Retrocomputing

1452 Articles

Weird Email Appliance Becomes AI Terminal

December 12, 2025 by 5 Comments

The Landel Mailbug was a weird little thing. It combined a keyboard and a simple text display, and was intended to be a low-distraction method for checking your email. [CiferTech] decided to repurpose it, though, turning it into an AI console instead.

The first job was to crack the device open and figure out how to interface with the keyboard. The design was conventional, so reading the rows and columns of the key matrix was a cinch. [CiferTech] used PCF8574 IO expanders to make it easy to read the matrix with an ESP32 microcontroller over I2C. The ESP32 is paired with a small audio output module to allow it to run a text-to-speech system, and a character display to replace the original from the Mailbug itself. It uses its WiFi connection to query the ChatGPT API. Thus, when the user enters a query, the ESP32 runs it by ChatGPT, and then displays the output on the screen while also speaking it aloud.

[CiferTech] notes the build was inspired by AI terminals in retro movies, though we’re not sure what specifically it might be referencing. In any case, it does look retro and it does let you speak to a computer being, of a sort, so the job has been done. Overall, though, the build shows that you can build something clean and functional just by reusing and interfacing a well-built commercial product.

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Cheap And Aggressive DRAM Chip Tester

December 8, 2025 by 6 Comments

People enjoy retrocomputing for a wide variety of reasons – sometimes it’s about having a computer you could fully learn, or nostalgia for chips that played a part in your childhood. There’s definitely some credit to give for the fuzzy feeling you get booting up a computer you built out of chips. Old technology does deteriorate fast, however, and RAM chip failures are especially frustrating. What if you got a few hundred DRAM chips to go through? Here’s a DRAM chip tester by [Andreas]/[tops4u] – optimized for scanning speed, useful for computers like the ZX Spectrum or Oric, and built around an ATMega328P, which you surely still have in one of your drawers.

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Off-Axis Rotation For Amiga-Themed Levitating Lamp

December 8, 2025 by 5 Comments

Do you remember those levitating lamps that were all the rage some years ago? Floating light bulbs, globes, you name it. After the initial craze of expensive desk toys, a wave of cheap kits became available from the usual suspects. [RobSmithDev] wanted to make a commemorative lamp for the Amiga’s 40th anniversary, but… it was missing something. Sure, the levitating red-and-white “boing” ball looked good, but in the famous demo, the ball is spinning at a jaunty angle. You can’t do that with mag-lev… not without a hack, anyway.

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34-Year-Old Macintosh ROM Bug Revealed By Emulator

December 7, 2025 by No comments

Generally, you’d hope that your computer manufacturer got the ROM just right before shipping your computer. As [Doug Brown] found out, Apple actually fumbled this with the release of the Macintosh Classic II several decades ago. And yet… the machines worked! That turns out to be due to a rather weird low-level quirk, as recent tinkering in an emulator revealed. 

The bug was revealed when [Doug] was experimenting with the emulated Macintosh Classic II in MAME. He was exploring keyboard shortcuts for launching the debugger, but soon found a problem. He needed to load MacsBug to enable the debugging shortcut, and that required the use of 32-bit addressing. However, the emulated system wouldn’t boot in this mode at all, instead landing on a Sad Mac error screen.

Heavy debugging ensued, which makes for great reading if you love to chase problems on an instruction-by-instruction basis. Ultimately, [Doug’s] conclusion was a mindboggling one. He determined that the crash in MAME came down to a difference between the emulator’s behaviour versus the original Motorola 68030 CPU in the Classic II. There was simply a problematic undocumented instruction baked into the ROM. The real CPU runs this undocumented instruction, which modifies a certain register, allowing boot without issue. Meanwhile, the emulated CPU tries to execute the bad instruction, fails to modify the right register, and everything falls in a heap. [Doug] speculates that had the 68030 CPU hadn’t hidden the bug, Apple’s engineers might have found it many years ago. He even proved his theory by whipping up multiple custom ROMs to verify what was going on.

We love it when bugs from decades past rear their heads; we love it even more when they get fixed. If you’re chasing down issues with an Amiga or you’re ironing out the kinks in software for the Acorn Archimedes, be sure to let us know on the tips line.

[via Tom’s Hardware, thanks to Jason Morris for the tip!]

USB Video Capture Devices: Wow! They’re All Bad!!

December 7, 2025 by 46 Comments

[VWestlife] purchased all kinds of USB video capture devices — many of them from the early 2000s — and put them through their paces in trying to digitize VHS classics like Instant Fireplace and Buying an Auxiliary Sailboat. The results were actually quite varied, but almost universally bad. They all worked, but they also brought unpleasant artifacts and side effects when it came to the final results. Sure, the analog source isn’t always the highest quality, but could it really be this hard to digitize a VHS tape?

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Anatomy Of A Minimalist Home Computer

December 7, 2025 by 21 Comments

There are plenty of well-known models among the 8-bit machines of the 1980s, and most readers could rattle them off without a thought. They were merely the stars among a plethora of others, and even for a seasoned follower of the retrocomputing world, there are fresh models from foreign markets that continue to surprise and delight. [Dave Collins] is treating us to an in-depth look at the VTech VZ-200, a budget machine that did particularly well in Asian markets. On the way, we learn a lot about a very cleverly designed machine.

The meat of the design centres not around the Z80 microprocessor or the 6847 video chip, but the three 74LS chips handling both address decoding and timing for video RAM access. That they managed this with only three devices is the exceptionally clever part. While there are some compromises similar to other minimalist machines in what memory ranges can be addressed, they are not sufficient to derail the experience.

Perhaps the most ingenuity comes in using not just the logic functions of the chips, but their timings. The designers of this circuit really knew the devices and used them to their full potential. Here in 2025, this is something novice designers using FPGAs have to learn; back then, it was learned the hard way on the breadboard.

All in all, it’s a fascinating read from a digital logic perspective as much as a retrocomputing one. If you want more, it seems this isn’t the only hacker-friendly VTech machine.

John Dalton, CC BY-SA 3.0.

The Key To Plotting

December 7, 2025 by 11 Comments

Plotters aren’t as common as they once were. Today, many printers can get high enough resolution with dots that drawing things with a pen isn’t as necessary as it once was. But certainly you’ve at least seen or heard of machines that would draw graphics using a pen. Most of them were conceptually like a 3D printer with a pen instead of a hotend and no real Z-axis. But as [biosrhythm] reminds us, some plotters were suspiciously like typewriters fitted with pens.

Instead of type bars, type balls, or daisy wheels, machines like the Panasonic Penwriter used a pen to draw your text on the page, as you can see in the video below. Some models had direct computer control via a serial port, if you wanted to plot using software. At least one model included a white pen so you could cover up any mistakes.

If you didn’t have a computer, the machine had its own way to input data for graphs. How did that work? Read for yourself.

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