Every summer in Las Vegas, the gamers descend for their annual convention. They come to see the hottest new wares for their favorite consoles and computers. But they're not interested in Microsoft's Xbox, Sony's Playstation 2, or Nintendo's GameCube. This is the Classic Gaming Expo. They're hovering around the Commodore 64, the Atari 2600, the Amiga, and the Apple II: the vintage machines from the 1970s and 1980s that, in their minds, aren't just sources of nostalgia but platforms for exciting and new software. They are retro coders, writing fresh programs for old hardware.

Though some of these programmers sell their work, it's primarily a labor of loveand logic. "They do this to prove their worth as programmers," says John Hardie, director of the Classic Gaming Expo. "It's incredibly hard to write for these systems because of their limitations, their lack of space. When you're working with 4 kilobytes of RAM, it's the ultimate challenge."

For many diehard techies, this pioneering generation of machines elicits the same kind of goose bumps as a classic pop song might for a music fan. These early computers, after all, provided the first means for an armchair gamer to create his answer to Asteroids. The Apple II, for example, has been a darling of the indie hacker set ever since the first machine was introduced at a meeting of the Homebrew Computer Club, a do-it-yourself group of programmers in California, a quarter century ago. Released in 1977, the Apple II was a groundbreaking, mass-market computer with a keyboard, compatibility with the BASIC programming language, and, best of all, color graphics. There was no hard drive but it came with two game paddles. It was perfect for game making.

"The important thing back then was that because the computers didn't have fancy graphics, the programmers had to make them fun to play," says Albert Yarusso, editor of Atari Age, an online magazine for fans of the early Atari systems. "That's why they're still fun today."

Programming for these machines carries a similar appeal today as it did when the computers first came on the marketnamely, their accessibility. In the 1970s and 80s, the video game market was dominated by proprietary arcade machines like Pac-Man and Space Invaders. Consumers could play these machines, but they couldn't hack them. The Commodore 64 and Apple II provided a means through which a self-taught coder with the will and the chops could write and play his own (it was usually, though not always, a guy thing) rudimentary software.