Remembering More Memory: XMS And A Real Hack

May 15, 2025 by 28 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” →

Picture of self landing drone satellite with orange and black body. Propellors are extended.

FPV Drone Takes Off From A Rocketing Start

May 15, 2025 by 24 Comments

Launching rockets into the sky can be a thrill, but why not make the fall just as interesting? That is exactly what [I Build Stuff] thought when attempting to build a self-landing payload. The idea is to release a can sized “satellite” from a rocket at an altitude upwards of 1 km, which will then fly back down to the launch point.

The device itself is a first-person view (FPV) drone running the popular Betaflight firmware. With arms that swing out with some of the smallest brushless motors you’ve ever seen (albeit not the smallest motor), the satellite is surprisingly capable. Unfortunately due to concerns over the legality of an autonomous payload, the drone is human controlled on the descent.

Using collaborated efforts, a successful launch was flown with the satellite making it to the ground unharmed, at least for the most part. While the device did show capabilities of being able to fly back, human error led to a manual recovery. Of course, this is far from the only rocketry hack we have seen here at Hackaday. If you are more into making the flight itself interesting, here is a record breaking one from USC students.

Continue reading “FPV Drone Takes Off From A Rocketing Start” →

Falling Down The Land Camera Rabbit Hole

May 15, 2025 by 24 Comments

It was such an innocent purchase, a slightly grubby and scuffed grey plastic box with the word “P O L A R O I D” intriguingly printed along its top edge. For a little more than a tenner it was mine, and I’d just bought one of Edwin Land’s instant cameras. The film packs it takes are now a decade out of production, but my Polaroid 104 with its angular 1960s styling and vintage bellows mechanism has all the retro-camera-hacking appeal I need. Straight away I 3D printed an adapter and new back allowing me to use 120 roll film in it, convinced I’d discover in myself a medium format photographic genius.

But who wouldn’t become fascinated with the film it should have had when faced with such a camera? I have form on this front after all, because a similar chance purchase of a defunct-format movie camera a few years ago led me into re-creating its no-longer-manufactured cartridges. I had to know more, both about the instant photos it would have taken, and those film packs. How did they work? Continue reading “Falling Down The Land Camera Rabbit Hole” →

Welcome Your New AI (LEGO) Overlord

May 15, 2025 by 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?

Smart Terrarium Run By ESP32

May 15, 2025 by 8 Comments

A terrarium is a little piece of the living world captured in a small enclosure you can pop on your desk or coffee table at home. If you want to keep it as alive as possible, though, you might like to implement some controls. That’s precisely what [yotitote] did with their smart terrarium build.

At the heart of the build is an ESP32 microcontroller. It’s armed with temperature and humidity sensors to detect the state of the atmosphere within the terrarium itself. However, it’s not just a mere monitor. It’s able to influence conditions by activating an ultrasonic fogger to increase humidity (which slightly impacts temperature in turn). There are also LED strips, which the ESP32 controls in order to try and aid the growth of plants within, and a small OLED screen to keep an eye on the vital signs.

It’s a simple project, but one that serves as a basic starting point that could be readily expanded as needed. It wouldn’t take much to adapt this further, such as by adding heating elements for precise temperature control, or more advanced lighting systems. These could be particularly useful if you intend your terrarium to support, perhaps, reptiles, in addition to tropical plant life.

Indeed, we’ve seen similar work before, using a Raspberry Pi to create a positive environment to keep geckos alive! Meanwhile, if you’re cooking up your own advanced terrarium at home, don’t hesitate to let us know.

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.

Continue reading “Fancy Adding A Transputer Or Two To Your Atari ST?” →

Inside Starlink’s User Terminal

May 14, 2025 by 33 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.

Continue reading “Inside Starlink’s User Terminal” →