Zilog’s name came out of an evening of wine. Federico Faggin and Ralph Ungermann had left Intel in the autumn of 1974 and spent their evenings trying out names. Each morning neither could remember the one they had liked the night before. Then Faggin tried “I-Log”, for Integrated Logic, and Ungermann said “Zilog!” Faggin explained it as “Z for the last word of Integrated Logic”. The next morning they both remembered it.
The company had no product yet. Within eighteen months it had the Z80. That chip ran the programs written for Intel’s 8080 and added a great deal more, and it went on to run the TRS-80, Sinclair’s ZX81 and Spectrum, the Amstrad CPC, every MSX computer and a generation of arcade boards. Zilog itself never became the rival to Intel that its founders hoped for. Faggin later called its potential “20 times, 100 times” that of the company he founded afterwards.
Fast facts
- Founded: 1974, by Federico Faggin and Ralph Ungermann, both from Intel. Masatoshi Shima joined in 1975 to design the Z80.
- First money: $500,000 from Exxon Enterprises, Exxon’s venture arm, in June 1975.
- Key product: the Z80, sampled from early 1976 and formally announced in May 1976.
- Other chips: Z80 peripheral chips, the Z8 microcontroller and the 16-bit Z8000.
- Owners: Exxon until 1989; its own managers; Texas Pacific Group from 1998; IXYS from 2010; Littelfuse from 2018.
- Today: a Littelfuse brand selling microcontrollers, including the Z80-compatible eZ80. The standalone Z80 reached its last-time-buy date on 14 June 2024.
Leaving Intel
Faggin had led the design of Intel’s 4004 and conceived the 8080, but by 1974 he felt “boxed in”. Intel was a memory company, he said, and saw microprocessors as a way to sell more memory. One night he asked Ungermann, one of his managers, out for a drink and proposed a company. “And he said, ‘Yeah! Let’s do it!’” Ungermann left first, in August or September 1974. Faggin’s last day was Halloween, 31 October 1974. Ungermann and his wife had already set up an office in State Street, in downtown Los Altos.
They had agreed not to decide on a product before leaving. A short item in the trade weekly Electronic News about the new company caught the eye of Exxon Enterprises, which was making venture investments in information technology, and Exxon asked to visit. With a meeting ten days away, Faggin sketched a single-chip microcontroller he called the 2001. He then set it aside: Zilog had no factory of its own, and a cheap microcontroller made by a foundry could not compete on price with one made by a company that owned its fab. In December 1974 he came up with what he called the Super-80, a processor that would run 8080 programs, with a family of peripheral chips designed around the same single 5-volt bus. Exxon agreed. After months of negotiation it paid $20,000 a month to start work and, in June 1975, invested half a million dollars.
Venture money was scarce. Faggin recalled that only $10 million of venture capital went into high technology in the whole of 1975, so “we were lucky to actually find Exxon Enterprises interested in us at that time.”
The Z80
Masatoshi Shima, who had designed the 8080’s logic under Faggin at Intel, had asked to come too. The accounts of his start date differ: Faggin’s long oral history puts it in April 1975, while in the 2007 panel Faggin said the architecture was mostly done “before Shima came in February of 1975”, and Shima dated the project’s kick-off to the middle of February. Shima said the work took “one year and one month from the kick-off meeting to fully working silicon”. The chip was taped out in November 1975. The first silicon arrived in January 1976 with only a few mistakes, and Faggin had promised Exxon a working processor by 9 March. “Shima was able to get the Z80, the first working Z80 on March 9,” he said. The whole project, chip, development system and software, cost about $400,000.
Second sources mattered. Customers would not commit their software to a start-up’s chip unless someone else could make it too, so Zilog licensed the Z80 to Mostek, and Ungermann summed up the sales pitch: “We’ve got the money of Exxon, and the brains of Intel.” BYTE reported in August 1976 that the new company in Los Altos had been sampling the Z80 “since early this year”. It ran the 8080’s 78 instructions as part of its own 158, needed only a single +5 V supply and refreshed dynamic memory by itself. It was not cheap. A single sample cost $200 and even 25 to 99 cost $80 each, “still more expensive … than either the 8080A, 6800 or 6502”, but BYTE reckoned that once the 8080’s support chips were counted, “the costs are comparable”. Ungermann recalled that customers soon told Zilog it needed a lower price.
The first buyers, as the founders remembered them, included the computer maker Cromemco, a Japanese competitor that turned up with cash to buy two samples (NEC, Ungermann said, and “that was just the start of the copying”), Tandy for the TRS-80, word-processor makers, and a maker of chess computers that Faggin remembered taking 100,000 to 200,000 chips a month. In 1976 Zilog also persuaded Exxon to pay for a wafer factory, so it would not depend on Synertek and Mostek. It moved into the building in October 1976 and had working Z80s from its own line by January 1977.
Where the Z80 went
| Machine | Year |
|---|---|
| TRS-80 | 1977 |
| ZX80 and ZX81 | 1980, 1981 |
| ZX Spectrum | 1982 |
| ColecoVision | 1982 |
| MSX | 1983 |
| Amstrad CPC | 1984 |
| Sega Master System | 1985 (Mark III in Japan) |
| Sega Mega Drive | 1988, as the sound processor |
Arcade boards used it too. Pac-Man runs on a single Z80. Galaga uses three sharing memory, and Capcom’s 1942 used two, one for the game and one for the sound. Not every famous coin-op was a Z80 game: Space Invaders ran on Intel’s 8080. The Game Boy’s processor is often called a Z80, but Nintendo never named it, and it lacks the Z80’s index registers and its ED-prefixed instructions; see Game Boy.
The Z8, the Z8000 and Exxon
After the Z80, Zilog started two chips at once. The Z8, a single-chip microcontroller built on Faggin’s 2001 idea, was finished in about 1978. The 16-bit Z8000 was designed by an architecture team led by Bernard Peuto, with Shima as project leader, and BYTE reported that Zilog began shipping samples in March 1979. Faggin thought the Z8000 better than Intel’s 8086 but blamed one decision, segmented memory, for holding it back, while Motorola’s 68000 offered a flat address space. In February 1983 Commodore signed a deal to make the Z8000 and its support chips under licence, in exchange for giving Zilog rights to some of its own custom chips. The same year Zilog, “a subsidiary of Exxon” in Personal Computer News’s words, asked the US International Trade Commission to investigate NEC for patent, trade mark and copyright infringement.
Exxon had paid for Zilog’s start, but Faggin came to see it as a liability. Exxon was building a group of office-equipment companies to challenge IBM, so customers saw Zilog as part of a competitor. Faggin believed it was one reason Zilog was not chosen for the IBM PC. Exxon also pushed the company to spend about 35% of its revenue on research, so it never turned a profit in his time. He and Ungermann fell out around 1978 and 1979. Ungermann left to co-found the networking company Ungermann-Bass, and Faggin stepped down as chief executive at the end of 1980.
Later history
Exxon sold Zilog back to its managers and employees in 1989, according to Wikipedia, which cites The New York Times. Wikipedia also reports that Zilog was listed on the stock market in 1991 and bought by the investment firm Texas Pacific Group in 1998. IXYS Corporation completed its purchase of Zilog on 18 February 2010, and Littelfuse completed its purchase of IXYS on 17 January 2018. Zilog now describes itself as a supplier of “application-specific embedded system-on-chip (SoC) solutions” and sells microcontroller families including the Z8 Encore! and the eZ80.
The Z80 itself outlived nearly every machine it powered. In 2007 Faggin estimated that “over two billion Z80s” had been sold by Zilog and its second sources. In April 2024 Littelfuse issued a product change notice ending the standalone Z84C00 Z80 family: its wafer foundry was “discontinuing support for the Z80 product”, and distributors had until 14 June 2024 to place final orders. Related notices covered the Z180 and peripheral chips such as the SIO, PIO and CTC. The eZ80, which runs Z80 code but is not a drop-in replacement, continues.
Sources
- Computer History Museum, “Oral History of Federico Faggin”, interviewed by Gardner Hendrie, 2004–2005, reference X2941.2005, pp. 83–116 (web): leaving Intel and the drink with Ungermann, Halloween 1974, the 2001 microcontroller and the Super-80, Exxon Enterprises and its $500,000, the first silicon in January 1976, the formal announcement in May 1976, the wafer fab and Bubb Road, R&D spending, Bernard Peuto and the Z8000, the Z8, segmentation, the falling-out with Ungermann, Exxon and IBM. https://archive.computerhistory.org/resources/text/Oral_History/Faggin_Federico/Faggin_Federico_1_2_3.oral_history.2004.102658025.pdf
- Computer History Museum, “Zilog Oral History Panel on the Founding of the Company and the Development of the Z80 Microprocessor”, with Federico Faggin, Masatoshi Shima and Ralph Ungermann, moderated by Michael Slater, 27 April 2007, reference X4023.2007 (web): pp. 1–4 (Intel in 1974, Ungermann’s and Faggin’s departures, the Los Altos office, Electronic News, venture capital in 1975, the Super-80 and second sourcing), p. 6 (Shima’s schedule), p. 8 (the fab and March 9), pp. 13–14 (pricing, first customers, “over two billion”), pp. 15–16 (Exxon, “the money of Exxon, and the brains of Intel”, the falling-out), p. 17 (the name). https://archive.computerhistory.org/resources/text/Oral_History/Zilog_Z80/102658073.05.01.pdf
- Burt Hashizume, “Microprocessor Update: Zilog Z80”, BYTE, August 1976, pp. 34–38: sampling since early 1976, the instruction set, single supply and refresh, prices.
- BYTE, May 1979, p. 118, news: “Zilog began shipping Z-8000 samples in March”.
- The Transactor vol. 4 no. 3, April 1983, p. 14, “Commodore and Zilog Announce Agreement”: the Z8000 licence, announced 2 February 1983.
- Personal Computer News issue 22, 10 August 1983, “View from America”: Zilog, “a subsidiary of Exxon”, and its complaint against NEC.
- Wireframe issue 9, March 2019, p. 32, “Source Code”: Space Invaders “ran on an Intel 8080 CPU operating at 2MHz”.
- MAME source code,
src/mame/pacman/pacman.cpp(web, secondary): the Pac-Man board’s single Z80. https://github.com/mamedev/mame - MAME source code,
src/mame/namco/galaga.cpp(web, secondary): Galaga’s three Z80s. https://github.com/mamedev/mame - Fabien Sanglard, The Book of CP-System (self-published, 2026 edition; modern book), p. 28: 1942’s two Z80s.
- Nintendo of America, Game Boy Programming Manual version 1.1 (1999), and Pan Docs, “Comparison with Z80” (web, secondary): the Game Boy’s processor described only as customised for the machine, and its differences from the Z80. https://gbdev.io/pandocs/
- Wikipedia, “Zilog” (web, secondary): the 1989 buyout, citing “Zilog Team Seeks Company”, The New York Times, 15 June 1989; the 1991 listing and the 1998 purchase by Texas Pacific Group, citing The New York Times, 22 July 1997. https://en.wikipedia.org/wiki/Zilog
- IXYS Corporation, “IXYS Closes Acquisition of Zilog”, press release, 18 February 2010, filed with the US Securities and Exchange Commission (web). https://www.sec.gov/Archives/edgar/data/0000945699/000095012310015031/f55021exv99w1.htm
- Littelfuse, “Littelfuse Completes Acquisition of IXYS Corporation”, press release, 17 January 2018 (web). https://investor.littelfuse.com/news/news-details/2018/Littelfuse-Completes-Acquisition-of-IXYS-Corporation-01-17-2018/default.aspx
- Zilog, home page (web): company description and product families. https://www.zilog.com/
- Gareth Halfacree, “Zilog calls time on the venerable Z80”, Hackster.io, republished by RadioLocman, 23 May 2024 (web, secondary): the Littelfuse notice, the foundry’s reason, 13 parts in the Z84C00 family, last-time buy on 14 June 2024. https://www.radiolocman.com/news/new.html?di=666395
- “Zilog Z80 End Of Life Notification”, RC2014, April 2024 (web, secondary): the notice of 15 April 2024, the related Z180 and peripheral notices, the eZ80’s continuation. https://rc2014.co.uk/?p=2757