Motorola 68008

The Motorola 68008 is an 8/32-bit microprocessor introduced by Motorola in 1982. It is a version of 1979's Motorola 68000 with an 8-bit external data bus, as well as a smaller address bus.[1] The 68008 was available with 20 or 22 address lines (respective to 48-pin or 52-pin package) which allowed 1 MB or 4 MB address space versus the 16 MB addressable on the 68000. The 68008 was designed to work with lower cost and simpler 8-bit memory systems. Because of its smaller data bus, it was roughly half as fast as a 68000 of the same clock speed.[1] It was still faster than competing 8-bit microprocessors, because internally the 68008 behaves identically to the 68000 and has the same microarchitecture.[2]

Motorola MC68008
68008 in a Sinclair QL motherboard
STEbus 68008 processor

Motorola ended production of the 68008 in 1996.[3]

Details

The 68008 is an HMOS chip with about 70 000 transistors; with a speed grade of 8 and 10 MHz. There are two versions of the chip. The original is in a 48-pin dual in-line package with a 20-bit address bus, allowing it to use up to 1 megabyte of memory. A later version is in a 52-pin plastic leaded chip carrier; this version has a 22-bit address bus and can support 4 megabytes of RAM.[4]

Usages

The Sinclair QL microcomputer and Luxor ABC 1600 use the 68008 as their main processor.

References
  1. Motorola (1993). "M68000 8-/16-/32-Bit Microprocessors User's Manual, Ninth Edition" (PDF). NXP Semiconductors.
  2. Motorola 1993, p. 1-2.
  3. comp.sys.m68k Usenet posting, May 16, 1995; also see other posts in thread. The end-of-life announcement was in late 1994; according to standard Motorola end-of-life practice, final orders would have been in 1995, with final shipments in 1996.
  4. Motorola 1993, p. 3-4.
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