Pong was based on the Magnavox Odyssey, which was an analog home system that ran on batteries.

Boing Boing has published a great collection of old print ads for Pong (and its many knockoffs), the game that kicked off the digital quarter-sucking arcade craze. The site also provides historical context. An excerpt:

“In September 1972, Atari’s Nolan Bushnell and Allan Alcorn installed the prototype Pong machine at Andy Capp’s Tavern in Sunnyvale, California. The idea was to make a computer game that was ‘so simple that any drunk in any bar could play.’ And boy, did they ever.

Now, was Pong a hit because America loved Ping Pong so much that they wanted to play it on TV too? Or as media theorist Douglas Rushkoff has said, was it empowering because finally anyone could control what was on the TV? Either or neither way, people lined up for their chance to ‘Avoid missing ball for high score,’ as per the machine’s only instructions. Within just a few months, the Pong clone wars had begun.

Atari didn’t have the patent on the technology and very quickly the vast majority in the machines eating quarters around the country were knock-offs. Of course, Pong itself was ‘inspired’ by an electronic ping pong game that was in the Magnavox Odyssey home system. To keep up, Bushnell continued to innovate, as did everyone else. Call it a volley between King Pong and his brethren, while an invasion from space was on its way.”