What a mess! But I guess that’s just the way I like it. :) We ended up moving from the PIC12C508A to the PIC12F629 because it is Flash-based and reprogrammable (great for mistakes!), and the chips were at about the same price point at the time. Anyway, enjoy me rambling on as we demo some games. MultiMode3 programmed successfully.

The CD burner we were burning test games with was actually faulty. In the excitement of getting games working, “Verify burn” was either switched off or ignored - whoops! The follow-up explains all that, but bad test discs didn’t mean every failure was a modchip fault.

Sources