So, I just hinted at this, but quoting from my Slashdot submission: "Gamasutra is partnering with the IGDA's Preservation SIG to present in-depth histories of the first ten games voted into the Digital Game Canon, beginning with a history of the 1961 mainframe-based shooter Spacewar, arguably the first ever video game."

From the article: "Spacewar had a life of its own, spreading across the computer world like a benign virus. “It was the program that was run into the PDP-1 before it was shipped. It was the last thing--it was used as actually as a final test,” [co-creator J.M.] Graetz said. Because the PDP-1’s memory was composed of magnetic cores, small ferrite rings whose polarity indicated whether a bit was 1 or 0, the game stayed in memory even after the power was turned off."

Hey, that's all kinds of awesome! Graetz continues: “Core memory is non-volatile and once Spacewar was working they just shut the machine down and shipped it. So when the customer set it up and turned it on the first thing they saw was Spacewar." Sorta like the built-in Master System games, only crazier, then. Look out for plenty more in this series - next up is Civilization (complete with Sid Meier and Bruce Shelley interviews) and the obscure but seminal Star Raiders (with a Doug Neubauer interview).