Retrocomputing

1402 Articles

Fancy Adding A Transputer Or Two To Your Atari ST?

May 14, 2025 by 9 Comments

Has anybody heard of the ATW800 transputer workstation? The one that used a modified Atari ST motherboard as a glorified I/O controller for a T-series transputer?  No, we hadn’t either, but transputer superfan [Axel Muhr] has created the ATW800/2, an Atari Transputer card, the way it was meant to be.

The transputer was a neat idea when it was conceived in the 1980s. It was designed specifically for parallel and scientific computing and featured an innovative architecture and dedicated high-speed serial chip-to-chip networking. However, the development of more modern buses and general-purpose CPUs quickly made it a footnote in history. During the same period, a neat transputer-based parallel processing computer was created, which leveraged the Atari ST purely for its I/O. This was the curious ATW800 transputer workstation. That flopped as well, but [Axel] was enough of a fan to take that concept and run with it. This time, rather than using the Atari as a dumb I/O controller, the card is explicitly designed for the Mega-ST expansion bus. A second variant of the ATW800/2 is designed for the Atari VME bus used by the STe and TT models—yes, VME on an Atari—it was a thing.

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Your Own Core Rope Memory

May 14, 2025 by 14 Comments

If you want read-only memory today, you might be tempted to use flash memory or, if you want old-school, maybe an EPROM. But there was a time when that wasn’t feasible. [Igor Brichkov] shows us how to make a core rope memory using a set of ferrite cores and wire. This was famously used in early UNIVAC computers and the Apollo guidance computer. You can see how it works in the video below.

While rope memory superficially resembles core memory, the principle of operation is different. In core memory, the core’s magnetization is what determines any given bit. For rope memory, the cores are more like a sensing element. A set wire tries to flip the polarity of all cores. An inhibit signal stops that from happening except on the cores you want to read. Finally, a sense wire weaves through the cores and detects a blip when a core changes polarity. The second video, below, is an old MIT video that explains how it works (about 20 minutes in).

Why not just use core memory? Density. These memories could store much more data than a core memory system in the same volume. Of course, you could write to core memory, too, but that’s not always a requirement.

We’ve seen a resurgence of core rope projects lately. Regular old core is fun, too.

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RADUGA: The Retro Computer From Behind The Curtain

May 14, 2025 by 7 Comments

When [Kasyan] was six years old, he saw a RADUGA computer, a Russian unit from the 1990s, and it sparked his imagination. He has one now that is a little beat up, but we feel like he sees it through his six-year-old eyes as a shiny new computer. The computer, which you can see in the video below, was a clone of the Spectrum 48K.

The box is somewhat klunky-looking, and inside is also a bit strange. The power supply is a — for the time — state-of-the-art switching power supply. Since it wasn’t in good shape, he decided to replace it with a more modern supply.

The main board was also not in good shape. A Zilog CPU is on a large PCB with suspicious-looking capacitors. The mechanical keyboard is nothing more than a array of buttons, and wouldn’t excite today’s mechanical key enthusiast.

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Remembering Memory: EMS, And TSRs

May 13, 2025 by 48 Comments

You often hear that Bill Gates once proclaimed, “640 kB is enough for anyone,” but, apparently, that’s a myth — he never said it. On the other hand, early PCs did have that limit, and, at first, that limit was mostly theoretical.

After all, earlier computers often topped out at 64 kB or less, or — if you had some fancy bank switching — maybe 128 kB. It was hard to justify the cost, though. Before long, though, 640 kB became a limit, and the industry found workarounds. Mercifully, the need for these eventually evaporated, but for a number of years, they were a part of configuring and using a PC.

Why 640 kB?

The original IBM PC sported an Intel 8088 processor. This was essentially an 8086 16-bit processor with an 8-bit external data bus. This allowed for cheaper computers, but both chips had a strange memory addressing scheme and could access up to 1 MB of memory.

In fact, the 8088 instructions could only address 64 kB, very much like the old 8080 and Z80 computers. What made things different is that they included a number of 16-bit segment registers. This was almost like bank switching. The 1 MB space could be used 64 kB at a time on 16-byte boundaries.

So a full address was a 16-bit segment and a 16-bit offset. Segment 0x600D, offset 0xF00D would be written as 600D:F00D. Because each segment started 16-bytes after the previous one, 0000:0020, 0001:0010, and 0002:0000 were all the same memory location. Confused? Yeah, you aren’t the only one.

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The ZX Spectrum Logic Analyzer

May 12, 2025 by 9 Comments

We know [Happy Little Diodes] frequently works with logic analyzer projects. His recent wireless logic analyzer for the ZX Spectrum is one of the oddest ones we’ve seen in a while. The heart of the system is an RP2040, and there are two boards. One board interfaces with the computer, and another hosts the controller.

The logic analyzer core is powered by a common open-source analyzer from [Eldrgusman]. This is one of the nice things about open source tools. Most people probably don’t need a logic analyzer that plugs directly into a ZX Spectrum. But if you do, it is fairly simple to repurpose a more generic piece of code and rework the hardware, if necessary.

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Unwinding An Unusual Slide Rule

May 12, 2025 by 15 Comments

If the Otis King slide rule in [Chris Staecker’s] latest video looks a bit familiar, you might be getting up there in age, or you might remember seeing us talk about one in our collection. Actually, we have two floating around one of the Hackaday bunkers, and they are quite the conversation piece. You can watch the video below.

The device is often mistaken for a spyglass, but it is really a huge slide rule with the scale wrapped around in a rod-shaped form factor. The video says the scale is the same as a 30-inch scale, but we think it is closer to 66 inches.

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Tearing Down A Forgotten Video Game

May 11, 2025 by 5 Comments

Remember Video Volley? No? We don’t either. It looks like it was a very early video game console that could play tennis, hockey, or handball. In this video, [James] tears one apart. If you are like us, we are guessing there will be little more than one of those General Instrument video game chips inside.

These don’t look like they were mass-produced. The case looks like something off the shelf from those days. The whole thing looks more like a nice homebrew project or a pretty good prototype. Not like something you’d buy in a store.

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