z80

106 Articles

End-Of-Life For Z80 CPU And Peripherals Announced

April 19, 2024 by 54 Comments

In a Product Change Notification (PCN) published on April 15, Zilog (now owned by Littelfuse) announced the End of Life for a range of Z80 products, specifically virtually all of the Z84C00 range. This also includes the peripherals, such as the Z84C10 range of MPUs. These are currently already marked as EoL on stores like Mouser, with Littelfuse noting that the last orders with them can be placed until June 14th of 2024. After that you’ll have to try your luck with shady EBay sellers and a lucky box of old-new-stock found in the back of a warehouse.

What this effectively means is that after just under 48 years since its launch in 1976, the Zilog Z80 will no longer be available for sale as discrete components, which is likely to primarily impact hobbyists and people who are trying to keep retro systems going. This does not mean that it’s the end of the road for Z80, however, as the eZ80 will be produced for the foreseeable future.

These new chips will of course not come in easy to drop in DIPs, making the challenge of breadboarding your own Z80-based microcomputer that much tougher. Yet one thing that definitely won’t happen is any of us witnessing the end of the era of the Z80, 6502 and 8051 architectures.

Thanks to [Techokami] for the tip.

Vintage Particle Counter Is A Treasure Trove Of Classic Parts

April 13, 2024 by 1 Comment

If you need a demonstration of just how far technology has come in the last 40 years, just take a look at this teardown of a 1987 laser particle counter.

Granted, the laser-powered instrument that [Les Wright] scored off of eBay wasn’t exactly aimed at consumers. Rather, this was more likely an instrument installed in cleanrooms to make sure the particulate counts didn’t come out of range. As such, it was built like a battleship in a huge case stuffed with card after card of electronics, along with the attendant pumps and filters needed to draw in samples. But still, the fact that we can put essentially the same functionality into a device that easily fits in the palm of your hand is pretty striking.

[Les] clearly bought this instrument to harvest parts from it, and there’s a ton of other goodness inside, including multiple copies of pretty much every chip from the Z80 family. The analog section has some beautiful Teledyne TP1321 op-amps in TO-99 cans. Everything is in immaculate condition, and obsolete or not, this is an enviable haul of vintage parts, especially the helium-neon laser at its heart, which still works. [Les] promises an in-depth look at that in a follow-up video, but for now, he treats us to a little tour of the optics used to measure particulates by the amount of laser light that’s scattered.

All things considered, [Les] really made out well on this find — much better than his last purchase.

Continue reading “Vintage Particle Counter Is A Treasure Trove Of Classic Parts” →

Revisiting A Z80 Game From 1990

February 8, 2024 by 16 Comments

Back in the days of 8-bit computers, like no doubt many readers of similar age, we wrote little games. First in BASIC, then augmented with little machine code speed-ups. We didn’t come close to [Óscar Toledo Gutiérrez] though, who’s reverse engineering a 2K all-machine-code game he wrote back in 1990. As a tale of software archaeology it’s fascinating.

The game itself is an avoid-the-monsters platformer with plenty of ladders for the little sprite-based protagonist to run down. The computer was a Mexican homebrew educational machine with a TMS9118 display chip and an AY-3-8910 synthesizer, so the result had both color and music. His run through the code breaks it down neatly into individual sections, so it’s possible to see what’s going on without an in-depth knowledge of machine code.

He readily admits it bears all the hallmarks of an 11-year-old’s knowledge at the time, and that it has some parts less elegant, but nevertheless it’s something of an achievement at any age. It was out of date gameplay-wise in 1990 but in 1982 it could probably have been bought on a tape by eager kids. Here in 2024 he’s got it for download should you have a Colecovision or an MSX. There’s a gameplay video below the break, take a look.

Continue reading “Revisiting A Z80 Game From 1990” →

Z80 I/O Madness

January 19, 2024 by 26 Comments

While the 8080 started the personal computer revolution, the Z80 was quickly a winner because it was easier to use and had more capabilities. [Noel] found out though that the Z80 OUT instruction is a little odd and, in fact, some of the period documentation was incorrect.

Many CPUs used memory-mapped I/O, but the 8080 and Z80 had dedicated I/O addressing pins and instructions so you could fill up the memory map with actual memory and still have some I/O devices. A quick look in the famous Zak’s book on Z80 programming indicates that an instruction like OUT (C),A would write the A register to the output device indicated by the BC register pair (even though the instruction only mentions C. However, [Noel] missed the note about the B register and saw in the Zilog documentation that it did. Since he didn’t read the note in the Zak’s book until later, he assumed it was a discrepancy. Therefore, he went to the silicon to get the correct answer.

Breadboarding a little Z80 system allowed him to look at the actual behavior of the instruction. However, he also didn’t appreciate the syntax of the assembly language statements. We’ve done enough Z80 assembly that none of it struck us as particularly crazy, especially since odd instruction mnemonics were the norm in those days.

Still, it was interesting to see him work through all the instructions. He then looks at how Amstrad used or abused the instructions to do something even stranger.

If you want to breadboard a minimal Z80 system, consider this one. If you enjoy abuse of the Z80 I/O system, you don’t want to miss this Z80 hack for “protected mode.”

Continue reading “Z80 I/O Madness” →

Brand-New PCB Makes Replica TRS-80 Possible

January 10, 2024 by 30 Comments

If like us, you missed out on the TRS-80 Model I back when it first came out, relax .With this brand-new PCB that’s a trace-for-trace replica of the original and a bunch of vintage parts, you can build your own from scratch.

Now, obviously, there are easier ways to enjoy the retro goodness that is the 46-year-old machine that in many ways brought the 8-bit hobby computing revolution to the general public’s attention. Sadly, though, original TRS-80s are getting hard to come by, and those that are in decent enough shape to do anything interesting are commanding top dollar. [RetroStack]’s obvious labor of love project provides the foundation upon which to build a brand new TRS-80 as close as possible to the original.

The PCB is revision G and recreates the original in every detail — component layout, connectors, silkscreen, and even trace routing. [RetroStack] even replicated obvious mistakes in the original board, like through-holes that were originally used to fixture the boards for stuffing, and some weird unused vias. There are even wrong components, or at least ones that appear on production assemblies that don’t show up in the schematics. And if you’re going to go through with a build, you’ll want to check out the collection of 3D printable parts that are otherwise unobtainium, such as the bracket for rear panel connectors and miscellaneous keyboard parts.

While we love the devotion to accuracy that [RetroStack] shows with this project, we know that not everyone is of a similar bent. Luckily there are emulators and clones you can build instead. And if you’re wondering why anyone would devote so much effort to half-century-old technology — well, when you know, you know.

Thanks to [Stephen Walters] for the tip.

Feature image: Dave Jones, CC BY-SA 4.0, via Wikimedia Commons

 

Cowgol Development Environment Comes To Z80 And CP/M

December 10, 2023 by 7 Comments

Cowgol on Z80 running CP/M ties together everything needed to provide a Cowgol development environment (including C and assembler) on a Z80 running the CP/M operating system, making it easier to get up and running with a language aimed to be small, bootstrapped, and modern.

Cowgol is an experimental modern language for (very) small systems.

The Zilog Z80 was an 8-bit microprocessor common in embedded systems of the 1970s and 1980s, and CP/M was a contemporary mass-market operating system. As for Cowgol? It’s an Ada-inspired compiler toolchain and programming language aimed at very small systems, such as the Z80.

What’s different about Cowgol is that it is intended to be self-hosted on these small systems; Cowgol is written in itself, and is able to compile itself. Once one has compiled the compiler for a particular target architecture (for example, the Z80) one could then use that compiler on the target system to compile and run programs for itself.

Thankfully, there’s no need to start from scratch. The Cowgol on Z80 running CP/M repository (see the first link of this post) contains the pre-compiled binaries and guidance on using them.

Cowgol is still under development, but it works. It is a modern language well-suited to (very) small systems, and thanks to this project, getting it up and running on a Z80 running CP/M is about as easy as such things can get.

Thanks to [feinfinger] for the tip!