Where did the time go? It seems like just yesterday that Gerald Ford was President and I was dumping quarters into the Pong video game machine at the City College of New York's south campus cafeteria. Now I play Angry Birds on my Android phone, but the Computer History Museum in Mountain View, California keeps those ancient days fresh with an online exhibit of the grandmother of computer video games: Spacewar!
First conceived by a crew of developers in and around the Massachusetts Institute of Technology in 1961 and built in 1962, Spacewar! let two control-stick-equipped users duke it out with torpedo guns on the background of an astronomically accurate star screen. You can even play simulated Spacewar! yourself here.
Subsequent editions of the game greatly improved, visually speaking. Steve Russell wrote the first version of the application at his impressive sounding "Hingham Institute Space Warfare Study Group" (which, it turns out, amounted to "a barely-habitable tenement on Hingham Street in Cambridge, MA"). Peter Samson, Dan Edwards, and J. Martin Graetz turned out more sophisticated versions in the spring of 1962.
Detectors full out
The inspiration for the game came from the "Space Opera" novels of Edward Elmer Smith, whose late 1930s Lensman series presaged Issac Asimov's wonderful Foundation trilogy. One does get a sense of space vessels confronting and stalking each other in first installation of the series, Triplanetary. Here's an excerpt:
Apparently motionless to her passengers and crew, the Interplanetary liner Hyperion bored serenely onward through space at normal acceleration. In the railed-off sanctum in one corner of the control room a bell tinkled, a smothered whirr was heard, and Captain Bradley frowned as he studied the brief message upon the tape of the recorder—a message flashed to his desk from the operator's panel. He beckoned, and the second officer, whose watch it now was, read aloud:
"Reports of scout patrols still negative," the second officer declares.
"According to the observatories we're in the clear ether, but I wouldn't trust them from Tellus to Luna," the captain meditates. "You have given the new orders, of course?"
"Yes, sir," his second replies. "Detectors full out, all three courses of defensive screen on the trips, projectors manned, suits on the hooks. Every object detected to be investigated immediately—if vessels, they are to be warned to stay beyond extreme range. Anything entering the fourth zone is to be rayed."
Literary origins aside, the most interesting part of Spacewar!'s back story is the machine upon which it was built, a computer whose later versions would host the ARPANET and early versions of the UNIX operating system. Spacewar! was written for the first of the Digital Equipment Corporation's PDP (Programmed Data Processor) series, whose formative editions are the focus of the Computer History Museum's PDP Restoration Project.
PDP-1
The 1959 launch of DEC's PDP-1 represented a huge shift in computer design. The PDP focused on accessibility and ease of use rather than just processing power. "For DEC it was the first in a long line of computers that focused on interactivity and affordability," the museum exhibit notes, "changing the industry forever by foreshadowing what would become an entirely new class of computer: the 'minicomputer'."
DEC originally built and sold modular devices for engineers, such as oscillators and digital circuit adders. Gradually the company began extending some of these modules to mainframes. The 18-bit PDP-1's I/O included a CRT screen, typewriter, and a magnetic tape interface.
But what made the first PDP-1 particularly unique was its size and price. Tiny compared to other models, the machine took up about the same amount of space as a studio kitchen with refrigerator, oven, and sink. And it cost around $120,000 in 1960—as opposed to the UNIVAC I, which, when realistically priced, set buyers back about ten times that sum.
Most universities and small businesses couldn't afford UNIVAC-like devices, but some of them could spring for the PDP-1, most notably MIT. That made sense, since PDP maker Ben Gurley had based his design on TX-0 and TX-2 computers coming out of the MIT Lincoln Laboratory. Crucially, the PDP-1 was a perfect fit for early versions of time sharing. The computer "swapped" users to a magnetic drum memory system, allowing for multi-participatory use.
Graphics were also a huge strong suit for the first machine. The system included a display module that allowed users to manipulate objects with a light pen. Users were wowed by multicolor programs like Snowflake, which could generate flashing geometric patternsacross the CRT screen.
A consistent framework
No big surprise that Spacewar! was a hit with computer exhibit attendees across the country. Indeed, the project was designed to show off the host system, J. Martin Graetz later explained:
- It should demonstrate as many of the computer's resources as possible, and tax those resources to the limit;
- Within a consistent framework, it should be interesting, which means every run should be different;
- It should involve the onlooker in a pleasurable and active way—in short, it should be a game.
But Spacewar! did more than just entertain tech newbies and help geeks waste time. DEC used the program to sell and popularize the PDP-1. In fact, as the museum observes, Spacewar! made the PDP-1 famous. Requiring over 100,000 calculations per second to determine gravity, ship trajectories, and the position of the sun and stars, Spacewar! consistently illustrated its three purposes to potential customers.
"With its companion light pen, non-specialist users could interact easily with the computer—a form of interactivity Digital pioneered with the PDP-1," the Museum observes. Armed with demos like Spacewar!, DEC's PDP empire grew.
Although only about 50 PDP-1s ever appeared on the market, engineers used several to design the networking software for the ARPANET. The PDP-10 appeared on various ARPANET "nodes" in the early 1970s, one of which was also used to simulate an aircraft carrier. Bell Labs employees Ken Thompson and Dennis Richie worked out an early version of the operating system that would become UNIX on a PDP-7 computer. Then they more fully developed the OS on a PDP-11/20.
Martinis and mice
Of course, before wrapping up this post, we have to tackle the inevitable question—was Spacewar! "the first computer video game"? Lots of history sites say yes. But there were predecessors, mostly notably Mouse in the Maze, written on the aforementioned TX-0, which also came with a light pen.
"Essentially, it was a short cartoon," Spacewar! developer Graetz recalled, "a stylized mouse searched through a rectangular maze until it found a piece of cheese which it then ate, leaving a few crumbs. You constructed the maze and placed the cheese (or cheeses—you could have more than one) with the light pen."
Another version of the game substituted a martini for the cheese—"after drinking the first one the mouse would stagger to the next."
Still, it does seem like Spacewar! is where it all really begins, the application that really got the public thinking about visual game programs. More significantly, it popularized the PDP computer series, upon which so much early Internet development depended. Thus we may thank Spacewar! not only for its contribution to gaming, but for the online platforms where we recreate and remember it to this day.
Listing image by Photograph by Nik Clayton
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