Isodontbelonghere

I'm not an Atari (or any other gamer) guy, but came here by accident while trying to get the answer to some CUPL questions, and thought I'd offer an answer. My suggestion would be that you find a copy of the original DOS CUPL (3.2b was the last version, afaIk). Unlike the Microchip (Atmel) version you ran across, it actually supports a broad range of parts from other manufacturers. And running old DOS software isn't the hardest thing in the world.