Motorola 6800

The 6800 is a microprocessor produced by Motorola and released shortly after the Intel 8080 in 1975. It had 78 instructions, including the (in)famous, undocumented Halt and Catch Fire (HCF) bus test instruction. It may have been the first µP with an index register.

Several first-generation microcomputers of the 1970s, available on postal order as kits or in assembled form, used the 6800 as their CPU; examples are the SWTPC 6800 (first to use the 6800) and the MITS Altair 680 range (MITS offering these as alternatives to its Altair 8800).

The 6800 'fathered' several descendants, the pinnacle being the greatly upgraded 6809, which was used in the Vectrex video game console and the TRS-80 Color Computer, among others. There are also many microcontrollers descended from the 6800 architecture, such as the 68HC11.

Competitor MOS Technologies cloned and upgraded the 6800 with its 6502 and successors, used in many computers and game consoles during the late 1970s and early-to-mid-1980s, most notably the Atari 2600, Apple II family and the Commodore PET, VIC-20 and C64.

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