* The 6507 CPU, used in the Atari VCS, has only 13 address lines. So it can only address 8KB instead of 64KB. It also lacks the IRQ and NMI interrupt lines.
* The 6510 CPU, used in the Commodore 64, is a 6502 with an additional AEC pin that puts the address bus in high impedance mode. It also includes a 6-bit I/O port that occupies addresses 0 and 1.
* Similarly, the 6502C used in Atari 8-bit computer range, adds an additional HALT pin. The 6502C is otherwise a regular NMOS 6502, not to be confused with the CMOS 65C02.