HP FOCUS

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".

The Focus CPU is microcoded with a 9,000 by 38-bit microcode control store. Internal data paths and registers are all 32-bit wide. The Focus CPU has a transistor count of 450,000 FETs.

References

• "HP Computer Museum: Technical Desktops: Series 500". See "Product Documentation". for HP Journal articles.
• "HP 9000" (PDF). HP Journal. 34 (8). August 1983.
• Beyers, J.W.; Dohse, L.J.; Fucetola, J.P.; Kochis, R.L.; Lob, C.G.; Taylor, G.L.; Zeller, E.R. (October 1981). "A 32-bit VLSI CPU chip". IEEE Journal of Solid-State Circuits. 16 (5): 537–542. doi:10.1109/JSSC.1981.1051634.