* The disk drive of the Commodore 64 has its own 6502 processor that acts as a floppy disk controller (FDC) and as a disk operating system (DOS) processor. It can also be used as a general coprocessor for the main system.
* The 6502C used in [[Atari 8-bit]] computer range, adds an additional HALT pinfor DMA. The 6502C is otherwise a regular NMOS 6502, not to be confused with the CMOS 65C02.
* The CMOS 65C02 fixed multiple bugs of the original NMOS 6502, but also removed access to all illegal instructions. Some cycle counts have been modified and some extra instructions have been added. In fact, there are multiple implementations of the 65C02 (WDC 65C02, WDC 65C02S, Rockwell R65C02, CSG 65CE02, ...), each with its own variant of the instruction set.