Nitpick. The 6502 was $25. The 6501 was $20. The 6501 was almost the same thing as the 6502. However it was more-or-less pin compatible with the Motorola 6800

Nitpick. The 6502 was $25. The 6501 was $20. The 6501 was almost the same thing as the 6502. However it was more-or-less pin compatible with the Motorola 6800 while the 6502 wasn't. The 6501 never became popular because a) Motorola objected b) the 6501 needed two-phase non-overlapping 5V rail-to-rail clocks, so it needed external clock generator circuitry, while the 6502 had a single TTL compatible clock input. https://en.wikipedia.org/wiki/MOS_Technology_6502#Introducing_the_6501_and_6502 https://en.wikipedia.org/wiki/MOS_Technology_6502#Introducin...