The Zilog Z80 reference article from the English Wikipedia on 24-Jul-2004
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Zilog Z80

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The Zilog Z80 is an 8-bit microprocessor designed and manufactured by Zilog from 1976 onwards. It was widely used both in desktop and embedded computer designs, and is one of the most popular CPU's of all time. Although Zilog made several attempts to move off the Z80 onto more powerful 16-bit (Zilog Z800) and 32-bit (Zilog Z8000) platforms, other companies were offering CPUs in this performance range years earlier, and the Zilog chips never caught on. Today the Z80 remains Zilog's only CPU design in production.

Table of contents
1 History
2 Notable Uses
3 Notes
4 External links


The Z80 came about when Federico Faggin left Intel after working on the 8080, and by July 1976 Zilog had the Z80 on the market. It was designed to be binary compatible with the Intel 8080 so that most 8080 code could run unmodified on it, notably the CP/M operating system.

The Z80 offered five real improvements over the 8080:

The Z80 quickly took over from the 8080 in the market, and became the most popular 8-bit CPU of all time - indeed, if one takes the absolute size of the market into account, the most successful CPU ever. Later versions increased in speed from the early models' 1 MHz up to as much as 20 Mhz.

Perhaps key to the success of the Z80 was the built-in DRAM controller, which allowed systems to be built with less support chips. Competitor MOS Technology, Inc, maker of the famous 6502 processor, later included this very useful feature in its second generation color video chip VIC-II.

Notable Uses

By the early 1980s it was used in a host of home computer designs including the Radio-Shack TRS-80, Sinclair ZX80² & ZX81² and ZX Spectrum. It also featured in the great number of fairly anonymous business-oriented CP/M machines (the Osborne 1 being a non-anonymous example) that dominated the market of the time in the way that Windows-based machines do today. In the mid-1980s the Z80 was used in Tatung's Einstein and the Amstrad CPC and PCW home/office computer ranges, as well as the dual-CPU Commodore 128 (to make it CP/M compatible). The MSX computer standard also employed Z80 processors.

Notable later uses of the processor include some Texas Instruments (TI) graphing calculators (like the TI-85 and the very popular TI-83), SEGA Master System and Game Gear (handheld) console. Both the SNK Neo-Geo and SEGA Megadrive / Genesis video games consoles use it as an audio coprocessor. Nintendo's Game Boy and Game Boy Color handheld game systems used a Z80 clone manufactured by Sharp Corporation, which had a slightly different instruction set. The Zilog Z80 has also become a popular embedded microprocessor and microcontroller core, where it remains in widespread use today.

See also: List of home computers by category


  1. These were considered very powerful at the time: modern 3DNow and SSE instructions work on highly advanced versions of the same basic principle.
  2. The Sinclair ZX80 and -81 were equipped with the Z80 clone NEC 780C.

External links