A burn-in room in a chip plant in California at night, a tall oven cabinet of grey enamelled steel with its heavy door swung open and warm air shimmering out, inside it a stack of horizontal green circuit boards on steel runners, each board set with eight rows of long narrow chips five centimetres long of dark grey-brown ceramic with forty silver legs, every chip plain smooth and unmarked, hands in thick white heat-proof gloves sliding one more loaded board into the rack, a steel trolley with further boards beside, a row of identical closed ovens along a bare cream wall, cool fluorescent light from above.
What it was used for
The 8086 was Intel's 16-bit microprocessor for systems needing more memory than the 8-bit generation could address. Stephen Morse, who designed the architecture, gives the requirements as at least 128 KB of address space and "8080 compatible (whatever that meant)". What came out was up to 1 MB through 20-bit addresses, divided into 64 KB segments with the registers CS, DS, SS and ES, plus 16-bit data, multiply and divide, string instructions, addressing modes for high-level languages and coprocessor support. The part appeared in June 1978; besides himself Morse names Bruce Ravenel and James McKevitt as its designers.
What was new
Morse puts memory first among the secrets of its success: 1 MB where the requirement had been 128 KB, bought with segmentation that cut the address space into 64 KB pieces. Morse gives two market pressures as the occasion: the Z80 was taking the 8-bit market, and the timetable of the 8800 - later the 432 - was slipping. The barb lies in that order. The processor meant to fill a gap until the big project was ready appeared in 1978 - and the big project fell behind it.
What the sources leave open: The entry rests on Morse's own account (2011 talk version, PDF on his site) and Benj Edwards's PC World article (16 June 2008), which describes the 8086 as a "minor stopgap project". It gives no price, no transistor count and no day in June 1978; the exact announcement date was not checked. No unit numbers.
Connections
Every connection names its kind. “Forerunner” on its own would be a claim.