 |
 |
|
680x information |
|
|
The 6800 processor was released by Motorola in 1974, shortly after the Intel
8080. It had 78 instructions, including the undocumented HCF (Halt and Catch Fire) bus test instruction.
The 650x design was based on the 6800.
The 6809 was a major advance over the Motorola 6800 and also over the 6502. The 6809 had two 8-bit accumulators (1 in the 6502) and could combine them into a single
16-bit register. It also featured two index registers and two stack pointers, which allowed for advanced addressing modes. The 6809 was source compatible with the 6800,
even though the 6800 had 78 instructions and the 6809 only had around 59.
Other features were one of the first multiplication instructions of the time, 16-bit arithmetic and a special fast interrupt. It was highly optimised, gaining up to
five times the speed of the 6800 series CPU.
The 6309 by Hitachi was a version with extra registers. The 6809 was used in the Dragon 32
and Thomson M06 home computers and was followed by
the Motorola 68000.
|
|
|
| add/correct 680x info |
|
|
|
