Motorola 68000 (MC68000) is the first member of 680x0 line of
microprocessors. Internally the 68000 is a 32-bit microprocessor - it
has 32-bit data and address registers. Externally the processor has
16-bit data bus and 24-bit address bus, which limits the size of
addressable memory to 16 MB. Motorola also made 68008 - a version of 68000 CPU with 8-bit
external data bus. In addition to basic HMOS 68000 and 68008
processors the following modifications were produced:
- 68HC000 - low-power HCMOS version of Motorola 68000
- 68HC001 - low-power HCMOS version with selectable 8/16 bit external data bus.
- 68EC000 - embedded version
- 68SEC000 - embedded version of Motorola 68000 with static core
The 68000 architecture was much more flexible than other CPU families
(z80, 80x86, z80000, etc) from programming point of view as it could
be easily expanded to support full 32-bit data and address buses.
This was done in Motorola 68020 family.
HMOS 68000 processors were manufactured at speeds up to 16 MHz. HCMOS
68000 microprocessors are still manufactured at this time (May 2007)
at speeds up to 20 MHz.
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