Not A Sewing Machine: A Multimedia Briefcase

May 15, 2025 by Al Williams 3 Comments

When you think of Singer, you usually think of sewing machines, although if you are a history buff, you might remember they diversified into calculators, flight simulation, and a few other odd businesses for a while. [Techmoan] has an unusual device from Singer that is decidedly not a sewing machine. It is a 1970s-era multimedia briefcase called the Audio Study Mate. This odd beast, as you can see in the video below, was a cassette player that also included a 35mm filmstrip viewer. Multimedia 1970s-style!

The film strip viewer is a bright light and a glass screen with some optics. You have to focus the image, and then a button moves the film one frame. However, that’s for manual mode. However, the tape could encode a signal to automatically advance the frame. That didn’t work right away.

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Remembering More Memory: XMS And A Real Hack

May 15, 2025 by Al Williams 18 Comments

Last time we talked about how the original PC has a limit of 640 kB for your programs and 1 MB in total. But of course those restrictions chafed. People demanded more memory, and there were workarounds to provide it.

However, the workarounds were made to primarily work with the old 8088 CPU. Expanded memory (EMS) swapped pages of memory into page frames that lived above the 640 kB line (but below 1 MB). The system would work with newer CPUs, but those newer CPUs could already address more memory. That led to new standards, workarounds, and even a classic hack.

XMS

If you had an 80286 or above, you might be better off using extended memory (XMS). This took advantage of the fact that the CPU could address more memory. You didn’t need a special board to load 4MB of RAM into an 80286-based PC. You just couldn’t get to with MSDOS. In particular, the memory above 1 MB was — in theory — inaccessible to real-mode programs like MSDOS.

Well, that’s not strictly true in two cases. One, you’ll see in a minute. The other case is because of the overlapping memory segments on an 8088, or in real mode on later processors. Address FFFF:000F was the top of the 1 MB range.

PCs with more than 20 bits of address space ran into problems since some programs “knew” that memory access above that would wrap around. That is FFFF:0010, on an 8088, is the same as 0000:0000. They would block A20, the 21st address bit, by default. However, you could turn that block off in software, although exactly how that worked varied by the type of motherboard — yet another complication.

XMS allowed MSDOS programs to allocate and free blocks of memory that were above the 1 MB line and map them into that special area above FFFF:0010, the so-called high memory area (HMA). Continue reading “Remembering More Memory: XMS And A Real Hack” →

Welcome Your New AI (LEGO) Overlord

May 15, 2025 by Al Williams 13 Comments

You’d think a paper from a science team from Carnegie Mellon would be short on fun. But the team behind LegoGPT would prove you wrong. The system allows you to enter prompt text and produce physically stable LEGO models. They’ve done more than just a paper. You can find a GitHub repo and a running demo, too.

The authors note that the automated generation of 3D shapes has been done. However, incorporating real physics constraints and planning the resulting shape in LEGO-sized chunks is the real topic of interest. The actual project is a set of training data that can transform text to shapes. The real work is done using one of the LLaMA models. The training involved converting Lego designs into tokens, just like a chatbot converts words into tokens.

There are a lot of parts involved in the creation of the designs. They convert meshes to LEGO in one step using 1×1, 1×2, 1×4, 1×6, 1×8, 2×2, 2×4, and 2×6 bricks. Then they evaluate the stability of the design. Finally, they render an image and ask GPT-4o to produce captions to go with the image.

The most interesting example is when they feed robot arms the designs and let them make the resulting design. From text to LEGO with no human intervention! Sounds like something from a bad movie.

We wonder if they added the more advanced LEGO sets, if we could ask for our own Turing machine?

Inside Starlink’s User Terminal

May 14, 2025 by Al Williams 28 Comments

If you talk about Starlink, you are usually talking about the satellites that orbit the Earth carrying data to and from ground stations. Why not? Space is cool. But there’s another important part of the system: the terminals themselves. Thanks to [DarkNavy], you don’t have to tear one open yourself to see what’s inside.

The terminal consists of two parts: the router and the antenna. In this context, antenna is somewhat of a misnomer, since it is really the RF transceiver and antenna all together. The post looks only at the “antenna” part of the terminal.

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Your Own Core Rope Memory

May 14, 2025 by Al Williams 12 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 Al Williams 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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Version Control To The Max

May 14, 2025 by Al Williams 36 Comments

There was a time when version control was an exotic idea. Today, things like Git and a handful of other tools allow developers to easily rewind the clock or work on different versions of the same thing with very little effort. I’m here to encourage you not only to use version control but also to go even a step further, at least for important projects.

My First Job

The QDP-100 with — count ’em — two 8″ floppies (from an ad in Byte magazine)

I remember my first real job back in the early 1980s. We made a particular type of sensor that had a 6805 CPU onboard and, of course, had firmware. We did all the development on physically big CP/M machines with the improbable name of Quasar QDP-100s. No, not that Quasar. We’d generate a hex file, burn an EPROM, test, and eventually, the code would make it out in the field.

Of course, you always have to make changes. You might send a technician out with a tube full of EPROMs or, in an emergency, we’d buy the EPROMs space on a Greyhound bus. Nothing like today.

I was just getting started, and the guy who wrote the code for those sensors wasn’t much older than me. One day, we got a report that something was misbehaving out in the field. I asked him how we knew what version of the code was on the sensor. The blank look I got back worried me. Continue reading “Version Control To The Max” →