Brand-New PCB Makes Replica TRS-80 Possible

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


Restoring The Cheapest TRS-80 At The Swap Meet

We don’t know if you’ve looked into it recently, but the prices for vintage computers are through the roof right now. These classic machines are going through something of a renaissance at the moment, with even relatively commonplace computers commanding several hundred dollars if they’re in good condition. For those looking to start a collection without breaking the bank, you may need to accept some specimens that have seen better days.

That’s the situation [Vlado Vince] recently found himself in — he wanted to get his hands on a TRS-80 Model I, but wasn’t willing to spend eBay prices. So he waited until the Vintage Computer Federation’s swap meet in June and was able to snag a “fully functional” example for $95. Unfortunately the seller must have been using some form of that phrase which we were previously unaware of, as it took a considerable amount of work to get it back online.

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TRS-80 Model 100 Inspires Cool Cyberdeck Build, 40 Years Down The Line

The TRS-80 Model 100 was a strange beast. When it debuted in 1983, it resembled nothing that was available at the time, and filled a gap between desktop computers and the mostly-not-invented-yet laptop segment of the market. Collectors covet these machines, but they’re getting harder to find four decades later. So, if you want one, you just might have to roll your own.

Honestly, it doesn’t appear [Roberto Alsina]’s purpose here we to recreate the Model 100 per se, but rather to take inspiration from its oddball form factor and experiment with the latest components. The design elements from the original that [Roberto]’s creation most strongly echo are the screen with the extreme landscape aspect ratio and the somewhat compressed keyboard. The latter is based on the cheapest mechanical 65% keyboard available, while the former is a 1920×480 LCD display intended for automotive applications. The display seems like it put up a fight, between its need for a custom HDMI cable to connect it to the Radxa Zero SBC under the hood as well as the custom kernel needed to support it.

Along with a USB hub for IO and some 18650s for power, everything went into a 3D printed case with considerably sleeker lines than the Model 100. It’s worth pointing out that [Roberto] didn’t have much experience with design or 3D printing when he kicked off this project. We love to see people stretching their skills like that, and we think the results are great in this case. We’ve seen a lot of Model 100 retrofits and brain transplants, but this may be the first time we’ve seen a build quite like this.

Emulating All The TRS-80 Software

Even if you didn’t own a TRS-80, the widespread footprint of Radio Shack in malls meant that if you are old enough, it is a good bet you have seen one and maybe even played with one. The games were crude, but state-of-the-art for 1982. If you wanted business software, that was there too, just don’t expect much on any of the personal computers of the day. My old TRS-80 Model III doesn’t boot anymore and is waiting for me to find time to pull it apart. But it turns out you can run all those old programs with almost no effort. If you’ve experimented with emulators before, you know there are two major problems. First, you need to install the sometimes-fidgety emulator. Second, you need to find the software you want to run and probably convert it into some format the emulator will read. The website named The Big List of TRS-80 Software solves both problems.

You are probably thinking this doesn’t solve any problem because it is just a list of links to software. That’s a reasonable thing to think, but we think the website really needs a new name. There are 15,873 pieces of software on the site, although some of them are duplicates or multiple versions of a single program. You can download them in a format that is useful for some emulators or, in some cases, the original files. But here’s the kicker. You can also click to launch a virtual TRS-80 in your browser and start the program.

Sounds great, right? Well, for the most part, it is. However, some of the programs are finicky and don’t run well in the browser. There’s also the problem of finding the documentation, but you can’t have everything. If you want a quick run of a very common game from back in the day, try Flying Saucers. Continue reading “Emulating All The TRS-80 Software”

A NABU PC opened up and powered on

NABU PC Gets CPU Upgrade, Emulates A TRS-80

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.

The motherboard of a NABU PC with a Teensy-based CPU upgradeOne 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 hardwareif they can still buy it, of course.

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Dirty TRS-80 Has A Surprise Hack

[Adrian] had a TRS-80 model IV that looks like it was stored in a mulch pile. However, it seemed to have some surprises. The first hint that something was up was that the keyboard looks like a model III and there are two mystery knobs in the back.

So what’s going on? You” have to watch [Adrian’s] video below to find out. At about the six-minute mark, you’ll find that things are not at all what you might think.

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TRS-80 Gains Multiple Monitor Support, And High-Resolution Graphics

To call [Glen Kleinschmidt] a vintage computing enthusiast would be an understatement. Who else would add the ability to control and address multiple VGA monitors to a rack-mounted TRS-80 Model 1? Multiple 64-color 640×480 monitors might not be considered particularly amazing by today’s standards, but for 70s-era computing, it’s a different story.

Drawing this sin(x)/x ripple surface can be done in only 17 lines of BASIC.

How does a TRS-80 even manage to output anything useful to these monitors? [Glen] wrote his own low-level driver in machine code to handle that. The driver even has useful routines that are callable from within BASIC, meaning that programs written on the TRS-80 are granted powerful drawing abilities. Oh, and did we mention that the VGA graphics cards themselves were designed and made by [Glen]?

Interested in making your own? [Glen] provides all the resources you’ll need to re-create his work, including machine code drivers and demonstration BASIC programs as downloadable audio files, just as they would have been on original cassette tapes.

Watch things in action in the videos embedded below. The first draws a Land Rover, and the second plots a simple Moiré pattern star. Not bad for 70s-era hardware and 74xx logic!

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