I USBORNEGUIDETO-.l

COMPUTER~~~oIiAME!iI How they workand howtowin

USBORNE GUIDE TO

COMPUTER~t~IiAME!i

Ian GrahamEdited by Lisa Watts

This book was designed by Round Designs and Roger Priddy and illustratedby Graham Smith, Graham Round, Ian Stephen and Tony Morris.Thanks to Simon Lowe for arcade games playing tips.The names of the games in this book are registered trade marks. Thebook has been produced independently of the games manufacturers andthe winning strategies for the games have been devised by our own experts.

Electronic gamesEach of these electronic gamescontains a tiny computer on a siliconchip, like those shown at the bottom ofthe page. The computer creates andcontrols all the effects of the game. Itcan pick a series of numbers for you toguess, or a sequence of notes to copy,and can control the mvading aliens in aspace game.

These are two space invader ~type games. In these, thecomputer lights up the columnsof invaders and the missiles inthe display.

In this game, called Simon, thecomputer plays a series ofnotes, then checks that youcopy them correctly.

A chip is a powerhouse of minuteelectrical circuits pulsing with tinycurrents of electricity. The electricalcircuits are embedded in the smallslice of silicon after which the chip isnamed.

The picture above shows two chips,one with its cover removed to show thechip of silicon. All the work ofthecomputer is done by the pulses ofelectricity flowing through the chip.

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Inside Astrq Wars

This picture shows an electronic gamewith the front taken off. The chip issurrounded by other electroniccomponents which control thesupply of electricity to the chipand the display. Thecomponents are attached toa printed circuit boardwhich has metal tracks onthe back to carry thecurrent between thecomponents.

Electronic components tocontrol the supply ofelectric current.

What the chip does

The chip is the brain and control centreof the game. It cdhtains all theinformation about the game andcontrols the action in the display, andthe sound effects.

Italso receives messages from theplayer's controls, processes them andsends them on to the display. You willfind out how the chip does all thesethings as you read through this book.

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How arcade games workArcade games have much larger,more powerful computers than hand-held electronic games, so the gamesare more exciting and complex.

An arcade game computer has over ahundred chips connected together on aprinted circuit board. Each chip has itsown job to do and they are controlled by amaster chip called the microprocessor.

Inside an arcade game

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At an Asteroids competition heldinWashingtonD.C., U.s.A.,thetopscore was 142,910points.

Most of the space insidea game is taken upby the coin box.

The world record for the longestga.IlUlplayed by one person is16hours 34 minutes. A player intheU.s.A-playedforthislongfor

~ /' 25 cents on the game Defender.

(' How to beatthe gamesThe better you get at arcade games, thelonger the games last and the less moneyyou spend. Before you playa new game,watch other players and get to know thegame. Try and develop a plan, or strategy,forbeating the computer. There are lots oftips from experts to help you inthis book.

The game created by the computer isalways the same and once you get to knowityou willprobably recognize the pattern.Mostgames have special sequenceswhich start at certain scores. The arcadeoperator can decide the score at whichthe sequences start, and also how many"lives"you get, so try playing the game onvarious machines to see ifit isdifferent.

An arcade game usuallyhas twocomputers, one to control the game andanother for the sound effects.Themaingame computer contains alltheinformation for the game and processesthe messages fromthe player's controls. Italso receives electronic messages fromthe coin accepter and onlystarts the gamewhen the correct coins are received.

ASTEROIDSThe aim of this game is to gainpoints by destroyinq asteroids andflying saucers by firing from yourspaceship. Destroying the smallflying saucers gives you the mostpoints. A good playing strategy is toclear the screen of all but oneasteroid (ifyou destroy them all, acomplete new set appears), thenwait for the small flying saucer.

At the beginning of the game it issafer to stay in the middle of thescreen. Ifyou move around you maybump into a rock. Watch out for thesmall asteroids. These travel fasterthan the larger ones, so ifthere areany hurtling towards your ship,shoot at them first. Aim in front ofrocks, so they fly into your fire.

Only use hyperspace in direemergencies, for instance, ifyoucannot avoid crashing into a rock.When you re-enter the screen youhave approximately a one in fivechance of hitting something.

The large saucer fires at random,but the small one can aim at you, sowhile you are waiting for it, keepusing thrust. Ifyou stay still, thesaucer will aim to hit you as soon asit appears, and the higher yourscore, the more accurate its aimbecomes.

A tip from the gamemanufacturer, Atari - the maximumnumber of objects that can appearon the screen at one time is 35 (27rocks, I saucer, 2 saucer bullets,your ship and 4 of your bullets). Ifyou have broken up lots oflargerocks and are getting close to thisnumber of objects, unusual thingscan happen on the screen. Forinstance, you can destroy a largerock with one bullet.

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Howa computer plays gamesThe picture on these two pages shows what is happening insidethe computer when you are playing a game. There are threemain parts in the computer the central processing unit (CPU)where all the work is done, the permanent memory where therules of the game are stored and the temporary memory whereinformation is stored during the game.

Central processing unitThis is the control centre of the computer.At the start of the game it receives all theinformation about the game from thepermanent memory, and sends it on to thedisplay. Then, during the game, itprocesses the messages from the player'scontrols, checks them with theinformation in the memories and sendsthem on to the display.

DisplayThe featuresin the displayare switchedon and off byelectricalmessages fromthe centralprocessing unit,followinginstructionsfrom thepermanentmemory and theplayer's controls.

Electronic messagesinside the computer

Permanent memoryThis contains step-by-stepinstructions telling the computerhow to play the game. In ~computer language it is \11

called ROM which standsfor Read Only Memory.The computer can only"read" the information tJ.in ROM, itcannot storeinformationthere.

Temporary memoryDuring the game, informationfrom the central processingunit about the player's moves,the score and how many "lives"the player has left, are storedin here. In computer languagethe temporary memory iscalled RAM which stands forRandom Access Memory.Afterthe game, all theinformation in RAM is wipedout.

Player's controlsElectrical messages fromthe player's controls tellingthe computer to "fire amissile" or "eat anenergizer" go first to thecentral processing unit andare then sent on to thedisplay.

Parts of a computerAll computers have the same basic partsas those shown here. The instructions inthe ROM memory will be different,though, as a computer built to guide asatellite or work out financial calculations,for instance, will need differentinformation from a computer for playing agame.

MISSilECOMMAND

In this game you control threemissile bases and have to defendcities from aerial attack. You gainpoints for destroying the attackersand for the number of missiles andcities you have left at the end ofeach phase of the game.

At the beginning of the game, tryand destroy as many as possible ofthe first wave of attack missiles withan intensive barrage of fire acrossthe centre of the screen Then aimat any remaming missiles, shootingthe lowest ones first before theyreach your bases and cities.

During the game, concentrate ondefendmg your bases. If all yourbases are destroyed you will haveno missiles left to defend the cities.To keep the game gomg, though,you must have one city mtact at theend of each phase of the game.

Each time you score a certainnumber of points (usually 10,000)you are gIven a bonus city. Expertplayers try to win a city towards theend of a phase so they do not have todefend it throughout the attack.

When the bombers appear, try tohit them before they can drop theirbombs on you, and attack enemymissiles before they can split andbecome doubly dangerous. Withskill and timing, you can aim at thepoint where the paths of twoattackers will cross and destroythem both with the same fire. Use upall the missiles from the end basesfirst, then you need no longerdefend them. Do not win more citiesthan you need to keep the gamegoing. You will have extra workdefending them.

Howa computer worksA computer consists of intricate sets ofmmute electncal circuits engraved ontiny chips of silicon The circuits are pulsing with thousands oftmy currents ofelectricity.

This picture shows the circuits in two ofthe many layers of a chip. The circuits arecomplicated networks of pathways andthey contain microscopic switches. Theswitches turn the currents off and on and

There are only two signals in computercode: "on" (pulse) and "off" (no-pulse). Inthis picture the signals are shown by therobots' torches. The signals can also berepresented by numbers, using I for onand 0 for off. *

convert them into streams of pulses ,shown here by red flashes. The pulses arethe signals in a code which the computeruses to do all its work.

Each piece of information in thecomputer is represented by a group ofeight signals, that is, ons (Is) and offs (Os).Each group is called a "byte". Each signalis called a "bit".

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This picture shows one of the circuits on achip, enlarged many times. Each part ofthe computer has different circuits toproduce and control different patterns ofpulses.

RAMcrup ROMcrupThe circuits for the <different parts of thecomputer may be im different chips, orthey may all be conttained in a single chipcalled a microprocessor. You can find outhow a chip is made 'on pages 34-35.

*A code based on the two digits 1and 0 is called binary code.

Single chip computer . '. Invaders on a ~<lfI" w.~\~II ~:~~~,ro,~_oro':~§;;!~J:"

"RAM

This watch is run by amicroprocessor chip and itcan play an invaders gameas well as telling the time.The chip is like the one onthe left and it controls all thefunctions of the watch,including the date, an alarmand a stopwatch as well asthe time and game. Somewatches contain a smallcalculator, too.

Most hand-held electronic games containmicroprocessor chips. A microprocessoris in fact a complete computer on a singlechip of silicon. Microprocessors are usedin other equipment too, such as electronicorgans and calculators.

More powerful computers, like the ones inarcade games, have lots of different chips.For instance, there are ROM chips andRAM chips and other chips to translate themessages coming into the computer intobinary code. All the chips are connectedtogether on a printed circuit board, with alarge microprocessor chip to control themall.

A computer with lots of chips has farmore processing power and memoryspace than a single chip computer. Thesize of the memory is measured by thenumber of bytes it can store. Most hand-held games have a memory of about 2,000bytes (that is enough for about 2,000pieces of information). An arcade gamehas about 32,000 bytes of memory. II

How the computer knowswhattodoThe instructions tellmg a computer what to do arecalled a program * and they are stored m thecomputer's memory. There are two ways of givinga computer its program: it can be built intothe computer when it is made, or put intothe computer each time you use it.

Computers with built-in programscan do only the tasks for which theyare made. They are called dedicatedcomputers. Computers which can begiven different instructions each timeyou use them are calledprogrammable computers.

.••You can play lots of different gameswith this hand-held game, by fittingdifferent cartridges into the main gameunit. It is not really programmable, though,as you cannot write your own programs

.••Most hand-held electronic games, andarcade games, have dedicatedcomputers. They can play only the gamesfor which they were programmed whenthey were built.

Cartridges

for it. Each games cartridge contains amemory chip with the program for a gamein it. The main game unit contains amicroprocessor chip which processes theinformation from the memory chip.

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This picture shows a group of pulses andno-pulses representing a piece ofinformation in computer code. Eachinstruction in the computer's memory isrepresented by a different group of pulsesand no-pulses.

"Usually spelt like this in computer language.

In a dedicated computer the instructionsare stored in ROM. This is done by settingthe switches at the time of manufacture sothey produce the same groups of pulsesevery time the current flows through them.

This is part of a program for amicrocomputer. It is written in aspecial computer language calledBASIC.

.••A microcomputer, like this one, is aprogrammable computer. You canprogram it to playa game, or drawpictures, work out complicatedcalculations, or whatever you like. Youplug it into a TV, then program it bytyping instructions on the keyboard.You can find out more about playinggames on a microcomputer onpages 24-27.

In a programmable computer theprogram is stored in RAM. Each time youput a different program into the computer,the positions of the switches in the RAMcircuits are changed to produce differentgroups of pulses.

PAC-MANThere are lots of different versionsof this game in which you guide thePac-rnan round the maze, eatmgdots, fruits and energizers whilebeing chased by monsters.

Pac-rnan experts gain scores ofover 300,000. The trick is to eat asmany dots and fruits as possible ansave the energizers until the bestmoment for eating the monsters. Asin other games, leave one dot orenergizer on the screen until youwant a new set to appear.Try and avoid the paths withenergizers until you are ready toattack the monsters. Until then, onlyeat an energizer m an emergency ifseveral monsters are closing in onyou.

Before you use the emergencyexits at the sides of the maze, makesure the other SIde of the maze isclear. There may be a monsterlurkmg there ready to eat youas you re-enter the maze.

OIXThis is a difficult game in which youtry to colour in the screen with yourdrawing head, while beingattacked by the Qix, Sparx andFuses.Start the game well away from theQix and keep an eye on the Fuseswhich chase you along unfinishedlines. Do not let them touch yourdrawing head.Try and draw a network of open-ended boxes to trap the Qix m. Ifyou manage to lure it into a box,quickly seal it up with another line,then switch to fast draw and try andfill in as much of the screen aspossible. If you fill in over 75% ofthescreen you win a new game.

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TV gamesA TV game IS a computer whichcan make pictures for a game onan ordinary TV screen. All themformation for makmg thepictures and playing the games ism the computer's ROM memory.Most TV games have gamesprograms in ROM cartridgeswhich you plug into thecomputer.

Cartridges

The computer can makea colour picture on thescreen if it is a celomtelevision set.

The computer for a TV game is called aconsole. It contains all the chips forrunning the game, except for the ROMchips. You plug the console into the aerialsocket on the TV and when you areplaying a game, the TV receives signals

from the computer, instead of from a TVstation. Most TV games have a switch forplaying games at different skill levels.This tells the computer to playa differentversion of the game program, or to run it ata different speed.

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Inside a games cartridge

Garnes cartridges have to be keptclean as dust on the printedcircuit board can interfere withthe flow of electrical informationfrom the chip.

Each cartridge contains asingle ROM chip and the circuitsin a chip are specially designedfor each game. The games arewritten by computer programmers, thentranslated into binary code. Electronicengineers then design the circuits whichwill produce the correct patterns of pulsesin the chip.

Howa TV game works

This picture shows how the computer in a TV game console works, and how it sendsmessages to the TV screen to make the pictures,Allthe informationaboutthe Temporarymemorygame flowsintothecomputer (RAM)where detailsfromthegame cartridge. ofthe player'smoves

\ and score are stored.

Here, messages incomputer code fromthe microprocessorare converted intovideo signals tomake a TV picture.Then they areadjusted to thecorrect frequencyfor the television.

This kind of handset is called a joystick.For each position of the joystick there isan electrically sensitive place insidethe handset. When the joystick makescontact with one of these places, anelectrical message is sent to thecomputer. The computer receives adifferent message from each position.

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Putting the game on the screen

1

To put the picture for a game on a TVscreen the computer has to translate allthe information in its memory into videosignals which the television canunderstand.

If you look closely at the picture on acolour TV screen you can see that it ismade up of tiny coloured dots. When youplaya TV game the colour of the dots isdecided by insUUctions from the computer.

Each instruction from the computercontrols the colour of a square group ofdots called a pixel (short for pictureelement), so all the dots in one pixel arethe same colour.Picture quality

The dots are lit up by beams of electronswhich scan the back of the televisionscreen. The beams are controlled by thecomputer according to the instructions foreach pixel.

A detailed picture with perspective ismade up of a large number of small pixels,whereas simpler, more stylized pictureshave fewer, larger pixels. For instance, apicture like the one on the left is made up

of about 30,000 pixels, and the one on theright has only about 2,000. To makedetailed, realistic pictures the computerneeds a large memory to store theinstructions for all the pixels.

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Special effects

The picture in an arcade game is made inthe same way as a television picture. Somearcade games, though, use special effectsto make the game more exciting.

For instance, in some games you see areflection of the screen, rather than thescreen itself, against a paintedbackground. The painting has more detailthan it is possible to create with a gamescomputer.

Inside the game there is a sheet of glasspositioned at an angle over the screen.The picture on the screen is upside downso that when it is reflected on the glass, it isthe right way up. You can see the paintedbackground through the glass.

FROGGERHere are a few tips for this game inwhich you score points by guiding afrog across roads and rivers toreach home safely.

Be careful to land accurately onlogs and lily pads. If the frog is halfon and half off it will fall in the river.

Watch out for the flashing greenleaves. The frog will blow up ifitlands on one of these. Watch out forthe crocodile on the Jog line and thesnake on the lilyleaves, too.

You get bonus points by jumpingon a purple frog, eating insects,helping a lady frog home andjumping into holes containing thepurple bird.

SCRAMBLEYou are a spaceship commander ona mission over enemy territory.Your aim is to destroy the robot atthe end of the maze and win a newmission.

It is crucialto watch your fuellevel and to gain fuel by destroyingfuel dumps. In the first, easy stretchof the mission, fly low and destroy asmany dumps as possible. Thisshould give you enough fuel to seeyou through to the end of themission. It is easier to hit the targetsby shooting from just above groundlevel than by bombing. When youare bornninq, aim just in front ofyour target to allow for the angle ofthe bombs as they fall.

When you are under attack, tryand dodge the attackers and shootthem down, but keep bombing theground at the same time. Watch outfor obstacles on the ground and beready to take evasive action.

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Sounds from a loudspeaker setupinvisible movements called More complicated sounds, such aswaves in the air. When the waves explosions, contain sound waves oflots ofreach your ears, messages are different frequencies. The sound wave forsent to your brain and you hear an explosion might look like this.

""m;J))))))))))) ))]))))))))))))))))))JI) ) )

Low)soun)d~'--)Hi)'9hso)und) ) ~~=~;r.~:Ei:;~~~:o.current vanes depending on thepatterns of pulses.

Making sound effectsThe instructions for making the sound 1How SOUnds~a~re~~eeffects for a game are stored In thecomputer's memory. Dunng a gamemessages from the computer causethe loudspeaker to make the sounds

Sound waves

2High sounds make rapid movements inthe air and lower sounds make slowermovements. To make sounds like this thecomputer has to make movements in theair using a loudspeaker. The rate ofmovement is called frequency. Simple

sounds, which have only one frequency,are easy to make using the pulses ofcomputer code. With the morecomplicated sounds the computer codehas to be translated into a single current.

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pulse to no-p e makes the discs vibrate.The vibrating discs make the air roundthem move, settinq up a sound wave.Different patterns of pulses producevibrations of different frequencies, and soproduce differentsounds.

GALAXIANThe aim of this game is to destroyaliens and their flagships. To get ahigh score, remember that aliensand flagships are worth double thenumber of points if you destroythem when they are attacking youthan when they are in formation.

Flagships on the attack are worththe most points, so concentrate onthem as soon as they attack If theflagship has an escort, try to destroyIt too.

While waiting for a flagshipattack, destroy any attacking aliens,then concentrate on the aliens stillin formation. Aim at the aliens in theoutside columns first, to narrowtheir field of attack In this game youcannot shoot very rapidly, so youhave to be careful to aim accurately.

LUNAR RESCUE

Pulses

In this game you are trying torescue astronauts under fire fromalien space vehicles.

In the first phase of the rescue thefire button operates your thrustcontrol as well. Use thrust to avoidbeing hit by asteroids, but watchyour fuel level. Be careful not to hitthe flashing beacons as they Willdestroy you.

Try to land on the corner landingpads first. On your return to yourship, destroy as many alien spacevehicles as possible. You mustenter the ship Without touching theside of the door. If you do, you dropthe astronaut.

When the alien space vehiclesare widely scattered, expect ameteor shower and use the firebutton to ascend to safety, fast. 21

The current passes through a evicecalled a voltage controlled oscillator andthen on to a loudspeaker. Theloudspeaker contains a cone of paperwhich vibrates and creates sound wavesin the air at various frequencies accordingto the strength of the current.

Talking gamesThere are lots of games which can"speak" to you, but it is not yet possibleto build a game which can understandspoken words. It is very difficult for acomputer to understand the humanvoice as everyone speaks slightlydifferently- A very large computer,though, which has lotsof memory, can be programmedto understand a few words.

Computers which cantalk have all the wordsthey can speak storedin binary code in theirmemones. Below youcan find out how this works.

Howa computer storessoundsThere are several different ways inwhich sounds can be stored, forinstance, on record or tape. Acomputer, though, can storeinformation only in binary code, andsounds, too, have to be coded in binary.

Most words contain several soundscreated by the arrangement of theletters in the word. In order to speak,the computer has to store all the soundsfor each word in its memory.

~~f:::-J~ ~The easiest way to do this is to break

the words up into word particles, forinstance, com-pu-ter. Each wordparticle, for instance, "com", isrepresented by a different piece ofbinary code. The word particles canthen be put together in lots of differentways to make different words.

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In its ROM the computer has a store of"word particles", that is, parts of wordswhich can be fitted together to make allthe words in the computer's vocabulary.The word particles are in binary code,along with rules telling the computer howto fit them together. Instructions from thecentral processing unit tell the memorywhich word particles to select. They aresent to a binary decoder where the binarycode is translated into an electrical

current. The strength of the current variescontinuously and represents the changesin the sounds in the words. The currentthen goes to a loudspeaker which vibratesto create the correct sound waves for thewords. Making a machine speak like thisis called speech synthesis.

SWARMIn this game you have to destroyenemy spacecraft. You score morepoints Ifyou hit the spacecraft whilethey are attackmg. The small yellowspacecraft with its two red escorts ISworth a lot of points, so shoot it downas soon as it appears. Do not try tofollow the purple spacecraft though.They fly at acute angles and aredifficult to hit. Be careful not to staytoo long in the corners of the screenas you are liable to be trapped there

In this game you control a spaceshipat the base of the screen. The gamehas five phases and the aim ofthegame is to survive the attacks by thebirds in the firstfour phases so thatyou can destroy the alien spaceshipand pilot in the fifthphase.

In the first and second phases,fire at the birds before they breakout of formation They are easier tohit like this, although they are notworth so many points.

In the second phase you can firemore rapidly, so aim at the highestconcentrations of birds and destroythem with continuous fire.

In the third and fourth phases, tryand destroy the eggs before theyhatch into birds which can dropbombs. Ifan egg hatches, you haveto destroy the bird by hitting it full inthe centre.

When the saucer appears,destroy all but one of its guardbirds. Ifyou destroy all of them, anew set appears. Then shoot a holethrough the protective ring roundthe ship, and through the bottom ofthe ship, so you can get at the pilot. 23

Playing games with a microcomputerYou can play any game you want ona microcomputer, and you caninvent your own games too, A microhas all the same parts as a computergame, except for the gamesprogram You give a micro itsprogram by typmg on thekeyboard, or by plugging in aprerecorded program from a ROMcartndge or cassette, You can findout more about this, and aboutwritino your own programs, overthe page, Here, there are someexamples of the kinds of games youcan play on a micro

IraAfilRf]

I-J,.=...--------------=~-"-- --..::..-_""":.-______ .......a •••..• -.-\.,;,,;, _------ •.....• _-----

Most microcomputers consist of a keyboardwhich you plug into a TV set. The game, orany other program you give the computer, isdisplayed on the TV screen, The kind ofgames you can play depends on how muchmemory the computer has, A computer witha memory of 16K(K stands for kilobytes and

one kilobyte is a thousand bytes), can copewith complex games such as chess andimitation arcade games, With a smallermemory of 4K to 6K you can play quitereasonable games and with a memory of IKyou can play only very simple games, Youcan buy extra memory for some micros.

This is a version of an arcade gamecalled Scramble which you can play ona micro, You can also buy programs forversions of Space Invaders, MissileCommand and Asteroids to play onmost micros.

Howa micro works

You can play chess on amicrocomputer. The computerdisplays all its own moves and yours onthe TV screen, and it can beat all but the

24 very best players,

Like all other computers, a micro is made upof chips and has a central processing unit(called CPU for short), a permanent memory(ROM) and a temporary memory (RAM),Some micros have as few as four chips to do

Keyboard

all the work, but an average sized micro has aprinted circuit board similar to that in anarcade game,

In a micro, the ROM contains instructionstelling the micro how to work, and theprograms you give it are stored in the RAM,

This is a game called lunar lander inwhich you have to land a space shipsafely on the moon, taking into accounthow much fuel you have and thevelocity and drift of the ship,

,... ....,STRENllTH 160STAMINA .•... , 80PSi 20TREASURE •...•.....•...... 125

THE BLACK KNIGHTSWINGS HIS AXE ATYOUR HEAD. YOU MUST FIGHT, RUN ORCAST ASPELL.

':OURMOVE ~

This is an "adventure game". Thecomputer describes a hazardousadventure in words on the screen andasks you what you want to do at variousstages. Your decisions affect whathappens to you in the adventure. Thereare lots of different kinds of adventuregames. Some are very complex,needing large computer memories andoften taking weeks to solve.

This is a maze game in which you haveto catch a creature in a maze inhabitedby bats, beasts and other hazards suchas slime pits. 25

Programs for micros

Chess computersA chess computer is a dedicatedcomputer which is programmed toplay only chess. People have beenwriting programs for computers toplay chess since the first electroniccomputers were built in 1940.Today'schess computers, though, are morepowerful and have more memory thanthe scientific computers of forty yearsago, and some can beat all but thevery best players.

In fact, people were trying to inventa machine which could play chessover two hundred years ago, beforecomputers were even invented.These two pages show the first chessmachines and some chess computersof today. You can find out how acomputer plays chess over the page.

First chess machinesThe first known chess machineconsisted of a chess-board and acabinet containing a complicated set oflevers and gears. Seated at the cabinetwas a model of a man in Turkish dressand the machine was called The Turk.It was invented in 1769 and rapidlybecame famous throughout Europeand America, as it could defeat most ofthe players who challenged it to agame.

The Turk is now believed to be avery clever hoax. It did not compute thechess moves itself, but had a humanplayer hidden in the cabinet whodetected his opponent's moves withmagnets. The Turk was destroyed in afire over 100 years ago.

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.••This chess game has a computer with akeypad for entering the player's movesand a display to show the computer'sresponses. The player has to be careful totype moves in accurately, or thecomputer's record of the game wil1bedifferent from the game on the board. Thisis sometimes discovered only when thecomputer wil\ not accept an apparentlylegal move.

~ This game has abuilt-in voicesynthesizer andcan speak itsmoves. It workslike the talkinggames on pages22-23. As well astelling you itsmoves it will alsoremind you that it isyour turn if you taketoo long.

The next chess machineappeared in the l890s. Itwas an electro-mechanicaldevice, that is, it worked bymeans by a combination ofelectricity andmechanical gears,levers and pulleys. Itwas designed to playan endgame ofKing and Rookagainst King. Italways playedWhite-andalways forcedcheckmate.

••.Some chess computers havesensory boards and can "feel" theplayer's moves. With these thereis no danger of the computerhaving a different record of thegame. Each chess piece has amagnet in its base and thecomputer can detect when a

magnet moves from one square toanother. The computer can tell whichpiece moves because it knows where allthe pieces started and how they havemoved since then.

Inside a chess computer

Inside a chess computer there is aprinted circuit board with all theusual chips. The program tellingthe computer how to play thegame is stored in the ROM chips.All the moves are worked out inthe microprocessor chip, basedon information from the ROM.The RAM chips provide extrawork space for the computer touse while it is calculating its bestmove, and the moves madeduring a game are stored in RAMtoo.

.••The robot arm on this chess-boardmakes all the computer's moves, andremoves your pieces when thecomputer captures them. If thecomputer loses the game, it flings itsarm about, flashes its lights and shrieks.

.••This is a small travelling chesscomputer. It has a liquid crystal display soyou do not need chess pieces. The movesare displayed in chess notation and theliquid crystal display is controlled bypulses from the game's microprocessor.

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How computers play chessAll the information a computer needsto play chess is stored in its ROMmemory. An average chess computerhas a memory size of about 12Kandavery powerful chess computer mayhave about 200K of memory. Theinformation in the ROM consists of therules of the game and the way thepieces move, strategies to follow atdifferent stages in the game and bookopenings. *

The computer chooses each of itsmoves by analyzing a number of thepossible moves and choosing the best.The number of moves the computercan test depends on the size of itsmemory. Even a very powerful chesscomputer cannot test all thepossibilities, though. There are over300 million for the first three movesalone.

Choosing the best moveTo find the best possible move thecomputer examines three or four differentmoves, looking several moves ahead foreach of them. It gives points to each moveaccording to how advantageous it is. Forexample, a move which would lead to thecapture of a Bishop in three moves wouldhave a higher point value than one whichled to the capture of a Pawn.

At the start of the game the computerloads the positions of all the pieces into itsRAM. Then, for its first few moves it mayfollow a book opening. When thepositions of the pieces begin to differ fromthose of the book opening, the computerabandons the opening and begins toanalyze each move.

Each year chess tournaments are heldin which people play againstcomputers and computers competeagainst each other. The title ofchampion chess computer is at presentheld by a computer called Belle whichhas a very high chess ratingof2,400points (U.S. rating). Belle can examine160,000 possible positions everysecond and contains over 1,700 chips.

Skill levelThe number of moves the computer canlook ahead is limited by the size of itsmemory. Each move by Black or White iscalled a ply, and a powerful chesscomputer can make a nine ply search. Onmost chess computers you can set the skilllevel at which the computer plays bylimiting the number of moves it examines.lit A book opening is a standard set of moves which can be followed in the first part of a game.Some computers hold over forty different openings.

30

ResponsetimeThe time the computer takes to choose itsmove varies according to which skill levelit is playing on, and how many movesahead it is looking. When playing at anadvanced level, some computers can takefour or five hours to decide their nextmove, or until you tell them to stop.

Next best moveWith some chess games you can ask thecomputer what its next best move wouldhave been, and some will tell you up toeight other moves that they wereconsidering. Another way of limiting thecomputer's skill is to instruct it to play itssecond best move, rather than the onewith the highest point value.

In the near future all chesscomputers will probably be givenratings according to how well theyplay, in line with the ratings given tohuman players. The ratings are workedout by giving each computer points forthe number oftimes it wins or draws ina fixed number of games against otherrated players.

CheatfunctionThis allows you to change sides inthe middle of a game if the computeris winning, of if you find the positionofits pieces more interesting.Some computers also allowyou to return the pieces to theirpositions of several moves agoand replay them differently.

Computer chess teacherMost chess computers can play gamesagainst themselves and some also havethe games of famous players stored intheir memories and can play them for youto watch. They can also set you chessproblems to solve and can indicate howthe computer would have solved them.

31

Computers on the moveKeyboardThese two pages show a completely different way

in which computers can be used. Both the toyvehicles shown here containmicroprocessor chips whichcan be programmed tocontrol all theirmovements.

This space age vehicle can be programmedto go certain distances in various directions,turn comers and fire "proton beams". Yougive it instructions via the keyboard at theback. The microprocessor inside the-vehiclestores the instructions in its RAM, thencarries them out in the correct order.

The computer keyboardDirection keys

Clears old instructions from the computer's memory.

Tells the computer to fire a proton beam.Instructs the computer to hold the vehicle stationary for afew seconds.Key for correcting mistakes. It wipes out the last instructionfrom the computer's memory.

Makes the vehicle carry out a short test sequence ofmovements which it holds in its ROM.Tells the computer to carry out your last instruction so youcan check that it makes the vehicle do what you intended.Distance keys. The figures represent the number of timesthe vehicle should travel its own length.

Key to tell the computer to carry out the program after ithasreceived all the instructions.

When you type in a program you haveto tell the vehicle which direction to go(forwards, backwards, left or right) andhow far to go. Distances are measured32

by the number of times the vehicletravels its own length, and this unit ofmeasurement is held in the computer'sROM.

How the computer steers the vehicle

The vehicle's tracks are powered by an electric motor. The computer can switchthe motor on and off with electrical messages, and so control the supply ofpower to the tracks.I _

(!!!i~••*To tum the vehicle to the right, power tothe right track is switched off. The drivefrom the left track pushes the vehicleround to the right.

When a message from the computerswitches offthe power to the left track, thevehicle swings round to the left.

2

&liJ···-Ifthe right track is started up again, bothtracks are pushing equally and the vehiclecarries on along a straight path.

4

In a program of instructions, sequences ofmessages drive the vehicle in variousdirections and fire the proton beam.

-This car has a keyboard under the bonnetfor programming the microprocessor.The computer can be programmed tosound the car's hom and control how far itgoes in various directions. Messages fromthe computer control the steeringmechanism on the front wheels and themotor which drives the back wheels.

33

Howa game ismadeElectronic games, arcade games andeven the games you write for amicrocomputer are all developed inmuch the same way. First you need anidea and a story setting for the game.Then you have to translate it into acomputer program With a homecomputer you can then type theprogram into your micro, butelectronic and arcade games have tohave the program built into their chips.

A game idea may start off as anarcade game, then a hand- held or TVversion may be developed underlicence to the original manufacturer.

The first stage in the development of agame is to make a detailed plan ofthegame and work out the rules and scoringsystem. A graphic designer will makesketches for the display and thecharacters in the game.

Then a computer program is written withinstructions telling the computer exactlyhow to play the game. The program iswritten in a computer language and theneach instruction is translated into thecomputer's code of Is and Os.

How chips are made

An electronic engineer designs circuits toproduce pulses and no-pulses in the samepatterns as in the program of Is and Os.The circuits are then built into a specialchip so that they can be tested and alteredif they are not correct.

Circuit

34

The silicon from which chips are made isvery pure crystal. It can be treated so thatit conducts current through precisepathways in the silicon. One slice ofsilicon will make over a hundred chips.

The circuits for the chips are drawn upenlarged over two hundred times, thenreduced to chip size and repeated lots oftimes on photographic masks which will fitover the slices of silicon.

Then the test chip, which is called anEPROM (Erasable Programmable ReadOnly Memory), is assembled on a printedcircuit board with the other componentsof the game such as the display andplayer's controls.

The game is tested to make sure that thecircuits on the chip are producing thecorrect patterns of pulses and thecomputer is playing the game correctly. Ifthe game is not working perfectly, thecircuits are checked and altered.

Then the circuit designs are sent to a chipmanufacturer and thousands of copies ofthe chip are produced. These arereturned to the game manufacturer andthe games are assembled and packagedin their plastic cases on a factory

roduction line.

The slices of silicon are then doped withimpurities under great heat. This createspathways which will conduct electricity inthe parts ofthe silicon which are notprotected by the mask.

This process is repeated several times toproduce layers of circuits in the surface ofthe silicon. Then the silicon slices are cutup to make the chips, and each chip ispackaged in its case. 35

Story of computer gamesThe story of computer games isclosely linked to the story ofcomputers themselves. The firstelectronic computers were made inthe 1940s.They were vast and not verypowerful machines. During the nexttwenty years, though, several newinventions which led to the siliconchip, enabled much smaller, morepowerful computers to be built.

The new computers could be usedto control all sorts of equipment,including computer games The firstelectronic games were made in theearly 1970s.

The first electronic computers were vast room-sized machines. They had very small memoriesand carried out their calculations very slowlycompared to present-day computers. Theywere invented to help crack enemy codes inWorld War II and track the positions of enemyplanes from radar reports.

& The first TV game was made in 1972 bya company called Magnavox. It had acomputer with player's controls and somecoloured overlays for the TV screen. Thecomputer could make only a spot of lighton the screen and you created differentgames with the screen overlays.

&This is Pong, the first TV game madeby Atari in 1975. It was a simple, black andwhite bat and ball game. Pong's computerwas a dedicated computer - it could playonly Pong. It was followed by Super Pongwhich could play four different bat andball games.

&This is Computer Space, the firstvideo arcade game. It was made in1971 and the game was a dogfightbetween a flying saucer and aspaceship. It had a very simpleblack and white screen picture andwas housed in a black fibreglasscase. Computer Space was inventedby Nolan Bushnell, the man whofounded Atari which is now one ofthe biggest video games companies.

Another kind of early TV game had a rifle which you aimedat a spot oflight on the screen. When the rifle was lined upwith the spot, the light triggered a switch in the rifle and youscored a point.

36

The early computers used components calledvalves to control the pulses in the computer. In1947, a new component called a transistor wasinvented. Transistors do the same work asvalves, but are much smaller. In the 1950s,smaller computers with much more computingpower were built using transistors.

In 1960 the first silicon chips weremade. The circuits on a single chipcould do the work of thousands oftransistors, and as the newtechnology improved it becamepossible to fit a whole computer on asingle chip.

In 1971 the first portable home computerwas built, using silicon chips. Around thesame time, pocket -sized electroniccalculators appeared, with their own built-in electronic display. These paved theway for the first hand-held electronicgames which appeared a few years later.

The first hand-held electronic gamesappeared in 1976. They contained acomputer on a chip and had their ownbuilt-in electronic display. Two of the firstgames were Football and Autoracemade by Manel.

37

Useful gamesMost games are used forentertainment only, but computergames can be built round realsituations and used as learning aids.Some computer games can also teachyou a subject, such as maths, as youplay the game.

The way a computer reproduces allthe features of a situation is calledcomputer simulation. A computer cansimulate, say, the econcmy ofacountry, or even a battle, by beingprogrammed with real, rather thaninvented data. Here are some types ofcomputer games which can be used inother ways than just for entertainment

Target practice simulation

This is a computer game based on theworkings of the stock exchange. Playersbuy and sell gold and stocks and sharesand the computer keeps track of all theinvestments.

This is a video game made specially forthe U.S. Army. It is based on an Atari gamecalled Battlezone, and shows the player'sview from a troop transport vehicle. Thesimulated landscape and enemy tanks getlarger and smaller as the player's vehicle

Flying practice

moves towards and away from them. Theplayer has to line up the tanks in the sightsand shoot them. The firing controlsinclude telescopic sights and missiletracking devices and the computer canset target identification problems.

38

In this simulation the computer creates apilot's view of an airport runway. Althoughnot strictly a game, it uses some ofthesame principles to give trainee pilotsflying practice. The pilot has a set of

simulated aircraft controls and as he orshe brings the plane in to land, the viewfrom the cockpit changes. Simulations likethis are also used to train people tonavigate oil tankers and drive cars.

2 .•. •43 ~ .5/t 1-DI

- - =?This game is a simulation of a battle. Theplayers can choose their method of attackand the size and position of their forces.Simulations like this are used by militaryplanners to test their theories andstrategies.

This is a TV game for children to improvetheir arithmetic. The players have to catchthe correct object or number to completethe equation and they score points forcorrect answers.

Learning gamesIn these electronic games the computertests your general knowledge, or helpsyou learn a new subject.

~ Speak and Spell and Speak andMaths are two talking games for learningspelling' and arithmetic. Their computersset problems to solve, and create gamessuch as code-breaking games and aversion of hangman.

T Little Professor is one ofthe earliest electronic learninggames. It was first made in1976. It poses a number ofproblems for you to solveand tells you if your answeris right or wrong.

.••This robot asks you generalknowledge questions andrecites riddles and jokes. It iscalled 2XL. The multiplechoice questions are recordedin cartridges and if you getstuck, the robot will give youmore information, or playmusic while you think. You tellthe robot which answer youthink is correct by pressing thebuttons on the front of it.

39

Future gamesWithin ten years the computer gamesof today will probably seem very basicand primitive. The games ofthe futurewill be faster and more exciting, withsuperbly realistic screen displays.

These games will containcomputers a hundred times morepowerful and faster than those of todayand capable of storing millions ofpieces of information. Computers likethese will be built by packing moreand more complicated circuits intoachip of silicon.

Here are some of the features wemight see in computer games in thenot too distant future.

\1; .:A TV game with a very large memory willbe able to reconstruct detailed pictures ofsay, the Battle of Waterloo or a spacebattle, and the players will be able tocontrol far more of the details in thepicture than they can today.

40

In TV sports games you will probably beable to control each of your teammembers individually. These games willalso have electronically synthesizedvoices and the referee will tell you whenyou are offside or given a free kick.

Powerful computers will be able to createadventure games infinitely more complexthan those you can play on a micro today.To help the human player there willprobably be a board and counters to planand keep track of their moves.

Multiplayer game ~At present, most computergames are for only one or twoplayers. More powerfulcomputers though, will beable to cope with instructionsfrom a number of peopleplaying at the same time,either as teams against eachother, or against thecomputer.

Hand-held electronic games will stillhave liquid crystal displays, but theywill probably be in full colour and willbe as detailed and realistic as thepictures for a TV programme today.

Long distance game

By the year 2000 you will be able tochallenge someone hundreds of milesaway to a game. The games will containminiature radio transmitters and receivers

which will transmit your moves andreceive those of your opponent with verylittle time delay. Your opponent's moveswill be automatically carried out in theliquid crystal display.

The ultimate game will be a super-realistic computersimulation which takes place all around you in a specialgames cubicle. The game, perhaps a space invasion oradventure game, will have three dimensional effects, laserlighting and quadrophonic sound.

41

Game variationsHere are some ideas for different waysto play electronic games to make themmore difficult,or to play them withmore than one person. Most oftheseideas will also work on arcade games,ifyou do not mind losing some money.

"Survival"

In this game you play to survive, not to winpoints. If you are playing against otherpeople, the person who survives thelongest is the winner. If anyone gets toogood at the game, make them play withtheir hands crossed.

Crossedhands SPACE

INVADERS

To make a game more difficult, trycrossing over your hands, so the hand youusually fire with is on the other control.This is quite tricky, so play the game onthe easier skill level first.

Lots ofpeople have worked out theirown strateqies for this well knowngame in which you have to destroyflying saucers and advancing columnsof invaders to score points.

The flying saucers are worth themost points, so as soon as one appears,you should try to hit it. Each saucer isworth anything from 50to 300points.When you hit a saucer the computerpicks a random number betweenthese two figures for your score.

While you are waitinq for thesaucer, try and destroy the twooutermost columns of invaders. Theinvaders move from side to side acrossthe screen and each time they reachthe edge, they advance down thescreen towards your laser bases. Bydestroying the outermost columns ofinvaders you increase the time theytake to reach the edge, so they alsomove down the screen more slowly.

Youshould also try and destroy allthe invaders in one column, so that youhave a safe place from which to shootat the saucers. Ifyou do not have anopen column, you have to use one ofyour laser bases as protection. Youcan either hide behind it and dart outwhen you see a saucer, or shoot a holethrough it and fire at the saucerthrough the hole.

Each time you destroy all theinvaders, a new set appears lowerdown the screen. In order to keep thegame going after the third new set ofinvaders, ignore the flying saucersand concentrate on destroying theinvaders before they reach your laserbases.

"Suicide"

This is the opposite of the survival game.The object is to see who can finish thegame the fastest with the least number ofpoints.

Two-person game

With two people playing the same game,one can be in charge of the firing buttonand the other can move the laser base, orwhatever controls the game has.

42

Alternatively, one person can be incharge of all the controls and the other canwatch the display and tell them what to do.You have to have very fast reactions tosucceed in this game.

STRATOSThe aim of this game is to destroyspaceships and aliens. There are fourdifferent phases in the game. Here aresome tips to help you in each phase.

In the first phase, watch out for threespaceships peeling offfrom the top ofthe screen and try to destroy them. Inthe second phase, stay to the left ofthescreen, but watch out for stray bombs.

Play the third phase firing fast.Destroy the centre columns ofbirdsfirst, and hit each bird twice to destroyit and the aliens it is carrying. Take thefourth phase slowly and try to destroyblue birds to gain bonus points andalso to destroy any aliens that may beattacking you from below.

FIELD GOALIn this game the aim IS to gain points bydestroying your opponents. Yougetbonus points each time you eliminate acomplete line ofplayers. Here aresome other tips for scoring bonuspoints.

Try and break through the red andyellow lines as soon as possible, butbe ready for the ball returning veryfast after a breakthrough. Try also tohit the footballer as soon as possibleafter he appears.

When you reach a score of 5,000youreceive a bonus ball. This ball attachesitself to your "foot"and stays with itwhile you take aim. Ifyou catch thisball when it returns, itwill again attachitself to your foot. Ifyou fail to catch it, itwill return to normal and bounce offyour foot as soon as it makes contact.

43

The computer's skill lies in the design of its electronic circuits. The pulses ofelectricity which do all the work in the computer travel through the circuits at the rateof millions of pulses a second. This enables the computer to make millions ofdecisions every second. It is also impossible for the computer to make a mistake,unless there is an electrical failure or the batteries are flat. The instructions for everysingle action carried out by the computer are built into its chips and have been testedand retested to make sure they are correct. Another strength of the computer is itsability to remember every move you make, as well as its own moves. All thisinformation is stored in its electronic memory, coded in binary code, and can berecalled in a fraction of a second.

Despite all this, there is still no computer which can beat the very best players atchess. This is not due to the limitations of the computer though, but to the design ofthe program worked out by a human computer programmer. The real skill of acomputer lies in the speed and accuracy with which it can carry out instructionsgiven it by human game designers.

Computer wordsBASIC The name of one of the languages used for writing computer programs. Theletters stand for Beginner's All Purpose Symbolic Instruction Code. It is the mostpopular language for writing programs for a microcomputer.Binary A number system based on only two digits: 0 and I. The code used bycomputers is composed of binary numbers.Bug A ntistake in a computer program that stops it from working properly.Byte A group of eight binary digits which usually represents one piece ofinformation in computer code.Cartridge A plastic case inside which there is a ROM chip which holds all theinformation telling a computer how to playa game.Chip Popular name for a silicon chip, a minute slice of silicon containing electricalcircuits.Central processing unit (CPU) The control centre of the computer where all thework is done.Computer A machine which can process information according to a'set ofinstructions it has been given, and store or display the results.Computer code The patterns of pulses and no-pulses which represent the Is and Osof binary code with which the computer does all its work.Dedicated computer A computer programmed at the time of manufacture to docertain tasks only.Hardware All the physical equipment of a computer, or computer game. The chips,printed circuit board, cartridges, etc, but excluding the program.Liquid crystal display (LCD) A kind of display often used in hand-held electronicgames and calculators. It contains liquid crystal which turns black when it receives apulse of electricity.Microprocessor A silicon chip which contains all the parts of a computer and cando the work of a computer.Printed circuit board A board with the metal tracks for an electrical circuit printedon it. The parts of a computer game are usually assembled on a printed circuit boardand the tracks carry the current between the parts.Program A list of instructions for a computer, written in a language the computercan understand. In English, the American spelling of program has become standardto distinguish it from a TV programme.RAM (Random Access Memory) The computer's temporary memory whereinformation is stored while the computer is being used. It is called random accessbecause the computer can find any piece of information in this memory without goingthrough all the material.ROM (Read Only Memory) The computer's permanent memory where theprogram telling it how to operate is stored. In a computer game the ROM contains theprogram which tells the computer how to play the game.

Why computers are good at gamesA computer is a difficult opponent to beat. It never makes mistakes, it nevergets tired or loses its concentration and it "thinks" extremely quickly. Ahuman player may take the best part of a second to make and carry outadecision, say on how to defend a laser base. Each time, the player has torecall the rules of the game, judge how to apply them inthis situation, thenreact with their hands. The computer can make a decision and carry itoutalmost simultaneously.

lfyou want to find out more about computers, how they work and what theycan do, here are some suggestions for more books you might like to read.Usborne Guide to Computers by Brian Reffin Sntith, Usborne 1981The Computer Book by Robin Bradbeer, Peter De Bono and Peter Laurie, BBC 1982Illustrating Computers by Colin Day and Donald Alcock, Pan 1982Introducing Computers by Ron Condon, Macdonald Guidelines 1981The Mighty Micro by Christopher Evans, Coronet 1980The Challenge of the. Chip by W. H. Mayall, HMSO 1980

Books about microcomputers and programmingIntroduction to Computer Programming by Brian Reffin Sntith, Usborne 1982Understanding the Micro by Judy Tatchell and Bill Bennett, Usborne 1982Illustrating Basic by Donald Alcock, Cambridge University Press 1977Computer Spacegames by Daniellsaaman and Jenny Tyler, Usborne 1982Computer Battlegames by Daniellsaaman and Jenny Tyler, Usbome 1982

Some computer stores and bookshops also sell books containing games programsfor microcomputers and most newsagents sell computer magazines which alsocontain listings. Make sure the programs are in the correct language for thecomputer you use.

Books about computers

Indexadventure games, 25, 40arcade games, 6-7, II, 12, 19,

24,25,34,36,42Asteroids, 24, 45

how to win at, 7Astro Wars, 5Atari, 36, 37, 38

BASIC, programminglanguage, 13,26-27,47

Battlezone, 38, 44how to win at, 15

Belle, champion chesscomputer, 31

binary code, 10, 11, 16,22,23,46,47

bit, 10bug,47byte, 10, 11,25,47

cartridges, games, 12, 16, 17,23,24,26,47

cassettes, 24, 26, 27central processing unit, see

CPUchess, 24, 2S, 28-31, 46chips, 4, 5, 6,10-11,16,17,24,

29,31,34,35,36,46,47how they are made, 34-35

circuits, 4, 10, 16,34,40,46coin accepter, 6computer code, 10, 17,20,34,

47Computer Space, 36computers, first, 28, 36Cosmic Avenger, 44CPU (central processing unit),

8, 11,23,24,47

dedicated computers, 12,28,37,47

Defender, 7, 44disk drive, 27display, 5, 9,14,34,35,37,40Donkey Kong, 44

Video creatures answers

electronic components, 5, 36EPROM chip, 35

Field Goal, how to win at, 43floppy disks, 27fluorescent tube display, 5, 14£rogger, how to win at, 19

Galaxian, 44how to win at, 21

hand-held games, 4-5, 6, II, 12,14-15,37,40

handsets, 16, 17hardware, 47

joystick, 17

keyboard, micro, 13, 24kilobytes, 24

liquid crystal display, 14,29,40,47

Little Professor, 39loudspeaker, 6, 15,20,21,23lunar lander, 25Lunar Rescue, how to win at, 21

memory, computer's, 8-9,12,18,20size of;ll, 18,24-25,30,40

microcomputers, 13,24-27,34,40

microprocessors, 6, 10, 11, 12,17,29,32,47

Missile Command, 24how to win at, 9

monitor, 6

Pac-man, 44how to win at, 13

permanent memory, see ROMPhoenix, how to win at, 23pixel,18player's controls, S, 6, 8-9,17,35

Pong,37printed circuit board, 5, 6, II,

16,29,35,47program, 12, 13, 16,24,26-27,

28,34,47programmable computers, 12, 13pulses, 10,12-13,20,21,34,46

Qix, how to win at, 13

RAM (temporary memory), 8-9,10, II, 15, 17, 24, 29, 30, 32, 47

records, world, 7, 45resistors, 11robot 2XL, 39ROM (permanent memory), 8,

10, II, 12, 16,22,23,24,29,30,32,47

score, 9,15,17,34Scramble, 24

how to win at, 19seven segment display, 15silicon, 4, 10,34,36,40Simon,4simulation, 38sound effects,S, 6, 20-21Space Invaders, 24, 44

how to win at, 43Speak and Maths, 39Speak and Spell, 39speech synthesis, 23, 28, 40Stratos, how to win at, 43Super Pong, 37Swarm, how to win at, 23

Tempest, 44temporary memory, see RAMtransistors, 11,36TV games, 16-17,26,34,37,40

screen pictures, 17, 18,24Turk, the, 28

watch, invaders on a, IIWizard of Wor, 44

1. Centipede; 2. Warrior from Wizard of Wor;3. Briter from Defender; 4. Donkey Kong;5. Bomber from Defender; 6. Monster fromPac-man; 7. Spiker from Tempest; 8. Pac-man;9. Alien from Space Invaders; 10. SubmarineIrom Cosmic Avenger; 11. Worluk fromWizard ofWor; 12. Fuseballfrom Tempest;13, Mutant from Defender; 14. Galaxian;15. Defender; 16. Wizard ofWor;17. Battlezone.

First published in 1982 by Usborne PublishingLtd, 20 Garrick Street, London WC2E 9Bl,England.© 1982 Usbome PublishingThe name Usborne and the device ~are Trade Marks ofUsbome Publishing Ltd.All rights reserved. No part of this publicationmay be reproduced, stored in a retrievalsystem or transmitted in any form or by anymeans, electronic, mechanical, photocopying,recording or otherwise, without the priorpermission of the publisher.48

Usborne Computer BooksComputers are fun. You can play games with them, ask them questions, writepoetry with them and play music on them too. This colourful new series of booksshows you some of the exciting things computers can do and explains how theywork and how to use them. Written in clear and simple language with lots ofpictures, these books provide a fun introduction to computers and computing forabsolute beginners.

Understanding the MicroA colourful guide tomicrocomputers, how theywork and what they can do,with lots of ideas for thingsyou can do with a micro.

Computer GamesA colourful look at howcomputers play SpaceInvaders, chess and othergames, with lots of tips onhow to beat the computer.

Computer ProgrammingA step-by-step guide toprogramming in BASIC forabsolute beginners. Withlots ofprogrmnsto run onany microcomputer.

Usborne Computer FunThese two superblyillustrated books arepacked with gamesproqrams to play on amicrocomputer. Each gameis suitable for use onthe most common micros,and there are lots of tips andhints for writing your ownproqrams,

Published in the USA byHayes Books, 8141 East44th Street, Tulsa,Oklahoma 74145, USA.

ISBN0860206815

Published in Canada byHayes Publishing Ltd,3312 Mainway, Burlington,Ontario, Canada, L7M 1A7.

Published in Australia byRigby Publishing Ltd,Adelaide, Sydney, Melbourneand Brisbane.

6789101112/83