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Home > Zilog Z80

1 History

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:

• an enhanced instruction set including new IX and IY index registers and instructions for them
• two instances of each register which could be quickly switched between, to speed up response to interruptIn computer engineering, an interrupt is a signal from a device which typically results in a context switch: that is, the processor sets aside what it's doing and does something else. Digital computers usually provide a way to start software routines in rs
• a limited ability for SIMDSIMD is an acronym for S ingle I nstruction, M ultiple D ata. It is a computing term that refers to a set of operations for efficiently handling large quantities of data in parallel, as in a vector processor or array processor. First popularized in large- (Single Instruction, Multiple Data) with block move and copy instructions. ¹
• a built-in DRAM refresh address counter that would otherwise have to be provided by external circuitry
• a much lower price

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 MHzA megahertz (MHz is one million (106) hertz, a measure of frequency. Megahertz in radio When used in the context of radio, MHz refers to the number of oscillations of electromagnetic radiation. Severel parts of the radio spectrum fall into the MHz range: 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 fewer support chips. Competitor MOS Technology, IncMOS Technology, Inc. also known as Commodore Semiconductor Group was a microprocessor and calculator company famous for its 6502 processor. Commodore 64 showing some important MOS Technology circuits: the 6510 CPU and the 6581 (SID). Company history MOS o, maker of the famous 6502The MOS Technology 6502 is an 8-bit microprocessor designed by MOS Technology in 1975. When it was introduced it was the least expensive full featured CPU on the market by far, at about 1/6th the price, or less, of competing designs from larger companies processor, later included this very useful feature in its second generation color video chip VIC-IIThe VIC-II (Video Interface Chip II specifically known as the MOS Technology 6567/8562/8564 ( NTSC versions), 6569/8565/8566 ( PAL), is the integrated circuit chip tasked with generating composite video graphics and DRAM refresh signals in the Commodore 6.

2 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 (plus the non-anonymous Osborne 1) 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 forming the CPU basis for the MSX computer standard.

Such was the popularity of the Z80 and CP/M that the Commodore 128 featured a Z80 processor alongside its MOS Technology 8502 processor for compatibility. Other 6502 based computers already on the market such as the BBC Micro, Apple II and the 6510 based Commodore 64 can make use of the Z80 with an external unit or a plug-in card or cartridge.

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.

A functionally equivalent core (T80 & TV80) is available for free under a BSD style license as VHDL [1] and Verilog [2] source. The VHDL version, once synthesized, can be clocked up to 35 Mhz on a Xilinx Spartan II FPGA.

In East Germany, an unlicenced clone of the Z80, known as the U880, was manufactured. It was very popular and was used in Robotron's and VEB Mikroelektronik Mühlhausen's computer systems (ex. the KC85-series) and also in many self-made computer systems (ex. COMP JU+TER).

See also: List of home computers by category

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Topics: Zilog Z80 Computer Market 8080 Popular Game Systems Processor...

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