by Steven Levy
Kotok knew that hurdle could be easily solved. Kotok at that point had been getting fairly cozy with the people at DEC, several miles away at Maynard. DEC was informal, as computer manufacturers went, and did not regard MIT hackers as the grungy, frivolous computer-joyriders that IBM might have taken them for. For instance, one day when a piece of equipment was broken, Kotok called up Maynard and told DEC about it; they said, “Come up and get a replacement.” By the time Kotok got up there, it was well after 5 P.M. and the place was closed. But the night watchman let him go in, find the desk of the engineer he’d been talking to, and root through the desk until he found the part. Informal, the way hackers like it. So it was no problem for Kotok to go up to Maynard one day, where he was positive someone would have a routine for sine and cosine that would run on the PDP-1. Sure enough, someone had it, and since information was free, Kotok took it back to Building 26.
“Here you are, Russell,” Kotok said, paper tapes in hand. “Now what’s your excuse?”
At that point, Russell had no excuse. So he spent his off-hours writing this fantasy PDP-1 game, the likes of which no one had seen before. Soon he was spending his “on” hours working on the game. He began in early December, and when Christmas came, he was still hacking. When the calendar wrapped around to 1962, he was still hacking. By that time, Russell could produce a dot on the screen that you could manipulate: by flicking some of the tiny toggle switches on the control panel, you could make the dots accelerate and change direction.
He then set about making the shapes of the two rocket ships: both were classic cartoon rockets, pointed at the top and blessed with a set of fins at the bottom. To distinguish them from each other, he made one chubby and cigar-shaped, with a bulge in the middle, while the second he shaped like a thin tube. Russell used the sine and cosine routines to figure out how to move those shapes in different directions. Then he wrote a subroutine to shoot a “torpedo” (a dot) from the rocket nose with a switch on the computer. The computer would scan the position of the torpedo and the enemy ship; if both occupied the same area, the program would call up a subroutine that replaced the unhappy ship with a random splatter of dots representing an explosion. (That process was called “collision detection.”)
All of this was actually a significant conceptual step toward more sophisticated “real-time” programming, where what happens on a computer matches the frame of reference in which human beings are actually working. In another sense, Russell was emulating the online, interactive debugging style that the hackers were championing—the freedom to see what instruction your program stopped dead on, and to use switches or the Flexowriter to jimmy in a different instruction, all while the program was running along with the DDT debugger. The game Spacewar, a computer program itself, helped show how all games—and maybe everything else—worked like computer programs. When you went a bit astray, you modified your parameters and fixed it. You put in new instructions. The same principle applied to target shooting, chess strategy, and MIT course work. Computer programming was not merely a technical pursuit, but an approach to the problems of living.
In the later stages of programming, Saunders helped Slug Russell out, and they hacked a few intense six-to-eight-hour sessions. Sometime in February, Russell unveiled the basic game. There were the two ships, each with thirty-one torpedoes. There were a few random dots on the screen representing stars in this celestial battlefield. You could maneuver the ships by flicking four switches on the console of the PDP-1, representing clockwise turn, counterclockwise turn, accelerate, and fire torpedo.
Slug Russell knew that by showing a rough version of the game, and dropping a paper tape with the program into the box with the PDP-1 system programs, he was welcoming unsolicited improvements. Spacewar was no ordinary computer simulation—you could actually be a rocket-ship pilot. It was Doc Smith come to life. But the same power that Russell had drawn on to make his program—the power that the PDP-1 lent a programmer to create his own little universe—was also available to other hackers, who naturally felt free to improve Slug Russell’s universe. They did so instantly.
The nature of the improvements might be summed up by the general hacker reaction to the original routine Slug Russell used for his torpedoes. Knowing that military weapons in real life aren’t always perfect, Russell figured that he’d make the torpedoes realistic. Instead of having them go in a straight line until they ran out of steam and exploded, he put in some random variations in the direction and velocity. Instead of appreciating this verisimilitude, the hackers denounced it. They loved smooth-running systems and reliable tools, so the fact that they would be stuck with something that didn’t work right drove them crazy. Russell later figured out that “weapons or tools that aren’t very trustworthy are held in very low esteem—people really like to be able to trust their tools and weapons. That was very clear in that case.”
But of course that could be easily fixed. The advantage that a world created by a computer program had over the real world was that you could fix a dire problem like faulty torpedoes just by changing a few instructions. That was why so many people found it easy to lose themselves in hackerism in the first place! So the torpedoes were fixed, and people spent hours in outer-space dueling. And even more hours trying to make the Spacewar world a better one.
Peter Samson, for instance, loved the idea of Spacewar, but could not abide the randomly generated dots that passed themselves off as the sky. Real space had stars in specific places. “We’ll have the real thing,” Samson vowed. He obtained a thick atlas of the universe, and set about entering data into a routine he wrote that would generate the actual constellations visible to someone standing on the equator on a clear night. All stars down to the fifth magnitude were represented; Samson duplicated their relative brightness by controlling how often the computer lit the dot on the screen which represented the star. He also rigged the program so that, as the game progressed, the sky would majestically scroll—at any one time the screen exposed forty-five percent of the sky. Besides adding verisimilitude, this “Expensive Planetarium” program also gave rocket fighters a mappable background from which to gauge position. The game could truly be called, as Samson said, Shootout-at-El-Cassiopeia.
Another programmer, named Dan Edwards, was dissatisfied with the unanchored movement of the two dueling ships. It made the game merely a test of motor skills. He figured that adding a gravity factor would give the game a strategic component. So he programmed a central star—a sun—in the middle of the screen; you could use the sun’s gravitational pull to give you speed as you circled it, but if you weren’t careful and got too close, you’d be drawn into the sun, which was certain death.
Before all the strategic implications of this variation could be employed, Shag Garetz, one of the Higham Institute trio, contributed a wild-card type of feature. He had read in Doc Smith’s novels how space hot-rodders could suck themselves out of one galaxy and into another by virtue of a "hyper-spatial tube,” which would throw you into “that highly enigmatic Nth space.” So he added a “hyperspace” capability to the game, allowing a player to avoid a dire situation by pushing a panic button that would zip him to this hyperspace. You were allowed to go into hyperspace three times in the course of a game; the drawback was that you never knew where you might come out. Sometimes you’d reappear right next to the sun, just in time to see your ship hopelessly pulled to an untimely demise on the sun’s surface. In tribute to Marvin Minsky’s original hack, Garetz programmed the hyperspace feature so that a ship entering hyperspace would leave a “warp-induced photonic stress emission signature”—a leftover smear of light in a shape that often formed in the aftermath of a Minskytron display.
The variations were endless. By switching a few parameters you could turn the game into “hydraulic spacewar,” in which torpedoes flow out in ejaculatory streams instead of one by one. Or, as the night grew later and people became locked into interstellar mode, someone might shout, “Let’s turn on the Winds of Space!” and so
meone would hack up a warping factor, which would force players to make adjustments every time they moved. Though any improvement a hacker wished to make would be welcome, it was extremely bad form to make some weird change in the game unannounced. The effective social pressures that enforced the Hacker Ethic—which urged hands-on for improvement, not damage—prevented any instance of that kind of mischief. Anyway, the hackers were already engaged in a mind-boggling tweak of the system—they were using an expensive computer to play the world’s most glorified game!
Spacewar was played a hell of a lot. For some, it was addictive. Though no one could officially sign up the PDP-1 for a Spacewar session, the machine’s every free moment that spring seemed to have some version of the game running. Bottles of Coke in hand (and sometimes with money on the line), the hackers would run marathon tournaments. Russell eventually wrote a subroutine that would keep score, displaying in octal (everyone could sight-read that base-eight number system by then) the total of games won. For a while, the main drawback seemed to be that working the switches on the console of the PDP-1 was uncomfortable—everybody was getting sore elbows from keeping their arms at that particular angle. So one day Kotok and Saunders went over to the TMRC clubroom and found parts for what would become the first computer joysticks. Constructed totally with parts lying around the clubroom and thrown together in an hour of inspired construction, the control boxes were made of wood, with Masonite tops. They had switches for rotation and thrust, as well as a button for hyperspace. All controls were, of course, silent, so that you could surreptitiously circle around your opponent or duck into Nth space, should you care to.
While some hackers lost interest in Spacewar once the fury of the programming phase had died down, others developed a killer instinct for devising strategies to mow down opponents. Most games were won and lost in the first few seconds. Wagner became adept at the “lie in wait” strategy, in which you stayed silent while gravity whipped you around the sun, then straightened out and began blasting torps at your opponent. Then there was a variation called the "CBS Opening,” where you angled to shoot and then whipped around the star: the strategy got its name because when both Spacewar gladiators tried it, they would leave a pattern on the screen that bore a remarkable resemblance to the CBS eye. Saunders, who took his Spacewar seriously, used a modified CBS strategy to maintain dominance through the tournaments—there was a time when he couldn’t be beaten. However, after twenty minutes of protecting your place in the king-of-the-hill-structured contest, even a master Spacewarrior would get a bit blurry-eyed and slower on the draw, and most everybody got a chance to play Spacewar more than was probably sensible. Peter Samson, second only to Saunders in Spacewarring, realized this one night when he went home to Lowell. As he stepped out of the train, he stared upward into the crisp, clear sky. A meteor flew overhead. Where’s the spaceship? Samson thought as he instantly swiveled back and grabbed the air for a control box that wasn’t there.
In May 1962, at the annual MIT Open House, the hackers fed the paper tape with twenty-seven pages worth of PDP-1 assembly-language code into the machine, set up an extra display screen—actually a giant oscilloscope—and ran Spacewar all day to a public that drifted in and could not believe what they saw. The sight of it—a science-fiction game written by students and controlled by a computer—was so much on the verge of fantasy that no one dared predict that an entire genre of entertainment would eventually be spawned from it.
It wasn’t until years later, when Slug Russell was at Stanford University, that he realized that the game was anything but a hacker aberration. After working late one night, Russell and some friends went to a local bar that had some pinball machines. They played until closing time; then, instead of going home, Russell and his coworkers went back to their computer, and the first thing his friends did was run Spacewar. Suddenly it struck Russell: “These people just stopped playing a pinball machine and went to play Spacewar—by gosh, it is a pinball machine.” The most advanced, imaginative, expensive pinball machine the world had seen.
Like the hackers’ assemblers and the music program, Spacewar was not sold. Like any other program, it was placed in the drawer for anyone to access, look at, and rewrite as they saw fit. The group effort that stage by stage had improved the program could have stood for an argument for the Hacker Ethic: an urge to get inside the workings of the thing and make it better had led to measurable improvement. And of course it was all a huge amount of fun. It was no wonder that other PDP-1 owners began to hear about it, and the paper tapes holding Spacewar were freely distributed. At one point the thought crossed Slug Russell’s mind that maybe someone should be making money from this, but by then there were already dozens of copies circulating. DEC was delighted to get a copy, and the engineers there used it as a final diagnostic program on PDP-1s before they rolled them out the door. Then, without wiping the computer memory clean, they’d shut the machine off. The DEC sales force knew this, and often, when machines were delivered to new customers, the salesman would turn on the power, check to make sure no smoke was pouring out the back, and hit the “VY” location where Spacewar resided. And if the machine had been carefully packed and shipped, the heavy star would be in the center, and the cigar-shaped rocket and the tube-shaped rocket would be ready for cosmic battle. A maiden flight for a magic machine.
• • • • • • • •
Spacewar, as it turned out, was the lasting legacy of the pioneers of MIT hacking. In the next couple of years many of the TX-0 and PDP-1 joyriders departed the Institute. Saunders would take a job in industry at Santa Monica (where he would later write a Spacewar for the PDP-7 he used at work). Bob Wagner went off to the Rand Corporation. Peter Deutsch went to Berkeley, to begin his freshman year of college. Kotok took a part-time job that developed into an important designing position at DEC (though he managed to hang around TMRC and the PDP-1 for years afterward). In a development that was to have considerable impact on spreading MIT-style hackerism outside of Cambridge, John McCarthy left the Institute to begin a new artificial intelligence lab on the West Coast, at Stanford University. Slug Russell, ever McCarthy’s LISP-writing coolie, tagged along.
But new faces and some heightened activity in the field of computing were to insure that the hacker culture at MIT would not only continue, but thrive and develop more than ever. The new faces belonged to breathtakingly daring hackers destined for word-of-mouth, living-legend fame. But the developments that would allow these people to take their place in living the hacker dream were already under way, initiated by people whose names would become known by more conventional means: scholarly papers, academic awards, and, in some cases, notoriety in the scientific community.
These people were the planners. Among them were scientists who occasionally engaged in hacking—Jack Dennis, McCarthy, Minsky—but who were ultimately more absorbed by the goals of computing than addicted to the computing process. They saw computers as a means to a better life for the human race, but did not necessarily think that working on a computer would be the key element in making that life better.
Some of the planners envisioned a day when artificially intelligent computers would relieve man’s mental burdens, much as industrial machinery had already partially lifted his physical yoke. McCarthy and Minsky were the vanguard of this school of thought, and both had participated in a 1956 Dartmouth conference that established a foundation for research in this field. McCarthy’s work in the higher-level language LISP was directed toward this end, and was sufficiently intriguing to rouse hackers like Slug Russell, Peter Deutsch, Peter Samson, and others into working with LISP. Minsky seemed interested in artificial intelligence with a more theoretical basis: a gleeful, bald-headed Johnny Appleseed in the field, he would spread his seeds, each one a thought capable of blooming into a veritable apple tree of useful AI techniques and projects.
The planners were also extremely concerned about getting the power of computers into the hands of more researchers, scientists, statisticians, an
d students. Some planners worked on making computers easier to use; John Kemeny of Dartmouth showed how this could be done by writing an easier-to-use computer language called BASIC. Programs written in BASIC ran much slower than assembly language and took up more memory space, but did not require the almost monastic commitment that machine language demanded. MIT planners concentrated on extending actual computer access to more people. There were all sorts of justifications for this, not the least being the projected scale of economy—one that was glaringly preferable to the then current system, in which even seconds of computer time were valuable commodities (though you would not know it around the Spacewar-playing PDP-1. If more people used computers, more expert programmers and theoreticians would emerge, and the science of computing—yes, these aggressive planners were calling it a science—could only benefit by that new talent. But there was something else involved in this. It was something any hacker could understand—the belief that computing, in and of itself, was positive. John McCarthy illustrated that belief when he said that the natural state of man was to be online to a computer all the time. “What the user wants is a computer that he can have continuously at his beck and call for long periods of time.”
The man of the future. Hands on a keyboard, eyes on a CRT, in touch with the body of information and thought that the world had been storing since history began. It would all be accessible to Computational Man.
None of this would occur with the batch-processed IBM 704. Nor would it occur with the TX-0 and PDP-1, with their weekly log sheets completely filled in within hours of being posted on the wall. No, in order to do this, you’d have to have several people use the computer at once. (The thought of each person having his or her own computer was something only a hacker would think worthwhile.) This multiuser concept was called time sharing, and in 1960 the heaviest of the MIT planners began the Long-Range Computer Study Group. Among the members were people who had watched the rise of the MIT hacker with amusement and assent, people like Jack Dennis, Marvin Minsky, and Uncle John McCarthy. They knew how important it was for people to actually get their hands on those things. To them, it was not a question of whether to time-share or not, it was a question of how to do it.