The 6502 was still mostly pin compatible with the 6800. You can see it on the schematic for the Apple 1. The most important difference was that the 6502 didn’t need an external clock generator ...

What if we could have had fast, high density ROM and RAM in the late ’70s, but the ability to put a microprocessor in silicon was beyond ... Gigatron is emulating a 6502 processor, the same ...