A microprocessor released shortly after the Intel 8080, in about 1975. It had 78 instructions, including the undocumented HCF (Halt and Catch Fire) bus test instruction. The 6800 evolved into the Motorola 6801 and 6803. The 6502 was based on the design of the 6800 but had one less data register and one more index register. (1994-10-31)