z8000

2 Articles

Z8000 Trump Card Needs Your Help

December 19, 2022 by 45 Comments

[Smbakeryt] needs your help. He bought a 1984-vintage Z8000 coprocessor card for the PC, but the software is missing in action. Apparently, the co-processor — called a Trump Card — appeared in Byte magazine courtesy of the famous [Steve Ciarcia]. The schematics were published, and if you sent [Steve] proof that you built it, he’d send you the software. The product was later commercialized, but no one seems to have the software, so [Smbakeryt] is on the lookout for it.

The board itself was pretty amazing for its day. It added a 16-bit Zilog Z8000 CPU with 512 K of RAM. Big iron for 1984 and a good bit more performance than a stock IBM PC of the era.

We miss the days when computer gear came with big binders of documentation. These days, you are more likely to get a sticker with a URL. The Z8000 was a nice processor and could emulate the Z80, but it never became hugely popular. In addition to Zilog’s System 8000, the CPU found its way into some Unix computers including the Onyx C8002 and several Olivetti computers. Commodore planned to use the CPU in a canceled project. The Z8000 was famous for not using microcode and, thus, it fit on a relatively small die with 17,500 transistors (compared to the 8086’s 29,000 transistors).

We hope someone can help out with the software. If you want your own Z8000 system, you might be better off with Clover. Or, stick with a Z80 on the cheap.

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Clover Computer: A Modern Z8000 CP/M Machine

August 21, 2022 by 20 Comments

Seeing some old Zilog 16-bit chips on eBay recently, [Scott Baker] was curious enough to snap them up and build himself a Z8000 computer. It started as a two-board solution, then he added a display module. Instead of layering the boards vertically à la a PC/104 stack, [Scott] decided to build them flat. His first backplane was triangular, but he opted for a square to accommodate one more expansion board in the future. The assembled contraption resembles a clover, hence the name Clover Computer.

The Z8000 was Zilog’s first 16-bit microprocessor, introduced in 1979. It was not hugely popular for a variety of reasons (the Z8000 Wikipedia article has some interesting details). The Z8000 was eclipsed in the marketplace by Intel’s 8088 and Motorola’s 32-bit 68000. One interesting point is that the Z8000 did not use microcode, and as a result, its transistor count was significantly less than its contemporaries. The Z8000 was used in some military applications, and despite its limited commercial success, it continued to be available from Zilog and licensed second sources up until 2012.

[Scott]’s design splits the system into a CPU board, a memory and serial board, and a display board. Along the way, he learns 1980’s era tricks from the Olivetti M20, one of the few computer systems designed around the Z8000. He also manages to find a recent Z8000 implementation of CP/M by GitHub user [], which [Scott] forked and adapted to his project (see project repo here). He succeeds in getting everything working, and ports a monitor, Tiny Basic, and Zork.

Check out his project write-up introductory link, and see it in action in the video below the break. Did you ever use or encounter the Z8000? Let us know in the comments!

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