“Herd tried fixing several problems in the C64 [while developing the C128 C64 compatibility mode] but those fixes inadvertently created new problems. "I started out as one of the only guys who knew where all the glitches were," says Herd. "I designed them out, and you know what? Cartridges stopped working... the guys who designed the cartridges would use the glitches on the IO select lines to clock data... I had to put them back in," laments Herd. "There was a wire on the C128 and next to it, it said 'Puts the glitches back in.”