RIP Z80 – Zilog announces end of historic and beloved chip

O Z80 It was not the first microprocessor, this primacy fell to the MP944, a story told in this excellent article here. Yes, it was one of the most popular, it won a place in the hearts of an entire generation, and now, after 48 years, it is finally being discontinued.

Nowadays, processors are highly complex components, when we study the manufacturing methods, it seems like something alien; Intel and AMD fight to make their products popular, but it wasn’t always like that.

The first microprocessor produced and sold on a commercial scale was the Intel 4004, designed by a team led by a genius called Federico Faggin, who worked at Olivetti, Fairchild and Intel.

With 2250 transistors and a 4-bit data bus, the 4004 probably wouldn’t run Crysis very well, but it was still a major advance, concentrating on a single chip several tasks that in normal equipment would be occupied by discrete circuits, with several other chips, taking up more space and costing more.

Still, the 4004 wasn’t cheap, costing US$60 at the time, US$462 in 2024. And it wasn’t aimed at… computers. For a very simple reason: It was a segment that didn’t exist, microprocessors were exclusive to embedded systems, industrial equipment and, perhaps, minicomputers that cost hundreds of thousands of dollars.

This market would only be discovered in 1975, when MITS announced the Altair 8800, the first PC in the world, based on the 8-bit Intel 8080 processor, launched a year earlier. But even so, calling the Altair a PC is complicated, it was a machine for curious nerds. There was no monitor, there was no keyboard, there was no mouse, there was no ceiling, there was nothing. Everything was done by moving switches on the panel.

A year after the Altair, the Apple I arrived on the market, running on a Motorola 6502, launched in 1975. The much more mature, refined and consumer-ready Apple II appeared in 1977, also using 6502 processors.

With all this happening, Intel still seemed not to realize the value of microprocessors, for it they were just components of products that were promoted by the company. Frederico Faggin was getting upset, seeing his talent being wasted. He decided to pay the bills and found his own company, with blackjack and prostitutes.

Masatoshi Shima, one of Intel’s main designers, found out and asked to be part of Faggin’s company. They got investors (including Exxon) and started designing a chip, whose main feature was compatibility with the Intel 8080, being able to natively run all the software made for it, including operating systems such as CP/M.

The Z80 had dual register sets, hardware interrupts, and an extensive instruction set, including a host of undocumented instructions, that programmers discovered and used to optimize (and obscure) their programs.

The ease of designing circuits for the Z80, and its simple and efficient assembler made it popular among developers and manufacturers. Its 2.5MHz clock, more than double the 6502’s measly 1MHz, was a bonus.

Launched in 1976, the Z80 had 8-bit internal processing and 16-bit addressing capacity, which in binary notation is equivalent to 1111111111111111. In decimal, 65536, an almost sacred number for old-time microsmiths.

Computers based on the Z80 started to pop up. We had the TRS-80 (launched in 1977), Osborne, Kaypro, Ringo, and among many others, in the United Kingdom an eccentric guy even by local standards, Sir Clive Sinclair, launched the ZX80, a computer that looked like a toy, cost expensive ($625 in 2024 values, £99.95 at the time) but still very cheap to have a real computer at home.

The ZX80 came in 1979, in 1981 Sinclair released the more improved ZX81. Two months later came the ZX Spectrum, which sold five million units.

With a Z80 as its brain, and several auxiliary chips to control I/O, video and other functions, the Z80 fought in categories well above its weight, helped by innovative equipment such as the microdrive, a mini-infinite tape recorder accessible via BASIC and with the ability to chain multiple units together.

An entire generation of nerds had their first contact with computers through the Z80. Countless engineers, programmers, scientists, game developers spent nights and nights typing magazine programs, debugging code, learning, tinkering, discovering how those wonderful little machines worked.

The appeal is easy to understand; kids without much social contact, trying to remain invisible at school. At home, they have zero decision-making power, they don’t choose what to eat, sometimes not even when to sleep, but there, in front of the Spectrum, they have total control, they can play adventures exploring distant lands, becoming a space pirate, creating cities. (yes, kids, Elite had a version for the ZX Spectrum, and it was a game)

A Personal Voyage

In Brazil, the Z80 arrived at the height of the Information Technology Market Reserve, manufacturers basically chose models from abroad, created “national similar ones” and the original companies were left sucking their thumbs, it was virtually impossible to win a case in a Brazilian court, involving copying foreign equipment.

A rare exception was the Mac 512, from Unitron, a TOTAL Macintosh kibbeh. I tell this saga in this article here.

My first computer (PC was a computer for grown-ups) was a CP-200, a copy of the Prológica ZX82. It had a horrible keyboard, but the ZX Basic had an interesting feature: Each key had a keyword. So if I were to write the line:

10 PRINT “HELLO WORLD”

I would type 10, press “P” and the PRINT command would appear in full. This had a second advantage: Commands were encoded with a single byte, instead of storing five characters in memory to encode “PRINT”.

With 16KB of memory, the CP-200 today would be a nightmare for people who download 100GB games, but with intelligent programmers, it was able to run even games (almost) in 3D, such as Dark Monster, Chess and much more.

At that time I took computer courses to use computers outside of class hours, mainly the TRS-80, with a real keyboard, and the CP-300, both also running Z80.

The CP-300 was the smallest in the Prológica line, basically the TRS-80 line in a different guise, but I admit that the CP-200 was pretty solid, I would be happy today with that keyboard.

Some time later, hyperinflation, my grandmother gave me a TK90-X as a gift, it cost a fortune, in 12 installments. The first installments ate up 90% of her pension, but as they were fixed, I paid the last ones with my allowance.

The Spectrum (I always saw it as ZX Spectrum) had a huge 48KB of RAM, and high resolution (256×192) and even SOUND! I spent endless hours exploring the galaxy in Elite, writing texts, creating programs to determine which girls at school I would have the best chance with (spoiler: none, my program got it right).

In this pre-internet era, even pre-BBS, friends from school came together into interest groups, which little by little expanded. To the horror of Generation Z, we went to micro-marketing events, visited stores and bookstores and started chatting with other enthusiasts.

At the weekend it was time to go out to visit the most committed friends, and carry out the sacred software exchange ceremony. Everyone brought their tapes, and the copying session began, usually on a thick tapedeck.

Basically all the software we used was pirated, which doesn’t cause any problem of conscience, since national companies also only sold pirated software.

The ZX Spectrum was a marvel for experimentation. Through trial and error, I managed to install a reset button on mine, and it became the talk of the town when I took it to show it to people.

My masterpiece was when I bought a Commodore 64 case, redid the entire keyboard matrix by hand, and installed my ZX Spectrum on it. I get sad when I realize that I don’t remember how it ended.

Among other merits of Speccy, once I went to visit some older friends at UFRJ, they were using a mainframe from the Mathematics Institute to generate fractals. I decided I would learn. I took FORTRAN listings, xeroxed articles and started headbanging. I must have been around 14 or 15 years old, but I set out to teach myself Complex Analysis. Just don’t ask me to explain WHY i is the square root of -1.

All I know is that my poor Spectrum suffered. I opened the case, put a fan on top and it stayed overnight to calculate a fractal. It worked, it just wasn’t perfect because the person writing to you forgot to include a subroutine to save the image at the end.

The Spectrum accompanied me for many years, I skipped the entire MSX phase, another very popular microcomputer, in Brazil represented by Sharp’s HotBit and Gradiente’s Expert.

MSX was an architecture created by Microsoft to standardize computers of different origins, running MS Basic. The idea was mainly bought by Japan, but it soon spread, becoming especially popular in Latin America.

In terms of graphics and sound, the MSX was undeniably superior to the Spectrum, but everyone used the good old Z80.

I only gave in to the upgrade when I discovered the Commodore Amiga, with all its idiosyncrasies, it ran the Macintosh’s 68000 processor, and its operating system was much better than any MS DOS (or Windows) at the time. More than that, the Amiga had the same feeling as the Spectrum; a computer that was created by enthusiasts, not by a committee.

The Amiga, like the Spectrum, had soul. None were the same, every Amiga had a little oddity, like not reading a disc that all the other Amigas read.

My Spectrum was my last computer with Z80, but the small processor continued to accompany me, in embedded systems, day-to-day electronic equipment. They say that for a while it was used as a PC keyboard controller.

Zilog began investing in 16-bit processors, but a series of purchases, mergers, changes in ownership and direction made it miss the bandwagon of History. They focused on the less profitable microcontroller market, but the newest model was released in 2007.

In 2009 they began selling their intellectual property and production lines. In 2009 it was purchased by IXYS for US$62.4 million, which in this market is small change.

Now a subsidiary, it lives off producing its old chips, which still have a market, such as controllers for TV remote controls. The oldest ones are being outdated.

On April 16, 2024, it issued a statement asking customers interested in purchasing batches of the Z80 to place their orders by June 14th, which will be the last batch. The Z80, after 48 years, will definitely be discontinued.

It’s completely irrational to be sad about this, but a part of me feels the childhood slipping away, the Z80 now lives only in my memories.

Or at Mercado Livre, where you can buy an original for R$50.