Zilog Z80 processor: The Intel fright is finally leaving the field

The news makes nerds sad: Production of the Z80 processor, one of the most versatile 8-bit processors ever, will be discontinued after almost 48 years. With a relatively plain message the manufacturer announced the end of production of the legendary 8-bit processor (pdf).

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First thought: Was it still built? Of course – the Z80 was intended from the start to be used for various purposes: from arcade machines to home computers to workstations or the first PCs. The Z80 was installed in many computers from the PC pioneer era and can still be found in printers, household appliances and embedded systems today. In short: it’s been hard to get past him in the past three decades. Its versatility, affordable price and relaxed licensing policy made it a perennial favorite.

The processor emerged from a dispute between Federico Faggin and Intel: He was dissatisfied with the status of microprocessor development at Intel. People preferred to make money from memory chips rather than processors. Faggin left Intel in October 1974 and founded the company Zilog with former Intel colleague Ralph Ungermann in Silicon Valley to develop their own processor.

The company name was made up of “Z integrated logic”, where the Z was supposed to represent the last word of the integrated logic – they wanted to have the last word in it. The processor should be compatible but better than the Intel 8080. This was done by a small team led by Faggin, who also brought Masatoshi Shima, another important Intel developer, on board in 1975.

Z80 in an efficient design

In 1976 the time had come: the Z80 was introduced and it was an Intel shock. It was not pin-but binary-compatible with the Intel 8080. It also received some improvements: It managed with a 5-volt supply voltage and did not need three like the Intel (+5V/-5V/+12V), the clock generation is the same The refresh control for RAM is also integrated. With the 8080, external components were necessary for this.

Thanks to its compatibility with the 8080, the CP/M operating system also ran on the processor, and that was a real killer argument in the days before Windows and Office. Programs such as the WordStar writing program, the DBase database and the VisiCalc spreadsheet were decisive reasons for using a computer for business. Thanks to the Z80 processor, which cost a fraction of the $360 8080PC technology also became affordable.

c’t veteran Detlef Grell described the success of the Z80 with CP/M in the background article on the history of CP/M:
“When designing the Z80, Faggin incorporated everything that he thought could be improved on the 8080. The success of the Z80 was so resounding that in my entire career, including my studies, I have never come across a single CP/M computer with an 8080 processor. However According to colleague Andreas Stiller, a Siemens computer with 8085, the slightly improved 8080, once found its way into the editorial office.”

The market success even went so far that Microsoft’s first hardware product was a Z80 expansion card for the Apple II so that CP/M could be used for it. In addition to the MOS 8502, the Commodore 128 also had a Z80 processor on board for precisely this purpose. With the Osborne 1, the first portable computer ever came onto the market with a Z80 CPU and CP/M operating system. In the Eastern Bloc in the 1980s, Z80 replicas such as the MME U880 were used, which only disappeared when the Berlin Wall fell.

Processor for machines and home computers

But the Z80 was also a success outside of professional use. It found its way into many home computers: It was installed in various computers from Tandy, in the ZX Spectrum as well as in the Amstrad CPC series, which recently celebrated its 40th birthday. In addition to home computers, machines were also a market for the processor: it was found in various arcade machines, such as Galaxian and Pac-Man. Z80 or licensed replicas could also be found in various consoles: The processor was installed in the Sega Master System, Game Gear and Mega Drive (the latter as a co-processor). Nintendo also used it, albeit in a modified form: a slightly modified Z80 clone from Sharp was used in various versions of the Game Boy series.

It was also later relevant for high school exams: it found its way into the pocket calculators of the TI-84 Plus series – they are still part of the calculators approved for high school exams today. Years ago, C’t colleague Tim Gerber clearly disliked the practice that safeguarded oligopoly. The Z80 was also found in other products such as synthesizers, printers and other everyday devices – it was a reliable and simple processor. The 16-bit successor Zilog Z8000 didn’t have anywhere near the success of the Z80 – in the field, Intel did far better.

It was hard to ignore him in the 1980s and 1990s. Many IT and programming careers started with this processor. Above all, for many it was their first significant contact with computer technology. Orders will be accepted until June, when manufacturer Zilog will stop producing the Z80 in its original form. Ironically, Zilog announced the end of the Z80 almost to the day on the 50th anniversary of the model: The Intel 8080 was introduced in April 1974. However, the Z80 has exceeded the lifespan of the 8080 by a whopping 34 years – Intel’s processor ended production in 1990. So the Z80 was on the market three times as long as its rival – at least Zilog definitely has the last word on that.

(mawi)