The Hewlett-Packard

Hewlett-Packard

Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...

 FOCUS microprocessor

Microprocessor

A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

, launched in 1982, was the first commercial, single chip, fully 32-bit

32-bit

The range of integer values that can be stored in 32 bits is 0 through 4,294,967,295. Hence, a processor with 32-bit memory addresses can directly access 4 GB of byte-addressable memory....

 microprocessor available on the market. At this time, all 32-bit competitors (DEC

Digital Equipment Corporation

Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...

, IBM

IBM

International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

, Prime Computer

Prime Computer

Prime Computer, Inc. was a Natick, Massachusetts-based producer of minicomputers from 1972 until 1992. The alternative spellings "PR1ME" and "PR1ME Computer" were used as brand names or logos by the company.-Founders:...

, etc.) used multi-chip bit-slice

Bit slicing

Bit slicing is a technique for constructing a processor from modules of smaller bit width. Each of these components processes one bit field or "slice" of an operand...

-CPU designs. The FOCUS architecture (Focus CPU, Focus I/O processor (IOP), Focus memory controller (MMU), 16Kx8 dynamic RAM, and a timer) was used in the Hewlett-Packard HP 9000 Series 500

HP 9000

HP 9000 is the name for a line of workstation and server computer systems produced by the Hewlett-Packard Company . The native operating system for almost all HP 9000 systems is HP-UX, a derivative of Unix. The HP 9000 brand was introduced in 1984 to encompass several existing technical...

 workstations and servers (originally launched as the HP 9020 and also, unofficially, called HP 9000 Series 600). It was a stack

Call stack

In computer science, a call stack is a stack data structure that stores information about the active subroutines of a computer program. This kind of stack is also known as an execution stack, control stack, run-time stack, or machine stack, and is often shortened to just "the 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

Processor register

In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...

. The design of the FOCUS CPU was richly inspired by the custom silicon on sapphire

Silicon on sapphire

Silicon on sapphire is a hetero-epitaxial process for integrated circuit manufacturing that consists of a thin layer of silicon grown on a sapphire wafer. SOS is part of the Silicon on Insulator family of CMOS technologies...

 (SOS) chip design, HP used in their 16-bit HP 3000

HP 3000

The HP 3000 series is a family of minicomputers released by Hewlett-Packard in 1973. It was designed to be the first minicomputer delivered with a full featured operating system with time-sharing. The first models were withdrawn from the market until speed improvements could be made. It ultimately...

 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 board

Printed circuit board

A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...

s, with a ~1 mm copper sheet at its core, called "finstrates".