NABU PC Gets CPU Upgrade, Emulates A TRS-80

January 1, 2023 by Robin Kearey 11 Comments

The NABU PC caused a bit of a buzz in the retrocomputing community a couple weeks back. After all, it doesn’t happen often that a huge batch of brand-new computers from the 1980s suddenly becomes available on eBay. Out of the box, the computer itself isn’t that useful: with no internal storage, or any application software whatsoever, it can really only serve as a bare-bones development platform. But since its hardware is quite similar to that of other contemporary home computers, emulating one of those shouldn’t be too difficult, which is exactly what [Ted Fried] did: he managed to turn his NABU into a TRS-80 clone by using his MCLZ8 CPU emulator.

The MCLZ8 is basically an 800 MHz Teensy CPU with an adapter board that allows it to be plugged into a Z80 socket. It emulates the Z80 CPU in real-time, but it also holds the TRS-80 ROM and performs real-time translation between peripherals. On the input side, it reads out the ASCII characters coming in from the NABU’s 8251A UART and stores them in the virtual TRS-80’s keyboard buffer. On the output side, it transfers the TRS-80’s video data to the NABU’s TMS9918 video chip.

One problem [Ted] ran into was a difference in screen resolution: the NABU has a 40×24 character display, while the TRS-80 generates a 64×16 character image. [Ted] solved the vertical difference by simply keeping the NABU logo on the screen at all times, and decided to just ignore the 24 characters that drop off the right side – it’s not a big issue for a typical BASIC program anyway.

The repurposed NABU might not be a perfect TRS-80 clone, but that’s not the point: it shows how easily the NABU’s hardware can be reprogrammed to do other things. For example, [Ted] has already started work on a new project that doesn’t emulate the Z80, but instead runs code directly on the Teensy’s ARM A9 processor. As you might imagine, this gives the NABU several orders of magnitude more processing power, although the practical use of this is limited because the CPU still has to wait for the NABU’s slow data bus and display chip. [Ted] explains the setup and runs a few impressive demos in the video embedded below.

[Ted]’s NABU experiments are a great example of the Teensy board’s flexibility: we’ve already seen how it can emulate a Z80 as well as an 8088. We’re also curious to see what others will develop with the NABU’s hardware — if they can still buy it, of course.

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Hackaday Podcast 195: No NABU For You, Self-Assembling 3D Prints, Black Hats Look At EV Chargers

December 2, 2022 by Tom Nardi 4 Comments

This week, Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi find themselves in the middle of a slow news week, so they dispense with the usual timely chit-chat and dive right into the results of a particularly tricky “What’s that Sound” challenge.

From there they’ll cover the new breed of ATtiny microcontollers (and why you probably won’t be buying them), a recently unearthed Z-80 consumer gadget that’s begging to be reverse engineered, the fine art of electrifying watercraft, and a particularly impressive speech recognition engine. Stick around till the end to hear about the potential dangers of unsecured EV chargers, and take a walk down memory lane to a time when soldering irons and paper schematics ruled the world.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download the podcast for safe-keeping!

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NABU PC – A 1984 Z-80 Computer You Can Buy Today

November 28, 2022 by Adam Fabio 62 Comments

Want to hack on brand new 8-bit 1980s hardware? Until recently you needed a time machine, or deep pockets to do this. All that has recently changed with the NABU PC. A retro machine that can be bought brand new for $59.99, (plus shipping) no time machine needed.

[Adrian] has one in his Digital Basement, and breaks it all down for us. The NABU PC was a Canadian computer. Designed to connect to the cable TV network, the standard system had no internal secondary storage. You read that right; the NABU used the cable network to download and play games, view documents — just about anything you’d want to do with a computer. Cable modems back in the 80s — maybe someone did have a time machine?

Unfortunately, the NABU network failed. Not due to the PC’s hardware, but because the cable system back then was not designed for bidirectional data. While the NABU PC did see a limited release in Canada, was never widely successful. When production was shut down, the machines couldn’t be liquidated, as they didn’t do anything without the network. So in the warehouse, they sat, until this month, where can find them being sold on eBay.

So what’s inside a NABU? It starts with a Z-80 CPU sporting 64 kB of RAM. A TMS9918 handles video, while a General Instrument AY-3-8910 does the sound. There are also two UARTs. An 8251 for serial io to the keyboard and joysticks, and a high-performance UART chip to handle comms with the network adapter. The keyboard is loaded with good old ALPS switches, and [Adrian] found it rather impressive.

That’s all well and good, but what can you actually do with a NABU PC? Right now, not much. The ROM software comes up and looks for the network adapter, then complains when it doesn’t find it. This means it’s hacking time! An army of retrocomputing enthusiasts are already working on bringing back the NABU computer. Check [Adrian]’s video description for all the documentation links, and check here on Hackaday for the latest updates!

This isn’t our first time watching this sort of liquidation — remember the HP touchpad?

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Ancient Cable Modem Reveals Its RF Secrets

April 22, 2024 by Dan Maloney 27 Comments

Most reverse engineering projects we see around here have some sort of practical endpoint in mind. Usually, but not always. Reverse-engineering a 40-year-old cable modem probably serves no practical end, except for the simple pleasure of understanding how 1980s tech worked.

You’ll be forgiven if the NABU Network, the source of the modem [Jared Boone] tears into, sounds unfamiliar; it only existed from 1982 to 1985 and primarily operated in Ottawa, Canada. It’s pretty interesting though, especially the Z80-based computer that was part of the package. The modem itself is a boxy affair bearing all the hallmarks of 1980s tech. [Jared]’s inspection revealed a power supply with a big transformer, a main logic board, and a mysterious shielded section with all the RF circuits, which is the focus of the video below.

Using a signal generator, a spectrum analyzer, and an oscilloscope, not to mention the PCB silkscreen and component markings, [Jared] built a block diagram of the circuit and determined the important frequencies for things like the local oscillator. He worked through the RF section, discovering what each compartment does, with the most interesting one probably being the quadrature demodulator. But things took a decidedly digital twist in the last compartment, where the modulated RF is turned into digital data with a couple of 7400-series chips, some comparators, and a crystal oscillator.

This tour of 80s tech and the methods [Jared] used to figure out what’s going on in this box were pretty impressive. There’s more to come on this project, including recreating the original signal with SDRs. In the mean time, if this put you in the mood for other videotext systems of the 80s, you might enjoy this Minitel terminal teardown.

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Brand-New PCB Makes Replica TRS-80 Possible

January 10, 2024 by Dan Maloney 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

A Digital Camera For The 1984 Market

August 14, 2023 by Jenny List 17 Comments

Digital cameras are a ubiquitous consumer and professional product here in 2023, and because of the wide availability of parts it’s relatively straightforward to construct one for yourself. Four decades ago though, film was king, but that hasn’t stopped [Georg Lukas] from building a digital camera for the 1984 market. The hardware is definitely from recent years, the extremely affordable ESP32-cam board that many of us will have worked with already. Meanwhile the 1984 part lies in the recording format, it makes EGA 16-colour low-res pictures and stores them in the archaic TGA file format.

A low-res camera is fun, but there are two other angles on this which are definitely worth some time. The first is that his description and code are worth a read for anyone with an interest in programming an ESP32 camera, while the second invites us to consider whether such a camera could have been made using parts available in 1984. We remember camera peripherals for 8-bit microcomputers which were a C-mount lens positioned over a decapped RAM chip, and thus we can’t help wondering whether an RGB split to three of those sensors could have been constructed. Whether a 6502 or a Z80 with 64k of memory could have processed the three images into one is another matter, but at least if any of you want to try there’s a handy 1984 computer still popping up on eBay.

Hackaday Podcast 200: Happy New Year, The Ultimate Game Boy, And Python All The Things

January 6, 2023 by Tom Nardi 1 Comment

This week, Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi ring in the New Year with…well, pretty much the same stuff they do every other week. After taking some time to talk about the nuts and bolts of the podcast in honor of Episode 200, discussion moves on to favorite stories of the week including an impeccably cloned Dyson lamp, one hacker’s years-long quest to build the ultimate Game Boy, developing hardware in Python, building a breadboard computer with the 6502’s simplified sibling, and the latest developments surrounding the NABU set-top box turned retrocomputer. The episode wraps up with a review of some of the biggest themes we saw in 2022, and how they’re likely to shape the tech world in the coming years.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download it in living MP3.