Z80 Based Raspberry Pi Look-alike

Homebrew computers are the ‘in thing’ these days and the Zilog Z80 is the most popular choice for making one on your own. We have seen some pretty awesome builds but [Martin K]’s Z-berry is the smallest on record yet. As the name suggests, the retrocomputer conforms to the Raspberry Pi form factor which includes the GPIO header.

The Z-berry is designed with a Z80 CPU running at 10 MHz (20 MHz possible) and comes with 32 kB ROM
and 512 kB RAM. In addition to the serial interface, the computer boasts an I2C bus, an SPI bus, and a PS/2 keyboard connector to boot. [Martin K] has a video where the finished system is enclosed in a Raspberry Pi case and has an I2C OLED display attached and working.

[Martin K] has posted a lot of details on how to make your own Z-berry which includes the BOM, schematic and preliminary information. We reached out to him to find out more about the software which is stable and available on request along with PCBs and sample code. Additionally, this project promises to draw much less current than the Raspberry Pi and should prove useful for anyone looking to create a retro solution to a modern problem.

It is interesting to see projects that combine modern techniques with retro technologies. One of the best Z80 projects we have seen is the FAP80 and there are some awesome homebrew computer projects on Hackaday.io for you to take a look and get inspiration.
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Integrated Circuit Reverse Engineering, 1970s Style

We are used to stories about reverse engineering integrated circuits, in these pages. Some fascinating exposés of classic chips have been produced by people such as the ever-hard-working [Ken Shirriff].

You might think that this practice would be something new, confined only to those interested in the workings of now-obsolete silicon. But the secrets of these chips were closely guarded commercial intelligence back in the day, and there was a small industry of experts whose living came from unlocking them.

Electron micrograph of a wire bond to the Z80 CTC die
Electron micrograph of a wire bond to the Z80 CTC die

Integrated Circuit Engineering Corporation were a Scottsdale, Arizona based company who specialised in semiconductor industry data. They have long since been swallowed up in a series of corporate takeovers, but we have a fascinating window into their activities because their archive is preserved by the Smithsonian Institution. They reverse engineered integrated circuits to produce reports containing detailed information about their mechanical properties as well as their operation, and just such a report is our subject today. Their 1979 examination of the Zilog Z80 CTC (PDF) starts with an examination of the package, in this case the more expensive ceramic variant, then looks in detail at the internal construction of the die itself, and its bonding wires. We are then taken in its typewritten pages through an extensive analysis of the circuitry on the die, with gate-level circuits to explain the operation of each part.

The detail contained in this report is extraordinary, it is clear that a huge amount of work went into its production and it would have been of huge value to certain of Zilog’s customers and competitors. At the time this would have been extremely commercially sensitive information, even if it now seems like a historical curiosity.

The Z80 CTC is a 4-channel counter/timer peripheral chip for the wildly succesful Z80 8-bit microprocessor, in a 28-pin dual-in-line package. We were surprised to find from a quick search that you can still buy this chip from some of the usual suppliers rather than the surplus houses, so it may even still be in production.

If IC reverse engineering takes your fancy, take a look at our archive of [Ken Shirriff] posts.

Thanks [fortytwo] for the tip.

Hackaday Links: May 7, 2017

The International Journal of PoC||GTFO is the hacker quarterly we all deserve. It’s Pastor Manul Laphroaig’s publication featuring crazy exploits and builds and neat woodcut illustrations. It’s going to be a freakin’ dead tree book published by No Starch Press. The word on the street is this is a literal bible. No, really. No Starch found a place that publishes (manufactures?) bibles, and they sent over the PDFs. There will probably be a Hackaday review of this book, but since all the content is freely available online, this review will literally only be judging a book by its cover.

Hoverboards are more innovative than a selfie stick. The snuggie is an innovative product. The iPhone came before greek yogurt. These are the findings of an online consumer research poll being held by CB Insights. As of this writing (and it might be updated by the time this is published), the bracket for the ‘Most Innovative Consumer Product Since The iPhone’ is down to two competitors — the Tesla Model S and the Raspberry Pi. That’s more opinion than anything, but check out the bracket. The Amazon Echo is more innovative than the ‘desktop 3D printer’, which as we all know was invented by MakerBot. The Dollar Shave Club — otherwise known as giving away the razor and selling subscriptions for the blades — is innovative. Taco Bell didn’t make it past the first round. What the hell is going on here?

This robot plays tiddlywinks. What’s tiddlywinks? It’s that game where you put your hand down on a table and stab a knife between your fingers. It’s a test of fine motor skills and courage, or in this case, programming. This robot also plays tiddlywinks.

This is a Kickstarter for an FPGA’d ZX Spectrum. With the blessing of Sky UK — the owner of the Amstrad brand — this team is cloning the ZX Spectrum, adding HDMI and SD card storage, creating a new enclosure, and calling this project the Spectrum Next. It’s fully compatible with the original and future proofs the Speccy for another few decades.

The Internet of Things comes to alcohol. This vodka comes with a wrap-around LED display that apparently has Bluetooth and is programmable with an iPhone or Android device. Why does this exist? Because it’ll sell. [Bryan Williams] bought one of these bottles and sent this in on the tip line. He’s currently waiting for the batteries to die so he can bust out the Dremel. If anyone else out there wants to check this out, it’s $11 at Sam’s Club.

Need a Z80 C compiler? Here you go.

Clickspring, the guy who has put far, far too much effort into building a clock is now working on the Antikythera Mechanism. His latest video demonstrates how the main plates of the Antikythera mechanism come together. There’s some interesting stuff here, but we’re really waiting for the main gears.

YouTube is well known for the technical astuteness of its community and the fair and level-headed comment section. This, for a short time, was one of the top trending videos on YouTube. It’s ‘free energy’ from two power strips. All you need to do is coil the leads of the power strips around each other. Free intermittent energy for life!

Z80 Fuzix Is Like Old Fashioned Unix

Classic Z80 computers tend to run CP/M. If you’re a purist you’ll be happy with that because that’s certainly what most serious Z80 computers ran back in the day. However, for actual use, CP/M does feel dated these days. Linux is more comfortable but isn’t likely to run on a Z80. Or is it? Linux borrows from Unix and back in the 1980s [Doug Braun] wrote a Unix-like OS for the Z80 called UZI. There have been lots of forks of it over the years, and a project called FuzixOS aims to make a useful Z80 Unix-like OS.

Of course, 1980 Unix was a lot different from modern-day Linux, but it is still closer to a modern system than CP/M. Fuzix also adds several modern features like 30 character file names and up-to-date APIs. The kernel isn’t just for the Z80, by the way. It can target a variety of older processors including the 6502, the 6809, the 8086, and others. As you might expect, the system can fit in a pretty small system.

The video below shows [Scott Baker’s] RC2014 computer running Fuzix. You’ll see it looks a lot like a Linux system, although that analogy only goes so far.

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CP/M 8266

Hands up if you’ve ever used a machine running CP/M. That’s likely these days to only produce an answer from owners of retrocomputers. What was once one of the premier microcomputer operating systems is now an esoteric OS, a piece of abandonware released as open source by the successor company of its developer.

In the 1970s you’d have seen CP/M on a high-end office wordprocessor, and in the 1980s some of the better-specified home computers could run it. And now? Aside from those retrocomputers, how about running CP/M on an ESP8266? From multi-thousand-dollar business system to two-dollar module in four decades, that’s technological progress.

[Matseng] has CP/M 2.2 running in a Z80 emulator on an ESP8266. It gives CP/M 64K of RAM, a generous collection of fifteen 250K floppy drives, and a serial port for communication. Unfortunately it doesn’t have space for the ESP’s party piece: wireless networking, but he’s working on that one too. If you don’t mind only 36K of RAM and one less floppy, that is. All the code can be found on a GitHub repository, so if you fancy a 1970s business desktop computer the size of a postage stamp, you can have a go too.

There’s something gloriously barmy about running a 1970s OS on a two-dollar microcontroller, but if you have to ask why then maybe you just don’t understand. You don’t have to have an ESP8266 though, if you want you can run a bare-metal CP/M on a Raspberry Pi.

MotorMouth For Future Artificial Humans

When our new computer overlord arrives it’ll likely give orders using an electromagnetic speaker (or more likely, by texting instead of talking). But for a merely artificial human being, shouldn’t we use an artificial mouth with vocal cords chords, nasal cavity, tongue,  teeth and lips? Work on such a thing is scarce these days, but [Martin Riches] developed a delightful one called MotorMouth between 1996 and 1999.

It’s delightful for its use of a Z80 processor and assembly language, things many of us remember fondly, as well as its transparent side panel, allowing us to see the workings in action. As you’ll see and hear in the video below, it works quite well given the extreme difficulty of the task.

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The Impressive Z80 Computer With The Unfortunate Name

We’ve seen a lot of retro builds around the Z80. Not many are as neatly done or as well-documented as [dekeNukem’s] FAP80 project. Before you rush to the comments to make the obvious joke, we’ll tell you that everyone has already made up their own variation of the same joke. We’ll also tell you the name is a cross between an old design from [Steve Ciarcia] called the ZAP80 and a reference to the FPGA used in this device.

[dekeNukem] says his goal was to create a Z80 computer without all the baggage of using period-correct support chips. You can argue about the relative merits of that approach versus a more purist build, but the FAP80 has a 5 slot backplane, VGA output, a PS/2 keyboard port and more. You can see one of many videos showing the machine below.

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