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16-BIT MICROPROCESSOR

Z8000; Z8001; Zilog Z16C01; Zilog Z8001; Zilog Z8002; Zilog Z-8000; U8000; Zilog Enhanced UNIX System; Zilog ZEUS; ZEUS (Zilog); ZEUS (Unix); Zilog System 8000 UNIX

Zilog Z8000

<processor> A microprocessor from Zilog introduced not long after the Intel 8086, but with superior features. It was basically a 16-bit processor, but could address up to 23 bits in some versions by using segment registers (to supply the upper 7 bits). There was also an unsegmented version, but both could be extended further with an additional MMU that used 64 segment registers. Internally, the Z8000 had sixteen 16-bit registers, but register size and use were exceedingly flexible. The Z-8000 registers could be used as sixteen 8-bit registers (only the first half were used like this), sixteen 16-bit registers, eight 32-bit registers, or four 64-bit registers, and included 32-bit multiply and divide. They were all general purpose registers - the stack pointer was typically register 15, with register 14 holding the stack segment (both accessed as one 32-bit register for painless address calculations). The Z8000 featured two modes, one for the operating system and one for user programs. The user mode prevented the user from messing about with interrupt handling and other potentially dangerous stuff. Finally, like the Zilog Z80, the Z8000 featured automatic DRAM refresh circuitry. Unfortunately it was somewhat slow, but the features generally made up for that. Initial bugs also hindered its acceptance (partly because it did not use microcode). There was a radiation resistant military version. There was a later 32-bit, pipelined version, the {Zilog Z80000}. (1997-12-16)

Z8000

Zilog Z8000

Zilog

AMERICAN MANUFACTURER OF MICROPROCESSORS

Curtis J. Crawford; ZiLOG; Multi-functional Operating System; Crawford, C. J.; Crawford, Curtis J.; Curtis Crawford; Zilog, Inc.

<company> The microprocessor manufacturer who produced the Zilog Z80 in July 1976 (as used by Sinclair in the ZX-80, ZX-81 and ZX Spectrum computers) and later the Zilog Z8000. Zilog was founded in 1974 and became a wholly owned subsidiary of Exxon Corp. by 1980. The company's management and employees purchased Zilog back from Exxon in 1989. Zilog became a publicly-held company in February, 1991. In March of 1998, Zilog was privatised, as a result of the merger and recapitalisation transaction by Texas Pacific Group (TPG). Zilog now produce a range of 8-bit microcontrollers, 8-, 16- and 32-bit microprocessors, and digital signal processors, covering the home entertainment, communications, and {embedded systems} markets. http://zilog.com/. Address: 910 East Hamilton Avenue, Suite 110, Campbell, CA 95008, USA. (1998-09-14)

ويكيبيديا

Zilog Z8000

The Z8000 ("zee- or zed-eight-thousand") is a 16-bit microprocessor introduced by Zilog in early 1979. The architecture was designed by Bernard Peuto while the logic and physical implementation was done by Masatoshi Shima, assisted by a small group of people. In contrast to most designs of the era, the Z8000 did not use microcode which allowed it to be implemented in only 17,500 transistors.

The Z8000 was not Z80-compatible, although it featured many of the well-received design notes that made the Z80 popular. Among these was the ability for its registers to be combined and used as a single larger register - while the Z80 allowed two 8-bit registers to be used as a single 16-bit register, the Z8000 expanded this by allowing two 16-bit registers to operate as a 32-bit register, or four to operate as a 64-bit register. These combined registers were particularly useful for mathematical operations.

Although it was an attractive design for its era, and saw some use in the early 1980s, it was never as popular as the Z80. It was released after the 16-bit Intel 8086 (April 1978) and the same time as the less-expensive Intel 8088, and only months before the Motorola 68000 (September 1979), which had a 32-bit instruction set architecture and was roughly twice as fast.

The Zilog Z80000 was a 32-bit follow-on design, launched in 1986.

https://en.wikipedia.org/wiki/Zilog Z8000