Nor was there such a thing, in 1982, as a cheap hard disk, on which users could store their documents and their software between sessions. Programs had to be loaded into the Atom from an audio cassette in a tape recorder, and you had to do it anew every time, because every time the computer was turned off, its memory was wiped clean. The only place that anything was stored permanently in the Atom was in its ROM chip. The small block of read-only memory contained two things. First was Acorn's operating system for the machine, which stopped it from being just dead silicon by telling the different components how to talk to each other. The other was a compact copy of the programming language BASIC, devised in the 1960s as a tool for non-scientists.

Taken together, the operating system and BASIC gave you everything you needed to write and run your own little programs. But the computer contained no word processor, no bells and whistles, no array of applications waiting for you to play with them, no instant pleasurable pay-off for buying a new computer. When you turned on the Atom or the BBC Micro, the ROM chip booted up its two pieces of cargo and on your television screen appeared this:

BASIC
>

and nothing else. The machine did nothing else, unless you made it.

Nevertheless, as 1982 wore on, and the BBC series that the BBC Micro had been commissioned to accompany proved a hit, thousands of people, and then tens of thousands, busily set to work writing programs that balanced their chequebooks, or administered French vocabulary quizzes to school children, or identified the leaves of common trees.

DOES THE LEAF HAVE SERRATED EDGES? PRESS Y/N.

If you had a certain kind of mind, as Braben did, the muteness of the machine, when you turned it on, was full of promise, not disappointment. It meant that it was going to do whatever you told it to do; whatever you could think of to tell it to do. It was a slicer, a condenser, a heaper-up, a puller-down, a sorter, a randomiser, a multiplier, a weaver, a mirror-image maker, and far more.

In his bedroom in Epping, Braben threw himself into learning the machine with the same intensity that, in other decades, he might have brought to building radio sets, or working out the aerodynamics of model planes. As he points out, he had no responsibilities apart from his A-levels. There was a psychological pay-off, too. In the small domain of a program, he had what the big world rarely gives to 18-year-olds: the chance to say yea or nay and have his instructions followed to the letter. It was a small but real kind of power.

Ian Bell was 19. Like Braben, he was bound for Cambridge in the autumn to start his degree, but first he was taking a gap year. He had a job in his dad's office at the Malaysian Rubber Producers' Research Association. During the day, he tended the microcomputer that controlled the MRPRA's tests on rubber samples; but after 5.30pm, when the lab emptied, the computer was effectively his own. To begin with he played Space Invaders. But he wasn't satisfied with the to-and-from interchange you got as a player; he wanted the deeper conversation you got by making the game.

His first effort was a computer version of the board game Othello. This required him to solve a fistful of problems: how to display the black and white counters and the board, how to manage the flip-over elegantly, how to code in routines that would turn the computer into an adequate strategist. There was literature on graphics programming and on strategy algorithms, of course, but it wasn't available in the MRPRA building in Wickendenbury between 5.30 and 7.30pm, so Bell made it up. Teaching himself didn't put him at any real disadvantage: there were no experts yet. If his Othello worked - and it did - it counted for as much as anyone's program. In fact, it seemed to him, as he started to look around the cassettes of entertainment software that were on the market in 1982, that it was probably better than most of them. (Braben had made a parallel discovery. Setting up his Atom had cleaned him out, so he couldn't afford to buy Acorn's Games Pack till he'd been programming for a couple of months; and then he found that his own home-grown games, among them a 3D space program, were already better than Acorn's official offerings. "I was so disappointed! I mean, I don't want to be rude, but they really were crap...") From this followed a train of thought that went past at lightning speed:

It was a moment of revelation, both philosophical and commercial.

But in order to do this, to do new things with the machine that other people would pay for, you had to get under the bonnet. BASIC was a fine tool to learn programming with. But programs in it occupied far too much of the limited working memory of a microcomputer, and it was horribly slow. The way to get anything ambitious done was to write the program directly in the language BASIC translated into: assembly code, only one layer up from the silicon. Suddenly, you were responsible for the entire flow of very simple commands that allowed the computer to function.

Next to a program listing in BASIC, a large amount of assembly language seemed disconcertingly featureless, its functional twists and turns not labelled as such but all blurred together into a giant soup of code. For every line of BASIC, you needed at least five lines of assembly code. If BASIC programming was like putting together an Airfix aeroplane kit with ready-made plastic parts, assembly-code programming was more like building a model suspension bridge from matchsticks.

Yet, if you succeeded, your program, as Braben puts it, "went like the wind". Assembly software didn't just run a bit faster; it ran 10 times faster. All at once your computer became immeasurably more powerful.

Bell's Othello ran so fast that he had to slow it down artificially. Otherwise, every time you put down a piece on the board, the computer came back with its move - bip! - before you even had time to take your finger off the key. It was spooky; it rather spoiled the illusion that you were engaged in a cagey battle of wits. He introduced a pause, during which nothing really happened at all, but which the human player could interpret as the computer thinking. Then he sent a clean copy of his code to Program Power, a software company temporarily riding high in the games market. As it happened, his was one of two digitised Othellos to fall through its letter box in a Jiffy bag. So Program Power played the two against each other to see which was better. The rival Othello beat Bell's at the higher skill settings - not surprisingly, since he had had to make up all the game strategies off the top of his head. But his performed better at the novice level most players would start on, and at every level it ran faster and smoother. Program Power announced it was thinking of releasing both.

In October 1982, Braben and Bell met at Jesus College, Cambridge. They became friends. They were never soulmates; they were too different in character for that. Where Braben was ebullient, Bell was melancholic. Where Braben saw possibilities, Bell would see problems. Braben had the seeds of worldly savoir-faire in him; Bell had the seeds of withdrawal and solitude. But they were both interested in the same things, and they were both better than most people at doing those things, which made them natural allies and collaborators.

To a good half of their fellow students, of course, they were just indistinguishable nerds. They had come to a place where the arts/science split in British education (and British culture, for that matter) manifested itself as a social split. (Braben was studying natural sciences, Bell was on the maths course. Neither went anywhere near the computer science department, which they had arrogantly but accurately decided offered them nothing useful.) The archetypal natural sciences student was thought of as a troglodyte in an anorak, given to unspeakable pastimes, which presumably made up for the sad fact that the large majority of them were male. Science students returned the favour by seeing arts students as weird, condescending, uninterested in truth and prone to absurd fits of the vapours about their weekly "essay crisis".

There was a wider dimension to the split as well. In 1982, popularised science hadn't yet risen above the horizon in Britain as a cultural phenomenon. No chaos theory as a universal reference point; not much evolutionary biology, since Richard Dawkins and Stephen Jay Gould were only then beginning to make their mark on public consciousness; no cosmology deployed à la Stephen Hawking as a modern replacement for religious truths. In particular, computing in its DIY phase didn't resonate as it would later. You wouldn't have found French literary theorists writing about cyberspace in 1982, any more than they'd have written about household plumbing. Computers weren't glamorous. The result of all this was that what Braben and Bell achieved together while they were at Cambridge was, effectively, invisible.

Space, both of them now insist, was the obvious next target for video games. "It was the easiest," says Bell, "because space didn't have anything else in it. With a flight sim you've got the ground, but space is beautiful because it's a sparse environment." All you had to get right were twinkles against blackness and the environment was already persuasive.

When they began writing their game, eventually to be called Elite, eventually to be a landmark in the history of computer games, what they were thinking of conformed pretty much to the standard video-game formulas of the time, albeit with extra graphical whizz. They wanted exciting space combat in three dimensions against enemy craft that exhibited some degree of tactical guile. Except that, come to think of it, programming the tactics for an organised, military enemy was probably out of reach. They needed disorganised villains. Who fit the bill in the science-fiction universe? Pirates. OK then: 3D combat against space pirates. And they also wanted there to be a bit of the game where you had to dock your spaceship with a space station, à la 2001. They thought Stanley Kubrick's docking sequence was deeply cool, and they wanted one of their own.

But while they were still sorting out the mechanics of combat and docking, they started to worry about the adequacy of what they'd be giving the player (whom they imagined, of course, as a hypercritical consumer like themselves, bored with Space Invaders after the first brief rapture). It wasn't too hard to come up with a solution. They could keep the player interested by letting them upgrade the weapons on their ship to ones that made bigger bangs and allowed you to use different tactics. But this little alteration perturbed the universe of the game. The classic action game of the early 1980s - Defender, Pac Man - was set in a perpetual present tense, a sort of arcade Eden in which there were always enemies to zap or gobble, but nothing ever changed apart from the score. By letting the player tool up with better guns, Bell and Braben were introducing a whole new dimension, the dimension of time. They were saying they wanted the player to hope, to scheme, to plan. Also, to play for much longer than a slam-bang 10 minutes. And that was only the beginning. The solution threw up a further problem, as each of their solutions would. How would the player get a bigger gun? They should earn it, Bell and Braben decided. No free lunches in this universe. But that implied money, in a set-up that a moment before had existed quite happily as an economy of pure explosions. "We put a bounty on the pirates. Then we thought even that would become quite samey..." They kept following the implications of each invention until they arrived at another invention. A money economy with more sources of income than just bounty for shooting pirates implied trading. Suddenly, the player's spaceship wasn't just a nimble 3D firing platform: it was a cargo hauler as well. And trading implied places in which to trade. The game needed serious three-dimensional geography. And things to trade. And prices. And markets... The new wishes multiplied. They kept going.

Perhaps the reason they kept going was that they wanted the universe they were building to feel solid: like a science-fiction novel that rings true because all its inventions are consistent with each other. But allied to this was an idea of the pleasure they wanted to give the player. They kept asking: "Will this be fun?" They didn't want the fun to be presented to the player as a set of arbitrary demands, a series of hoops you had to jump through just because that was the game and your score went up every time you got it right. They wanted the flying, the shooting and the trading to be fun in a way that respected the integrity of the experience you'd have when you were playing, that went with, rather than against, the deeper grain of your imagination. It's a wish that might sound modest, but what made it cumulatively radical in its effect on the game was the indirectness it made necessary. Most video games stipulated the experience the player was going to have. They said: you stand here and we'll throw aliens/dragons/humorous frogs at you. Bell and Braben's sequence of inventions amounted to a gradual refusal to do anything of the kind. They were arriving at a game that left what to do and where to go entirely up to the player.

They were now committed to writing a game in which you flew from solar system to solar system, fighting pirates, dealing in commodities ranging from vegetables to narcotics, and spending your profits on improvements to your ship. Since the point was that playing it would generate your own story of success or failure, gradual glory or gradual oblivion, they envisaged people immersing themselves in it for sessions lasting hours at a time, then being able to save their position on a cassette or disk and pick it up again where they'd left off, after the irritating need for sleep or food or going to work had been dealt with. It was clear that, just as it would take a lot longer to play than usual, it was going to take a lot more time to write than the customary three or four months of spare-time concentration. Before they went ahead with miniaturising a cosmos, it was time to see if anyone actually wanted the gigantic effort they were about to make.

Each of them had a contact: Thorn EMI for Braben, Acornsoft for Bell. They decided to try Thorn EMI first, because it seemed to the fledgling commercial sense of Braben that it would be better to go with an independent publisher. An interview was arranged. The grown-up executives in their nice suits smiled, but they didn't seem to get it. In fact, they sent a rejection letter that missed the point with almost comical thoroughness. "It said," remembers Braben, "'The game needs three lives, it needs to play through in no more than about 10 minutes, users will not be prepared to play for night after night to get anywhere, people won't understand the trading, they don't understand 3D, the technology's all very impressive but it's not very colourful'."

So they tried Acornsoft. Acorn was a Cambridge company, and its publishing arm operated from one room of a warren of offices above the marketplace. There they found a rat's nest of desks and cables, and four people not much older than themselves. This audience knew what they were looking at when Bell and Braben fired up their demo. Acornsoft's managing director, David Johnson-Davies, was a tall, thin 27-year-old who leaned forward when concentrating, like a human version of an Anglepoise lamp. Chris Jordan, the chief editor, 24, had programmed the BBC Micro's sound chip and was the author of the standard handbook on computer music. Unlike the suits at Thorn EMI, all of them had an intimate knowledge of the BBC Micro's innards and an intimate sense of what the view on the screen implied about what was going on in those innards.

The demo featured some combat and the completed space station docking sequence. "Like everyone else," Jordan tells me, "I was knocked dead by its appearance; and the appearance was remarkable simply because it was real-time 3D graphics. Of course, we were programmers, so we knew how hard it was, and what really impressed us was that this wasn't just smart programming, it was smart maths. Somebody had gone hell for leather making the absolute best that was possible." After the demo was over, Bell and Braben explained that what they had shown was just an instalment. They wanted to go on, they said. They wanted trading, travelling, destinations. While they talked, they hovered protectively over the disk they'd brought, not wanting to disclose the code on it unless Acornsoft committed itself. When they'd finished, they carefully took it away with them.

Acornsoft had a quite different set of doubts from Thorn EMI. Bell and Braben's game was far more ambitious, far more demanding than anything they had ever taken on. It was unfinished. And it had two authors. This last anxiety seems strange now, when all video games are produced by teams of people numbering in the tens and, occasionally, in the hundreds. But back then it seemed disturbingly complicated, perhaps a recipe for chaos, to have the plan for a game shared between two brains. Taking on a partnership was another jump into uncertainty for Acornsoft.

On the other hand, Johnson-Davies and Jordan were free to ignore all the rules of thumb if they wanted to. Acornsoft was a coders' company, with a coders' outlook on the world. The managers of the parent company were busy coping with a boom of their own in hardware; they were quite happy to let the publishing arm go its own way, so long as its profits kept on rising, which they did, and its office was a hive of frantic industry, which it demonstrably was. So really the only question was whether Acornsoft wanted to take the risk with Bell and Braben.

Hell, of course it did. If a bird of paradise comes and settles on your wrist, you stay very still in case it flies away.

So began 18 months of effort, which, at times, looked as if it might go on for ever. One thing Braben and Bell explored was the prospect of getting the computer to generate the game's universe by itself. Their first idea had been to furnish the machine with the details of (say) 10 solar systems they'd lovingly handcrafted in advance: elegant stars, advantageously distributed, orbited by nice planets in salubrious locations, inhabited by contrasting aliens with varied governments and interesting commodities to trade. But it quickly became clear that the wodge of data involved was going to make an impossible demand on memory.

What if, they asked themselves, they got the machine to invent the map as well? To avoid the storage problem, it would need to build solar systems on the fly; that is, it would have to come up with names and distances and dimensions right when they were called for, that instant, rather than pulling them out of memory. Yet these unstored, instantaneous inventions also needed to be solid and dependable. Stars and planets needed to stay where they were put.

At this point, they thought of the Fibonacci sequence. In its most generic form, it works like this: you take any old pair of numbers and add them together to produce a third number. Then you add the second and third together to produce a fourth, the third and fourth together to produce a fifth, and so on, ad infinitum. So if you start with 2 and 7, the sequence goes:

2 7 9

Adding the 7 and the 9 is going to give you the two-digit number 16, but the Fibonacci sequence consists of single digits. Consequently you ignore the carried 1 in the 16 and only take notice of the 6, giving you:

2 7 9 6

It's this that creates the apparent randomness with which the sequence continues:

2 7 9 6 5 1 6 7 3 0 3 3 6 9 5 4 9 3...

These numbers are "pseudo-random". They look random and, after the sequence has been going for a while, it produces statistically equal quantities of each of the digits under 10, so the numbers can be used as a source for any process in which you want the corners and crannies of probability to be scoured out as thoroughly as truly random numbers would do. But because they are all generated by a rule, they are, in fact, completely predictable. All you need to know to know them is the rule that was used and the pair of starting numbers. All the later numbers are, so to speak, there in the first pair, latent.

Hence the sequence's value to Bell and Braben. They could encode all the information on a particular solar system in a relatively short row of digits. That number, it occurred to them, wouldn't have to be stored if it were an iteration in a Fibonacci sequence - or a Fibonacci-like sequence, anyway. All you would need would be a starting point, a rule for doing the iterations, and a mechanism for extracting the information from the number.

Some digits controlled the physical specs of the system: the size, the location, the number of planets. Some determined local politics. Others grew into brief flourishes of verbal description - which always read a little weirdly, put together as they were from stray adjectives and nouns. Since the adjective list contained "carnivorous" and the noun list contained "arts graduates", it was possible to land on a planet where all the inhabitants were, yes, carnivorous arts graduates: a little swipe maybe at Cambridge - not random but pseudo-random. As the player entered the star system, then, it swelled into existence as if it had always been there.

Braben and Bell called the starting number for a galaxy "a seed" and, in truth, creating the game this way was more like gardening than deliberately constructing something. You had to plant the seed and see what grew. It was another sense in which they were ceding direct control over the game in favour of working indirectly on the player's experience. But they did want to start the player off in a reasonably friendly bit of space, where the pickings were good and they wouldn't get instantly clobbered. Since there was no way to edit a galaxy, you just had to try galaxy after galaxy, seed after seed, until something suitable grew. "I remember thinking it was very wasteful," Braben says. "You'd type in a number, a birthday or something, and see what galaxy that came out with. 'No, I don't like that. No, I don't like that. That cluster looks horrible'." They also decided they had better check the 256 system names in the galaxy where the player would be plunked down, in case any of the four-letter words were actually four-letter words. "One of the first galaxies we tried had a system called Arse. We couldn't use the whole galaxy. We just threw it away!"

Obviously, Bell and Braben couldn't have an infinity of other galaxies. That would just be silly. But they could, they agreed, have a coolly huge number of galaxies, as they explained to Acorn, showing off the feature. In fact, they said, they planned to have... 2 to the power of 48 of them, approximately 282,000,000,000,000 - two hundred and eighty-two million million galaxies. It was one of the few moments when Acornsoft put its foot down.

Acornsoft could see that having 282,000,000,000,000 galaxies would rub the player's nose in the artificiality of what they were enjoying. A number that gigantic made it inescapably clear that some sort of mathematical concoction was involved. And it exposed the underlying sameness of all the star systems, generated as they were from only a handful of varying qualities. The pink volcanoes would come round again and again. It would be better to be more modest. Somewhere between the unimpressed response to a small game universe and the disbelieving response to a ridiculously large one lay a zone of awe. That was where they should be aiming, and eight galaxies containing 256 stars each seemed like a reasonable guess at its whereabouts.

But the publishers could also see that, on the right scale, having the computer generate the game universe offered a powerful imaginative advantage - and therefore a marketing advantage. Braben and Bell's Fibonacci-derived mechanism meant that Acornsoft could hold out to players the seductive possibility of finding stuff in the game that not even the authors knew about. This was not just a figure of speech. The two of them just set the seeds sprouting; they really didn't know in advance what the 251st iteration of the sixth galaxy was going to throw up. In this would lie one part of the game's permanent originality. Almost every space game since has offered an environment more richly detailed and more graphically varied than Bell and Braben's bare-bones universe of the 1980s, but few have followed them in opening up the construction of the game world to chance, and so letting it be autonomous and unpredictable.

One thing you couldn't do was cooperate with anyone. All the other apparent actors in the game universe were ingenious mathematical routines in paper-thin disguise. You were on your own with your enemies and the market prices. In this, of course, the game was beautifully in sync with the times. Margaret Thatcher had recently declared that there was no such thing as society; in the game universe, that was literally true. Bell and Braben were creating a cosmos of pure competition. It was a kind of reflection, not of the reality of 1980s Britain, but of the defiant thought in the heads of those who were benefiting from Thatcherism, who wanted to believe that behaviour not much more complex than the choices you got in the game was enough to satisfy the country's needs. Bell and Braben got a lot of the inspiration for the game's universe from the "libertarian" American sci-fi they were reading, but at that time they also shared a broadly Conservative outlook. If Thatcher represented clear ideas with hard edges, they were on her side. Soon after they signed up with Acornsoft, she won the 1983 election.

Finishing writing the game sometimes seemed nearly impossible. Bell and Braben went on coding, fitting their Cambridge coursework around it. But the longer the writing process stretched out, the more paranoid all concerned grew, that someone, somewhere, was going to steal Elite's thunder; not by publishing something as ground-breaking, necessarily, but just by independently inventing any part of Elite's package of graphics and gameplay. By the summer of 1984, it was time to declare an arbitrary halt to the quest for perfection and stop.

Acornsoft packaged Elite in a box bigger than the box for any of their other games, and it bulged. They stuffed it with a plethora of coloured paper and cardboard items, all devised by Jordan and Johnson-Davies to drive home the message that here was an event. Besides the game itself, on cassette or on disk, there was a novella, a manual, a chart, some stickers, a forgery-proof sepia postcard you could send in to enter a competition if you became "Elite". For the launch in the summer of 1984, Johnson-Davies hired Thorpe Park in Surrey, where the world's first underground roller-coaster ride had just opened. In 1984, computer games did not have launch parties. Again, Acornsoft was announcing a difference, a departure from the norm.

The unveiling took place in a big darkened room, with atmospheric music playing and a BBC Micro hooked up to a huge projection TV. Bell and Braben walked in, feeling summery, feeling glad to have their second-year university exams out of the way and to be computer-game authors to boot - and discovered that there were 40 people waiting for them. In the dark, they loaded the game, and the display appeared, with the scanner in the centre and a star field beckoning ahead, full of danger, full of promise. The audience hurtled forward into the space behind the screen.

The reviews of the game were rapturous. The bulging boxes flew out of the shops. Evidence began to trickle back to Acornsoft that people were exploring the bottled universe more obsessively even than the publishers had dared to hope: for hour after hour, day after day, week after week. Word reached them that an intrepid explorer had, indeed, discovered a Planet Arse in one of the seven galaxies, which Bell and Braben hadn't checked for expletives. Sales of Acornsoft's Elite would finally reach a total of almost 150,000. There were only 150,000 or so BBC Micros in the world at that point, so the ratio was almost 1:1, one copy of Elite for every computer that could run it.

When Bell and Braben had done the deal with Acornsoft 18 months before, they had asked for a higher royalty rate than Johnson-Davies could agree to. Instead, they had been allowed to keep the rights to publish the game on other platforms. Now, with the BBC Micro version a bestseller, interest in the other rights was so intense that the boys' agent was able to hold an auction. The rights were won by BTSoft, the software division of the newly privatised British Telecom. The auction became news in itself. Braben and Bell appeared on Channel 4 News to show the country a new category of person, soon to be familiar, currently exotic: the geeky genius. They were 20 and 21 and, though they had none of the credentials that said Engineer or Scientist, on the one particular subject of their creation, they knew best. They were Thatcher babies, not in the sense of being born in the 1980s, but in the sense of coming to adulthood then and taking as normality the landscape after the great shredding of the industrial base. The sources of technological prowess that existed in Britain before their time scarcely touched them. They hadn't had to win support for their project from the hierarchy of an aerospace company or a research institute. They had appointed themselves to be the authors of Elite, and now Elite was proliferating across the world.

The two of them have multiple candidates for the moment when they really understood how big the game was going to be. Braben's choice is the moment when he saw the sepia postcards people had sent in to Acornsoft on becoming "Elite". With 6,400 enemies to kill, they had never expected to see more than a handful coming back. But in Johnson-Davies's secretary's office, the cards arrived in a flood. There were thousands and thousands, each one representing uncounted hours of bedroom warfare. Sales statistics were just statistics. Here you could see what they meant; you could take in the number of total strangers who were spending mighty fractions of their lives absorbed in what had once been just an idea, in his head and Bell's.

Postscript: David Braben used the rewards of Elite to build himself a career in the games industry. He is a businessman with a development company of his own, just outside Cambridge. He worries about the euro and hopes to create games still bigger than Elite. At the moment, he's working on a Wallace & Gromit game. Ian Bell lives quietly in the countryside with his girlfriend, a vet. He used the rewards of Elite to study aikido and get into the rave scene. He breeds pedigree Burmese cats and worries about American imperialism and developing-world debt. He does a little exploratory coding now and again, but he doesn't play modern computer games: too obvious, too violent. He doesn't read fiction much, either. Like the intelligent horses at the end of Gulliver's Travels, he thinks it only says "the thing which is not". He doesn't much like the world he helped to create.

· This is an edited extract from Backroom Boys: The Secret Return Of The British Boffin, by Francis Spufford, published by Faber on November 6 at £14.99.

Mark Wilson, CIX Ltd: mw@cix.co.uk
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