z80

118 Articles

RADUGA: The Retro Computer From Behind The Curtain

May 14, 2025 by 7 Comments

When [Kasyan] was six years old, he saw a RADUGA computer, a Russian unit from the 1990s, and it sparked his imagination. He has one now that is a little beat up, but we feel like he sees it through his six-year-old eyes as a shiny new computer. The computer, which you can see in the video below, was a clone of the Spectrum 48K.

The box is somewhat klunky-looking, and inside is also a bit strange. The power supply is a — for the time — state-of-the-art switching power supply. Since it wasn’t in good shape, he decided to replace it with a more modern supply.

The main board was also not in good shape. A Zilog CPU is on a large PCB with suspicious-looking capacitors. The mechanical keyboard is nothing more than a array of buttons, and wouldn’t excite today’s mechanical key enthusiast.

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What’s An LCR Databridge?

May 13, 2025 by 6 Comments

[Thomas Scherrer] has an odd piece of vintage test equipment in his most recent video. An AIM LCR Databridge 401. What’s a databridge? We assume it was a play on words of an LCR bridge with a digital output. Maybe. You can see a teardown in the video below.

Inside the box is a vintage 1983 Z80 CPU with all the extra pieces. The device autoranges, at least it seems as much. However, the unit locks up when you use the Bias button, but it isn’t clear if that’s a fault or if it is just waiting for something to happen.

The teardown starts at about six minutes in. Inside is a very large PCB. The board is soldermasked and looks good, but the traces are clearly set by a not-so-steady hand. In addition to AIM, Racal Dana sold this device as a model 9341. The service manual for that unit is floating around, although we weren’t able to download it due to a server issue. A search could probably turn up copies.

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Single-Board Z80 Computer Draws Inspiration From Picasso

May 1, 2025 by 19 Comments

Picasso and the Z80 microprocessor are not two things we often think about at the same time. One is a renowned artist born in the 19th century, the other, a popular CPU that helped launch the microcomputer movement. And yet, the latter has come to inspire a computer based on the former. Meet the RC2014 Mini II Picasso!

As [concretedog] tells the story, what you’re fundamentally looking at is an RC2014 Mini II. As we’ve discussed previously, it’s a single-board Z80 retrocomputer that you can use to do fun things like run BASIC, Forth, or CP/M. However, where it gets kind of fun is in the layout. It’s the same fundamental circuitry as the RC2014, but it’s been given a rather artistic flair. The ICs are twisted this way and that, as are the passive components; even some of the resistors are dancing all over the top of one another. The kit is a limited edition, too, with each coming with a unique combination of colors where the silkscreen and sockets and LED are concerned. Kits are available via Z80Kits for those interested.

We love a good artistic PCB design; indeed, we’ve supported the artform heavily at Supercon and beyond. It’s neat to see the RC2014 designers reminding us that components need not live on a rigid grid; they too can dance and sway and flop all over the place like the eyes and or nose on a classic Picasso.

It’s weird, though; in a way, despite the Picasso inspiration, the whole thing ends up looking distinctly of the 1990s. In any case, if you’re cooking up any such kooky builds of your own, modelled after Picasso or any other Spanish master, don’t hesitate to notify the tipsline.

 

Z80 Testing The 80s Way

November 12, 2024 by 24 Comments

According to [MTSI], if you used a Z80 chip back in the 1980s, it almost certainly passed through the sole Fairchild Sentry 610 system that gave it the seal of approval.

The Sentry was big iron for its day. The CPU was a 24-bit device and ran at a blistering 250 kHz. Along with a tape drive and a specialized test bed, it could test Z80s, F8s, and other Mostek products of the day. There was a disk drive, too. The 26-inch platters stored under 10 kilobytes. Despite the relatively low speed of the CPU, the Sentry could test devices running up to 10 MHz, which was plenty for the CPUs it was testing. The actual test interface ran at 11 MHz and used an exotic divider to generate slower frequencies.

According to the post, an informal count of the number of chips in the device came up with around 60,000. That, as you might expect, took a huge power supply, too.

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Strange English Teaching Computer Might Have Been Big In Japan

October 21, 2024 by 9 Comments

[Ctrl-Alt-Rees] bought something strange on an auction site: a Japanese Cefucom-21 from 1983. No? Didn’t ring a bell for us either. The legend on the front boldly proclaims: “CCI Multipurpose SLAP Computer,” so maybe it is some kind of computer, but it is definitely strange. For one thing, the “screen” isn’t a screen at all. [Rees] has found that it has something to do with teaching English. You can see the odd beast in the video below.

We don’t know how common these were in Japan, but they appear to be virtually unknown everywhere else. Inside is a Z80 computer based on a  Sanyo PHC-25, which is a little better known.

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DIY Core Rope Memory Z80 Demonstrator Generating A Fibonacci Sequence

October 16, 2024 by 14 Comments

We’ve seen a few retro products using core rope memory, such as telephone autodiallers. Obviously, we’ve covered the Apollo program computers, but we don’t think we’ve seen a complete and functional DIY computer using core rope memory for program storage until now. [P-lab] presents their take on the technology using it to store the program for a Z80-based microprocessor demoboard, built entirely through-hole on a large chunk of veroboard.

For the uninitiated, core rope memory is a simple form of ROM where each core represents a bit in the data word. Each wire represents a single program location. Passing a wire through the core sets the corresponding bit to a logic 1, else 0. These wires are excited with an AC waveform, which is coupled to the cores that host a wire, passing along the signal to a pickup coil. This forms an array of rudimentary transformers. All that is needed is a rectifier/detector to create a stable logic signal to feed onto the data bus.

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No Z80? No Problem!

September 16, 2024 by 17 Comments

Earlier this year Zilog stopped production of the classic 40-pin DIP Z80 microprocessor, a move that brought a tear to the eye of retro computing enthusiasts everywhere. This chip had a huge influence on both desktop and embedded computing that lingers to this day, but it’s fair to say that the market for it has dwindled. If you have a retrocomputer then, what’s to be done? If you’re [Dean Netherton], you create a processor card for the popular RC2014 retrocomputer backplane, carrying the eZ80, a successor chip that’s still in production.

The eZ80 can be thought of as a Z80 system-on-chip, with microcontroller-style peripherals, RAM, and Flash memory on board. It’s much faster than the original and can address a relatively huge 16MB of memory. For this board, he’s put the chip on a processor daughterboard that plugs into a CPU card with a set of latches to drive the slower RC2014 bus. We can’t help drawing analogies with some of the 16-bit upgrades to 8-bit platforms back in the day, which used similar tactics.

So this won’t save the Z80, but it might well give a new dimension to Z80 hacking. Meanwhile, we’re sure there remain enough of the 40-pin chips out there to keep hackers going for many years to come if you prefer the original. Meanwhile, read our coverage of the end-of-life announcement, even roll your own silicon if you want., or learn about the man who started it all, Federico Faggin.