z80

112 Articles

Grok The Z80 With This Simulator

July 20, 2020 by 18 Comments

Many of us will have at some point encountered a Z80 microprocessor, whether we’ve bare-metal programmed for it, or simply had a go at blasting some invaders on a game system using one. Like all the processors of its era, it’s got a relatively simple and accessible internal block diagram, so there’s a good chance that readers well even know how it works, too. But do any of know how it really works, down to the gate, transistor, and net level? [Goran] does, because he’s written a Z80 netlist simulator that allows the running of code alongside the examination of the chip and its signals. It’s not particularly fast, achieving a modest 2.3kHz clock speed when run of a fairly high-end PC, but we’re guessing readers needing to run Z80 code for anything other than learning would use the real thing anyway.

There’s a video of the software in operation which we’ve placed below the break, and we can see it will be a fascinating tool even to people who aren’t dedicated reverse engineers. To be able to bring up a logic analyzer view of the internals of a processor while it is in operation is truly astounding if you are used to it as a black box, and to have logic diagrams at your fingertips rather than puzzling out individual transistors really gives a window into what is going on.

This isn’t the only such simulator out there, in the past we’ve mentioned Visual6502, when we covered the Monster 6502.

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A Z80 Board With Very Few Parts

July 17, 2020 by 25 Comments

The Z80 is one of those old CPUs that is both obtainable and easy to work with — at least in some versions. [Doctor Volt] put together what may be the simplest possible setups to get a working Z80 system. He has the processor, of course. But everything else — clock, memory, and power — are from an Arduino Mega 2560. You could argue that’s two chips, but the board actually has several chips on it. On the other hand, you could probably pull off the same stunt with a bare ATMega 2560.

We’ve seen this done before, but usually with a few more support chips. If you are a purist, [Doctor Volt] also has some Z80 and CP/M experiments where the Arduino only acts as a disk drive for the computer and there are only two support chips. There are three videos for both projects that you can see below.

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(Re)Making A ColecoVision

July 12, 2020 by 13 Comments

[Leaded Solder] found some ColecoVision game cartridges at a flea market, and like most of us would, thought, “I’ll build a ColecoVision console from scratch to play them!” Well, maybe most of us would think of that, but not actually do it. He did and you can read about the results in great detail since he wrote up two posts, one covering the design and one covering the construction.

The ColecoVision was a game console that famously could be expanded into a nice — for its day — personal computer. It even had a daisy wheel printer in that configuration. However, in either configuration, the game console was the brains of the operation. According to [Leaded Solder] the price of a unit in working order is high even though over 2 million were made because of several design problems that make them less likely to survive the decades. Rather than repair and modify an original unit, it was cheaper and much more educational to build new.

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Teardown: The Writer Word Processor

June 9, 2020 by 60 Comments

For modern students, the spiral notebook has given way to the laptop and the pocket calculator has been supplanted by the smart phone. We’re not just talking about high school and college, either. Today, the education of even grade school children is intrinsically linked with technology. While some might question the wisdom of moving away from the pencil and pad at such a young age, there’s little question that all the kids stuck at home right now due to COVID-19 would have had a much harder time transitioning to remote learning otherwise.

But that certainly wasn’t the case when Advanced Keyboard Technologies released the Writer in 2003. Back then, five years before the first netbooks hit the market, you’d be hard pressed to find a laptop cheap enough to give to a grade school student. In comparison, these small electronic word processors could be purchased for as little as $150. Not only was the initial price low, but the maintenance costs were almost negligible. They ran for hundreds of hours on a standard AA batteries, and didn’t require schools to have any IT staff to manage them. Sure they couldn’t get on the Internet or even run any software, but they would give students a chance to hone their keyboarding skills. Continue reading “Teardown: The Writer Word Processor” →

Z80 Computer Is Both Arduino And Shield

March 7, 2020 by 7 Comments

There have been plenty of Z80 computer builds here on Hackaday, but what sets them apart is what you do with them. [Andrew] writes in with his Z80 single-board computer made from scratch, using the Arduino standard headers for its I/O. In turn, since he needed an easy way to program the flash memory which holds the software to run on the Z80, he used an Arduino Mega as a debugger, making the SBC an Arduino shield itself.

Using such a common header pinout for the Z80 computer allows it to be used with a variety of readily-available Arduino shields. This compatibility is achieved with an analog-digital converter and a 3.3 V regulator, mimicking the pins found in an Arduino Uno. The code, available on GitHub, includes an extensive explanation and walkthrough over the process in which the Mega takes over the bus from the Z80 to function as a fully-featured debugger. Programs can be loaded through embedding an assembly listing into the Mega’s sketch, or, once the debugger is up you can also upload a compiled hex file through the serial connection.

This isn’t the first time [Andrew] has been featured here, and his past projects are just as interesting. If you need to translate a Soviet-era calculator’s buttons into English, hack a metallurgical microscope or even investigate what’s that Clacking Clanking Scraping Sound, he’s the one you should call.

A Z80 Computer At The Next Level

February 23, 2020 by 40 Comments

At the close of the 8-bit home computer era there were some machines produced that attempted to bridge the gap between the 8- and 16-bit worlds, either by providing a 16-bit device with a backwards compatibility mode, or an 8-bit one with enhanced capabilities to compete with its newer rivals. These products largely fell by the wayside in the face of new 16-bit only platforms, but they and the various enhanced versions of 8-bit processors that appeared over subsequent decades present a fascinating glimpse of what might have been. It’s a theme [Konstantin Dimitrov] explores with his Z20X computer project, a machine using the Zilog eZ80 processor running at 20 MHz, with 512 kB of external memory, and an interface for a 7″ TFT screen module.

The eZ80 is a more recent development, a pipelined processor capable of much higher clock speeds and addressing up to 16 MB of memory while maintaining software compatibility with the Z80. Had it come to market in the late 1980s it would have been a sensation, but instead it has appeared in embedded computers and perhaps of most interest to Hackaday readers, in TI’s line of programmable calculators.

The Z20X is designed to be a through-hole board, with the only SMD component the eZ80 itself. We can understand the motivation behind this, but at the same time wonder whether its likely builders in 2020 will be people unfazed by SMD assembly. It has a system of processor modules in case of future upgrades, and an expansion backplane with an option of an RC2014-compatible bus. There are also PS/2 keyboard and mouse connectors, a serial bus, and an on-board sound chip. The website is short on details of any software, but we’d expect it to work with the typical Z80 retrocomputer offerings such as a BASIC interpreter and the CP/M operating system.

This machine is likely to appeal to retrocomputing enthusiasts, but had it appeared even without the display in a previous decade it would no doubt have become an object of desire. It does however serve as a reminder that the Z80 line has been updated, and though most of us will have moved on it still offers a few chips that could be of interest. Meanwhile for a comparison, take a look at last year’s review of the latest in the range of RC2014 retrocomputer boards.

Thanks [yNos] for the tip.

Laptop Like It’s 1979 With A 16-Core Z80 On An FPGA

December 10, 2019 by 43 Comments

When life hands you a ridiculously expensive and massively powerful FPGA dev board, your first reaction may not be to build a 16-core Z80 laptop with it. If it’s not, perhaps you should examine your priorities, because that’s what [Chris Fenton] did, with the result being the wonderfully impractical “ZedRipper.”

Our first impression is that we’ve got to start hanging around a better class of lab, because [Chris] came by this $6000 FPGA board as the result of a lab cleanout; the best we ever scored was a few old Cat-5 cables and some power strips. The Stratix FPGA formed the heart of the design, surrounded by a few breakout boards for the 10.1″ VGA display and the keyboard, which was salvaged from an old PS/2. The 16 Z80 cores running in the FPGA are connected by a ring-topology network, which [Chris] dubs the “Z-Ring”. One of the Z80 cores, the server core, runs CP/M 2.2 and a file server called CP/NET, while the other fifteen machines are clients that run CP/NOS. A simple window manager shows 80 x 25 character terminal sessions for the server and any three of the clients at once, and the whole thing, including a LiPo battery pack, fits into a laser-cut plywood case. It’s retro, it’s modern, it’s overkill, and we absolutely love it.

Reading over [Chris]’s build log puts us in the mood to break out our 2019 Superconference badge and try spinning up a Z80 of our own. If you decide to hack the FPGA-est of conference badges, you might want to check out what [Sprite_TM] has to say about it. After all, he designed it. And you’ll certainly want to look at some of the awesome badge hacks we saw at Supercon.

Thanks to [yNos] for the tip.