1979 · 32-Bit-Internal Microprocessor · Work 910 of 1,871
A sample shipping room in a chip plant in Austin in Texas, on a long table a grey foam tray with twenty cut-out slots, nineteen of them bare, in the last a single very long flat chip of dark violet-grey ceramic eight centimetres long with thirty-two silvery legs along each side, in its middle a square gold lid with a fine gold stripe running to the edge, a half-round notch at one end, plain smooth and unmarked, a hand in a short-sleeved shirt lifting it toward a clear plastic tube, stacks of plain brown cardboard boxes, a roll of packing tape, strong sunlight through venetian blinds in bright stripes.
What it was used for
The MC68000 was Motorola's microprocessor of 1979. According to IEEE Spectrum's Chip Hall of Fame piece it computed with 32 bits internally but presented a 24-bit address and a 16-bit data bus outside, because a 32-bit bus would have been too expensive; the logic was designed by Nick Tredennick, who circulated reduced-size copies of flowcharts for the purpose. Spectrum gives 68,000 transistors, more than twice the Intel 8086's count. It went into early Macintosh computers, the Amiga and the Atari ST; its large volumes came, per Spectrum, mainly from embedded uses - laser printers, arcade machines, industrial controls.
What was new
The characteristic thing was the width inside: 32-bit registers in a part whose pins stayed 16 bits wide. The design anticipated a stage the circuit board could not yet pay for. The barb: in the same piece Motorola was "late to the 16-bit microprocessor party", and when IBM looked for a processor for its PC the 68000 was passed over partly because it was "still relatively scarce". The bigger design lost on supply, and then found its volume business where nobody saw it as a computer at all.
What the sources leave open: The only source in this run is the IEEE Spectrum piece (30 June 2017, updated 4 December 2023). It gives no unit numbers, no price and no clock rate, and does not explain its "hybrid 16-bit/32-bit" label. Tredennick's words appear there at second hand and have therefore been paraphrased.
Connections
Every connection names its kind. “Forerunner” on its own would be a claim.