180

730 X=X-1:NEXT:FORG=l5TO0STEP-1:POKE54296,G:NEXT:P

OKES+4,16 7 35 FORE=STOS+28:POKEE,0:NEXT:RETURN 750 FORA=49152T049453 760 READD 770 POKEA,D 780 NEXT 790 RETURN 800 DATA169,12,141,3 3,208,169,147,32,210,255,162,8

,160,16,32,240,255,169,18,32 810 DATA210,255,169 820 DATA169,32,210,255,169,127,32,210,255,169,146,

32,210,255,169,32,32,210 825 DATA 255,169,18,32 830 DATA210,255,169,169,32,210,255,169,12 7,32,210,

255,24,162,9,160,15,32 835 DATA 240,255,169,169 840 DATA32,210,255,169,160,162,5,32,210,255,202,22

4,0,208,248,169,127 845 DATA 32,210,255,24 850 DATA162,10,160,15,32,240,255,169,146,32,210, 25

5,169,127,32,210,255 855 DATA 169,18,32,210,255 860 DATA169,160,162,5,32,210,255,202,224,0,208,248

,169,146,32,210,255 865 DATA 169,169,32,210,255 870 DATA24,162,11,160,15,32,240,255,169,32,32,210,

255,169,18,32,210 875 DATA255,169,160,162,5,32 880 DATA210,255,202,224,0,208,248,169,146,32,210,2

5 5,169,32,32,210,255,24 885 DATA 24,162,11,160,7 890 DATA32,240,255,169,18,32,210,255,24,162,12,160

,15,32,240,255,169,169 895 DATA 32,210,255,169 900 DATA160,162,5,32,210,255,202,224,0,208,248,169

,127,32,210,255,24 905 DATA 162,13,160,15,32,240

122

Arcade-Style Games

910 DATA255,169,146,32,210,255,169,127,32,210,255,

169,18,32,210,255 915 DATA 169,160,162,5,32,210 920 DATA255,202,224,0,208,248,169,146,32,210,255,1

69,169,32,210,255,24 925 DATA 169,146,32,210 930 DATA255,24,162,14,160,16,32,240,255,169,127,32

,210,255,169,169,32 935 DATA 210,255,169,32,32 940 DATA210,255,169,127,32,210,255,169,169,32,210,

255,24,96 1000 RESTORE:CLR

1060 DEFFNA(A)=INT(RND(1)*X+A):TT=1482 1070 POKE53272,(PEEK(53272)AND240)+12 1080 N1=1042:N2=1922:N3=1464:N4=1502:V1=36876 1090 CS=53281:C=54272:W1=30:W2=20:W3=10:W4=5:W5=1 1100 A1$="D..":A2$="U..":A3$="D..":A4$="C..^M:A5$=^M

O. ." 1110 POKECS,l:PRINT"{CLR}":GOTO2190 1120 BASE=3:Sl=l:S2 = l:S3=l:S4=l:BOM=3:SC=0 1130 POKECS,12:X=15:Y=1:I=40 1140 PRINT^u{CLRHWHT}":POKECS,8 1150 GOSUB1450 1160 PRINT"{HOME}{WHT}SCORE"SC:PRINT"{HOME}{DOWN}B

ASES"BA:PRINT"{WHT}BOMBS"BO 1170 J0=15-(PEEK(56321)AND15) 1180 G=42:FB=(PEEK(56321)AND16) 1190 POKETT,102

1200 POKETT+C,INT(RND(l)*7+l) 1210 IFJ0=1 THEN1510 1220 IFJ0=2 THEN1570 1230 IFJ0=4 THEN1630 1240 IFJ0=8 THEN1690 1250 IFFB=0ANDBOM>0THEN2590 1260 A1=FNA(1) 1270 A2=FNA(2) 1280 A3=FNA(3) 1290 A4=FNA(4)

1300 IFA1 = 1ANDSK>0THENS1=0: GOSUB2680 1310 IFA2=2ANDS2<>0THENS2=0: GOSUB2680 1320 IFA3=3ANDS3<>0THENS3=0: GOSUB2680 1330 IFA4=4ANDS4<>0THENS4=0: GOSUB2680 1340 IFSl=0ANDPEEK(Nl+40)<>102THENN1=N1+I:POKEN1+C

,4:POKEN1,40:POKEN1-I,32 1350 IFPEEK(N1+40)=102THENGOSUB2050 1360 IFS2=0ANDPEEK(N2-40)<>102THENN2=N2-I:POKEN2+C

,3:P0KEN2,37:P0KEN2+I,32 1370 IFPEEK(N2-40)=102THENGOSUB2050

1380 IFS3=0ANDPEEK(N3+1)<>102THENN3=N3+Y:POKEN3+C, 5:POKEN3,39:POKEN3-Y,3 2

123

^^ Arcade-Style Games

1390 IFPEEK(N3+1)=102THENGOSUB2050

1400 IFS4=0ANDPEEK(N4-1)<>102THENN4=N4-Y:POKEN4+C,

6:P0KEN4,38:P0KEN4+Y,32 1410 IFPEEK(N4-1)=102THENGOSUB2050 1420 IFBASE=0THENGOTO2130 1430 IFSO50THENX=4 1440 GOTO1160

1450 PRINT"{RED}^M:SYS49152:POKECS,11 1460 POKE1362+C,1:POKE1362,33:POKE1602+C,1:POKE160

2,36:POKE1479+C,1:POKE1479,34 1470 POKE1485+C,l:POKE1485,35 1480 POKETT-1,102:POKETT+1,102:POKETT-40,102:POKET

T+40,102 1490 POKETT-1+C,1:POKETT+1+C,1:POKETT-40+C,1:POKET

T+40+C,l 1500 RETURN 1510 POKE54296,15:POKE542 73,33:POKE54272,133:POKE5

4277,50:POKE54278,120 1520 POKE54276,129 1530 FORF=1362TO1042STEP-40 1540 IFPEEK(F-40)<>40THENPOKEF+C,1:POKEF,41:FORT=l

TO5:NEXT:POKEF,32:NEXT

1550 IFPEEK(F-40)=40THENPOKEN1+C,2:POKEN1,42:GOSUB

1830:POKEN1,32:Nl=1042:Sl=l 1560 POKE54296,0:POKE1362,33:GOTO1260 1570 POKE54296_#15:POKE54273_/33:POKE54272_/133:POKE5

4277,50:POKE54278_/120 1580 POKE54276_/129 1590 FORF=1602TO1944STEP40 1600 IFPEEK(F+40)<>37THENPOKEF+C,1:POKEF,41:FORT=l

TO5:NEXT:POKEF,32:NEXT 1610 IFPEEK(F+40)=3 7THENPOKE2+C,2:POKEN2,42:GOSUB1

830:POKEN2,32:N2=1922:S2=l-40 1620 POKE54296,0:POKE1602,36:GOTO1260 1630 POKE54296_#15:POKE54273,33:POKE54272_#133:POKE5

4277,50:POKE54278,120 1640 POKE54276,129 1650 FORF=1479T01464STEP-l 1660 IFPEEK(F-l)<>39THENPOKEF+C,1:POKEF,43:F0RT=1T

05:NEXT:POKEF,32:NEXT 1670 IFPEEK(F-l)=39THENPOKEN3+C,2:POKEN3,42:GOSUBl

830:P0KEN3,32:N3=1464:S3=l 1680 POKE54296,0:POKE1479,34:GOTO1260 1690 POKE54296,15:POKE54273,33:POKE54272,133:POKE5

4277,50:POKE54278,120 1700 POKE54276,129 1710 FORF=1485TO1502 1720 IFPEEK(F+l)<>38THENPOKEF+C,l:POKEF,43:F0RT=1T

05:NEXT:POKEF,32:NEXT

124

Arcade-Style Games

1730 IFPEEK(F+l)=38THENPOKEN4+C,2:P0KEN4,42:G0SUB1

830:POKEN4,32:N4=l502:S4=l 1740 POKE54296,0:POKE1485,35:GOTOl260 1745 FORS0=54272TO54272+28:POKES0,0:NEXT 1750 POKE54296,15:POKE54277,53:POKE54278,69:POKE54

276,33 1770 RESTORE :F0RGB=1T012 : READHA, LA, DU.-POKE54273, HA

:POKE54272,LA 1780 FORT=lTODU:NEXTT

1790 NEXTGB:FORS0=54272TO54272+28:POKES0,0:NEXT

1800 RETURN

1810 DATA217,200,213,200,223,200,227,100,234,100,2

30,200 1820 DATA227,100,234,100,230,200,223,200,227,200,2

17,200,213,300,-1 1830 POKE54296,15:POKE54277,53:POKE54278,67:POKE54

276,129 1840 POKE54272,200:POKE54273,33

1850 FORL=15TO0STEP-1

1860 POKE54296,L

1870 NEXT:POKE54276,0

1880 SC=SC+1

1890 IFSC=30THENX=INT(X/2):Y=2

1900 IFSC=50THENX=4:1=80:BOM=BOM+l

1910 IFSC=60ORSC=110ORSC=150THENGOTO1930

1920 RETURN

1930 PRINT"{CLR}{10 DOWN}{10 SPACES}BONUS";

1940 PRINT" BASE - BOMB":L=0

1950 POKE54296,15:POKE54277,50:POKE54278,167:POKE5

4276,17 1960 FORT=1TO10

1970 POKE54272,230:POKE54273,33

1980 NEXT

1990 FORT=1TO10

2000 POKE54272,180:POKE54273,28

2010 NEXT

2020 IFL<6THENL=L+1:GOTO1950

2030 FORD=54272T054272+28:POKED,0:NEXT

2040 BOM=BOM+l:BA=BA+1:SC=SC+5:PRINT"{CLR}"iGOSUBI

450:GOTO1890 2050 POKE54296,14:Q1=1482:Q2=1484:Q3=1522:Q4=1524:

K=0:Q5=Q1-41:Q6=Q3+41:Q7=Ql+39 2060 Q8=1526:POKE54277,44:POKE54278,56:POKE54276,1

29 2070 POKE54272,200:POKE54273,34:KK=8 2080 FORZ=15TO0STEP~2 2090 POKE54296,Z:GOSUB2260:NEXT:POKECS,8:POKE54276

125

Arcade-Style Games

2100 N1=1042:S1=1:N2=1922:S2=1:N3=1464:S3=1:N4=150

2:S4=1:PRINT"{CLR}" 2110 BASE=BASE-1:IFBASE<>0THENGOSUB1450 2120 RETURN 2130 PRINT"{CLR}"

2140 IFSC=>W1THENA5$=A4$:A4$=A3$:A3$=A2? 2150 IFSC=>W1THENA2$=A1$:W5=W4:W4=W3:W3=W2:W2=W1:W

1=SC:GOTO2730

2154 REM LINE 2155 MUST BE ENTERED USING KEYWORD A BBREVIATIONS

2155 IFSC>=W2ANDSC<W1THENA5?=A4?:A4$=A3$:A3$=A2$:W 5=W4:W4=W3:W3=W2:W2=SC:GOT02740

2160 IFSC=>W3ANDSC<W2THENA5$=A4$:A4$=A3?:W5=W4:W4=

W3:W3=SC:GOTO2750 2170 IFSC=>W4ANDSC<W3THENA5$=A4$:W5=W4:W4=SC:GOT02

760 2180 IFSC=>W5ANDSC<W4THENW5=SC:GOTO2 770 2190 GOSUB2510:PRINT"{HOME}{BLK}{21 DOWN}

{12 SPACES}TO PLAY HIT {RVS}{BLK}Y^u2200 GETZ$:IFZ$=""THENFORCC=55312T055315:POKECC,IN

T(RND(1)*7+1):NEXT 2210 POKE56165,INT(RND(l)*7+l) 2220 IFZ$=""THEN2200 2230 IFZ$="Y"THEN1120

2240 IFZ$="N"THENPRINT"{CLR}iBLU}":POKECS,27:END 2250 GOTO2190

2260 K=K+1:M=41:N=40:0=39:R=INT(RND(1) *7+l) 22 70 IFK>3ANDK<110THENPOKECS,KK:KK=KK+31 2280 P0KEQ1,G:P0KEQ2,G:P0KEQ3,G:P0KEQ4,G:P0KEQ5,G:

P0KEQ6,G:P0KEQ7,G:P0KEQ8,G 2290 P0KEQ1+C,R:P0KEQ2+C,INT(RND(1)*7+l)IP0KEQ3+C,

R:P0KEQ4+C,INT(RND(1)*7+l) 2 300 POKEQ5+C_#R:POKEQ6+C_/INT(RND(l)*7+l):P0KEQ7+C,

R:P0KEQ8+C,INT(RND(1)*7+l) 2310 FORT=1TO10:NEXT 2320 IFK>3THENG=46:PRINT"{CLR}" 2330 IFK<8THENQ1=Q1-0:Q2=Q2»M:Q3=Q3+0:Q4=Q4+M:Q5=Q

5-N:Q6=Q6+N:Q7=Q7-l:Q8=Q8+l 2340 RETURN

2350 PRINT"{CLR}":RETURN 2360 PRINT"{3 DOWN}":CH=1160:E=l 2370 J0=15-(PEEK(56321)AND15) 2380 FB=PEEK(56321)AND16 2390 IFJ0=8THENE=E+1 2400 IFJ0=4THENE=E-1 2410 IFE=0THENE=26 2420 IFE=27THENE=1 2430 P0KECH,E:P0KECH+C,7 2440 FORT=1TO100:NEXT

126

Arcade-Style Games

2450 P0KECH+C,1

2460 IFFB=0 ANDCH=1160THENNl$=CHR$(E+64):CH=CH+1:E

=1:GOTO2370 2470 IFFB=0ANDCH=1161THENN2$=CHR$(E+64):CH=CH+1:E=

1:GOTO2370 2480 IFFB=0 ANDCH=1162THENN3$=CHR$(E+64):CH=CH+l:E

=32:GOTO2370 2490 IFCH=1163THENN5$=N1$+N2?+N3$:RETURN 2500 GOTO2370 2510 POKE53281,l 2 515 REM THE NEXT LINE MUST BE ENTERED USING KEYWO

RD ABBREVIATIONS 2520 PRINT"{CLR}{2 SPACES}{BLK}{9 SPACESjCYLON ZAP HEROS":PRINT:PRINT"{RED}{12 SPACES}BEST 5 SC

ORES{OFF}" 2530 PRINT"{HOME}{DOWN}{BLK}{4 DOWN}{14 SPACES}"Al

$"..."Wl 2540 PRINT"{BLU}{2 DOWN}{14 SPACES}"A2$"..."W2 2550 PRINT"{GRN}{2 D0WN}{14 SPACES}"A3$"..."W3 2560 PRINT"{PUR}{2 DOWN}{14 SPACES}"A4$"..."W4 2570 PRINT"{RED}{2 DOWN}{14 SPACES}"A5$"..."W5 2 580 RETURN 2 590 POKE54296,15:POKE5427 7,43:POKE54278,73:POKE54

276,129 2600 FORCO=127T08STEP-17 2610 POKECS,CO

2620 FORT=1TO100:NEXT:NEXTCO:POKECS_/ 11 2630 IFS1=0THENSC=SC+1:GOSUB1890:POKENl,32:N1=1042

:S1 = 1

2640 IFS2=0THENSC=SC+1:GOSUB1890:POKEN2,32:N2=1922

:S2=1 2650 IFS3=0THENSC=SC+1:GOSUB1890:POKEN3,32:N3=1464

:S3=1 2660 IFS4=0THENSC=SC+1:GOSUB1890:POKEN4,32:N4=1502

:S4=1 2670 FORS0=542 72TO542 72+28:POKES0_/0:NEXT:BOM=BOM-1

:GOTO1260 2680 S=542 72:FORE=STOS+28:POKEE,0:NEXT 2690 POKE54296, 15 :POKE54277_# 51 :POKE54278, 84 2700 POKE 54276, 17 :FORJ=1TO40STEP4:POKE 54273,J:

POKE54272,255-J-2 5:NEXT 2710 FORT=lTO 100 :NEXT:POKE54276, 32:F0RT=1T0 50:

NEXT 2 720 FORE=STOS+28:POKEE,0:NEXT:RETURN 2730 PRINT"{HOME}NUMBER 1 ENTER YOUR INITIALS":GOS

UB1745:GOSUB2360:A1$=N5$:GOTO2190

2740 PRINT"{HOME}NUMBER 2 ENTER YOUR INITIALS":GOS UB1745:GOSUB2360:A2$=N5$:GOTO2190

127

Arcade-Style Games

2750 PRINT"{HOME}NUMBER 3 ENTER YOUR INITIALS":GOS UB1745:GOSUB2360:A3$=N5$:GOTO2190

2760 PRINT"{HOME}NUMBER 4 ENTER YOUR INITIALS":GOS UB1745:GOSUB2360:A4$=N5$:GOTO2190

2770 PRINT"{HOME}NUMBER 5 ENTER YOUR INITIALS":GOS UB1745:GOSUB2 360:A5$=N5$:GOTO2190

128

Laser Gunner

Gary R. Lecompte 64 Translation by Philip 1. Nelson___________________

This arcade-style game achieves an impressive graphics animation without the use of any machine language.

"Laser Gunner" is an arcade-type action game. The player controls a laser gun which moves up and down on the left of the screen behind a force field and fires at invading enemy spaceships. The invaders also fire lasers and attempt to open holes in the force field. Every hit weakens the force field until an entire hole is made. A hit through a hole ends the game.

Laser Gunner is an example of animation accomplished without the use of machine language routines. The drawback of this type of programming is obvious. Only one string may be animated at a time with any speed. However, by working your game format around this limitation, you can still make action games fast and challenging.

The animation of the laser gun and the position of laser fire, as well as the location of the invaders, are controlled by the location routines. The row and column values are POKEd into memory locations 214 and 211. A PRINT statement following these routines will print that string beginning at the location determined by the row and column values. Changing the row and column values and printing the same string again accomplishes animation.

The force field changes are made by PEEKing the location of the hit, determining the character at that location, and POKEing the value of the next character to that location.

Invader explosions are done by coding cursor movements and printing characters from the invader string.

Sound routines are intermixed with laser and explosion routines. This assures that animation and sound will blend.

Invader ship location and laser fire are determined by randomizing routines. Skill level is provided by giving the player a minimum preset delay Actual time before invader laser blasts is always unpredictable.

129

Arcade-Style Games

Stars are created with simple POKE statements to predetermined locations.

All routines are placed in order of importance, with those used most at the beginning. This allows for the fastest program execution possible to increase animation speed. REM statements should be deleted for best effect. The key to speed is simplicity. The shorter the program statements, the greater the speed.

Changing the Shapes

It is possible to change the shape of the ships. Lines 85 and 86 contain the statements which produce the shape. To make your own ships, you can use any graphic symbols from the front of the 64 keyboard. Pick the characters you want, and substitute them for the shifted characters within the quotes for IN$, Gl$ and G2$ in lines 85 and 86. Remember, you get the left-side graphic character by holding down the Commodore key rather than SHIFT.

Laser Gunner

5 POKE53280,0:POKE53281,0:GOSUB190:PRINT"{CLR}":GO T085

10 POKEROW,X:POKECOL,Y:PRINT"{UP}"; .-RETURN

11 POKEROW,A:POKECOL,B:PRINT"{UP}";:RETURN

12 POKEROW,Z:POKECOL,B:PRINT"(UP}";:RETURN

13 GOSUB10:PRINTG1$;

14 GOT038

16 TT=TT+1:R=1+INT(RND(1)*10):IFTT>TDTHENIFR=10GOT 043

18 IFPEEK(197)=6THEN29

19 IFPEEK(197)=5THEN23

20 IFPEEK(197)=3THEN26

21 G0T016

23 X=X-1:IFX<1THENX=1

24 GOSUB10:PRINTG1$;:G0T016

26 X=X+1:IFX>21THENX=21

27 GOSUB10:PRINTG2$;:G0T016

29 GOSUB180

30 X=X+1:Y=3:GOSUB10:FORI=1TO185STEP5:PRINT"{PUR}> ";:NEXT::GOSUB10

31 F0RI=1T037:PRINT" ";:NEXT:X=X-1:Y=0

33 IFX+1=ATHEN60

34 IFX+1=A+1THEN60

35 IFX+1=A+2THEN60

36 G0T016

38 A=1+INT(RND(1)*21):IFA<3THENA=3

39 IFA>19THENA=19

41 G0SUB11:PRINTIN$:G0T016

130

Arcade-Style Games

43 GOSUBl70:Z=A+1:B=B-1:GOSUBl2:F0RI=1T072STEP2:PR

INT" {RED}<-{2 LEFT}" ; :NEXT 45 PRINT"{RIGHT}{UP}N{2 DOWN}{LEFT}M":GOSUBl2:FORI

=1T036:PRINT" {2 LEFT}";:NEXT:PRINT"{RIGHT}{UP} {2 DOWN}{LEFT} ":B=B+1

47 HT=SR+((Z-l)*40):RD=PEEK(HT)

48 IFRD=160THENRN=1:GOTO57

49 IFRD=231THENRN=2:GOT057

50 IFRD=234THENRN=3:GOT057

51 IFRD=246THENRN=4:GOT057

52 IFRD=97THENRN=5:GOT057

53 IFRD=117THENRN=6:GOT057

54 IFRD=116THENRN=7:GOT057

55 IFRD=101THENRN=8:GOTO57

56 IFRD=32THENRN=8:GOT068

5 7 FORI=1T0RN:READFE:NEXT:POKEHT,FE:RESTORE:GOTOl6 58 DATA 231,234,246,97,117,116,101,32

60 GOSUBll:PRINT"{RED}{2 LEFT}-* {UP} {YEL} + {2 DOWN} {3 LEFT}{DOWN}{2 LEFT}&*i{DOWN}{RVS}£"

61 FORI=1TO20:NEXT:GOSUB11:PRINT"{2 LEFT} {UP} {2 DOWN}{3 LEFT}{DOWN}{2 LEFT} {DOWN} "

62 GOSUBll:PRINT"{2 UP}{LEFT}£{2 DOWN}{3 LEFT} {RED}M{YEL}T{2 DOWN} {3 LEFT} {YEL}<-{DOWN} {LEFT} {DOWN}{LEFT}"

63 FORI=1TO20:NEXT:GOSUBl1:PRINT"{2 UP}{LEFT} {2 DOWN}{3 LEFT}{2 SPACES}{2 DOWN}{3 LEFT} {DOWN}{LEFT}{DOWN}{LEFT}":GOSUBl60

64 FORI=1TO20:NEXT

65 GOSUBl1:PRINT" {LEFT}{DOWN} {LEFT}{DOWN} {LEFT} {DOWN}":GOSUB77

67 SC=SC+1:TT=0:GOTO38

68 FORI=1TO500:NEXT

70 PRINT"{CLR}{WHT}{3 DOWN}{10 SPACES}YOU HIT";SC; "INVADERS":GOSUB170:GOSUB170:GOSUB160

71 GOSUB160:GOSUB160:GOSUB160:PRINT"{3 DOWN} {14 SPACES}TRY AGAIN?{3 SPACES}"

72 GOSUBl70:GOSUB160:GETC?:IFC$=""THEN72

73 IFC$<>^,,Y"ANDC$o^MN^,,THEN72

74 IFC$="N"THENPRINT"{CLR}":END

75 SC=0:GOTO123

76 REM------GENERATE STARS------------

77 SR=SR-2:P=46

78 POKESR+15,P:POKESR+28,P:POKESR+127,P:POKESR+158 ,P:POKESR+175,P:POKESR+226, P

79 POKESR+330,P:POKESR+460,P:POKESR+474,P:POKESR+3 90,P:POKESR+575,P

80 POKESR+605,P:POKESR+628,P:POKESR+703,P:POKESR+7 15,P:POKESR+730,P

131

^% Arcade-Style Games

81 POKESR+806,P:POKESR+819,P:POKESR+83 7,P:POKESR+8 68,P:POKESR+883,P

82 POKESR+904,P:POKESR+928,P:POKESR+947,P:POKESR+9 64,P:POKESR+992,P

83 SR=SR+2:RETURN

84 REM--------SET VARIABLES------------

85 ROW=214:COL=211:X=5:Y=.:IN$="{YEL}{RVS}£{DOWN} {LEFT} {RVS}«{OFF} {DOWN} {LEFT}g*§ {WHT} ^m :B=39: Gl$="{CYN}{RVS}V{OFF}{DOWN}{LEFT}+{D0WN}{LEFT}

{rvs}v{off}{down}{left} "

86 g2$="tcyn}{up} {down}{left}{rvs}v{off}{down} {left}+{down}{left}{rvs}v{off}":sr=1026:m=21:i=

RND(-Tl)

87 GOSUB77:GOT091

88 REM--------LOCATION ROUTINE--------

89 POKEROW,M:POKECOL,Y:PRINT^M{UP}^M;:RETURN

90 REM-------TITLES TO 118-----------

91 M=M-l:GOSUB89:PRINTGl$;

92 IFM>7THEN91

93 FORI=1TO200:NEXT:GOSUB89

94 PRINT"{DOWN}{2 RIGHT}";:FORI=1TO110STEP10:PRINT

^M{GRN}>^M;:NEXT;PRINT"{RVS} LASER GUNNER {OFF}";

95 GOSUB180:FORI=1TO120STEP10:PRINT">"7:NEXT

96 GOSUB89:PRINT"{DOWN}{2 RIGHT}";:F0RI=1T011:PRIN

T" ";:NEXT:PRINT"{14 RIGHT}";

97 F0RI=1T012:PRINT" ";:NEXT:GOSUB160

98 GOSUB89:M=M+1:PRINT"{DOWN}"G2$;

99 IFM<12THEN98

100 GOSUB89:PRINT"{DOWN}{2 RIGHT}";:FORI=1TO200:NE

101 F0RI=1T0170STEP10:PRINT"{RED}>";:NEXT:GOSUB170

:PRINT^u{PUR}ANⁿ;

102 F0RI=1T0170STEP10:PRINT"{RED}>";:NEXT:GOSUB170

103 GOSUB89:PRINT"{DOWN}{2 RIGHT}";:F0RI=1T017:PRI

NT" "; .-NEXT: PRINT" {2 RIGHT} " ; :F0RI=1T017

104 PRINT" "; .-NEXT

105 GOSUB89:M=M+1:PRINT"{DOWN}"G2$;

106 IFM<16THEN105

107 GOSUB89:PRINT"{DOWN}{2 RIGHT}";:FORI=1TO200:NE

108 FORI=1TO112STEP10:PRINT"{PUR}>";:NEXT:GOSUB170

:PRINT"{YEL}ACTION GAME";

109 F0RI=1T0110STEP10:PRINT"{PUR}>";:NEXT:GOSUB170

110 GOSUB89:PRINT"{DOWN}{2 RIGHT}";:FORI=lT012:PRI

NT" "; .-NEXT: PRINT "{11 RIGHT}";

111 F0RI=1T013:PRINT" ";:NEXT

112 GOSUB89:M=M+1;PRINT"{DOWN}"G2$?

113 IFM<22THEN112

114 GOSUB89:PRINT"{DOWN}{2 RIGHT}";:FORI=1TO200:NE

132

Arcade-Style Games

115

116 117

118 119 120

121 122 123

124 125 126

127 128 129 130 131 132

133 134

135

136

137

138 141

142

143 144

145

146

147

148

FORI=1TO90STEP10:PRINT"{RED}>";:NEXT:GOSUB180: PRINT" {CYNHrVS} WANT INSTRUCTIONS?{OFF}"; FORI=1TO100STEP10:PRINT"{RED}>";:NEXT:GOSUB160 GOSUB89:PRINT"{DOWN}{2 RIGHT}";:F0RI=1T09:PRIN T" ";:NEXT:PRINT"{19 RIGHT}"; FORI=1TO10:PRINT" ";:NEXT

REM-----WANT INSTRUCTIONS-------

GETC$:IFC$=""THENGOSUB170:GOSUB170:GOSUB170:GO

SUB160:GOTO114

IFC$="Y"THEN134

REM------PICK SKILL LEVEL---------

PRINT"{CLR}{YEL}{6 DOWN}{5 SPACES}{RVS}

{2 SPACES}PICK SKILL LEVEL{5 SPACES}(1-3)

{OFF}"

GOSUB170:GETC:IFC=0THEN124

IF0 3THEN124

PRINT"{CLR}{YEL}{6 DOWN}{8 SPACES}{RVS} PRESS

{SPACE}[SPACE] TO BEGIN {OFF}"

GOSUB160:GETC$:IFC$=""THEN127

IFC=1THENTD=15

IFC=2THENTD=8

IFC=3THENTD=0

REM-----BUILD FORCE FIELD---------

PRINT"{CLR}":GOSUB77:PRINT"{HOME}";:FORI=0TO23 :PRINTTAB(2)"{RVS}{GRN} {OFF}":NEXT:GOT013 REM--------INSTRUCTIONS----------

PRINT" {SPACE PRINT" ADERS" PRINT"

INTO" PRINT" OY"

PRINT" PRINT"

FORCE PRINT" D"

PRINT" PRINT" HE GAME" PRINT {RVS} PRINT {OFF} PRINT" {OFF} PRINT" NTINUE

CLR}{DOWN}{2 SPACES}{RVS}{CYN}

LASER GUNNER ON A STARSHIP "

DOWN} YOU ARE UNDER ATTACK BY ALIEN

YOU ARE

INV

DOWN}{5 SPACES}YOU MUST MOVE YOUR LASER

4 SPACES}POSITION, AND FIRE IT TO DESTR

11 SPACES}THE ALIEN SHIP"

2 DOWN}{3 SPACES}YOU ARE PROTECTED BY A

FIELD"

4 SPACES}BUT THE FORCE FIELD IS WEAKENE

SPACES}WITH EVERY HIT BY AN INVADER" DOWN}{5 SPACES}A HIT IN A HOLE ENDS T

DOWN}{7 SPACESjTO MOVE UP----HIT

{OFF} KEY"

SPACES }TO FIRE-------HIT

2 F3

7 SPACES }TO FIRE-------HIT {RVS} F5

KEY"

7 SPACES}TO MOVE DOWN—HIT {RVS} F7 KEY"

2 DOWN}{8 SPACES}{RVS}PRESS SPACE TO CO

OFF}"

133

Arcade-Style Games

149 GETC$:IFC$=^,,HTHEN149

150 GOT0123

155 REM--------SOUND SUBROUTINES-------

160 POKEWl,21:POKEW2,129:FORZ=20TOlSTEP-2:POKEHl,Z •POKEL1 Z

161 POKEH2,INT(RND(1)*70)+3:POKEL2,Z:NEXT:POKEWl,0 :POKEW2,0:RETURN

170 POKEWl,17:POKEW2,129:FORZ=35TO0STEP-7:POKEHl,Z :POKEL1,Z:POKEL2,Z

171 POKEH2,INT(RND(1)*70):NEXT:POKEWl,0:POKEW2,0:R ETURN

180 POKEWl,21:F0RZ=1T03:FORZX=0TO100STEP15:POKEHl, ZX:POKEL1,ZX:NEXT 2 NEXT

181 POKEWl₇0:RETURN

190 POKE54296,15:POKE54277,15:POKE54291,65 :W1=542 76:W2=542902H1=54273 2L1=54272

191 H2=54287:L2=54286:RETURN

134

Using the Machine Language Editor: MLX____________

Charles Brannon

Three of the games in this chapter are written completely in machine language. The "Machine Language Editor" will make typing a perfect copy of those games a snap.

Remember the last time you typed in a long machine language program? You typed in hundreds of DATA statements, numbers, and commas. Even then, you couldn't be sure if you'd typed it in right. So you went back, proofread, tried to run the program, crashed, went back and proofread again, corrected a few typing errors, ran again, crashed, rechecked your typing .... Frustrating, wasn't it?

Until now, though, that has been the best way to enter machine language into your machine. Unless you happen to own an assembler and are willing to wrangle with machine language on the assembly level, it is much easier to enter a BASIC program that reads the DATA statements and POKEs the numbers into memory.

Some of these BASIC loaders will use a checksum to see if you've typed the numbers correctly. The simplest checksum is just the sum of all the numbers in the DATA statements. If you make an error, your checksum will not match up. Some programmers have made your task easier by creating checksums every ten lines, so you can zero in on your errors.

But MLX comes to the rescue! The "Machine Language Editor" (MLX) is a great way to enter all those long machine language programs with a mininum of fuss. MLX lets you enter the numbers from a special list that looks similar to BASIC DATA statements. It checks your typing on a line-by-line basis. It won't

137

f% Machine Language Games

let you enter illegal characters when you should be typing numbers. It won't let you enter numbers greater than 255. It will prevent you from entering the wrong numbers on the wrong line. In short, MLX will make proofreading obsolete.

Boot Disks

In addition, MLX will generate a ready-to-use tape or disk file. You can then use the LOAD command to read the program into the computer, just like any other program. Specifically, you enter:

LOAD "program" 1,1 (for tape) or

LOAD "program", 8,1 (for disk)

To start the program, you need to enter a SYS command that transfers control from BASIC to machine language. The starting SYS will always be given in the appropriate article.

Using MLX

Type in and save MLX (you'll want to use it in the future). When you're ready to type in the machine language program, RUN MLX. The program will ask you for two numbers: the starting address and the ending address. Below is a table that lists this information for each of the games that use MLX.

Starting and Ending Addresses

Game Start address End address Command to Run

Munchmaze 12288 13956 SYS 12311

Richthofen's 2049 5817 RUN or SYS 2063

Revenge

ZuiderZee 49152 52040

Once you have entered the starting and ending addresses, you'll get a prompt to start entering the data. The prompt is the current line you are entering from the listing. Each line is six numbers plus a checksum. If you enter any of the six numbers wrong, or enter the checksum wrong, the 64 will ring the buzzer and prompt you to reenter the line. If you enter it correctly, a pleasant bell tone will sound, and you go on and enter the next line.

A Special Editor

You are not using the normal Commodore 64 editor with MLX. For example, MLX will accept only numbers as input. If you need to make a correction, press the <INST/DEL> key; the entire

138

Machine Language Games

number is deleted. You can press it as many times as necessary to get back to the start of the line. If you enter three-digit numbers as listed, the computer will automatically print the comma and go on to accept the next number. If you enter less than three digits, you can press either the comma, space bar, or RETURN key to advance to the next number. The checksum will automatically appear in inverse video; don't worry—it's highlighted for emphasis.

When testing it, I've found it to be extremely easy to enter long listings. With the audio cues provided, you don't even have to look at the screen if you're a touch-typist.

When you get through typing, assuming you type it all in one session, you can then save the completed and bug-free program to tape or disk. Follow the screen instructions. If you get any errors while writing, you probably have a bad disk, or the disk was full, or you made a typo when entering the MLX program. (Sorry, it can't check itself.)

Command Control

What if you don't want to enter the whole program in one sitting? MLX lets you enter as much as you want, save the whole schmeer, and then reLOAD the file from tape or disk when you want to continue. MLX recognizes these few commands:

SHIFT-S: Save SHIFT-L: Load SHIFT-N: New Address SHIFT-D: Display

Hold down SHIFT while you press the appropriate key. You will jump out of the line you've been typing, so I recommend you do it at a new prompt. Use the Save command to save what you've been working on. It will write the tape or disk file as if you've finished, but the tape or disk won't work, of course, until you finish the typing. Remember what address you stop on. The next time you RUN MLX, answer all the prompts as you did before, then insert the disk or tape. When you get to the entry prompt, press SHIFT-L to reLOAD the file into memory. You'll then use the New Address command to resume typing.

New Address and Display

After you press SHIFT-N, enter the address where you previously stopped. The prompt will change, and you can then continue typing. Always enter a New Address that matches up with one of the line numbers in the special listing, or else the checksum won't

139

f% Machine Language Games

match up. You can use the Display command to display a section of your typing. After you press SHIFT-D, enter two addresses within the line number range of the listing. You can abort the listing by pressing any key.

Tricky Stuff

The special commands may seem a little confusing, but as you work with MLX, they will become valuable. For example, what if you forgot where you stopped typing? Use the Display command to scan memory from the beginning to the end of the program. When you see a bunch of 170s, stop the listing (press a key) and continue typing where the 170s start. Some programs contain many sections of 170s. To avoid typing them, you can use the New Address command to skip over the blocks of 170s. Be careful, though; you don't want to skip over anything you should type.

You can use the Save and Load commands to make copies of the completed game. Use the Load command to reLOAD the tape or disk, then insert a new tape or disk and use the Save command to create a new copy.

One quirk about tapes made with the Save command: when you load them, the message "FOUND program" may appear twice. The tape will load just fine, however.

Programmers will find MLX an interesting program, in protecting the user from mistakes. There is also some screen formatting. Most interesting is the use of ROM Kernal routines for LOADing and SAVEing blocks of memory. Just POKE the starting address (low byte/high byte) into 251 and 252, and POKE the ending address into 254 and 255. Any error code can be found in location 253 (an error would be a code less than ten).

I hope you will find MLX to be a true labor-saving program. Since it has been tested by entering actual programs, you can count on it as an aid for generating bug-free machine language.

MLX

100 PRINT"{CLR}{RED}^M;CHR$(142);CHR$(8);:POKE53281 ,1:POKE53280,1

101 POKE 788,52:REM DISABLE RUN/STOP 110 PRINT"{RVS}{40 SPACES}";

120 PRINT"{RVSH15 SPACES}{RIGHT}{OFF}i*3£{RVS} {RIGHT} {RIGHT}{2 SPACES}g*§{OFF}g*§£ {RVS}£{RVS}{13 SPACES}";

140

Machine Language Games

130 PRINT"{RVS}{15 SPACES}{RIGHT} &G3tRIGHT} {2 RIGHT} tOFF}£{RVS}£g*3{OFF}B*§{RVS} {13 SPACES}"7

140 PRINT"{RVS}{40 SPACES}"

150 V=53248;POKE2040,13:POKE2041,13:FORI=832TO894:

POKEI,255:NEXT:POKEV+27,3 160 POKEV+21,3:POKEV+39,2:POKEV+40,2;POKEV,144:POK

EV+1,54:POKEV+2 , 192:POKEV+3,54 170 POKEV+29_f3 180 FORI=0TO23:READA:POKE679+I,A:POKEV+39,A:POKEV+

40_fA:NEXT 185 DATA169,251,166,254,164,255,32,216,255,133,253

,96

187 DATA169,0,166,251,164,252,32,213,255,133,253,9

6 190 POKEV+39,7:POKEV+40,7 200 PRINT"{2 DOWN}{PUR}{BLK}{3 SPACESjA FAILSAFE M

ACHINE LANGUAGE EDITOR{5 DOWN}" 210 PRINT"E53l2 UPjSTARTING ADDRESS?{8 SPACES}

{9 LEFT}";:INPUTS:F=1-F:C$=CHR$(31+119*F) 220 IFS<256OR(S>40960ANDS<49152)ORS>53247THENGOSUB

3000:GOTO210 225 PRINT:PRINT:PRINT 230 PRINT"E53{2 UP}ENDING ADDRESS?{8 SPACES}

{9 LEFT}";:INPUTE:F=1-F:C$=CHR$(31+119*F) 240 IFE<256OR(E>40960ANDE<49152)ORE>53247THENGOSUB

3000:GOTO230 250 IFE<STHENPRINTC$;"{RVS}ENDING < START

{2 SPACES}":GOSUB1000:GOTO 230 260 PRINT:PRINT:PRINT

300 PRINT"{CLR}";CHR$(14):AD=S:POKEV+21,0 310 PRINTRIGHT$("0000"+MID$(STR$(AD),2),5);":";:FO

RJ=1T06 320 GOSUB570sIFN=-lTHENJ=J+N:GOTO320

390 IFN=-211THEN 710 400 IFN==-204THEN 790 410 IFN=-206THENPRINT:INPUT"{DOWN}ENTER NEW ADDRES

S";ZZ 415 IFN*-206THENIFZZ<SORZZ>ETHENPRINT"{RVS}OUT OF

{SPACE}RANGE":GOSUB1000:GOTO410 417 IFN=-206THENAD*ZZ:PRINT:GOT0310 420 IF NO-196 THEN 480

430 PRINT:INPUT"DISPLAY:FROM";F:PRINT,"TO";:INPUTT 440 IFF<SORF>EORT<SORT>ETHENPRINT"AT LEAST";S;"

{LEFT}, NOT MORE THAN";E;GOTO430

450 FORI=FTOTSTEP6;PRINT;PRINTRIGHT$("0000"+MID$(S TR$(I),2),5);":^H;

451 FORK=0TO5:N=PEEK(I+K)iPRINTRIGHT$("00"+MID$(ST R$(N),2),3);",";

141

y% Machine Language Games

460 GETA$:IFA$ >""THENPRINT:PRINT:G0T0310

470 NEXTK:PRINTCHR?(20);:NEXTI:PRINT:PRINT:G0T0310

480 IFN<0 THEN PRINT:GOTO310

490 A(J)=N:NEXTJ

500 CKSUM=AD-INT(AD/256)*256:F0RI=1T06:CKSUM=(CKSU

M+A(I))AND255:NEXT 510 PRINTCHR$(18);:GOSUB570:PRINTCHR$(20) 515 IFN=CKSUMTHEN530 520 PRINT:PRINT"LINE ENTERED WRONG : RE-ENTER":PRI

NT:GOSUB1000:GOTO310 530 GOSUB2000 540 F0RI=1T06:POKEAD+I-1,A(I):NEXT:POKE54272,0:POK

E54273,0 550 AD=AD+6:IF AD<E THEN 310 560 GOTO 710 570 N=0:Z=0

580 PRINT "E+-I" 7

581 GETA$:IFA$=""THEN581

585 PRINTCHR?(20);:A=ASC(A$):IFA=130RA=440RA=32THE

N670 590 IFA>128THENN=-A:RETURN 600 IFA<>20 THEN 630 610 GOSUB690:IFI=1ANDT=44THENN=-1:PRINT"{LEFT}

{LEFT}";:GOTO690 620 GOTO570

630 IFA<48ORA>57THEN580 640 PRINTA$; :N=N*10+A-48

650 IFN>255 THEN A=20:GOSUB1000:GOTO600 660 Z=Z+1:IFZ<3THEN580 670 IFZ=0THENGOSUB1000:GOTO570 680 PRINT",";:RETURN

690 S%=PEEK(209)+256*PEEK(210)+PEEK(211)

691 FORI=lT03:T=PEEK(S%-l)

695 IFT<>44ANDT<>58THENPOKES%-I,32:NEXT

700 PRINTLEFT$("{3 LEFT}",1-1);:RETURN

710 PRINT" {CLRHRVS}*** SAVE ***{3 DOWN}"

720 INPUT"{DOWN} FILENAME";F$

730 PRINT:PRINT"{2 DOWN}{RVS}T{OFF}APE OR {RVS}D

{OFFjlSK: (T/D)" 740 GETA$:IFA$<>"T"ANDA$<>"D"THEN740 750 DV=l-7*(A$="D"):IFDV=8THENF$="0:"+F$ 760 OPEN l_/DV_#l_#F$:POKE252,S/256:POKE251,S-PEEK(25

2)*256 765 POKE255,E/256:POKE254,E-PEEK(255)*256 770 POKE253,10:SYS 679:CL0SE1:IFPEEK(253)>90RPEEK(

253)=0THENPRINT"{DOWN}DONE.":END 780 PRINT"{DOWN}ERROR ON SAVE.{2 SPACES}TRY AGAIN.

":IFDV=1THEN720

142

Machine Language Games

781 OPENl5,8,15:INPUT#15,DS,DS$:PRINTDS;DS$:CLOSE1

5:GOTO720 790 PRINT" {CLRHRVS}*** LOAD ***{2 DOWN}" 800 INPUT"{2 DOWN} FILENAME";F$ 810 PRINT:PRINT"{2 DOWN}{RVS}T{OFF}APE OR {RVS}D

{OFFjlSK: (T/D)" 820 GETA$:IFA$ <>"T"ANDA$ < >"D"THEN820 830 DV=l-7*(A$="D"):IFDV=8THENF$="0:"+F$ 840 OPEN 1,DV_#0_/F$:POKE252,S/256:POKE251,S-PEEK(25

2)*256 850 POKE253,10:SYS 691:CL0SE1 860 IFPEEK(253)>9 OR PEEK(253)=0 THEN PRINT:PRINT:

GOTO310 870 PRINT"{DOWN}ERROR ON LOAD.{2 SPACES}TRY AGAIN-

{DOWN}":IFDV=1THEN800 880 OPEN15,8,15:INPUT#15,DS,DS$:PRINTDS;DS$:CLOSEl

5:GOTO800

1000 REM BUZZER

1001 POKE54296,15:POKE54277,45:POKE54278,165

1002 POKE54276,33:POKE 54273,6:POKE54272,5

1003 FORT=1TO200:NEXT:POKE54276,32:POKE54273,0:POK E54272,0:RETURN

2000 REM BELL SOUND

2001 POKE54296,15:POKE54277,0:POKE54278,247

2002 POKE 54276,17:POKE54273,40:POKE54272,0

2003 FORT=1TO100:NEXT:POKE54276,16:RETURN

3000 PRINTC$;"{RVS}NOT ZERO PAGE OR ROM":GOTO1000

143

Munchmaze

Gary E. Marsa 64 Translation by Gregg Peele

"Munchmaze" is a fast-action strategy game. Since it is written in machine language, it requires the use of the Machine Language Editor (MLX)for mistake-proof entering.

The character in ^//Munchmaze^,, hurries through the maze dropping bread crumbs as it goes. You move your character around by using the I, J, K, and M keys trying to munch up as many of the bread crumbs as you can before the character catches you. The game ends when the two characters collide or when you accumulate 10,000 points.

There are three speed levels: slow, moderate, and fast. Both characters move at the same speed, but the computer character beats you on the corners. Also, you have to change directions manually; it doesn't. The computer character always goes left if it can; it's helpful to remember this when you are looking for a temporary hiding place.

There's another tricky feature, too. Sometimes, when the two characters are moving from opposite directions toward each other, the computer character goes right on by and no collision occurs. Just breathe a sigh of relief and continue munching—you were lucky.

The maze in Munchmaze is not constructed on the screen, but in another area of RAM. It is then transferred to the screen, where it appears all at once; then there is a one-second delay before the action begins. If you break out of the program for any reason, just type SYS 12331 and RETURN to restart.

Typing in Munchmaze

This program is written entirely in machine language, so it is necessary to enter it using the Machine Language Editor (MLX) found at the beginning of this chapter. Be sure to read the directions for using the MLX.

The information needed to enter Munchmaze with the MLX is:

144

Machine Language Games

Starting address: 12288 Ending address: 13956

Once Munchmaze is saved to disk or tape, the procedure for loading the program is as follows: From disk: type

LOAD "MUNCHMAZE", 8,1

From tape: type

LOAD"", 1,1

When the program is loaded into memory, type SYS 12311 to run it.

Munchmaze

12288 :020,004,010,000,088,178,044

12294 :187,040,171,084,073,041,090

12300 :058,158,049,048,052,056,177

12306 :000,000,000,234,234,169,143

12312 :021,141,024,208,169,000,075

12318 :141,096,010,141,097,010,013

12324 :169,147,032,210,255,169,250

12330 :007,162,000,157,000,216,072

12336 :157,000,217,157,000,218,029

12342 :157,000,219,232,208,241,087

12348 :169,120,141,229,051,169,171

12354 :052,141,230,051,162,031,221

12360 :169,005,032,220,051,169,206

12366 :000,141,098,010,141,099,055

12372 :010,133,162,024,165,161,227

12378 :105,002,133,166,165,161,054

12384 :197,166,208,250,169,147,209

12390 :032,210,255,169,000,162,162

12396 .-000,157,000, 216,157,000,126

12402 :217,157,000,218,157,000,095

12408 :219,232,208,241,032,168,196

12414 :051,162,039,169,160,157,096

12420 -.039,004,157,151,007,202,180

12426 :208,247,169,080,133,168,119

12432 :169,004,133,169,162,021,034

12438 :160,000,169,160,145,168,184

12444 :160,038,145,168,032,250,181

12450 :051,202,208,240,169,119,127

12456 :141,229,051,169,053,141,184

12462 :230,051,162,166,169,004,188

12468 2032,220,051,162,000,169,046

12474 :032,157,000,011,157,000,031

12480 :012,157,000,013,157,000,019

12486 :014,232,208,241,169,081,119

145

f% Machine Language Games

12492	:133	,168	,169	,040	,133	,170	,249
12498	:169	_r011	_r133	,169	133	,171	,228
12504	:162	,000	,160	,000	169	,160	,099
12510	:145	,170	,200	,192,	039	208	152
12516	:249	,024	,165	,170	105	040	,213
12522	:133	,170	,144	,002	230	,171	,060
12528	:232	224	,023	,208	229	160	036
12534	:000	,169	,004	,145,	,168	,032	,252
12540	:151	224	,165	143	041	003	211
12546	:133	,165	,170	010	168	024	,160
12552	:185	075	,052	101	168	133	,210
12558	:180	,185	,076	,052	,101	,169	,009
12564	:133	,181	,024	,185	,075	,052	,158
12570	:101	,180	,133	,170	,185,	076	,103
12576	:052	,101	,181	,133	171	160	,062
12582	:000	,177	,170	,201	160	,208	,186
12588	:018	,138	,145	,170	,169	,032	,204
12594	:145	,180	,165	,170	,133	,168	,243
12600	:165,	,171	,133	,169,	076	,251	,253
12606	:048	232	,138	,041	003	,197	,209
12612	:165	,208	,189	,177	168	170	121
12618	:169	032	,145	,168,	224	004	,048
12624	*240,	026	,138	,010	168	162	,056
12630	:002	,056	,165	,168,	249	075	,033
12636	:052	,133	,168	,165,	169,	249	,004
12642	:076	,052	,133	,169,	202	208	,170
12648	:238	,076	,251	,048	169	,013	,131
12654	:141	,229	,051	,169	054	,141	,127
12660	:230,	051	,162	,006,	138,	032	,223
12666	:220,	,051	,032,	,228,	255,	,208	,092
12672	:251,	032	228	255,	240,	251	105
12678	.-201,	081	,208	032	169	147	204
12684	:032,	210	,255	,169,	000	162	,200
12690	:000,	157	,000,	,216,	157,	000	,164
12696	:217,	157	000	218,	157,	000	133
12702	.-219,	232	,208	241,	032	168	234
12708	:051,	169	013	076,	210,	255,	170
12714	:201,	049	,048	211,	201	,052	,164
12720	:016,	207	056	,233,	048	133	101
12726	:166,	169	,147	,032,	210	,255	,137
12732	:169,	000	162,	000,	157	000	164
12738	:216,	157	,000	217,	157,	000	,173
12744	1218,	157	,000,	219,	232,	208,	210
12750	.-241,	162	,000	189,	000	,011.	,041
12756	:157,	000,	004,	189,	000,	012,	062
12762	1157,	000,	005,	189,	000,	013,	070
12768	:157,	000	,006	189,	000,	014	,078
12774	.-157,	000	,007	232,	208,	229	,039
12780	:032	168	,051	,024	165	166	,074

146

Machine Language Games

147

12786 :105,176,141,000,004,141,041

12792 1038,004,024,165,162,105,234

12798 :060,133,254,165,162,197,201

12804 :254,208,250,169,081,133,075

12810 :168,133,180,169,004,133,029

12816 :169,133,181,169,001,133,034

12822 :254,162,002,134,165,160,131

12828 :000,169,102,145,168,169,013

12834 :000,133,162,166,165,138,030

12840 ;010,168, (0^41185,075,052,042

12846 :101,168,T3^,170,185,076,111

12852 :052,101,169,133,171,160,070

12858 :000,177,170,201,160,208,206

12864 :009,202,138,041,003,133,078

12870 :165,076,037,050,201,081,168

12876 :208,003,076,004,051,169,075

12882 :102,145,170,169,058,145,103

12888 :168,165,170,133,168,165,033

12894 :171,133,169,232,138,041,210

12900 :003,133,165,165,254,240,036

12906 :008,160,000,132,254,169,061

12912 :081,145,180,162,000,165,077

12918 :197,221,083,052,240,008,151

12924 -.232,224, 004, 208, 246,076,090

12930 :183,050,138,010,168,024,191

12936 :185,075,052,101,180,133,094

12942 :195,185,076,052,101,181,164

12948 :133,196,160,000,177,195,241

12954 :201,160,240,025,201,058,015

12960 :208,003,032,006,052,160,109

12966 :000,169,081,145,195,169,157

12972 :032,145,180,165,195,133,254

12978 :180,165,196,133,181,165,174

12984 :162,197,166,208,250,173,060

12990 :098,010,201,016,208,061,016

12996 :173,099,010,201,039,208,158

13002 :054,169,081,133,168,169,208

13008 :004,133,169,162,000,160,068

13014 :000,177,168,201,058,208,002

13020 -.007,032,006,052,169,032,006

13026 :145,168,200,192,037,208,152

13032 :238,032,250,051,232,224,235

13038 :021,208,228,162,000,189,022

13044 :093,054,240,006,157,051,077

13050 :004,232,208,245,076,127,118

13056 :051,076,033,050,169,102,225

13062 -.145,170,169,058,145,168,093

13068 :165,180,133,168,165,181,236

13074 :133,169,056,165,168,233,174

Machine Language Games

148

13080 :041,133,170,165,169,233,167

13086 :000,133,171,169,240,133,10s

13092 :166,169,255,133,162,165,062

13098 .-170,133,180,165,171,133, 226

13104 .-181,169,000,133,165,160,088

13110 :000,162,000,177,180,221,026

13116 :087,052,240,005,232,224,132

13122 :008,208,246,134,253,056,203

13128 :169,007,229,253,170,189,065

13134 :087,052,145,180,200,192,166

13140 :003,208,224,024,165,180,120

13146 .-105,040,133,180,144,002,182

13152 .-230,181,230,165,165,165,208

13158 :201,003,208,203,165,162,020

13164 .-208,252,198,166,208,179,039

13170 :162,000,189,110,052,240,099

13176 .-006,157,055,004,232,208,014

13182 .-245,056,173,098,010,237,177

13188 z096,010,141,100,010,173,150

13194 :099,010,237,097,010,013,092

13200 :100,010,240,017,144,015,158

13206 :173,098,010,141,096,010,166

13212 :173,099,010,141,097,010,174

13218 :032,194,051,076,077,048,128

13224 :162,000,189,095,052,240,138

13230 :006,157,006,004,232,208,019

13236 .-245,162,000,189,104,052,164

13242 :240,006,157,022,004,232,079

13248 ;208,245,172,096,010,173,072

13254 :097,010,032,145,179,032,181

13260 :221,189,162,000,189,000,197

13266 .-001,240,006,157,027,004,133

13272 :232,208,245,096,134,168,019

13278 :133,169,162,000,160,000,078

13284 .-189,120,052,240,010,201,016

13290 .- 255, 240,012,145,168, 200, 230

13296 :232,208,241,032,250,051,230

13302 :232,208,233,096,024,165,180

13308 :168,105,040,133,168,144,242

13314 :002,230,169,096,138,072,197

13320 :152,072,024,173,098,010,025

13326 .-105,002,141,098,010,144,002

13332 :003,238,099,010,162,000,020

13338 :181,168,072,232,224,008,143

13344 :208,248,172,098,010,173,173

13350 .-099,010,032,145,179,032,023

13356 :221,189,162,000,189,000,037

13362 s001,240,006,157,012,004,214

13368 :232,208,245,162,008,104,247

Machine Language Games

13374 :149,167,202,208,250,104,118

13380 :168,104,170,096,234,234,050

13386 :234,001,000,216,255,255,011

13392 :255,040,000,037,033,034,223

13398 :036,160,032,058,102,170,132

13404 :186,127,255,019,003,015,185

13410 :018,005,058,032,048,000,003

13416 :008,009,007,008,058,000,194

13422 :135,129,141,133,160,143,183

13428 :150,133,146,000,079,077,189

13434 :032,032,078,080,099,080,011

13440 :032,079,099,079,077,032,014

13446 :079,080,078,099,099,099,156

13452 :077,079,080,032,079,080,055

13458 :000,101,032,077,078,032,210

13464 :103,032,103,032,101,032,043

13470 :101,032,077,101,103,032,092

13476 :032,079,076,100,101,103,143

13482 :032,101,103,000,101,032,027

13488 :032,032,032,103,032,103,254

13494 :032,101,032,101,032,032,000

13500 :032,103,032,032,101,032,008

13506 :032,101,032,099,032,103,081

13512 :000,101,103,077,078,101,148

13518 :103,032,103,100,101,032,165

13524 :101,103,077,032,103,032,148

13530 :032,076,079,099,101,103,196

13536 :099,101,103,000,076,122,213

13542 :032,032,076,122,077,100,157

13548 :100,100,078,076,122,032,232

13554 :077,122,077,100,100,100,050

13560 :078,076,122,032,076,122,242

13566 :000,000,160,223,032,032,189

13572 :233,231,032,233,160,223,092

13578 :032,160,160,160,160,231,145

13584 :160,160,160,160,160,032,080

13590 :002,025,000,160,160,223,080

13596 : 233,160,231,233,160,226,247

13602 :160,223,032,032,233,160,106

13608 :105,160,160,000,160,160,017

13614 :160,160,160,231,160,160,053

13620 :098,160,231,032,233,160,198

13626 :105,032,160,160,160,160,067

13632 :032,032,007,001,018,025,179

13638 :000,160,160,095,105,160,238

13644 :231,160,160,226,160,231,220

13650 :233,160,105,032,032,160,036

13656 :160,000,160,160,032,032,120

13662 :160,231,160,160,032,160,229

Machine Language Games

13668 13674 13680 13686 13692 13698 13704 13710 13716 13722 13728 13734 13740 13746 13752 13758 13764 13770 13776 13782 13788 13794 13800 13806 13812 13818 13824 13830 13836 13842 13848 13854 13860 13866 13872 13878 13884 13890 13896 13902 13908 13914 13920 13926 13932 13938 13944 13950 13956

231,160, 160,160, 013,001, 255,032, 032,032, 022,005, 032,034, 019,009, 032,032, 032,032, 012,005, 019,058, 032,032, 060,067, 032,032, 013,015, 016,000, 032,032, 032,061, 005,032, 000,032, 032,032, 061,032, 032,018, 000,032, 032,032, 061,032, 032,004, 255,160, 032,032, 019,005, 005,004, 020,015, 160,032, 032,061, 044,032, 013,015, 020,005, 061,032, 000,000, 032,032, 032,032, 016,018, 145,032, 021,009, 153,143, 160,129, 146,161, 255,255,

160,160, 160,160, 018,019, 032,032, 032,032, 032,020, 081,034, 014,007, 030,032, 020,008, 020,020, 032,032, 032,093, 081,067, 009,032, 022,005, 032,032, 032,032, 032,013, 012,005, 032,032, 032,032, 013,015, 009,007, 032,032, 032,032, 013,015, 015,023, 032,160, 003,008, 032,019, 032,006, 018,058, 160,032, 006,001, 178,032, 004,005, 044,032, 019,012, 160,032, 032,032, 032,032, 005,019, 020,015, 020,046, 149,167, 137,142, 161,032, 255,255,

160,231, 160,032, 001,000, 009,032, 013,015, 008,005, 032,021, 000,032, 032,032, 005,032, 005,018, 032,000, 000,010, 062,011, 061,032, 032,021, 032,093, 032,010, 015,022, 006,020, 022,032, 011,032, 022,005, 008,020, 013,032, 013,032, 022,005, 014,000, 032,032, 015,015, 016,005, 001,003, 000,000, 032,177, 019,020, 061,032, 018,001, 179,032, 015,023, 160,032, 032,032, 032,032, 019,032, 032,017, 000,255, 146,133, 142,133, 255,032, 255,255,

178 170 164 254 024 222 114 223 082 027 240 083 115 014 126 042 145 116 127 038 114 141 124 076 129 167 148 094 171 123 120 081 147 123 187 177 116 122 234 206 020 026 205 107 203 237 195 145 126

150

Richthofen's Revenge________

Chris Metcalf Marc Sugiyama

"Richthofen's Revenge" is an arcade-style game that even the most experienced game players will find challenging. This program requires special care to enter correctly; please see the section "Typing in the Program"

The airborne forces of Richthofen, the dreaded Red Baron, have been mobilized. Because of your reputation as a swift pilot and accurate gunner, you have been chosen to defend the front line. Only a few planes are available, with no time to build more. Prepare yourself to meet the hordes of Richthofen.

As you encounter each succeeding wave of the enemy, another airplane will be delivered to the front. Once all the planes have been destroyed, however, there will be nothing to stop the enemy from an all-out invasion. Your skills are all that stand between Richthofen's forces and your country.

Typing in the Program

This program is written entirely in machine language, so it should be entered using the Machine Language Editor (MLX) found earlier in this chapter.

The steps to typing in a machine language program using MLX are simple, but they must be followed exactly in order to get a playable copy of the game. Once you have a copy of "Richthofen's Revenge" saved on disk or tape, you will be able to LOAD and RUN it just as you would any BASIC program even though it is machine language.

The steps for typing in Richthofen's Revenge are:

1. Reset the computer by turning it off, then back on.

2. Type this line:

POKE 44,23:POKE 23*256,0;NEW

3. LOAD the Machine Language Editor into memory.

(If you have not typed in and SAVEd MLX, you will have to do that first.)

151

y% Machine Language Games

4. RUN the MLX program.

5. Answer the prompts

START ADDR: 2049 END ADDR: 5817

6. Type in the data.

7. MLX will prompt you for a filename.

8. Before you load the program, reset the computer. That's all there is to it. It is not necessary to type in all the

data in one session. The instructions for using MLX are at the beginning of this chapter. If you do decide to enter the data in more than one session, it will be necessary to follow the above steps each time you begin a session.

Preparing for Battle

When you first RUN the game, the screen will come up with a landscape, a status line, and the message RICHTHOFEN'S REVENGE. The information given in the status line is the high score, the score of the current game, and the number of backup planes remaining. A short tune will play to prepare you for the combat.

When the message PRESS FIRE TO BEGIN appears, you may begin playing or move to a higher level. By moving the joystick up or down, you can pick any level from 1 to 30. Levels 31 through 40 are reserved for expert players, and the levels above that are only for the true masters.

Once you have selected a level, or at any point after the music begins, you may press the fire button and begin playing. Every time you enter a level, or when a new plane is called up, you begin at the very top of the screen. This area is off-limits to Rich-thofen's forces due to their limited flight ceilings. However, once you go down into their midst, you too are sealed off from this high-altitude bracket for the duration of the level.

Your Opponents

Richthofen is employing three types of aircraft. Surveillance balloons patrol the areas they have been assigned to in accordance with random wind currents. These have been judged least important by the Air Force (50 points each). The remainder of the enemy forces consists of two types of aircraft: the main attack force, consisting of blue-green planes which always fly west, and the equally important red spy craft. Both types are worth 75 points each.

152

Machine Language Games

Some strategies and tips have been given to you by Air Force command. Although your aircraft can dodge mountains and the like without any danger, a number of civilian residences are scattered throughout the combat area. These present a very definite threat to navigation. You can neither fly nor fire through them. Furthermore, the explosions of the enemy craft are deadly to you.

Air Force Briefing

The Air Force has also given you a short list of pointers for fighting the enemy. You will find that balloons are often extremely difficult to hit. This problem may be at least partially remedied by the use of the rapid-fire aspect of your controller. Holding down the fire button will cause your machine gun to fire rapidly after a slight initial delay At times you may find yourself flying on and on without encountering any enemy craft. Often the problem is that the few surviving enemy fighter planes are going in the same direction as yourself. In such cases, simply turn and wait for them. To determine how far you are from the end of a level, consult the table below.

One final item is of some importance to you as a fighter pilot. The first planes sent out to you were of undeniably high quality and workmanship. The components were all painstakingly hand-formed, and the result was an airplane that could achieve an unusually high speed—enough, in fact, to overtake even the enemy fighter pilots. But as the production of these airplanes increased, the quality declined. Thus as you continue to play, you will find that your planes lose efficiency, until after a number of levels your top speed is barely that of the enemy planes.

Several keyboard controls have been included in the program. Pressing f7 causes all game action and sound to stop until the key is pressed again or the fire button pushed. RUN/ STOP has the same effect. F8 ends the program, leaving your country to Richthofen's mercy. F3 turns the sound of your engines on and off, but leaves the noise of shooting and explosions as always. Fl functions as a reset key, checking for a high score then returning you to the initial display.

A variety of melodies has been included in the program. All of them may be skipped by pressing the fire button on your joystick.

153

Levels of Play

Play Number Accumulated

Level of Enemy Score

1 12 650

2 16 1650

3 20 2900

4 24 4400

5 24 5900

6 24 7400

7 24 9000

8 28 10800

9 28 12600

10 28 14400

11 28 16300

12 32 18400

13 32 20500

14 32 22700

15 36 25100

16 36 27500

17 36 30000

18 40 32600

19 40 35200

20 40 37700

21 44 39800

22 44 42750

23 44 45550

24 48 48650

25 48 51850

26 48 55100

27 52 58500

28 52 61900

29 52 65450

30 56 69150

31 56 72850

32 56 76650

33 60 80650

34 60 84750

35 60 88850

36 64 93050

37 64 97300

38 64 101350

39 64 105725

40 64 110100

41 64 113300

42 64 118100

43 64 122900

44 64 127275

45 64 130475 etc.

Machine Language Games

RichthoferTs Revenge

2049 :013,008,100,000,158,040,064

2055 :050,048,054,051,041,000,251

2061 :000,000,165,001,041,254,218

2067 :133,001,169,197,141,000,148

2073 .-221,169,000,141,023,208,019

2079 :141,029,208,141,027,208,017

2085 :032,006,017,169,003,141,149

2091 :178,002,169,027,141,017,065

2097 :208,169,172,141,000,208,179

2103 :169,011,141,032,208,169,017

2109 :014,141,033,208,169,000,114

2115 :141,034,208,169,012,141,004

2121 :035,208,162,127,169,000,006

2127 :157,000,168,202,016,250,104

2133 :162,032,189,03 3,017,157,163

2139 :015,168,189,066,017,157,191

2145 :079,168,202,016,241,160,195

2151 :000,185,099,019,153,000,047

2157 .-176,200,192,144,208,245,250

2163 :160,000,185,179,019,153,043

2169 :000,177,200,192,168,208,042

2175 :245,160,000,185,091,020,060

2181 .-153,000,178,200,192,208,040

2187 :208,245,169,160,141,032,070

2193 :164,169,000,141,000,164,015

2199 :168,185,000,164,024,105,029

2205 :040,153,001,164,185,032,220

2211 :164,105,000,153,033,164,014

2217 :200,192,025,208,234,169,173

2223 :000,141,175,002,141,176,042

2229 :002,141,177,002,169,255,159

2235 :141,168,002,169,001,133,033

2241 :033,120,169,127,141,013,028

2247 :220,169,001,141,026,208,196

2253 :169,000,141,018,208,173,146

2259 :017,208,041,127,141,017,250

2265 .-208,173,020,003,141,123,117

2271 :016,173,021,003,141,124,189

2277 :016,169,072,141,020,003,138

2283 :169,016,141,021,003,088,161

2289 :169,000,141,172,002,141,098

2295 :173,002,141,174,002,169,140

2301 :004,141,183,002,173,168,156

2307 :002,141,167,002,169,001,229

2313 -141,033,208,169,160,141,093

2319 .-136,002,169,147,032,210,199

2325 :255,169,004,141,136,002,216

2331 :169,006,141,033,208,160,232

Machine Language Games

2337 2343 2349 2355 2361 2367 2373 2379 2385 2391 2397 2403 2409 2415 2421 2427 2433 2439 2445 2451 2457 2463 2469 2475 2481 2487 2493 2499 2505 2511 2517 2523 2529 2535 2541 2547 2553 2559 2565 2571 2577 2583 2589 2595 2601 2607 2613 2619 2625

023,	185,	105,	021,	153,
163,	136,	016,	247,	169,
141,	187,	163,	160,	002,
000,	185,	175,	002,	032,
015,	157,	179,	163,	165,
157,	180,	163,	232,	232,
016,	237,	169,	001,	133,
238,	167,	002,	173,	167,
201,	043,	144,	005,	169,
141,	167,	002,	160,	063,
255,	153,	064,	164,	136,
250,	172,	167,	002,	185,
021,	072,	141,	180,	002,
172	021,	072,	024,	109,
002,	141,	180	002,	185,
021,	170,	024,	109,	180,
141	180,	002	160,	000,
000	,240,	009	,169	001,
064	164,	200	202	208,
104	,170,	240	,009	,169,
153	,064	164	,200	,202,
249,	104,	170,	240,	009,
003,	153,	064,	164,	200,
208	249,	160	063,	032,
015	041,	031	056	233,
048	246,	201,	002,	144,
153	192,	164	032,	148,
153	128,	164	136,	016,
169	130,	133	025,	032,
017	173,	183	002,	032,
015	141,	188	163,	165,
141	189	163	169	049,
001	208	169	141	141,
208	169	003	141	039,
169	011	141	032	208,
000	141	028	208	169,
141	248	163	169	001,
021	,208	,169	,000	141,
002	133	032	,173	031,
165	,027	,208	,010	,165,
240	,003	032	,241	010,
006	,011	173	,178	002,
179	,002	032	,237	013,
000	,133	,027	,160	018,
001	,153	,153	,217	,152,
105	,128	,153	,154	,161,
007	_r185	,043	,021	,032,
010	,202	,016	,247	rl36,
230	,162	,000	,032	,131,

154,	162
081,	083
162,	092
202,	135
021,	245
136,	139
027,	140
002,	056
039,	170
169,	021
016,	113
215,	066
185,	194
180	177
129	244
002	117
224	,068
153	,195
247	,202
002	,073
208	,120
169	076
202,	183
148	007
010	051
242	042
015	125
230	254
006	184
202	048
021	138
141	047
024	141
208	231
169,	199
160	,181
141	,088
182	,208
208	,072
033	,107
076	,107
141	,022
169	,149
169	,030
024	,229
162	,142
221	,050
016	,174
016	,124

156

Machine Language Games

2631 :224,051,208,111,162,000,059

2637 :160,018,185,062,021,032,043

2643 :221,010,136,016,247,173,118

2649 :000,220,201,111,240,091,184

2655 :142,169,002,162,100,032,190

2661 :245,015,174,169,002,232,170

2667 :224,008,144,222,173,167,021

2673 :002,024,105,001,032,179,200

2679 :015,032,202,015,141,243,255

2685 :161,165,021,141,244,161,250

2691 :173,000,220,201,111,240,052

2697 :048,201,126,208,017,238,207

2703 :167,002,173,167,002,201,087

2709 :030,144,026,169,000,141,147

2715 .-167,002,240,019, 201,125,141

2721 :208,224,206,167,002,173,117

2727 :167,002,201,255,208,005,237

2733 :169,029,141,167,002,162,075

2739 :060,032,245,015,076,111,206

2745 :010,160,018,169,032,153,215

2751 :154,161,136,016,250,141,025

2757 :243,161,141,244,161,173,040

2763 :000,220,201,127,208,249,184

2769 :206,167,002,173,167,002,158

2775 :141,168,002,076,075,009,174

2781 :010,010,010,141,235,010,125

2787 :152,010,010,010,141,238,020

2793 :010,189,000,178,157,000,255

2799 :180,096,169,000,141,005,062

2805 :212,169,240,141,006,212,201

2811 :169,001,141,001,212,169,176

2817 :033,141,004,212,096,173,148

2823 :000,220,073,127,133,036,084

2829 :169,000,133,031,165,036,035

2835 :041,001,240,010,173,001,229

2841 :208,201,059,144,019,206,094

2847 :001,208,165,036,041,002,228

2853 :240,010,173,001,208,201,102

2859 :214,176,003,238,001,208,115

2865 :165,036,041,004,240,034,057

2871 :169,001,133,031,169,161,207

2877 :141,248,163,173,178,002,198

2883 :041,007,201,007,240,006,057

2889 :238,178,002,076,127,011,193

2895 :169,000,141,179,002,198,000

2901 ;025,032,063,014,165,036,164

2907 -.041,008,240,032,169,001,070

2913 :133,031,169,160,141,248,211

2919 :163,173,178,002,041,007,155

f\ Machine Language Games

2925 1240,006,206,178,002,076,049

2931 :127,011,169,007,141,179,237

2937 :002,230,025,032,063,014,231

2943 .-173,178,002,141,179, 002, 034

2949 :165,031,208,007,169,000,201

2955 :141,000,212,240,005,169,138

2961 :064,141,000,212,238,182,214

2967 :002,169,012,056,237,167,026

2973 :002,048,004,201,007,176,083

2979 :002,169,007,205,182,002,218

2985 .-240,012,165,031,208,016,073

2991 :162,001,032,245,015,076,194

2997 :191,011,032,056,014,169,142

3003 :000,141,182,002,173,031,204

3009 .-208,208,003,076,129,012,061

3015 :032,006,017,169,141,141,193

3021 .-019,212,169,000,141,020,254

3027 :212,141,014,212,169,070,005

3033 :141,015,212,169,008,141,135

3039 :018,212,169,129,141,018,142

3045 .-212,173,183,002,072,248,095

3051 :056,233,001,216,141,183,041

3057 :002,169,002,141,039,208,034

3063 :169,000,133,029,133,028,227

3069 :133,030,141,032,208,165,194

3075 :029,024,105,006,133,029,073

3081 :144,002,230,030,165,028,096

3087 :024,101,029,133,028,008,082

3093 :173,001,208,101,030,141,163

3099 :001,208,176,027,040,176,143

3105 :004,165,030,240,008,173,141

3111 .-032,208,073,002,141,032,015

3117 :208,173,178,002,141,179,158

3123 :002,032,056,014,076,002,233

3129 :012,104,169,003,141,039,013

3135 :208,169,011,141,032,208,064

3141 :162,255,032,245,015,104,114

3147 :240,003,076,205,009,162,002

3153 :104,032,131,016,160,002,014

3159 .-185,172,002,217,175,002,072

3165 :144,016,208,003,136,016,104

3171 :243,160,002,185,172,002,095

3177 .-153,175,002,136,016,247,066

3183 :169,000,141,024,212,162,051

3189 :255,032,245,015,169,015,080

3195 .-141,024,212,076,241,008,057

3201 .-165,032,240,002,198,032,030

3207 :165,036,041,016,208,007,096

3213 :169,080,133,032,076,138,001

158

Machine Language Games

3219 :013,165,032,201,079,240,109

3225 :008,201,000,208,243,169,214

3231 :030,133,032,169,009,141,161

3237 :012,212,169,000,141,013,200

3243 :212,141,007,212,169,030,174

3249 :141,008,212,169,129,141,209

3255 :011,212,160,018,173,248,237

3261 :163,056,233,160,141,170,088

3267 :002,208,002,160,021,162,238

3273 :007,169,000,157,080,176,022

3279 :202,016,250,173,001,208,033

3285 :056,233,002,141,169,002,048

3291 :041,007,170,169,085,157,080

3297 :080,176,173,169,002,074,131

3303 :074,074,056,233,005,141,046

3309 :169,002,170,032,131,015,244

3315 2 177,251,201,043,144,004,039

3321 :201,046,144,046,201,052,171

3327 :176,012,201,046,176,032,130

3333 :201,007,144,004,201,010,060

3339 :144,024,169,010,145,251,242

3345 :169,001,145,253,192,000,009

3351 :240,012,136,173,170,002,244

3357 .-208,212,200,200,192,040,057

3363 :144,206,140,171,002,076,006

3369 :089,013,140,171,002,162,106

3375 :063,189,192,164,205,169,005

3381 :002,240,006,202,016,245,252

3387 :076,089,013,173,171,002,071

3393 .-024,101,025, 221,128,164, 216

3399 :208,239,189,064,164,201,112

3405 :004,176,232,142,181,002,046

3411 :206,180,002,032,004,016,011

3417 :162,005,032,245,015,169,205

3423 2 032,172,171,002,192,020,172

3429 2 240,013,145,251,136,174,036

3435 2170,002,240,244,200,200,139

3441 2 076,099,013,162,001,032,240

3447 2 245,015,173,031,208,169,192

3453 2000,141,011,212,173,178,072

3459 2 002,141,179,002,032,063,038

3465 2 014,165,197,201,004,208,158

3471 2 003,076,085,012,201,005,013

3477 2 208,020,165,033,073,001,137

3483 2 133,033,240,005,032,241,071

3489 2 010,208,061,169,008,141,246

3495 2 004,212,208,054,201,003,081

3501 2 240,004,201,063,208,050,171

3507 2 173,141,002,240,015,169,151

Machine Language Games

160

3513 :071,141,024,003,169,254,079

3519 :141,025,003,169,000,133,150

3525 :198,000,036,197,080,252,192

3531 :169,000,141,024,212,173,154

3537 :000,220,201,111,240,014,227

3543 :165,197,201,063,240,004,061

3549 :201,003,208,239,036,197,081

3555 :080,252,169,015,141,024,140

3561 :212,076,006,011,165,026,217

3567 :141,169,002,165,025,141,114

3573 :170,002,160,000,173,171,153

3579 :002,240,005,044,017,208,255

3585 :016,251,173,179,002,141,251

3591 :178,002,174,169,002,189,209

3597 :099,017,170,032,131,015,221

3603 .-169,032,145, 251,174,170,192

3609 :002,189,099,018,072,189,082

3615 :099,017,170,032,131,015,239

3621 .-169,013,145, 253,104,145,098

3627 .-251,238,169,002,238,170,087

3633 .-002,200,192,040,208,210,133

3639 :096,169,000,141,171,002,122

3645 .-240,005,169,001,141,171,020

3651 .-002,032,237,013,162,000,001

3657 :142,169,002,174,169,002,219

3663 .-189,064,164,201,016,144,089

3669 :071,201,057,144,058,160,008

3675 .-015,173,180,002,208,043,200

3681 .-236,181,002,208,038,169,163

3687 .-003,141,039,208,169,012,163

3693 .-141,032,208,248,173,183,070

3699 .-002,024,105,001,141,183,059

3705 :002,216,165,025,133,026,176

3711 :162,052,032,131,016,169,177

3717 :011,141,032,208,076,075,164

3723 .-009,072,104,136,208,251,151

3729 .-076,113,015,074,074,074,059

3735 :024,105,003,254,064,164,253

3741 :141,184,002,188,128,164,196

3747 :140,185,002,188,192,164,010

3753 :140,186,002,172,171,002,074

3759 :208,105,201,003,240,055,219

3765 :201,002,240,032,176,095,159

3771 :032,173,015,240,003,032,170

3777 :255,014,032,173,015,240,154

3783 :082,032,173,015,240,006,235

3789 :206,185,002,206,185,002,223

3795 .-238,185,002,076,026,015,241

3801 :238,185,002,032,148,015,069

3807	:041	,007	,208	,055,	,032
3813	2014,	,206	,185	,002,	,076
3819	:015	,206	rl85,	,002,	,032
3825	:015	,041	,007	,208,	036
3831	:255	,014	,238	,185,	,002
3837	2026,	,015	,032	,173,	015
3843	2011,	,173	,186,	,002,	,201
3849	:240	,014	,206	,186,	002
3855	:173	,186	,002	,201,	,021
3861	2003,	,238	,186,	,002,	096
3867	2128,	,164	,056	,229,	,026
3873	:040	176	,017	,168	,189
3879	:164	,170	,032	,131	,015
3885	2032	,145	,251	,136,	,048
3891	:145	,251	,173	,185	,002
3897	_S229,	,025	,201	,040	,176
3903	:168	,174	,186	,002	,032
3909	2015,	,174	,184	,002	,189
3915	:021	,145	,253	,138	,024
3921	:042	,145	,251	,136,	,048
3927	:189	,080	,021	,145	,253
3933	:024	,105	,032	,145,	,251
3939	:169	,002	,173	,185	,002
3945	2128,	,164	,173	,186,	,002
3951	2192,	,164	,238	,169,	,002
3957	:169	002	,201	,064	,240
3963	:076	,076	,014	,165	,025
3969	2026,	,096	,189	,000,	,164
3975	2251,	,133	,253	,189,	,032
3981	:133	,252	,073	,120	,133
3987	2 096	,056	,165	,140	,101
3993	2101,	,144	,133,	,139,	,138
3999	2162,	,004	,181,	,139,	,149
4005	2202,	016	,249,	,104,	,170
4011	2139,	,096	,032	,148	,015
4017	2 001,	,096	,162	,000,	,134
4023	2162,	,008	,248	,010,	,072
4029	2020,	,101,	,020	,133,	,020
4035	2 202	,208	,244	,165	,020
4041	2096,	,072	,041	,015,	,024
4047	2071,	,133	,021,	,104	,074
4053	2074,	074	,024,	,105,	,071
4059	2020,	,096	,160	,002	,162
4065	2185,	,172	,002	,032,	,202
4071	2157,	,160,	,163,	,165,	,021
4077	2161,	163,	,232,	,232,	136
4083	2237,	096	,152,	,072,	160
4089	2072,	104	,136,	208,	251
4095	2208,	,248	,104	,168,	,096

Machine Language Games

255,	,053
026,	,226
148,	055
032,	068
076,	,249
240,	,242
002,	066
096,	241
240	,070
189,	,223
201,	,063
192,	047
169,	,208
002	,147
056	,095
035,	,251
131	,244
089	,210
105	,249
011	,202
138	,145
174,	,056
157	,019
157,	,147
173,	,025
003	,028
133	,100
133	,225
164,	,133
254	,082
143	,080
072,	,112
140,	,166
165,	,047
041	,130
020	,078
165,	,080
104,	,075
216	,226
105,	,042
074,	,172
133,	,182
000	,147
015,	,065
157,	,030
016,	153
255,	,191
202,	198
188,	,243

161

f\ Machine Language Games

4101 .-064,164,185,098,021,248,017

4107 :024,109,172,002,141,172,119

4113 :002_#173,173,002,105,000,216

4119 :141,173,002,17a,174,002,176

4125 :105,000,141,174,002,216,155

4131 :169,016,157,064,164,032,125

4137 :221,015,169,138,141,019,232

4143 :212,169,000,141,020,212,033

4149 :141,014,212,169,060,141,022

4155 :015,212,169,008,141,018,110

4161 :212,169,129,141,018,212,178

4167 :096,17 3,025,208,141,025,227

4173 :208,041,001,240,043,162,004

4179 :233,173,178,002,009,016,182

4185 :168,173,018,208,016,004,164

4191 :162,006,160,000,142,018,071

4197 :208,173,017,208,041,127,107

4203 :141,017,208,140,022,208,075

4209 :173,013,220,041,001,240,033

4215 :005,198,002,076,049,234,171

4221 :104,168,104,170,104,064,071

4227 :032,006,017,232,189,002,097

4233 :022,141,169,002,202,160,065

4239 :000,189,002,022,153,003,000

4245 :212,153,010,212,153,017,138

4251 :212,232,200,192,004,208,179

4257 :238,169,002,141,170,002,115

4263 :169,212,133,021,032,016,238

4269 :017,172,170,002,185,102,053

4275 :021,13 3,020,160,000,189,190

4281 :002,022,145,020,232,200,038

4287 :192,002,208,245,189,002,005

4293 :022,240,062,232,142,171,042

4299 :002,170,160,004,169,008,204

4305 :145,020,173,169,002,145,095

4311 :020,134,002,172,000,220,251

4317 :192,111,208,011,032,006,013

4323 :017,172,000,220,192,111,171

4329 :240,249,096,166,002,208,170

4335 :234,041,254,160,004,145,053

4341 :020,172,170,002,136,016,249

4347 :002,160,002,140,170,002,215

4353 :174,171,002,208,168,160,116

4359 :023,169,000,153,000,212,052

4365 :136,016,250,169,008,141,221

4371 :004,212,141,011,212,141,228

43 7 7 :018,212,169,015,141,024,092

4383 :212,096,248,000,000,160,235

4389 1031,252,144,001,000,136,089

162

163

4395 :002,124,135,255,249,128,16s

4401 :000,005,127,000,007,017,205

4407 :240,133,000,015,249,000,180

4413 :002,032,000,001,192,000,032

4419 :000,031,063,248,005,000,158

4425 :128,009,062,064,017,159,000

4431 :255,225,160,000,001,224,176

4437 :000,254,161,015,136,159,042

4443 :240,000,004,064,000,003,146

4449 :128,000,022,022,022,022,057

4455 :022,022,022,022,022,022,235

4461 :022,022,022,022,022,022,241

4467 :022,022,022,022,022,022,247

447 3 :022,022,022,022,022,022,253

4479 :022,022,022,022,022,022,003

4485 :022,022,022,022,022,022,009

4491 :022,021,021,020,019,018,004

4497 :017,016,015,014,014,015,236

4503 :016,017,018,019,019,020,004

4509 :020,019,018,017,017,016,008

4515 :016,016,017,017,017,017,007

4521 :017,018,019,020,021,021,029

4527 :021,020,020,020,019,019,038

4533 :018,018,018,018,019,019,035

4539 .-020,021,021, 021, 021, 021, 056

4545 :021,021,021,021,021,021,063

4551 :021,021,021,020,020,019,065

4557 :018,017,016,016,015,015,046

4563 :015,016,016,016,016,017,051

4569 :017,017,017,017,017,017,063

4575 :017,016,016,016,016,017,065

4581 :018,018,017,017,016,016,075

4587 :015,015,014,013,013,012,061

4593 :011,010,009,008,007,007,037

4599 :006,006,006,006,007,008,030

4605 :009,010,011,012,013,014,066

4611 :015,016,017,018,019,020,108

4617 :021,022,022,022,022,022,140

4623 :022,022,021,021,020,020,141

4629 :020,020,020,019,018,017,135

4635 :016,016,015,014,014,013,115

4641 :013,013,013,013,014,014,113

4647 :015,015,016,016,017,018,136

4653 :018,019,019,020,020,021,162

4659 :021,021,021,021,021,021,177

4665 :020,020,019,019,018,018,171

4671 :017,017,016,016,015,015,159

4677 :014,014,013,013,013,013,149

4683 :013,014,014,015,015,016,162

164

4689 :017,01s,019,019,020,020,194

4695 :020,020,020,021,021,021,210

4701 :020,020,020,021,021,022,217

4707 :000,000,000,000,000,000,099

4713 :000,000,000,000,000,000,105

4719 :000,000,000,000,000,000,111

4725 :000,000,000,000,000,000,117

4731 :000,000,000,000,000,000,123

4737 :000,000,000,000,000,000,129

4743 :000,000,000,000,000,003,138

4749 :004,001,001,001,001,001,150

4755 :001,001,002,002,002,002,157

4761 :002,005,006,000,000,001,167

4767 :001,003,004,001,000,002,170

4773 :005,006,007,008,009,002,202

4779 :002,002,000,000,000,003,178

4785 :004,000,003,004,001,000,189

4791 :000,002,005,006,002,000,198

4797 :000,000,000,000,000,000,189

4803 :000,000,000,000,000,000,195

4809 :000,003,004,001,001,001,211

4815 :001,000,007,008,009,000,232

4821 :000,005,006,000,000,000,224

4827 :000,000,000,000,000,003,222

4833 :004,000,002,002,000,000,233

4839 s003,004,003,004,003,004,252

4845 :001,003,004,001,001,001,248

4851 :001,001,003,004,003,004,003

4857 :000,002,002,002,002,002,003

4863 :002,002,002,002,002,002,011

4869 :002,002,002,002,002,000,015

4875 :000,000,000,000,000,000,011

4881 :003,004,007,008,009,003,051

4887 :004,001,001,001,003,004,037

4893 :001,003,004,003,004,000,044

4899 :005,006,005,006,005,006,068

4905 :005,006,002,005,006,005,070

4911 ;006,005,006,000,000,000,064

4917 -.000,000,000,000,003,004,060

4923 :003,004,003,004,003,004,080

4929 :003,004,003,004,003,004,086

4935 :003,004,000,005,006,005,094

4941 :006,005,006,002,002,002,100

4947 :005,006,000,000,000,005,099

495 3 :006,000,000,000,007,008,110

4959 :009,005,006,000,085,000,200

4955 ;000,000,000,000,000,000,101

4971 :001,001,004,004,016,016,149

4977 :064,064,064,064,016,016,145

Machine Language Games

4983 :004,004,001,001,000,000,129 4989 :000,000,001,004,016,064,210 4995 :001,004,016,064,000,000,216 5001 :000,000,064,016,004,001,222 5007 :000,000,000,000,000,000,143 5013 :000,000,064,016,004,001,234 5019 :005,005,024,024,106,03s,101 5025 :038,070,000,000,067,067,147 5031 :147,128,128,149,000,192,143 5037 :240,240,240,128,128,149,018 5043 :000,000,000,000,000,000,179 5049 :000,000,003,015,015,015,233 5055 :003,001,002,002,194,192,073 5061 :240,058,042,010,002,000,037 5067 :063,008,032,255,249,246,032 5073 :063,008,000,000,001,003,028 5079 :003,001,000,000,000,003,222 5085 :007,015,015,007,003,000,012 5091 :003,015,062,058,058,062,229 5097 :015,003,000,003,006,012,016 5103 :012,006,003,000,000,000,004 5109 :001,002,002,001,000,000,251 5115 :000,000,000,001,001,000,253 5121 :000,000,000,000,000,000,001 5127 :000,000,000,000,192,240,183 5133 :240,240,192,064,128,128,237 5139 :168,048,012,170,218,122,245 5145 :168,048,194,002,010,248,183 5151 :252,240,192,000,000,000,203 5157 :128,192,192,128,000,000,165 5163 :000,192,224,240,240,224,139 5169 :192,000,192,240,188,172,009 5175 .-172,188,240,192,000,192,015 5181 :096,048,048,096,192,000,029 5187 :000,000,128,064,064,128,195 5193 :000,000,000,000,000,128,201 5199 :128,000,000,000,000,000,207 5205 :000,000,000,000,000,000,085 5211 :238,238,238,254,254,238,015 5217 :238,238,254,254,056,056,169 5223 :056,056,254,254,124,254,077 5229 :224,238,238,238,254,124,145 5235 :126,254,224,252,126,014,087 5241 :254,252,124,254,238,224,187 5247 :224,238,254,124,252,254,193 5253 :238,254,252,238,238,238,055 5259 :254,254,224,252,252,224,063 5265 :254,254,124,254,238,238,227 5271 :238,238,254,124,056,120,157

Machine Language Games

5277 :248,056,056,056,254,254,057

5283 .-252,254,014,028,112,224,023

5289 :254,254,252,254,014,124,041

5295 :124,014,254,252,014,030,095

5301 :126,238,254,254,014,014,057

5307 :254,254,224,252,254,014,159

5313 :254,124,124,252,224,252,143

5319 :254,238,254,124,254,254,041

5325 :014,028,056,056,056,056,215

5331 :124,254,238,124,254,238,163

5337 :254,124,124,254,238,254,185

5343 :126,014,126,124,000,000,101

5349 :114,038,254,240,000,000,107

5355 :254,254,056,056,056,056,199

5361 :056,056,254,254,224,252,057

5367 .-252,224,224,224,206,238,079

5373 :254,254,254,254,238,230,201

5379 :028,056,112,000,000,000,199

5385 :000,000,238,238,238,238,193

5391 :238,238,124,056,252,254,153

5397 :238,254,252,224,224,224,157

5403 :252,254,238,254,252,238,235

5409 :2 54,252,000,000,000,000,027

5415 :000,000,000,000,005,001,045

5421 :004,000,018,007,019,006,099

5427 :020,021,003,025,005,006,131

5433 :022,006,020,002,006,023,136

5439 :005,006,003,003,025,019,124

5445 :001,005,006,025,018,007,131

5451 .- 025,024, 006, 002, 001, 020,153

5457 :009,015,011,001,001,009,127

5463 :003,004,002,009,011,011,127

5469 :001,001,009,003,004,002,113

5475 :080,117,117,000,007,014,178

5481 :067,068,071,069,070,032,226

5487 :071,071,071,071,071,071,025

5493 :032,032,064,065,066,064,184

5499 :032,067,068,071,069,070,244

5505 .-004,008,010,012,012,012,187

5511 :008,012,012,012,008,012,199

5517 :012,008,012,012,008,016,209

5523 :016,020,018,014,020,020,255

5529 :016,014,020,020,014,020,001

5535 :020,016,020,016,016,024,015

5541 .-022,030,017,017,000,000,251

5547 :064,003,004,004,002,006,254

5553 :010,008,008,006,010,004,223

5559 :010,014,010,012,006,010,245

5565 :012,016,010,018,016,012,017

Machine Language Games

5571 :014,016,020,016,024,014,04a

5577 :018,014,020,020,022,026,065

5583 :020,016,017,017,030,000,051

5589 :064,000,003,004,006,010,044

5595 :006,002,008,008,010,006,003

5601 .-016,010,006,014,012,018,045

5607 :018,012,008,010,008,014,045

5613 :012,014,016,014,016,008,061

5619 :024,018,022,020,020,022,113

5625 :018,020,026,017,030,017,121

5631 :064,000,000,000,033,076,172

5637 :201,031,021,015,143,010,170

5643 :015,024,014,060,031,021,176

5649 :015,143,010,015,024,014,238

5655 :060,031,021,015,143,010,047

5661 .-015,024,014,030,031,021,164

5667 :015,143,010,015,024,014,000

5673 :030,031,021,015,143,010,035

5679 :015,024,014,060,000,000,160

5685 :000,000,033,076,201,209,060

5691 :018,015,000,000,005,209,050

5697 2018,010,031,021,010,209,108

5703 :018,010,195,016,010,210,018

5709 2 015,011,195,016,012,209,023

5715 2 018,021,165,031,022,165,249

5721 .-031,023,049,028,024,030,018

5727 .-025,042,041,021,043,209,220

5733 2 018,044,000,000,000,002,165

5739 2 065,128,249,071,006,020,134

5745 2 071,006,010,097,008,060,109

5751 2 071,006,020,097,008,010,075

5757 2 143,010,060,071,006,020,179

5763 2 097,008,010,143,010,030,173

5769 2 071,006,020,097,008,010,093

5775 2 143,010,030,071,006,020,167

5781 2097,008,010,143,010,060,221

5787 2 097,008,020,143,010,010,187

5793 2 143,012,060,143,010,020,037

5799 2097,008,010,071,006,060,163

5805 2 071,006,020,071,006,010,101

5811 :097,008,060,000,000,000,088

5817 2 000,000,000,000,000,000,185

167

Zuider Zee

MarcSugiyama

Your mission is to save your village from flooding. This BASIC and machine language game will provide hours of fun. Requires the use of the MLX program.

Your village in Holland is built on land reclaimed from the ocean. High dikes keep the cold waters of the North Sea from flooding your land. But word has come that a terrible storm is approaching. Heavy rains and giant waves will undoubtedly break down sections of the dikes, flooding parts, perhaps all, of your land.

But you are prepared. You and your fellow Dutchmen have been battling the sea for centuries. In the old days, bucket brigades and sandbaggers would have fought the storm, and many lives might have been lost. Times have changed. Helicopters will rescue all the people whose homes are flooded, and as for repairing damage to the dikes and pumping out the water, that can all be done by one person. You.

You Are the Dikemaster

As dikemaster, you are responsible for repairing the dikes and pumping out the flood waters.

You have a truck with the latest landfill equipment, so that all you have to do is back it into place where you want to repair a broken dike. The truck does the rest.

You also have four pumps. When a dike has been repaired, you then have to pick up one of the pumps and put it in place on the dike. Then you set it up to pump water from the flooded fields and dump it back into the ocean. But be careful. If you set the pump wrong, it can pump water from the ocean and pour it onto land, making the flood worse than ever.

When you have successfully repaired all the dikes and pumped out all the water, you can't relax. You immediately get a promotion, and have to do the same for another village, where the storm is even worse.

And if you ever get so far behind that all your land is flooded

168

Machine Language Games

at the same time—well, you can certainly understand why your fellow villagers will start looking for a new dikemaster.

How to Play

At the beginning of the game, you will be asked to choose a starting level. Until you get the hang of driving the truck and setting up the pumps, you'd probably better start at level 1, in which the storm is pretty mild and new gaps don't open up so often. Later, though, you can try higher levels.

The village. At the beginning of the game, the screen is filled with plowed fields, trees, and houses. The dikes are built, with the dikemaster's depot in the middle. Then the sea covers all the land outside the dikes. Finally, several breaks open in the dikes, and sections of the village lands are flooded. It's time for you to get to work!

Scoring. Scoring depends on several factors: how much land is covered with water; what level you are playing at; and how long you can keep the storm from entirely flooding the village.

Moving the truck. You drive your truck along the tops of the dikes by using the joystick. The dikes are slightly wider than the truck, so you can maneuver a little from side to side. You can't accidentally drive the truck off the dike.

Repairing the dike. Drive the truck to a break in the dike. You will want to dump a load of dirt into the break, to block it. Hold down the joystick button. This puts the truck in reverse. When you move the joystick, the truck will back up, moving the opposite direction from the direction in which you moved the joystick.

As long as you keep pressing the button and moving the joystick, the truck will keep backing up. When it reaches the edge of the dike, it stops and dumps a load of dirt off the edge of the dike. This creates a new section of dike. If you steered the truck correctly, the new section will repair the break in the dike. If not, you'll just have an extra load of dirt that doesn't connect with anything.

Your truck constantly scoops up more dirt as you drive from place to place—you will never run out of material to repair the dike.

Pumping out the water. Once a flooded area is completely surrounded by the dike, with no breaks, you can begin pumping. First, you must go and pick up a pump. At the beginning of the game, all four pumps are just outside the depot. Drive on top of

^% Machine Language Games

the pumps, push the joystick button, and your truck will automatically pick up a pump. Then drive to the edge of the flooded field you want to drain.

You will need to place the pump on the dike between the flooded field and the place where you want the water to be dumped. Usually you will want the water to be dumped in the ocean, but sometimes you will dump from one flooded field to another, or even from a flooded field to a field with no water on it.

You place the pump by holding down the joystick button and then moving the joystick in the direction where you want the pump to dump the water. Remember, move the joystick in the direction where you want the flood water to end up.

You will hear the sound of the pump starting up, and when you drive away, the pump will stay behind.

At any time you can go to a pump and pick it up by driving right onto it and pushing the joystick button without moving. You'll always hear the sound of the truck picking up the pump. Then, when you release the button and drive away, the pump will go with you.

How pumps work. The pumps are just machines. They aren't very smart. If you set a pump to pick up water from the ocean and dump it onto a field, the pump will do exactly that, and the flooding will get worse instead of better. You'll also come closer to losing your job.

However, if you set the pump to draw water from a field that isn't flooded, or set it so that it dumps onto or picks up from the dike instead of a field or the ocean, nothing will happen at all.

The joystick button. When you move the joystick without pressing the button, the truck drives around.

Pressing down the joystick button can do one of three things:

If you do not move the joystick, and the truck is touching a pump but not already carrying one, the truck will pick up that pump and the pump will stop functioning.

If you move the joystick when the truck is not carrying a pump, the truck will go into reverse and move the opposite way from the direction you are moving the joystick. As soon as it reaches the edge of the dike, it will dump a load of dirt.

If you move the joystick when the truck is carrying a pump, the truck will unload the pump and, if possible, begin dumping water where the joystick movement indicated.

Getting promoted. If you ever uncover all the land of your village, you will be promoted and moved to the next village. The

170

Machine Language Games

game will stop, and the new village will be drawn on the screen. You will be at a harder level of play, which means that breaks will occur more often, and more land will be flooded at the beginning of play However, you will also get more points at the higher levels.

Strategy Tips

At lower levels of play, it is possible to repair all the dikes and completely pump out all the water. At higher levels, however, the storm is too intense, and dikes break too often. Here the best strategy is to choose four relatively small enclosures, set a pump on each, and then spend the rest of your time repairing breaks in the dikes as often as possible. The pumps will function whenever the field they are pumping is completely enclosed by dike walls. Since the game ends as soon as all the fields are completely flooded, it's better to keep one area dry, sacrificing the others, than to overextend yourself.

You can also take advantage of the fact that your truck will create a dike section wherever you want it. It is possible to build whole new dikes and create new fields. It is also possible to divide a large field into several smaller ones by building new dikes across it. This is particularly helpful at higher levels, when the dike breaks so often that you can't keep a large field completely enclosed long enough for it to be pumped dry.

Typing in the Program

Most of the program is written in BASIC, but certain key routines are written in machine language and must be entered and SAVEd using the Machine Language Editor (MLX) found at the beginning of this chapter.

The MLX is a program that checks your DATA statements as you enter them and prevents you from entering the data incorrectly. Several other games in this chapter and programs in other COMPUTE! books for the Commodore 64 use the MLX program, so if you type it in once and SAVE it, you will use it again and again to enter error-free machine language programs.

The first step is to enter and SAVE the machine language routines using MLX. The MLX will ask you for two numbers. Answer the prompts as follows:

Starting address: 49152

Ending address: 52040 Then start entering the data using the instructions given with the MLX program.

171

f\ Machine Language Games

The next step is to type in and SAVE the BASIC program. The best way to save the two parts of this program is to save the machine language on a tape first and then save the BASIC part immediately after the machine language program.

Loading the Program

Once you have both parts of the program SAVEd, you are ready to LOAD the program. First LOAD the machine language as follows:

From disk: LOAD"fn",8,l From tape: LOAET',1,1

where fn is the filename.

Type NEW and LOAD the BASIC part as you would any other BASIC program. To begin play type RUN and the game will begin.

Program 1. Zuider Zee: Part 1. BASIC

100 FORI=0TO27:POKE54272+I,0:NEXT:POKE53264,0 110 IFPEEK(49161)<>76THENPRINT"{DOWN}?NO MACHINE L ANGUAGE{2 SPACES}ERROR"7:END

120 print" {cLRHBLKjeeeeeg"

130 SYS49161:SYS49164:POKE53272,4:POKE648,128

140 PRINT"{CLR}{GRN}"CHR$(8)CHR$(14):POKE53280,0:P

OKE53281,0 150 POKE55,0:POKE56,128:CLR 160 GOSUB1040 170 :

180 REM MAIN LOOP 190 SYS49167:SYS49170

200 IFPEEK(908)THENP0KE851,1:GOSUB410:P0KE851,0 210 IFPEEK(844)=0THEN220 215 PN=PEEK(844)-2:P0KE851,1:GOSUB660:PF(PN)=PF:PO

KE844,0:P0KE851,0:GOSUB560 220 IFPEEK(845)=0THEN260 230 PF(PEEK(845)-2)=0:POKE845,0 240 POKEFQ,20:POKEAD,0:POKESR,243:POKECT,17:POKECT

,16 250 GOSUB560

260 IFPEEK(908)=0ANDPEEK(851)=0THEN300 2 70 FORPN=1TO4:IFPF(PN)=0THEN290 280 GOSUB670:PF(PN)=PF 290 NEXT:PQKE851,0;POKE908,0 300 GOSUB870:SYSHM:H1=FND(690):P=Hl/H0 310 IFP>=1THEN2410

172

Machine Language Games

320 IFINT(P*100)<3THEN2610 330 GOSUB560:SC=SC+INT(MD*P) 340 GETA$:IFA$=""THEN190 350 IFA$="Q"THEN2620 360 IFA$<>"{Fl}"THEN190

370 POKE53280,14:POKE834,0:POKE198,0:WAIT198,1:POK

E198,0:POKE834,1:POKE53280,6 380 GOTO190 390 :

400 REM FLOOD

410 FS=FND(900):IS=FND(902) 420 X=PEEK(680):Y=PEEK(681) 430 IT=PEEK(907):FI=PEEK(906):FL=PEEK(909)-33:TL=P

EEK(910)-33 440 IFFL<0ORTL>14ORFL>14THENRETURN 450 IFTL<0THENTL=0

460 POKEX+YM0+S, 11:IFFIANDITTHENLV=40:GOTO510 470 IFTL=FLTHENLV=TL:GOTO510 480 IFFIORITTHENLV=7:GOTO510

490 POKEFQ,8:POKEAD,0:POKESR,122:POKECT,129 500 LV=(TL*IS+FL*FS)/(IS+FS) 510 IFLV=0THENLV=7

520 SYSFM,X,Y,31,14:SYSFM,X,Y,LV+33,14:POKECT,128

530 RETURN

540 :

550 REM STATUS LINE

560 POKE214_/23:PRINT:PC=-(P>.25)-(P>.50)-(P>.75)-(

P>1)+1 570 PRINT" {RVSHYEL} RANK:"MID$(STR$(SK),2)" SCORE

580 PRINTTAB(14)RIGHT?("000000"+MID$(STR$(INT(SC/1

0)*10),2),6); 590 PRINT" ST:"MID$("{RED}{CYN}{YEL}{GRN}{WHT}"_#PC

,1)" {YEL}";

600 PRINT" PUMPS:";:F0RI=1T04:PRINTTAB(1*2+30); 610 IFPF(I)THENPRINTMID?("{RED}{CYN}{PUR}{GRN}^u,I,

1)MID$(STR$(I),2);:GOT06 30 620 PRINT"{YEL} ";

630 NEXT:PRINT"{HOME}":RETURN 640 :

650 REM START/CHECK PUMP

660 XP(PN)=PEEK(848):YP(PN)=PEEK(849):DP(PN)=PEEK(

850) 670 PF=0:X=XP(PN):Y=YP(PN):D=DP(PN) 680 FP(PN)=X+40*Y+S-D(D):TP(PN)=X+40*Y+S+D(D) 690 FC=PEEK(FP(PN)):IFFC=11ORFC=32ORFC=31THENFC=40 700 FC=FC-33:IFFC<0ORFC>14THENRETURN

710 TC=PEEK(TP(PN)):IFTC=11ORTC=32ORTC=31THENTC=40 720 TC=TC-33:IFTC<0THENTC=0

173

f% Machine Language Gaimes

730 IFT014THENRETURN

740 NX=X-XD(D):NY=Y-YD(D):SYSFM,NX,NY,11,14

750 SYSFM_/NX,NY_/FC+33,14

760 MF(PN)=0:IFPEEK(905)=0THENMF(PN)=l/FND(690)*(8

-SK/2) 770 NX=X+XD(D):NY=Y+YD(D):SYSFM,NX,NY,11,14 780 IFPEEK(FP(PN))=11THENSYSFM,NX,NY,TC+33,14:MF(P

N)=0:MT(PN)=0:GOTO810 790 SYSFM,NX,NY,TC+33,14 800 MT(PN)=0:IFPEEK(905)=0THENMT(PN)=l/FND(690)*(8

-SK/2) 810 IFPF(PN)THEN840 820 FL(PN)=0:TL(PN)=0 830 POKEFQ,30:POKEAD,0:POKESR,243:POKECT,17:POKECT

,16 840 PF=1:RETURN 850 :

860 REM OPERATE PUMPS 870 FORI=1TO4:IFPF(I)=0THEN1010

880 C1=0:CF=0:FL(I)=FL(I)+MF(I):TL(I)=TL(I)+MT(I) 890 IFFL(I)<1THEN920 900 CF=1:FL(1)=FL(I)-1:FC=PEEK(FP(I))-34:IFFC<0THE

NFC=-3 3:PF(I)=0 910 IFFO14THENPF(I)=0:FC=14 920 IFTL(I)<1THEN950 930 Cl=l:TL(I)=TL(1)-1:TC=PEEK(TP(I))-32:IFTO14TH

ENTC=14:PF(I)=0 940 IFTC<0THENPF(l)=0:TC=0 950 IFMF(I)=0ORCF=0THEN980

960 XN=XP(I)-XD(DP(I)):YN=YP(I)-YD(DP(I)) 970 POKE851,1:SYSFM,XN,YN,11,12:SYSFM,XN,YN,FC+33,

14+(FC=-33):POKE851,0 980 IFMT(I)=0ORC1=0THEN1010

990 XN=XP(l)+XD(DP(l)):YN=YP(l)+YD(DP(l)) 1000 POKE851,1:SYSFM,XN,YN,11,12:SYSFM,XN,YN,TC+33

,14:POKE851,0 1010 NEXT:RETURN 1020 :

1030 REM INITIALIZE 1040 PRINT"{CLR}";

1050 JY=56320:IFPEEK(1024)=0THENGOSUB2090 1060 I=RND(-RND(0))

1070 DIM X0(7),X1(7),Y0(7),Y1(7),XP(4),YP(4),DP(4) 1080 DIM PF(4),FL(4),TL(4),FP(4),TP(4),MT(4),MF(4) 1090 S=32768:C=22528:FM=49152:BX=49155:HM=49158 1100 FQ=54280:AD=54284:SR=54285:CT=54283 1110 DEFFNR(X)=INT(RND(l)*X) 1120 DEFFND(X)=PEEK(X)+256*PEEK(X+1) 1130 REM SPRITE DATA

174

Machine Language Games

1140 IFPEEK(1024)THENFORI=1TO605:READA:NEXT:GOTO12

20 1150 POKE1024,1:FORI=0TO25:SQ=34816+I*64:J=0 1160 READA:IFA<0THENSQ=SQ-A:J=J-A:GOTO1180 1170 P0KESQ,A:SQ=SQ+1:J=J+1 1180 IFJ<63THEN1160 1190 NEXT 1200 PRINTSPC(5)" £RESS THE TRIGGER TO CONTINUE

{UP}":GOSUB2750 1210 GOSUB1990 1220 POKE53272,8 1230 REM CHAR DATA 1240 PRINT"{CLR}{GRN}":F0RI=1T012:READB:FORJ=0TO7:

READA 1250 POKE40960+B*8+J,A:NEXT:NEXT 1260 FORI=0TO3:READXD(I),YD(I):NEXT:FORI=0TO3:READ

D(I):NEXT 1270 POKE53280,6:POKE53281,0:SK=PEEK(1026):GOSUB13

60 1280 POKE53269,251 1290 A=0:FORI=53254TO53260STEP2:POKEI,162+A:POKEI+

1,132:A=A+2:NEXT 1300 A=2:FORI=53290TO53293:POKEI,A:A=A+1:NEXT:FORI

=33786TO3 3 790:POKEI,46:NEXT 1310 TT=0:MD=3+SK*2:MR=26+52*(SK-l) 1320 SC=FND(1027)*10

1330 POKE904,MD:POKE912,MR:POKE834,1:RETURN 1340 :

1350 REM MAKE ISLAND 1360 POKE214,23:PRINT:PRINT"{RVS}{YEL}{39 SPACES}

{HOME}"; 1370 POKE33767,160:POKE56295,7 1380 GOSUB560

1390 SYSFM,RND(1)*40,RND(1)*25,0,13 1400 SYSBX,18,9,21,12,64,14:SYSFM,19,10,1,9:POKES,

0:POKES+C,13 1410 POKE419+S,1:POKE420+S,2:POKE459+S,64:POKE459+

S+C_#13 1420 POKE460+S,3:POKE460+S+C_/13 1430 REM DAMS 1440 FORI=0TO7 1450 X0=FNR(10)*3:X1=X0+(FNR(10)+1)*3:IFX0=0ORX1> 3

8THEN1450 1460 Y0=FNR(7)*3:Y1=Y0+(FNR(7)+1)* 3:IFY0=0ORY1> 23T

HEN1460 1470 SYSBX_fX0,Y0,XI,Yl,64,14:X0(I)=X0:Y0(I)=Y0:X1(

I)=X1:Y1(I)=Y1:NEXT 1480 SYSFM,0,0,5,13 1490 REM TREES/HOUSES

f% Machine Language Games

1500 FORI=1TO30

1510 X=FNR(37)+1:Y=FNR(22)+1:T=X+Y*40+S

1520 IFPEEK(T)=0ORPEEK(T)=5THENPOKET,3

1530 NEXT

1540 FORI=0TO9

1550 X=FNR(37)+1:Y=FNR(22)+1:T=X+Y*40+S

1560 IFPEEK(T)THEN1550

1570 POKET_/4:POKET+C,11:POKE52320+I_/X:POKE52352+I_/

Y:NEXT 1580 REM WATER/AMOUNT LAND 1590 SYSFM,0_/0_/40,14:SYSHM:H0=FND(690):ID=INT(H0*S

K/10) 1600 REM FIRST BREAKS 1610 R=0:K=0:F2=0:NT=4

1620 FORI=0TO7:GOSUB1760:IFR=5THENI=8 1630 NEXT:K=K+1:IFR<5ANDK<5THEN1620 1640 REM EXTRA BREAKS 1650 F2=1:SYSFM,0,0,32,14:SYSHM:H1=FND(690):IFH0-I

D>H1THEN1720 1660 SYSFM,0,0,40,14

1670 I=(1 + 1)AND7:GOSUB1760:IFFTHEN1670 1680 IFF1=0THENPOKET,64:GOTO1670 1690 SYSFM,0,0,32,14:SYSHM:H2=FND(690) 1700 IFH1-H2<3THENPQKET,64:GOTO1660 1710 IFH0-ID<H2+1THENH1=H2:GOTO1660 1720 SYSFM,0,0,40,14 1730 RETURN 1740 :

1750 REM MAKE BREAK 1760 F1=0:F=1:J=0:DI=(RND(1)>.5) 1770 IFDITHEN1800

1780 Y0=Y0(I):X=X0(I):IFRND(1)>.5THENX=X1(I) 1790 GOTO1810

1800 X0=X0(I):Y=Y0(I):IFRND(1)>.5THENY=Y1(I) 1810 J=J+1:IFJ>NTTHENRETURN 1820 IFDITHEN1890

1830 Yl=(Y+FNR(Yl(l)-Y-2)-fl) :T=Y1*40+X+S 1840 IF(Y1>9ANDYK13)AND(X=18ORX=21)THEN1810 1850 IFPEEK(T+1)=64ORPEEK(T-1)=64THEN1810 1860 IFPEEK(T+40)<>64ORPEEK(T-40)<>640RPEEK(T)<>64

THEN1810 1870 IFF2ANDPEEK(T+l)=40ANDPEEK(T-l)=40THEN1810 1880 GOTO1930 1890 X1=X+FNR(X1(I)-X-2)+1:T=X1+Y*40+S:IF(XI>17AND

XK22)AND(Y=9ORY=12)THEN1810 1900 IFPEEK(T+40)=64ORPEEK(T-40)=64THEN1810 1910 IFPEEK(T+1)<>640RPEEK(T-1)<>640RPEEK(T)<>64TH

EN1810 1920 IFF2ANDPEEK(T+40)=40ANDPEEK(T-40)=40THEN1810

176

Machine Language Games

1930 PL=0:F=0

1940 IFPEEK(T+40)=40ORPEEK(T-40)=40ORPEEK(T+l)=400

RPEEK(T-l)=40THENPL=40:Fl=l 1950 IFF2THENPL=6

1960 POKET+C, 13- ( PL=40 ) : POKET, PL: R=R+1: RETURN 1970 :

1980 REM SKILL/TITLE 1990 SK=1:PRINT"{CLR}"SPC(14)CHR$(142)"{GRN}

{2 D0WN}ZUIDER{2 SPACES}ZEE":PRINTSPC(14)" {3 DOWN}RANK NUMBER" 2000 PRINTSPC(12)"{DOWN}{RVS} 1 {OFF} 2{2 SPACES}3

{2 SPACES}4{2 SPACES}5 " 2010 J=PEEK(JY):IFJ=127THEN2010 2020 PRINTSPC(9+SK*3)"{UP}"SK"{LEFT} " 2030 IF(JAND4)=0THENSK=SK-1:IFSK<1THENSK=5 2040 IF(JAND8)=0THENSK=SK+1:IFSK> 5THENSK=1 2050 PRINTSPC(9+SK*3)"{UP}{RVS}"SK"{LEFT} ":IF(JAN

D16)THEN2010 2060 PRINT"{CLR}":POKE1026,SK:RETURN 2070 :

2080 REM DO INSTRUCTION SCREEN FOR POWER UP 2090 PRINT"{CLR}{4 DOWN}"SPC(14)"ZUIDER ZEE" 2100 PRINT"{DOWN} YOUR VILLAGE IN HOLLAND IS BUILT

ON" 2110 PRINT" LAND RECLAIMED FROM THE SEA.{2 SPACES}

HIGH" 2120 PRINT" DIKES HAVE KEPT THE WATER FROM FLOOD-" 2130 PRINT" ING YOUR LAND, BUT NOW A TERRIBLE" 2140 PRINT" STORM IS APPROACHING.{2 SPACESjHEAVY R

AINS AND" 2150 PRINT" GIANT WAVES WILL UNDOUBTEDLY BREAK" 2160 PRINT" DOWN SECTIONS OF THE DIKES, FLOODING" 2170 PRINT" YOUR LAND.{2 SPACES}AS DIKEMASTER YOU

{SPACE}ARE" 2180 PRINT" RESPONSIBLE FOR REPAIRING THE DIKES" 2190 PRINT" AND PUMPING OUT THE FLOODWATERS." 2200 PRINTSPC(5)"{2 DOWN}PRESS THE TRIGGER TO CONT

INUE:":GOSUB2750 2210 : 2220 PRINT"{CLR}{DOWN} USE THE JOYSTICK TO DRIVE T

HE TRUCK" 2230 PRINT" ALONG THE TOPS OF THE DIKES.{2 SPACES}

YOU" 2240 PRINT" MAY NOT DRIVE OVER DIKES THAT ARE" 2250 PRINT" DECAYING.{2 SPACES}REMEMBER THAT YOU C

AN" 2260 PRINT" REPAIR THE DIKES BY DUMPING DIRT ON" 2270 PRINT" THEM.{2 SPACESjTHE DIKES BEGIN TO DECA

Y BEFORE"

177

m% Machine Language Games

2280 PRINT" THERE ARE VISIBLE SIGNS OF DAMAGE." 2290 PRINT"{DOWN} PRESSING THE TRIGGER CAN HAVE ON

E OF" 2300 PRINT" THREE EFFECTS:":PRINT"{DOWN} 1) PICK U

P THE PUMP UNDER THE TRUCK." 2310 PRINT" 2) DROP THE PUMP UNDER THE TRUCK." 23 20 PRINT" 3) PUT THE TRUCK IN REVERSE AND DUMP A

2330 PRINT"{4 SPACES}LOAD OF DIRT AT THE EDGE OF A

DIKE."

2340 PRINT"{DOWN} THERE ARE TWO KEYBOARD CONTROLS: ii

2350 PRINT"{DOWN} 1) 'Fl' PAUSES THE GAME; PRESSIN

G ANY" 2360 PRINT"{4 SPACESjKEY WILL RESUME YOUR GAME." 2370 PRINT" 2) *Q' QUITS THE GAME." 2380 PRINTSPC(6)"{DOWN}THE STORM IS APPROACHING!

{UP}":RETURN 2390 :

2400 REM NEXT LEVEL 2410 POKE834,0:PRINT"{HOME}{RVS}{BLU}{4 SPACES}YOU

HAVE UNFLOODED THE ISLANDlI":POKE54283,0 2420 POKEFQ, 20:POKEAD,0:POKESR,240 2430 B=0:FORI=0TO9:B=B-(PEEK(52384+I)=0):NEXT:B=IN

T(P*1000*SK)+B*500 2435 FORSC=SCTOSC+BSTEP75:GOSUB560:POKECT, 33:POKEC

T,32:NEXT 2440 FORI=1TO750:NEXT 2450 PRINT"{CLR}{GRN}":POKE53272,6:POKE53280,0:POK

E53281,0:POKE53269,0 2460 PRINT"SCORE:"MID$(STR$(INT(SC/10)*10),2) 2470 PRINT"T2 DOWN} YOU HAVE SUCCEDED IN RECOVERIN

G THE" 2480 PRINT" ENTIRE ISLAND.{2 SPACESjYOU ARE BEING

{SPACE}PROMOTED" 2490 PRINT" BECAUSE OF THIS GREAT ACCOMPLISHMENT!" 2500 PRINT"{DOWN} ANOTHER, STRONGER STORM IS APPRO

ACHING"

2510 PRINT" AND YOU HAVE BEEN GIVEN AN ISLAND THAT it

2520 PRINT" HAS SUFFERED GREATER DAMAGE THAN YOUR"

2530 PRINT" FIRST ASSIGNMENT."

2540 PRINTSPC(15)"{DOWN}GOOD LUCK!"

2550 PRINTSPC(7)"{4 DOWNTPRESS THE TRIGGER TO BEGI

2560 POKE1027,(SC/10)AND255:POKE1028,SC/2560

2570 GOSUB2750:SK=SK+1:IFSK>5THENSK=5

2580 POKE1026,SK:RUN

2590 :

178

Machine Language Games

2600 REM ISLAND FLOODED

2610 POKE834/0:PRINT"{HOME}{RVS}{BLU}{4 SPACESjTHE

ENTIRE ISLAND HAS FLOODED11":POKE54283,0 2620 POKEFQ,15:POKEAD,17:POKESR,250:POKECT,33 2630 FORI=1TO250:NEXT:POKECT,32:FORI=1TO750:NEXT 2640 POKE834,0:PRINT"{CLR}{GRN}":POKE53272,6:POKE5

3280,0:POKE53281,0:POKE53269,0 2650 PRINT"{DOWN}YOUR SCORE WAS:"MID§(STR$(INT(SC/

10)*10),2) 2660 PRINT"{2 DOWN}YOU HAVE FAILED TO SAVE THE ISL

AND" 2670 PRINT"AND HAVE BEEN RELIEVED OF YOUR" 2680 PRINT"POSITION AS DIKEMASTER." 2690 PRINT"{DOWN}PERHAPS ALL YOU NEED IS MORE PRAC

TICE;" 2700 PRINT"WOULD YOU LIKE TO TRY AGAIN?" 2710 PRINTSPC(4)"{2 DOWN}PRESS THE TRIGGER TO BEGI

N AGAIN"

2715 PRINT"{DOWN}{2 SPACES}'Q' TO QUIT AND 'V FOR

INSTRUCTIONS"

2716 GETA$:IFA$="Q"THENPOKE648,4:POKE1024,0:SYS102 4

2717 IFA$o"I"THEN2719

2718 GOSUB2090:PRINTSPC(6)"PRESS TRIGGER TO CONTIN UE":GOSUB2750:GOTO2640

2719 IFPEEK(JY)AND16THEN2716

2720 IF(PEEK(JY)AND16)=0THEN2720

2721 POKE1027,0:POKE1028,0:SC=0:GOSUB2750:GOSUB199 0:RUN

2730 :

2740 REM TRIGGER?

2750 IFPEEK(JY)AND16THEN2750

2760 IF(PEEK(JY)AND16)=0THEN2760

27 70 RETURN

2780 :

2790 REM SPRITE IMAGES

2800 REM TRUCK{2 SPACES}(U/D/L/R)

2810 DATA -25,60,-2,126,-2,126,-2,126,-2,126,-25

2820 DATA -25,126,-2,126,-2,126,-2,126,-2,60,-25

2830 DATA -25,63,-2,255,-2,255,-2,255,-2,63,-25

2840 DATA -25,252,-2,255,-2,255,-2,255,-2,252,-25

2850 :

2860 REM COPTER (U/D//L/UL/DL//R/UR/DR)

2870 DATA -10,60,-2,102,-2,102,-2,126,-2,126,-2,60

,-2,60,-2,60,-2 288121 DATA 24,-2,24,-2,24,-2,24,-2,24,-2,8,-2,56,-1

0 2890 DATA -10,56,-2,8,-2,24,-2,24,-2,24,-2,24,-2,2

179

m% Machine Language Games

2900 DATA -2,60,-2,60,-2,60,-2,126,-2,126,-2,102,-

2,102,-2,60,-10, -63 2910 DATA -24,7,128,0,15,240,0,9,255,224,9,255,160

,15,240,32,7,128,0,-21 2920 DATA -9,3,128,0,7,192,0,12,96,0,12,112,0,7,24

0,0,3,248,-2,124,-2 2930 DATA 60,-2,14,-2,7,-2,3,128,0,1,192,-2,96,-2,

192,-12 2940 DATA -14,192,-2,96,0,1,192,0,3,128,0,7,-2,14,

-2,60,-2,124,0 2950 DATA 3,248,0,7,240,0,12,112,0,12,96,0,7,192,0

,3,128,-10, -63 2960 DATA -22,1,224,4,15,240,5,255,144,7,255,144,0

,15,240,0,1,224,-24 2970 DATA -10,3,128,0,7,192,0,12,96,0,28,96,0,31,1

92,0,63,128,0,62,-2,60,-2 2980 DATA 112,-2,224,0,1,192,0,3,128,0,6,-2,3,-14 2990 DATA -9,3,-2,6,-2,3,128,0,1,192,-2,224,-2,112

,-2,60,-2,62,-2,63,128 3000 DATA 0,31,192,0,28,96,0,12,96,0,7,192,0,3,128

,-12 3010 :

3020 REM PUMPS (U/D/L/R) 3030 DATA -22,24,-2,60,-2,126,-2,255,-2,219,-2,24,

-2,24,-2,24,-19 3040 DATA -22,24,-2,24,-2,24,-2,219,-2,255,-2,126,

-2,60,-2,24,-19 3050 DATA -22,24,-2,56,-2,112,-2,255,-2,255,-2,112

,-2,56,-2,24,-19 3060 DATA -22,24,-2,28,-2,14,-2,255,-2,255,-2,14,-

2,28,-2,24,-19 3070 :

3080 REM COPTER ROTOR (FRAMES 0-7) 3090 DATA 0,24,-2,24,-2,24,-2,24,-2,24,-2,24,-2,24

,-2,24,-2,24,-2,24,-2,24 3100 DATA -2,24,-2,24,-2,24,-2,24,-2,24,-2,24,-2,2

4,-2,24,-2,24,-2,24,0 3110 DATA -3,3,-2,3,-2,1,128,0,1,128,-2,192,-2,192

,-2,96,-2,96,-2,48,-2,56 3120 DATA -2,28,-2,6,-2,6,-2,3,-2,3,-2,1,128,0,1,1

28,-2,192,-2,192,-3 3130 DATA -9,24,-2,12,-2,6,-2,3,-2,1,128,-2,192,-2

,112,-2,24,-2,14,-2,3,-2,1 3140 DATA 128,-2,192,-2,96,-2,48,-2,24,-9 3150 DATA -18,96,-2,60,-2,7,-2,1,192,-2,126,-2,3,1

28,-2,224,-2,60,-2,6,-18 3160 DATA -30,255,255,255,-30 3170 DATA -20,6,-2,60,-2,224,0,3,128,0,126,0,1,192

,0,7,-2,60,-2,96,-20

180

Machine Language Games

3180 DATA -11,24,-2,48,-2,96,-2,192,0,1,128,0,3,-2

,14,-2,24,-2,112,-2,192,0,1 3190 DATA 128,0,3,-2,6,-2,12,-2,24,-11 3200 DATA -5,192,-2,192,0,1,128,0,1,128,0,3,-2,3,-

2,6,-2,6,-2,12,-2 3210 DATA 24,-2,48,-2,96,-2,96,-2,192,-2,192,0,1,1

28,0,1,128,0,3,-2,3,-5 3220 :

3230 REM CHARACTER DATA 3240 DATA 0,255,204,0,51,255,204,0,51 3250 DATA 1,255,250,238,235,238,250,255,85 3260 DATA 2,253,189,237,173,237,189,253,85 3270 DATA 3,0,60,255,255,255,255,60,0 3280 DATA 4,85,255,255,168,255,255,69,69 3290 DATA 5,255,204,0,51,255,204,0,51 3300 DATA 6,0,0,0,0,0,0,0,0 3310 DATA 10,0,90,90,60,60,60,0,0 3320 DATA 11,255,255,255,255,255,255,255,255 3330 DATA 12,85,0,60,60,60,60,0,85 3340 DATA 31,255,255,255,255,255,255,255,255 3350 DATA 64,0,0,0,0,0,0,0,0 3360 :

3370 REM DIRECTIONAL DATA 3380 DATA 0,-1,0,1,-1,0,1,0 3390 DATA -40,40,-1,1

Program 2. Zuider Zee: Part 2.

Machine Language Data to Use with MLX

49152 :076,021,192,076,175,192,220

49158 :076,060,193,076,139,193,231

49164 :076,023,202,076,205,193,019

49170 :076,226,194,032,116,193,087

49176 :141,000,205,032,116,193,199

49182 :141,000,206,032,116,193,206

49188 :133,002,032,116,193,133,133

49194 :010,169,000,141,137,003,246

49200 :141,179,002,133,013,169,173

49206 2 001,141,143,003,141,178,149

49212 :002,133,009,162,003,024,137

49218 :189,243,202,164,013,121,230

49224 :000,206,141,183,002,201,037

49230 :024,176,072,024,189,247,042

49236 :202,121,000,205,141,182,167

49242 :002,201,040,176,058,172,227

49248 .-183,002,185,000,207,133,038

49254 :158,185,064,207,133,159,240

49260 :172,182,002,177,158,201,232

49266 :064,176,041,197,002,240,066

181

y% Machine Language Games

49272 :037,165,002,032,043,193,080 49278 :238,178,002,208,003,238,225 49284 :179,002,164,009,173,182,073 49290 :002,153,000,205,173,183,086 49296 :002,153,000,206,230,009,232 49302 :076,158,192,169,001,141,119 49308 :137,003,202,016,160,230,136 49314 :013,166,009,228,013,208,031 49320 :150,169,000,141,143,003,006 49326 :096,160,000,132,018,032,100 49332 :116,193,164,018,153,180,236 49338 :002,200,192,004,208,241,009 49344 :032,116,193,133,002,032,188 49350 :116,193,133,010,174,183,239 493 56 :002,189,000,207,133,253,220 49362 :189,064,207,133,254,174,207 49368 :181,002,189,000,207,133,160 49374 :158,189,064,207,133,159,108 49380 :172,180,002,165,002,032,013 49386 :025,193,200,204,182,002,016 49392 :208,245,174,181,002,238,008 49398 :183,002,189,000,207,133,192 49404 :158,189,064,207,133,159,138 49410 -.165,002,172,180,002,032,043 49416 :043,193,165,002,172,182,253 49422 :002,032,043,193,232,236,240 49428 :183,002,208,224,096,072,037 49434 :145,253,165,254,072,07 3,220 49440 :088,133,254,165,010,145,059 49446 :253,104,133,254,104,145,007 49452 :158,165,159,072,073,088,247 49458 :133,159,165,010,145,158,052 49464 :104,133,159,096,169,000,205 49470 :141,178,002,141,179,002,193 49476 :133,158,169,128,133,159,180 49482 :169,004,13 3,018,160,000,046 49488 :162,000,177,158,201,011,021 49494 :240,012,201,031,176,008,242 49500 :238,178,002,208,003,238,191 49506 :179,002,230,158,208,002,109 49512 :230,159,232,224,240,208,117 49518 :227,198,018,208,223,096,056 49524 :032,253,174,032,158,173,170 49530 :165,013,240,003,104,104,239 49536 :096,032,247,183,165,021,104 49542 :208,246,165,020,096,160,005 49548 :000,132,158,132,253,169,216 49554 :208,133,159,169,160,133,084 49560 :254,120,165,001,041,251,216

182

Machine Language Games

49566 :133,001,177,158,145,253,001

49572 :200,208,249,230,159,230,160

49578 :254,165,159,201,216,208,093

49584 :239,165,001,009,004,133,215

49590 :001,088,173,000,221,041,194

49596 :252,009,001,141,000,221,044

49602 :169,008,141,024,208,169,145

49608 :024,141,022,208,096,173,096

49614 :173,002,205,136,003,176,133

49620 :081,169,000,141,175,002,012

49626 :169,020,141,145,003,173,101

49632 :027,212,041,031,201,022,246

49638 .-176,247,170,232,142,169,086

49644 :002,173,027,212,041,063,242

49650 .-201,038,176,247,170,232,026

49656 .-142,168,002,172,169,002,135

49662 :185,000,207,024,109,168,179

49668 :002,133,158,185,064,207,241

49674 .-105,000,133,159,160,000,055

49680 :177,158,201,064,208,016,072

49686 :169,000,141,174,002,032,028

49692 .-052,194,173,174,002,240,095

49698 :003,032,121,194,206,145,223

49704 .-003,240,008,174,173,002,128

49710 .-236,136,003,144,172,096,065

49716 :162,003,142,171,002,174,194

49722 :171,002,173,168,002,024,086

49728 .-125,247,202,072,173,169,028

49734 .-002,024,125,243,202,168,066

49740 :104,024,121,000,207,133,153

49746 :253,185,064,207,105,000,128

49752 :133,254,160,000,177,253,041

49758 :201,033,144,017,201,048,226

49764 :176,013,169,001,141,174,006

497 70 :002,173,175,002,240,008,194

49776 .-032,100,195,206,171,002,050

49782 :016,193,096,173,173,002,003

49788 :205,136,003,176,096,160,132

49794 :000,200,192,016,240,089,099

49800 :185,000,204,208,246,152,107

49806 .-072,169,001,153,000,204,229

49812 :173,168,002,153,032,204,112

49818 .-173,169,002,153,064,204,151

49824 :169,006,133,010,172,169,051

49830 :002,185,000,207,024,109,181

49836 .-168,002,133,158,185,064,114

49842 :207,105,000,133,159,104,118

49848 :024,105,064,072,160,000,097

49854 :032,043,193,238,173,002,103

f% Machine Language Games

49860 1104,132,159,010,038,159,030

49866 :200,192,003,208,248,133,162

49872 :158,165,159,024,105,160,211

49878 :133,159,169,000,160,007,074

49884 :145,158,136,016,251,096,254

49890 :173,173,002,240,119,169,078

49896 :000,141,140,003,173,136,057

49902 :003,074,141,145,003,169,005

49908 :001,141,175,002,173,027,251

49914 :212,041,015,201,015,240,206

49920 :247,170,232,142,177,002,202

49926 :189,000,204,240,083,188,142

49932 :064,204,140,169,002,189,012

49938 :032,204,141,168,002,024,077

49944 :121,000,207,133,158,185,060

49950 :064,207,105,000,133,159,186

49956 :160,000,177,158,201,064,028

49962 :240,019,169,000,141,174,017

49968 :002,032,052,194,173,174,163

49974 :002,240,006,173,140,003,106

49980 :240,032,096,174,177,002,013

49986 :169,000,157,000,204,188,016

49992 :064,204,185,000,207,133,097

49998 :158,185,064,207,133,159,216

50004 :169,064,188,032,204,145,118

50010 :158,206,173,002,206,145,212

50016 :003,208,149,096,173,027,240

50022 :212,205,144,003,144,001,043

50028 :096,120,165,001,041,254,017

50034 :133,001,173,177,002,024,112

50040 :105,064,160,000,132,254,067

50046 :010,038,254,200,192,003,055

50052 :208,248,133,253,165,254,113

50058 :024,105,160,133,254,174,220

50064 :171,002,224,002,208,018,001

50070 :160,255,200,192,008,240,181

50076 :088,177,253,208,247,169,018

50082 :25 5,145,253,076,245,195,051

50088 :224,003,208,016,160,008,019

50094 :136,048,068,177,253,208,040

50100 :249,169,255,145,253,076,047

50106 :245,195,160,007,224,001,250

50112 :208,025,177,253,162,000,249

50118 :232,224,008,240,010,010,154

50124 :176,248,189,064,203,017,077

50130 :253,145,253,136,016,234,223

50136 5076,245,195,224,000,208,140

50142 :022,177,253,162,000,232,044

50148 :224,008,240,010,074,176,192

184

Machine Language Games

50154 :248,189,056,203,017,253,176

50160 :145,253,136,016,234,160,160

50166 :007,17 7,253,201,255 240,099

50172 :008,165,001,009,001,133,057

50178 :001,088,096,136,016,239,066

50184 :165,001,009,001,133,001,062

50190 :088,169,000,141,079,003,238

50196 :174,177,002,169,000,157,187

50202 :000,204,206,173,002,169,012

50208 :003,133,018,166,018,173,031

50214 :168,002,024,125,247,202,038

50220 :141,132,003,072,173,169,222

50226 :002,024,125,243,202,141,019

50232 :133,003,168,104,024,121,097

50238 .-000,207,133,158,185,064,041

50244 .-207,105,000,133,159,173,077

50250 .-168,002,056,253,247,202,234

50256 :141,134,003,072,173,169,004

50262 .-002,056,253,243,202,141,215

50268 :135,003,168,104,024,121,135

50274 .-000,207,133,253,185,064,172

50280 .-207,105,000,133,254,160,195

50286 :000,177,158,141,141,003,218

50292 .-201,033,144,013,201,048,244

50298 :176,009,177,253,141,142,252

50304 .-003,201,048,144,058,198,012

50310 :018,016,154,174,171,002,157

50316 .-173,169,002,024,125,243,108

50322 :202,168,185,000,207,133,017

50328 :253,185,064,207,133,254,224

50334 ;173,168,002,024,125,247,129

50340 :202,168,177,253,072,172,184

50346 :169,002,185,000,207,133,098

50352 :253,185,064,207,133,254,248

50358 :172,168,002,104,145,253,002

50364 :076,029,197,172,169,002,065

50370 :185,000,207,133,253,185,133

50376 :064,207,133,254,172,168,174

50382 :002,169,160,145,253,169,080

50388 .-011,133,002,169,006,133,154

50394 :010,173,132,003,141,000,165

50400 :205,173,133,003,141,000,111

50406 :206,032,043,192,173,178,030

50412 :002,141,132,003,173,179,098

50418 :002,141,133,003,173,137,063

50424 :003,141,138,003,173,134,072

50430 :003,141,000,205,173,135,143

50436 :003,141,000,206,032,043,173

50442 .-192,173,178,002,141,134,062

Machine Language Games

50448 :003,173,179,002,141,135,137

50454 :003,173,137,003,141,139,106

50460 :003,169,001,141,140,003,229

50466 :141,079,003,096,162,009,012

5047 2 :189,160,204,208,036,188,001

50478 :128,204,185,000,207,133,135

50484 :251,185,064,207,133,252,120

50490 2 188,096,204,177,251,201,151

50496 :004,240,014,169,010,145,134

50502 :251,165,252,073,088,133,008

50508 :252,169,001,145,251,202,072

50514 :016,212,096,120,173,066,253

50520 :003,208,003,076,049,234,149

50526 :032,038,197,206,071,003,129

50532 :208,023,169,010,141,071,210

50538 :003,238,072,003,173,072,155

50544 :003,041,003,141,072,003,119

50550 :168,185,052,203,141,080,179

50556 :160,173,143,003,208,041,084

50562 :162,009,188,128,204,185,238

50568 :000,207,133,251,185,064,208

50574 :207,133,252,188,096,204,198

50580 :177,251,208,016,189,160,125

50586 :204,008,169,004,040,240,051

50592 :002,169,012,188,096,204,063

50598 :145,251,202,016,217,169,142

50604 :000,141,067,003,173,000,044

50610 :220,201,127,208,008,169,087

50616 :000,141,078,003,076,092,062

50622 :199,141,068,003,041,016,146

50628 :208,007,169,001,141,067,021

50634 :003,208,005,169,000,141,216

50640 :078,003,162,000,169,001,109

50646 :044,068,003,240,009,010,076

50652 :232,224,004,208,245,076,185

50658 :228,198,138,009,032,141,204

50664 :255,131,142,167,002,142,047

50670 :170,002,173,067,003,240,125

50676 :008,173,167,002,073,001,156

506S2 :141,167,002,032,149,199,172

50688 :160,003,173,014,208,056,102

50694 :249,036,203,141,064,003,190

50700 :144,008,173,016,208,041,090

50706 :128,208,001,024,173,064,104

50712 :003,106,074,074,141,064,230

50718 :003,173,015,208,056,249,222

50724 :040,203,074,074,074,141,130

50730 :065,003,032,199,199,208,236

50736 :006,136,016,206,076,092,068

186

Machine Language Games

50742 1199/169,001,077,167,002,157

50748 :141,167,002,032,149,199,238

50754 :173,014,208,056,233,012,250

50760 :072,144,009,173,016,208,182

50766 :041,128,024,240,001,056,056

50772 :104,106,074,074,141,064,135

50778 :003,072,17 3,015,208,056,105

50784 :233,040,074,074,074,141,220

50790 :065,003,168,185,000,207,218

50796 :133,251,185,064,207,133,057

50802 :252,104,168,169,064,145,248

50808 :251,173,067,003,240,099,185

50814 :173,079,003,240,094,173,120

50820 :143,003,208,089,173,083,063

50826 :003,208,084,174,170,002,011

50832 :173,065,003,056,253,251,177

50838 :202,201,002,144,070,201,202

50844 :023,176,066,168,173,064,058

50850 :003,056,253,255,202,201,108

50856 :001,144,054,201,039,176,015

50862 :050,024,121,000,207,133,197

50868 .-251,185,064,207,105,000,224

50874 :133,252,160,000,177,251,135

50880 :240,025,201,011,240,016,157

50886 :201,081,176,023,201,031,143

50892 :144,019,201,065,176,009,050

50898 .-201,048,176,011,169,001,048

50904 :141,083,003,169,064,160,068

50910 :000,145,251,076,092,199,217

50916 :173,067,003,240,115,173,231

50922 :078,003,208,110,173,069,107

50928 :003,240,059,172,076,003,025

50934 :208,100,141,076,003,173,179

50940 .-014,208,056,233,012,072,079

50946 :144,004,173,016,208,010,045

50952 :104,106,074,074,141,080,075

50958 :003,173,015,208,056,233,190

50964 :040,074,074,074,141,081,248

50970 :003,173,170,002,141,082,085

50976 :003,169,000,141,069,003,161

50982 :169,001,141,078,003,076,250

50988 :092,199,173,077,003,208,028

50994 :041,173,030,208,044,017,051

51000 :208,016,251,173,030,208,174

51006 :010,144,027,074,074,074,209

51012 .-074,160,003,074,176,007,050

51018 :200,192,007,208,248,240,145

51024 :011,140,069,003,140,077,008

51030 :003,169,001,141,078,003,225

f% Machine Language Games

51036 1173,069,003,240,049,170,028

51042 :188,044,203,173,016,208,162

51048 :010,144,006,152,013,016,189

51054 :208,208,006,152,073,255,244

51060 :045,016,208,141,016,208,238

51066 :173,255,131,024,105,014,056

51072 :157,248,131,138,010,170,214

51078 :173,014,208,157,000,208,126

51084 :173,015,208,157,001,208,134

51090 :076,225,199,174,167,002,221

51096 :208,003,206,015,208,224,248

51102 :001,208,003,238,015,208,063

51108 :224,002,208,013,206,014,063

51114 :208,016,008,173,016,208,031

51120 :041,127,141,016,208,224,165

51126 :003,208,013,238,014,208,098

51132 : 208,008,173,016,208,009,042

51138 :128,141,016,208,096,174,189

51144 :065,003,189,000,207,024,176

51150 :109,064,003,133,251,189,187

51156 :064,207,105,000,133,252,205

51162 :162,000,161,251,201,064,033

51168 :096,173,052,003,240,003,023

51174 :076,028,201,173,061,003,004

51180 :024,105,001,041,007,141,043

51186 :061_f003_f024,105,050,141,114

51192 :249,131,206,075,003,208,096

51198 :024,173,073,003,073,001,089

51204 :141,073,003,240,004,169,122

51210 :128,208,002,169,129,141,019

51216 :004,212,169,002,141,075,107

51222 :003,169,000,141,053,003,135

51228 :173,016,208,024,041,001,235

51234 :240,001,056,173,000,208,200

51240 :106,205,054,003,240,047,183

51246 :176,024,169,008,013,053,233

51252 :003,141,053,003,238,000,234

51258 :208,208,032,169,001,013,177

51264 :016,208,141,016,208,076,217

51270 :093,200,169,004,013,053,090

51276 :003,141,053,003,206,000,226

51282 :208,016,008,169,254,045,014

51288 :016,208,141,016,208,173,082

51294 :001,208,074,205,055,003,128

51300 :240,027,176,014,169,002,216

51306 :013,053,003,141,053,003,116

51312 :238,001,208,076,129,200,196

51318 :169,001,013,053,003,141,242

51324 :053,003,206,001,208,173,000

188

Machine Language Games

51330 :053,003,208,060,169,001,112 51336 :141,052,003,174,056,003,053 51342 :224,010,176,045,189,160,178 51348 :204,208,040,169,001,157,159 51354 :160,204,188,128,204,185,199 51360 :000,207,133,251,185,064,232 51366 :207,133,252,188,096,204,222 51372 :169,011,145,251,165,252,141 51378 :073,088,13 3,252,169,014,139 51384 2 145,251,169,030,141,070,222 51390 .-003,076,049,234,024,105,169 51396 .-035,141,248, 131, 174, 053, 210 51402 .-003,173,001,208,024,125,224 51408 :025,203,141,003,208,173,193 51414 :000,208,024,125,003,203,009 51420 .-141,002,208,173,016,208,200 51426 :041,001,125,014,203,041,139 51432 :001,010,141,068,003,173,116 51438 :016,208,041,253,013,068,069 51444 :003,141,016,208,173,016,033 51450 :208,041,001,208,018,173,131 51456 :000,208,201,005,176,011,089 51462 :173,021,208,041,252,141,074 51468 .-021,208,076,025,201,173,204 51474 .-021,208,009,003,141,021,165 51480 2 208,076,049,234,169,128,120 51486 2 141,004,212,206,070,003,154 51492 .-240,000,169,255,141,057,130 51498 2 003,141,058,003,141,056,188 51504 2 003,173,016,208,024,041,001 51510 2 001,240,001,056,173,000,013 51516 2 208,106,074,074,141,059,210 51522 2 003,173,001,208,074,074,087 51528 2 074,141,060,003,162,009,009 51534 2 189,160,204,208,108,188,111 51540 2 128,204,140,055,003,185,031 51546 2 000,207,133,251,185,064,162 51552 2 207,133,252,188,096,204,152 51558 2 140,054,003,177,251,201,160 51564 2 004,240,080,173,059,003,155 51570 2 056,237,054,003,016,005,229 51576 2 073,255,024,105,001,032,098 51582 .-252,201,165,252,072,165,209 51588 .-251,072,173,060,003,056,235 51594 2 237,055,003,016,005,073,015 51600 2 255,024,105,001,032,252,045 51606 :201,104,024,101,251,133,196 51612 2 251,104,101,252,133,252,225 51618 2 205,058,003,144,011,208,023

mft Machine Language Games

51624 :022,165,251,205,057,003,103

51630 :144,002,208,013,165,251,189

51636 :141,057,003,165,252,141,171

51642 :058,003,142,056,003,202,138

51648 :016,140,174,056,003,224,037

51654 :255,240,025,189,096,204,183

51660 :010,010,024,105,008,141,246

51666 :054,003,189,128,204,010,030

51672 :010,024,105,022,141,055,061

51678 :003,076,236,201,169,001,140

51684 :141,054,003,169,072,141,040

51690 :055,003,169,000,141,052,142

51696 :003,141,073,003,169,002,119

51702 :141,075,003,076,049,234,056

51708 :134,251,162,000,133,252,160

51714 :168,240,011,169,000,024,102

51720 :101,252,144,001,232,136,106

51726 :208,247,134,252,166,251,248

51732 :133,251,096,169,143,141,185

51738 :024,212,169,255,141,014,073

51744 :212,141,015,212,169,240,253

51750 :141,020,212,169,129,141,082

51756 :018,212,169,050,141,000,122

51762 :212,169,017,141,005,212,038

51768 :169,241,141,006,212,169,226

51774 :000,141,173,002,141,076,083

51780 :003,141,077,003,141,061,238

51786 :003,141,035,208,169,006,124

51792 :141,032,208,169,001,141,004

51798 :046,208,141,039,208,141,101

51804 :040,208,141,071,003,141,184

51810 :079,003,169,166,141,014,158

51816 :208,169,132,141,015,208,209

51822 :169,000,141,000,208,169,029

51828 :144,141,001,208,169,032,043

51834 :141,255,131,169,005,141,196

51840 :034,208,141,001,212,169,125

51846 :128,141,064,207,162,000,068

51852 :142,000,207,189,000,207,117

51858 :024,105,040,157,001,207,168

51864 :157,026,207,189,064,207,234

51870 :105,000,157,065,207,157,081

51876 :090,207,232,224,024,208,125

51882 :228,169,000,160,000,153,112

51888 .-000,204,174,000,004,208,254

51894 :021,153,000,136,153,000,133

51900 .-137,153,000,138,153,000,001

51906 :139, 153,000,140,153,000,011

51912 :141,153,000,142,200,208,020

190

Machine Language Games

51918 :224,169,255,160,127,153,014

51924 :000,161,136,016,250,120,127

51930 :169,085,141,020,003,169,037

51936 :197,141,021,003,169,000,243

51942 :141,066,003,141,069,003,141

51948 :169,001,141,052,003,088,178

51954 ;096,000,000,255,001,001,083

51960 :255,000,000,255,001,000,247

51966 :000,000,000,255,001,000,254

51972 :000,000,000,253,254,253,252

51978 :000,002,001,002,000,000,015

51984 :000,000,255,255,255,000,013

51990 :000,000,000,000,254,002,022

51996 .-000,001,254,002,000,000,029

52002 .-254,002,010, 014, 012, 012, 082

52008 :040,040,039,041,001,002,203

52014 :004,008,016,032,064,128,042

52020 .-102,060,102,195,001,003,003

52026 :007,015,031,063,127,255,044

52032 :128,192,224,240,248,252,068

52038 :254,255,080,255,084,251,225

▲

A Beginner's Guide to Typing In Programs

What Is a Program?

A computer cannot perform any task by itself. Like a car without gas, a computer has potential, but without a program, it isn't going anywhere. Most of the programs in this book are written in a computer language called BASIC. BASIC is easy to learn and is built into all Commodore 64s.

BASIC Programs

Computers can be picky. Unlike the English language, which is full of ambiguities, BASIC usually has only one right way of stating something. Every letter, character, or number is significant. A common mistake is substituting a letter such as O for the numeral 0, a lowercase 1 for the numeral 1, or an uppercase B for the numeral 8. Also, you must enter all punctuation such as colons and commas just as they appear in the book. Spacing can be important. To be safe, type in the listings exactly as they appear.

Braces and Special Characters

The exception to this typing rule is when you see the braces, such as {DOWN}. Anything within a set of braces is a special character or characters that cannot easily be listed on a printer. When you come across such a special statement, refer to "How To Type In Programs."

About DATA Statements

Some programs contain a section or sections of DATA statements. These lines provide information needed by the program. Some DATA statements contain actual programs (called machine language); others contain graphics codes. These lines are especially sensitive to errors.

195

If a single number in any one DATA statement is mistyped, your machine could lock up, or crash. The keyboard and STOP key may seem dead, and the screen may go blank. Don't panic-no damage is done. To regain control, you have to turn off your computer, then turn it back on. This will erase whatever program was in memory, so always SAVE a copy of your program before you RUN it. If your computer crashes, you can LOAD the program and look for your mistake.

Sometimes a mistyped DATA statement will cause an error message when the program is RUN. The error message may refer to the program line that READs the data. The error is still in the DATA statements, though.

Get to Know Your Machine

You should familiarize yourself with your computer before attempting to type in a program. Learn the statements you use to store and retrieve programs from tape or disk. You'll want to save a copy of your program, so that you won't have to type it in every time you want to use it. Learn to use your machine's editing functions. How do you change a line if you made a mistake? You can always retype the line, but you at least need to know how to backspace. Do you know how to enter inverse video, lowercase, and control characters? It's all explained in your computer's manuals.

A Quick Review

1) Type in the program a line at a time, in order. Press RETURN at the end of each line. Use backspace or the back arrow to correct mistakes.

2) Check the line you've typed against the line in the book. You can check the entire program again if you get an error when you RUN the program.

3) Make sure you've entered statements in braces as the appropriate control key (see "How To Type In Programs" elsewhere in the book).

196

How to Type In Programs

Many of the programs which are listed in this book contain special control characters (cursor control, color keys, reverse video, etc.). To make it easy to know exactly what to type when entering one of these programs into your computer, we have established the following listing conventions.

Generally, any Commodore 64 program listings will contain words in braces which spell out any special characters: {DOWN} would mean to press the cursor down key. {5 SPACES} would mean to press the space bar five times.

To indicate that a key should be shifted (hold down the SHIFT key while pressing the other key), the key would be underlined in our listings. For example, S would mean to type the S key while holding the shift key This would appear on your screen as a heart symbol. If you find an underlined key enclosed in braces (e.g., {10 N}), you should type the key as many times as indicated (in our example, you would enter ten shifted N's).

If a key is enclosed in special brackets, B 3 , you should hold down the Commodore key while pressing the key inside the special brackets. (The Commodore key is the key in the lower-left corner of the keyboard.) Again, if the key is preceded by a number, you should press the key as many times as necessary.

Rarely, you'll see a solitary letter of the alphabet enclosed in braces. These characters can be entered on the Commodore 64 by holding down the CTRL key while typing the letter in the braces. For example, {A} would indicate that you should press CTRL-A.

About the quote mode: you know that you can move the cursor around the screen with the CRSR keys. Sometimes a programmer will want to move the cursor under program control. That's why you see all the {LEFT}'s, {HOME}'s, and {BLU}'s in our programs. The only way the computer can tell the difference between direct and programmed cursor control is the quote mode.

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Once you press the quote (the double quote, SHIFT-2), you are in the quote mode. If you type something and then try to change it by moving the cursor left, you'll only get a bunch of reverse-video lines. These are the symbols for cursor left. The only editing key that isn't programmable is the DEL key; you can still use DEL to back up and edit the line. Once you type another quote, you are out of quote mode.

You also go into quote mode when you INSerT spaces into a line. In any case, the easiest way to get out of quote mode is to just press RETURN. You'll then be out of quote mode and you can cursor up to the mistyped line and fix it.

Use the following table when entering cursor and color control keys:

Maze Generator

Maze

Generator_______

Charles Bond Translated to machine language by Gary E. Marsa and for the 64 by Gregg Peele.

This program can be the basis for many excellent games.

Here's a remarkably short algorithm which produces random mazes on your TV screen.

To understand how it works, refer to the flowchart and Program 1. The following explanation should clarify the details.

The Background Field

The algorithm operates on a background field which must be generated on the screen prior to line number 210 in Program 1. The field must consist of an odd number of horizontal rows, each containing an odd number of cells: a rectangular array. It's convenient to think of the field as a two-dimensional array with the upper-left corner having coordinates X = 0 and Y = 0, where X is the horizontal direction and Y is vertical. No coordinates are used to identify absolute locations by the program, but the concept is useful in configuring the field.

Given that the upper-left cell of the field has coordinates 0,0, then the terminal coordinates both horizontally and vertically must be even numbers. In addition, the background field must be surrounded on all sides by memory cells whose contents are different from the number used to identify the field. That is, if the field consists of reversed (or inverse video) spaces, then the number corresponding to that character must not be visually adjacent to the field.

This could happen inadvertently if the screen RAM and system ROM have contiguous addresses. A sufficient precaution is to avoid covering the entire screen with field. Leave at least one space at the beginning or end of each line and, in general, leave the uppermost and lowermost lines on the screen blank.

203

The Maze Generator

The creation of the maze begins by placing a special marker in a suitable starting square. The program here always begins at the square just inside the upper-left cell of the previously drawn field. (Note that with our coordinate scheme this would be cell 1,1.) Any cell with odd-numbered coordinates would work, however, as long as it is internal to the field.

Next, a random direction is chosen by invoking the random number generator in your machine and producing an integer from 0 to 3. This integer, with the aid of a short table, determines a direction and a corresponding cell just two steps away from the current cell. This new cell is examined (PEEKed) to see if it is part of the field. If it is, the direction integer is put there as a marker, and the barrier between it and the current cell is erased.

In addition, the pointer to the current cell is moved to point to the new one. This process is repeated until the new cell fails the test; that is, it is not a field cell. When this happens, the direction vector is rotated 90 degrees and the test is repeated. Thus, the path carved out of the field will continue until a dead end is reached.

A dead end, incidentally, could occur in as few as five steps. When it does occur, we can make use of the markers which were dropped along the way Hansel and Gretel style. These can be checked to determine which direction we came from, so that we can back up and look for untrodden paths. So long as none can be found, the program will back up, one step at a time, erasing the markers as it goes. When a new direction can be taken, the pointer is set off in that direction, and the process continues as before.

Ultimately, the pointer will return to the start, a condition which is detected by the recovery of the special starting (now "ending") marker. This cell is then blanked and the program is done, leaving the pointer as it was at the start.

The Program

The direction table set up in lines 100 and 110 converts an integer to an address offset. In this case (40-column screen), we wish to step two cells to the right, up, left, or down.

Line 120 contains the variable SC, which is the memory address of the start of screen RAM. Lines 130-160 establish the background field on the screen.

The rest of the program draws the maze, as previously

204

explained. Line 310 is simply a convenient stopping point which prevents the screen from scrolling.

It may not be immediately obvious that this algorithm always produces a maze with only one nontrivial path between any two points, or that the maze will always be completely filled, but this can be proved. While the proofs will not be provided here, math buffs may find it interesting that for a maze of any size there will be exactly:

(H-D(V-l) -1 empty cells in the completed maze,

where H is the number of cells in each field row and V is the number of rows.

An interesting feature of this algorithm is that it works equally well in certain types of nonrectangular fields. U-shaped fields or fields with holes in them are quite suitable—as long as certain restrictions are observed. Just make sure that the coordinates of the upper-left and lower-right cells of any cut-out area are pairs of odd numbers. Also, if there is a single row of field cells between any cut-out areas and the outside of the original field, it may be removed.

Machine Language Mazes

Program 2 is a machine language translation of Program 1. It is in the form of a BASIC loader. It can be inserted into any BASIC program just as Program 1.

Program 3 is the assembly listing of the machine language routine found in Program 2.

The Mouse

The subroutine on lines 1000 to 1020 of Program 1 produces an artificial mouse which roams the maze endlessly. The mouse adheres to a "left-hand rule" when a choice of directions is possible. That is, when it is confronted with a branch-point, it will move off to the left, if possible. Otherwise, it will go forward. When no choice is available, it will turn around. These lines are unnecessary for the creation of the maze and may be deleted. Programs 2 and 3 do not contain the mouse.

Program 1. BASIC Maze Generator

100 DIMA(3)

110 A(0)=2:A(1)=-80:A(2)=-2:A(3)=80

120 WL=160:HL=32:SC=1024:A=SC+81

205

Appendix

130 PRINT"{CLR}"

140 F0RI=1T023

150 PRINT"{RVS}{WHT}{39 SPACES}"

160 NEXTI

210 POKEA,4

220 J=INT(RND(1)*4):X=J

2 30 B=A+A(J) :IFPEEK(B)=WLTHENPOKEB,J:POKEA+A(J)/2,

HL:A=B:GOTO220 240 J=(J+1)*-(J<3):IFJ<>XTHEN230

250 J=PEEK(A):POKEA,HL:IFJ<4THENA=A-A(J):GOTO220 310 GETC?:IFC$=""THEN310 1000 POKEA,81:J=2 1010 B=A+A(J)/2:IFPEEK(B)=HLTHENPOKEB,81:POKEA,HL:

A=B:J=(J+2)+4*(j>l) 1020 J=(J-1)-4*(J=0):GOTO1010

Program 2. Machine Language Maze Generator

10 I=49152:IF PEEK(1+2)=216THENSYS49160:END 20 READ A:IF A=256 THENSYS49160:END 30 POKE I,A:1=1+1:GOTO 20 49152 DATA 1,0,216,255,255,255,40 49160 DATA 0,169,81,133,251,169,40 49168 DATA 133,253,169,4,133,252,133 49176 DATA 254,169,147,32,210,255,162 49184 DATA 0,160,0,169,160,145,253 49192 DATA 200,192,39,208,249,24,165 49200 DATA 253,105,40,133,253,144,2 49208 DATA 230,254,232,224,23,208,229 49216 DATA 160,0,169,4,145,251,169 49224 DATA 255,141,15,212,169,128,141 49232 DATA 18,212,173,27,212,41,3 49240 DATA 133,173,170,10,168,24,185 49248 DATA 0,192,101,251,133,170,185 49256 DATA 1,192,101,252,133,171,24 49264 DATA 185,0,192,101,170,133,253 49272 DATA 185,1,192,101,171,133,254 49280 DATA 160,0,177,253,201,160,208 49288 DATA 18,138,145,253,169,32,145 49296 DATA 170,165,253,133,251,165,254 49304 DATA 133,252,76,62,192,232,138 49312 DATA 41,3,197,173,208,189,177 49320 DATA 251,170,169,32,145,251,224 49328 DATA 4,240,26,138,10,168,162 49336 DATA 2,56,165,251,249,0,192 49344 DATA 133,251,165,252,249,1,192 49352 DATA 133,252,202,208,238,76,62 49360 DATA 192,169,1,160,0,153,0 49368 DATA 216,153,0,217,153,0,218 49376 DATA 153,0,219,200,208,241,96,256

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Program 3. Source Listing

C000 01 00 C002 D8 C003 FF C004 FF C005 FF C006 28 C007 00

C008 A9 51 LDA #$51

C00A 85 FB STA $FB

C00C A9 28 LDA #$28

C00E 85 FD STA $FD

C010 A9 04 LDA #$04

C012 85 FC STA $FC

C014 85 FE STA $FE

C016 A9 93 LDA #$93 C018 20 D2 FF JSR $FFD2

C01B A2 00 LDX #$00

C01D A0 00 LDY #$00

C01F A9 A0 LDA #$A0

C021 91 FD STA ($FD),Y

C023 C8 INY

C024 C0 27 CPY #$27

C026 D0 F9 BNE $C021

C028 18 CLC

C029 A5 FD LDA $FD

C02B 69 28 ADC #$28

C02D 85 FD STA $FD

C02F 90 02 BCC $C033

C031 E6 FE INC $FE

C033 E8 INX

C034 E0 17 CPX #$17

C036 D0 E5 BNE $C01D

C038 A0 00 LDY #$00

C03A A9 04 LDA #$04

C03C 91 FB STA ($FB),Y

C03E A9 FF LDA #$FF C040 8D 0F D4 STA $D40F

C043 A9 80 LDA #$80 C045 8D 12 D4 STA $D412 C048 AD IB D4 LDA $D41B

C04B 29 03 AND #$03

C04D 85 AD STA $AD

C04F AA TAX

C050 0A ASL

C051 A8 TAY

C052 18 CLC C053 B9 00 C0 LDA $C000,Y

C056 65 FB ADC $FB

C058 85 AA STA $AA

C05A B9 01 C0 LDA $C001,Y

C05D 65 FC ADC $FC

C05F 85 AB STA $AB

C061 18 CLC

C062 B9 00 C0 LDA $C000,Y

C065 65 AA ADC $AA

C067 85 FD STA $FD

C069 B9 01 C0 LDA $C001,Y

C06C 65 AB ADC $AB

C06E 85 FE STA $FE

C070 A0 00 LDY #$00

C072 Bl FD LDA ($FD),Y

C074 C9 A0 CMP #$A0

C076 D0 12 BNE ?C08A

C078 8A TXA

C079 91 FD STA ($FD),Y

C07B A9 20 LDA #$20

C07D 91 AA STA ($AA),Y

C07F A5 FD LDA $FD

C081 85 FB STA $FB

C083 A5 FE LDA $FE

C085 85 FC STA $FC

C087 4C 3E C0 JMP $C03E

C08A E8 INX

C08B 8A TXA

C08C 29 03 AND #$03

C08E C5 AD CMP $AD

C090 D0 BD BNE $C04F

C092 Bl FB LDA ($FB),Y

C094 AA TAX

C095 A9 20 LDA #$20

C097 91 FB STA ($FB),Y

C099 E0 04 CPX #$04

C09B F0 1A BEQ $C0B7

C09D 8A TXA

C09E 0A ASL

C09F A8 TAY

C0A0 A2 02 LDX #$02

C0A2 38 SEC

C0A3 A5 FB LDA $FB

C0A5 F9 00 C0 SBC $C000,Y

C0A8 85 FB STA $FB

C0AA A5 FC LDA $FC

C0AC F9 01 C0 SBC $C001,Y

C0AF 85 FC STA $FC

C0B1 CA DEX

C0B2 D0 EE BNE $C0A2

C0B4 4C 3E C0 JMP $C03E

Appendix

C0B7 A9 01 C0B9 A0 00 C0BB 99 00 D8 C0BE 99 00 D9 C0C1 99 00 DA C0C4 99 00 DB C0C7 C8 C0C8 D0 Fl C0CA 60

LDA #$01 LDY #$00 STA $D800,Y STA $D900,Y STA $DA00,Y STA $DB00,Y INY

BNE $C0BB RTS

Maze Generator Flowchart

209

Do You Want to Write Your Own Games?

Orson Scott Card

I remember when videogames first reached my town back in the early seventies. A friend and I dropped a few quarters into a Pong machine and had a great time. But all in all, we preferred playing Ping-Pong on a real table.

But then, in a theater lobby, we met Breakout, and it changed my life. I became a dedicated videogamer from that time forward.

Because there on a TV screen—not even a color screen, then, just black-and-white with colored plastic strips—the videogame was offering an experience that I couldn't get anywhere else. The speed and the concept both were something entirely new.

Everybody knows where it went from there. Turn Breakout's paddle into a spaceship, give the bricks a different shape, and let them march down the screen at you, and you have Space Invaders. Turn Breakout's paddle into a race car and let it drive over dots instead of bricks, and you have the earliest gobble games. The shoot-outs and gobble games, the climbing games and the simulations—they have all become more sophisticated.

Now, on your own TV at home, you can have the little airplanes of "Richthofen's Revenge" flying around. And you typed the game into your computer yourself.

Getting Behind the Games

If you're like me, however, playing was never really enough. Right from the beginning, I wondered how it was done. I knew nothing about computers then—like many people, I thought computers were for people who were good in math or interested in engineering, and I was definitely neither. But for the first time I wanted to have whatever abilities it took to program computers. Because I wanted to make my own games.

213

I wanted to create a game where I could handle old-time sailing ships through currents and winds to explore different islands and conduct sea battles.

I wanted a game where I could build cities and design traffic flow patterns, create the image of a city's life.

I wanted to have the power of a computer to create whatever world I wanted, and whatever game I wanted to play within that world.

But I knew it would never happen. I wasn't good in math or interested in engineering, and to people like me computers would never be anything but big black boxes.

Unlocking the Little Black Box

The big black boxes have changed, haven't they? You can treat your 64 as a black box, if you want—plug in a game on a ROM cartridge and away you go. But for most games, you still need to type things like LOAD and RUN. And for the games in this book, you need to type in entire programs.

And if it hasn't occurred to you before, it certainly should be plain now. You have the equipment to program all those games you have always wished you could play. Your Commodore 64 can do almost everything the videogames in the arcade can do.

Best of all, though, it can do things that have never been done before. It can display worlds that you create, and carry out actions that you designed.

And as for the myth that programmers have to be good in math or engineering—you don't believe that anymore, do you? My wife still has to balance the checkbook for me and I can't tell a circuit diagram from a plate of vermicelli, but I have written games that actually work, using BASIC and machine language both. And like those old-time ads ("My Friends Laughed When I Sat Down At The Piano"), I assure you that if I can do it, anybody can.

How to Learn How to Program Games

Unfortunately you won't find a night school class in videogame programming. Colleges and high schools tend to teach programming with a business or mathematical slant. They rarely teach much about the graphics and sound techniques at the heart of game programming.

So the best way to learn programming is to find a friend who's an expert videogame programmer and get him to teach

214

Appendix

you, step by step, how to solve the problems you run into trying to program your first game. Because you can only learn to program by programming, and having an expert (and patient) friend gets you through the rough places.

The second best way is books.

There are books that teach you BASIC programming for the Commodore 64, reference books that give you valuable information about memory locations and special techniques, books that teach machine language programming for the 6510 that runs your 64, and even a book called Creating Arcade Games on the Commodore 64, which sounds like exactly the book you want.

(Before I give you my full list of recommended reading, I'd better explain something. This list will include mostly books published by COMPUTE! Books, which is the publisher of COMPUTEl's First Book of Commodore 64 Games. However, this is not merely shameless self-promotion. Wherever I knew of a valuable teaching or reference book by another publisher, I have listed it. But the Commodore 64 is such a new computer that at the time of this writing, most publishers don't have their Commodore 64 books out yet. In fact, many of the books on my list haven't been published yet, either. But because I'm an editor at COMPUTE! Books, I know all about our books that are at the printer or in production or still coming, a chapter at a time, from authors in California, Michigan, Utah, Virginia, Pennsylvania, and New Jersey. Therefore, I can include those books on the list and promise you that they'll help you learn programming. But I can't tell you about forthcoming books by other publishers because, unfortunately, in the world of publishing we don't always tell each other what we have planned. By the time you read this, there may be a hundred other books that can help you; this list will only tell you about the ones I know.)

In the following list, an asterisk (*) marks the books that are useful only if you are planning to use machine language.

BASIC Programming. If you're new at programming, here are some books that can help supplement the manuals published by Commodore.

Camp, David. Creating Arcade Games on the Commodore 64. Greensboro, North Carolina: COMPUTE! Books.

Chamberlain, Craig. All About the Commodore 64. 2 vols. COMPUTE! Books.

Heilborn, John and Ron Talbott. Your Commodore 64: A Guide to the Commodore 64 Computer. Berkeley, California: Osborne/ McGraw-Hill.

215

COMPUTEI's First Book of Commodore 64.

Commodore 64 Programmer's Reference Guide. West Chester, Pennsylvania: Commodore Business Machines, Inc.

Graphics and Sound Techniques. Once you've mastered the basics of BASIC, you can get into the fascinating techniques of moving shapes and colors on the TV screen and creating sounds from the TV speaker. This is an area where the Commodore 64 is different from every other computer, even its little brother, the VIC-20.

Heilborn, John. COMPUTEI's Reference Guide to Commodore 64 Graphics.

Heilborn, John. COMPUTEI's Reference Guide to Commodore 64 Sound.

COMPUTEI's First Book of Commodore 64 Sound and Graphics.

Reference Books. These are books that give you detailed information about features and key memory locations of the Commodore 64. Many of these features are only usable in machine language, but others are valuable to BASIC programmers as well.

*Heeb, Dan. The Commodore 64 Tool Kit: Kernal Routines. COMPUTE! Books.

*Heeb, Dan. The BASIC Tool Kit: Commodore 64 and VIC-20. COMPUTE! Books.

Leemon, Sheldon. Mapping the Commodore 64. COMPUTE! Books.

Learning Machine Language. These are books that help you learn how to put real speed and complex but smooth animation into your videogames.

Fernandez, Judi N., Donna N. Tabler, and Ruth Ashley. 6502 Assembly Language Programming. New York: John Wiley and Sons.

Leventhal, Lance A., and Winthrop Saville. 6502 Assembly Language Subroutines. Osborne/McGraw-Hill.

Mansfield, Richard. Machine Language for Beginners. COMPUTE! Books.

Zaks, Rodnay Programming the 6502. Berkeley, California: Sybex.

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