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Zilog Z80

The Zilog Z80 is an 8-bit microprocessor designed and manufacted by Zilog. It came about when Federico Faggin left Intel after working on the 8080, and by July 1976 had the Z80 on the market. The Z80 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 three real improvements over the 8080: a built-in memory controller for DRAM that would otherwise have to be provided by external circuitry, a much lower price, and a limited ability for SIMD (Single Instruction, Multiple Data) with block move and copy instructions. (These were considered very powerful at the time: modern 3DNow! and SSE instructions work on highly advanced versions of this same basic principle.)

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 sucessful CPU ever. Later versions increased in speed from the early models' 1MHz up to as much as 12Mhz.

By the early 1980s it was used in a host of computer designs, including the Radio Shack TRS-80, the Sinclair ZX80, ZX81 and ZX Spectrum, and the great number of fairly anonymous business-oriented CP/M machies that dominated the market of the time in the way that Windows-based machines do today. Notable later-day uses of the processor include some Texas Instruments (TI) calculators, and SEGA's Game Gear handheld video game console. Nintendo's Game Boy and Game Boy Color handheld game systems used a Z80 clone made by Sharp Electronics, which had a slightly different instruction set. The Z80 has also become a popular embedded microprocessor, where it remains in widespread use today.

Computers that used the Z80

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