Nick Bensema's Atari 64 Commits 1980s Sacrilege by Running Commodore's OS on Atari's Hardware
Bringing together two rival eight-bit computing camps the Atari 64 project gets the Commodore 64 KERNAL and BASIC running on an Atari 800XL.
Developer Nick Bensema has brought together two giants of the eight-bit computing era, Commodore and Atari, by modifying the operating system of the former to run on the computers of the latter.
"They're practically the same machine," Bensema notes of his work to take the core of the Commodore 64, known through a typographical error as the "kernal" rather than kernel, and port it to the Atari 800XL. "Why didn't someone try this 30 years ago?"
Released in 1982, the Commodore 64 would go on to become the single best-selling computer model thanks to impressive audio capabilities, entirely adequate video capabilities, and a relatively low selling price. It ran a custom operating system dubbed the Commodore KERNAL with a port of Microsoft's BASIC, stored in ROM, on a MOS Technology 6510 processor.
The Atari 800XL, by contrast, launched in 1983 as a follow-up to the Atari 800 with a custom operating system running atop a MOS Technology 6502B — a chip which is entirely compatible with the 6510 found in the considerably more successful Commodore 64, hampered by supply issues for the critical holiday sales period.
With compatible processors, it's no surprise that the operating systems are interchangeable — with a little effort. "The difference in address space wasn't that much," Bensema explains of the work that went into the project, which included modifying the operating system to accommodate differences in hardware between the two platforms. "The I/O chips are at $D000, the ROMs are near the end of memory, the rest is just software."
"The keyboard, the PETSCII screen editor, and BASIC work. Currently, there's no I/O outside of the screen and keyboard whatsoever. It'll take more expertise than I have to figure out any possible way of saving and loading programs. Even describing the obstacles is a bit out of my league at this point."
Bensema has published the source code for the project, with a build script to compile it, on GitHub under an unspecified license.