Godzil (./12087) :
il semblerais que la toute premiere fab du 6502 contenais un autre bug bien gênant qui a été corrigé de suite, je ne me rappelle plus ce que c'était par contre , mais on peux encore trouver des KIM-1 qui ont ce chip )

https://en.wikipedia.org/wiki/MOS_Technology_6502#Bugs_and_quirks :The earliest revisions of the 6502, such as those shipped with some KIM-1 computers, had a severe bug in the ROR (rotate right memory or accumulator) instruction. The operation of ROR in these chips is effectively an LSR instruction that does not affect the carry bit in the status register. MOS left the instruction out of chip documentation entirely because of the defect, promising that ROR would appear on 6502 chips starting in 1976. The vast majority of 6502 chips in existence today do not exhibit this bug.