central processing unit

Posted on May 28, 2009
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Some projects are just so uneccesary, so wildy redundant that they have to be honored. Steve Chamberlain made his own CPU out of nothing but little bits of wire. Here’s the full story from (appropriately enough) Wired magazine.

Intel’s fabrication plants can churn out hundreds of thousands of processor chips a day. But what does it take to handcraft a single 8-bit CPU and a computer? Give or take 18 months, about $1,000 and 1,253 pieces of wire.

Steve Chamberlin, a Belmont, California, videogame developer by day, set out on a quest to custom design and build his own 8-bit computer. The homebrew CPU would be called Big Mess of Wires or BMOW. Despite its name, it is a painstakingly created work of art.

“Computers can seem like complete black boxes. We understand what they do, but not how they do it, really,” says Chamberlin. “When I was finally able to mentally connect the dots all the way from the physics of a transistor up to a functioning computer, it was an incredible thrill.”

The 8-bit CPU and computer will be on display doing an interactive chess demo at the fourth annual Maker Faire in San Mateo, California, this weekend, May 30-31. It will be one of 600 exhibits of do-it-yourself technology, hacks, mods and just plain strange hobby projects at the faire, which is expected to draw 80,000 attendees.

The BMOW is closest in design to the MOS Technology 6502 processor used in the Apple II, Commodore 64 and early Atari videogame consoles. Chamberlin designed his CPU to have three 8-bit data registers, a 24-bit address size and 12 addressing modes. It took him about a year and a half from design to finish. Almost all the components come from the 1970s- and 1980s-era technology.

“Old ’80s vintage parts may not be very powerful, but they’re easy to work with and simple to understand,” he says. “They’re like the Volkswagen Beetles of computer hardware. Nobody argues they’re the best but we love them for their simplicity.”

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