Z80s From The ’80s Had Futuristic Design

Ever heard of a Dutch company called Holborn (literally, born in Holland)? We hadn’t either, but [Bryan Lunduke] showed us these computers from the early 1980s, and we wondered if they might have appeared in some science fiction movies. They definitely look like something from a 1970s movie space station.

The company started out tiny and only lasted a few years. The Holborn 9100 looked like a minicomputer and, honestly, other than the terminal, looks more like an air conditioner or refrigerator. While it was a Z-80 system, it was clearly aimed at business. The processor ran at 3.5 MHz, there was 72K of RAM that could expand to 220 K — a whopping amount for the early ’80s. They also could accept loads of 8-inch floppies. It even had a light pen, which seems exotic today but was actually fairly common back then.

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CP/M Porting In A Few Hours

If you’ve ever wanted to watch someone bring CP/M up on a new system and you have a couple of hours to spare, check out the recorded live stream of [Poking Technology]. The system in question is an Agon Light, a modern board with a Z-80-derived CPU. If you want to get right to the porting part, you might want to skip about 31 minutes of the nearly 2.5-hour video.

The first half hour is more about the built-in assembler and the board in general. If you’ve ever ported CP/M before, you know it isn’t as hard as bootstrapping a modern operating system. There are two major things you need: A BIOS, which is specific to your machine, and a BDOS, which is usually taken verbatim from the operating system sources. Your programs typically call one of the 40 or so functions in the BDOS.

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Retrocomputing For $4 With A Z80

Sure, you’d like to get in on all the retrocomputing action you read about on Hackaday. But that takes a lot of money to buy vintage hardware, right? Sure, you can build your own, but who has time for a big major project? [Just4Fun] has a Hackaday.io project that disproves those two myths and gives you no more excuses. His retrocomputer? A 4MHz Z80 that can run BASIC with 64K of RAM, all built on a breadboard with 4 ICs. The cost? About $4.

Of course, that’s with some power shopping on eBay and assuming you have the usual stuff like breadboards, wire, small components, and a power supply. While it will gall the anti-Arduino crowd, [Just4Fun] uses an Arduino (well, an ATmega32A with the Arduino bootloader) to stand in for a host of Z80 peripheral devices. You can see a video of the device below, and there are more on the Hackaday.io project page.

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“Zero Overhead” Z80 Computer Focuses On Performance


There’s something quite satisfying about building your own computer. Nowadays, constructing your own desktop PC is relatively easy, so if you really want to get your hands dirty, you have to take a step back in time and give some vintage hardware a spin.

[YT2095] has spent a good portion of the last two months building a computer based on the classic Z80 CPU. His machine, called “Z Eighty Development” or “ZED” for short is an amazing build, and most definitely a labor of love. He has put an estimated 700+ hours into this machine and it’s a beaut! When closed, the machine is pretty unassuming, but once he folds down the keypad, you can see that all of his time has been put to good use.

Most of the board’s components are connected together via wire wrap, including the large 48k memory card he built, as you can see from the link above. The wide array of add on cards all work together to accomplish his goal of “zero overhead” – freeing up the Z80 from having to do any unnecessary processing, such as I/O, etc.

It’s quite an impressive build, and ranks up there with some of the best Z80 based computers we have seen through the years.

Generating Music With Credit Cards


[Steve] was browsing around at a local electronics surplus store when he spotted an old Tranz 330 point-of-sale terminal that seemed pretty interesting. He took it home and after disassembling it, found that it contained a Z-80 based computer. Because the 330 shares the same processor as other hobbyist-friendly devices such as the TRS-80, he figured it would be quite fun to hack.

While the Z-80 processor is pretty common, [Steve] still had to figure out how it was interfaced in this particular device. After spending some time reverse engineering the terminal, he had free reign to run any program he desired. After thinking for a bit, he decided it would be cool to use the terminal to generate music based on whatever card was swiped through the reader – he calls his creation “Mozart’s Credit Card”.

He found that just playing sounds based on the raw contents of the mag strips didn’t produce anything coherent, so he wrote a small application for the terminal based on the Melisma Stochastic Melody Generator. Music is generated somewhat randomly using various card characteristics, as you can see in the video below.

We think it’s pretty cool, but [Steve] says he’s always open to suggestions, so let us know what you think in the comments.

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