HP FOCUS

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The Hewlett-Packard FOCUS microprocessor, launched in 1982, was the first commercial, single chip, fully 32-bit microprocessor available on the market. At this time, all 32-bit competitors (DEC, IBM, Prime Computer, etc.) used multi-chip bit-slice-CPU designs. The FOCUS architecture (Focus CPU, Focus I/O processor (IOP), Focus memory controller (MMU), 16 KB x8 dynamic RAM, and a timer) was used in the Hewlett-Packard HP 9000 Series 500 workstations and servers (originally launched as the HP 9020 and also, unofficially, called HP 9000 Series 600). It was a stack architecture, with over 220 instructions (some 32 bits wide, some 16 bits wide), a segmented memory model, and no general purpose programmer-visible registers. The design of the FOCUS CPU was richly inspired by the custom silicon on sapphire (SOS) chip design, HP used in their 16-bit HP 3000 series machines.

Because of the high density of HP's NMOS-III IC process, heat dissipation was a problem. Therefore the chips were mounted on special printed circuit boards, with a ~1 mm copper sheet at its core, called "finstrates".

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