At Last! CP/M For Protected Mode

August 4, 2026 by 28 Comments

If you used a serious computer pre-IBM PC, there was a fair chance its operating system was CP/M. CP/M was a staple among 8080 and Z80 computers and while there were other versions, we’ll always associate CP/M with the Z-80. There was a CP/M made for the PC which used an 8088 (a hybrid 8-bit bus with a 16-bit 8086 core), but it was overwhelmed by MSDOS. However, there was another interesting version made for the 68000, and now [johnsonjh] has ported that over to create an early version of CP/M for 80386 protected mode.

The Z-80 only had a 16-bit address bus, so it could only handle 64K of memory. It was common to “bank switch” some memory, and CP/M Plus could be made to understand that (for example, you might have 32K of common memory and three banks of 32K memory; you could address one bank at a time). However, the 386 had a full-blown memory management unit that could remap physical 4K memory pages to anywhere in a program’s virtual address space.

Ordinary CP/M couldn’t handle that, but the Motorola 68000 had a similar page management model, so it makes sense it might be easier to port CP/M-68K to the 80386 than starting from the original, even though the instruction set for the Z-80 is conceptually more similar to the 80386.

What can you do with it? We don’t know. Presumably, it will allow you to use lots of memory. Historically, CP/M software from one variant would not run on another, so you’ll have to build anything you want to use. Of course, the real killer for lots of CP/M memory was multitasking, but that takes MP/M, and only about half of that is currently working. But we won’t be surprised to see it completed soon.

While CP/M skills won’t land you many jobs these days, it is a pretty good way to get mentioned on Hackaday.

BornHack Radio 102.8 FM, Playing Radio At A Hacker Camp

August 4, 2026 by 8 Comments

Over the years I have been to many hacker camps and done a lot of very cool things, but BornHack 2026 brought me something entirely new: Radio. By which I don’t mean radio in terms of amateur radio, LoRa, or whatever, but Radio. Broadcast radio, because the camp had a special event FM radio station for the first time. And because in a previous life I spent an inordinate amount of time in my university’s student radio station and have the Radio Voice to prove it, I was totally there for it.

A view of a tent shelter in bright sunlight with studio equipment visible on a table in it. There's a sign: "BornHack FM".
The BornHack Radio nerve centre.

For a hacker camp, one of the special things about BornHack Radio was unexpected, that it was entirely analogue. No online streams, the only broadcast was over the air, 5 watts ERP from a vertical antenna stuck on a mast at the highest point of the Hylkedam scout camp site. I don’t know whether any of the residents of the isle of Funen listened, or what they made of it, but it certainly reached as far as the two closest towns.

The other unexpected feature of the station was that it had no music licensing. Personally I viewed this as an asset, because it forced the programming to be hacker-focused rather than suit the musical tastes of whichever people are enthusiastic enough to be DJs. I sincerely hope they don’t get a music licence at future events, speech-only gives it a special quality.

The studio for an analogue station like this one can be surprisingly simple, in that it’s a mixing desk to bring all the different microphones and other inputs together and set the levels, and not a lot else. the whole thing was in a Coleman shelter on the main drag through the camp, so as studios go it could have been quieter. Programming varied from talk shows through interview shows, a live feed from the speaker tent — is this the first ever Hacker Jeopardy broadcast? — and a beautifully done robotic numbers station which I suspect may also have been part of one of the on-camp games.

I brought two shows to the airwaves, both recorded, the first of which was a BornHack take on the Hackaday Podcast format, and the second a half-hour roving interview show. I believe I may be the first person ever to live-commentate a pixelflood screen in the style of Formula One coverage.

The thing that struck me most in my first foray into radio journalism was how straightforward it was. Wander the camp with microphone (complete with fluffy windshield and 3D-printed Hackaday cube), drop the results into Audacity, and a remarkably straightforward editing process compared to video. Last time I did this it involved 1/4″ tape and a razor blade.

So that was BornHack Radio, a new experience at a hacker camp both for those of us who ventured forth on the airwaves, and I hope also for the listeners. A format in which the live shows disappeared into the aether rather than having an online afterlife gave the whole thing a freedom rarely found in 2026. I really hope this isn’t the last time I break out the fluffy microphone at a hacker camp.

Thanks to [⁨Morel Sourvalley⁩] for the images.

Un Ordinateur Pour Le Minitel-1 (A Computer For The Minitel-1)

August 4, 2026 by 4 Comments

In the 1980s, France was the stage for one of the boldest public computing projects of the era. Minitel was the French take on viewdata, and instead of making it an expensive and unattainable luxury, they made the terminals universally available. Many Minitel services cost extra to use, but despite this it was a runaway success that lingered on into the 21st century.

The ubiquitous terminals are now surplus to requirements, but that’s not to say they are useless. [MemoireMorte] has proved this with the Memo-1, a 6502-based computer designed to plug into a Minitel-1 terminal. It’s just the accessory your Minitel needs!

Hardware wise it’s a relatively conventional device with the usual RAM, ROM, and BASIC. There’s an expansion port, and a 6522 to provide a couple of Atari joystick ports. The serial port uses a a 6551 ACIA rather than the more usual W65C51 because of an incompatibility between the latter chip and the Minitel-1.

We like this computer, not because of novelty, after all it’s hardly the first 6502 we’ve seen, but because of its use of the Minitel terminal. These devices are magnificent, and deserve more love. We subjected another terminal to a teardown a year or two ago.

Road Trains Roam The Backroads Of Australia

August 4, 2026 by 21 Comments

Trains and the railways they run on are a great way to move lots of stuff, or lots of people, a long way. Steel wheels on steel rail can shift great loads at good speeds and railways remain a backbone of logistics for this very reason. The only problem is that they require a great deal of initial investment to build and plenty of maintenance to keep them functional over time.

These concerns can make a railway a difficult proposition when it comes to getting large amounts of goods in and out of remote areas. It’s a problem that Australia faces, with settlements far off the beaten track that are nevertheless in need of high-throughput freight connections. And if you can’t go rail, you go road… in a big way.

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Testing Hundreds Of Used LFP Cells Requires Some Automation

August 4, 2026 by 6 Comments

Although Li-ion cells have become a lot cheaper over the years, if you wish to buy hundreds of high-quality ones for that performance go-kart project, you may feel financially pressured into going for the option of stripping down years-old commercial battery packs instead.

While this is a financially sound option, you do have to figure out what the condition is of each cell before you happily stuff them into a new battery pack for said go-kart, as [Within Tolerance] recently did.

This is something that can be done manually, but for the 768 lithium iron phosphate (LFP) cells that were obtained for this project that’d be quite the tedious task. Hence it was decided to instead spend that time designing a system to automate this process, capable of charging, discharging, measuring and quantifying individual cells.

You can find the resulting Cell Goblin battery tester project on GitHub, which entails a custom PCB featuring an ESP32-S2 as the brains and associated software to monitor the process on a connected PC. Fortunately the issues on the PCB that are described in the video are claimed to be fixed in the repository version.

Using five of these dual-cell cell testers it was possible to run through the hundreds of cells with ten cells at a time. An internal resistance meter was also wired into the PC-based software via its UART. As of publication of the video the testing was still in progress, which gives some idea of how long it takes to work through those cells.

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Yellow YAG Produces Powerful Pulses In Les’ Leftover Laser

August 4, 2026 by 7 Comments

[Les] likes lasing lasers, and who doesn’t? [Les] likes larger lasers than lots of folks, with his current project being an Nd:YAG (that’s Neodymium:Yttrium Aluminum Garnet) flash pumped laser intended for tattoo removal. Like most of its ilk, the YAG crystal at the heart of that device is a rosy purple color, so when [Les] spotted a Yellow YAG with different doping promising powerful pulses, he purchased it promptly.

Specifically, the retailer was claiming a 30-50% efficiency increase for this yellow rod, thanks to cerium doping. It’s still considered an Nd:YAG, though you can label it as an Nd:Ce:YAG for clarity. The efficiency gain comes from the cerium atom taking unused energy from the flashbulb pulse — which is much broader-wavelength than the thin absorption line of the Nd ions in the rod — and giving that energy to the Nd atoms that do the lasing via fluorescence. He doesn’t try it, but reports on a paper showing these crystals can actually lase with reasonable efficiency from sunlight alone, which we’d love to see. Send us a tip if you try.

His original Nd:YAG rod produced 72.8 mJ pulses, while in the same setup with the yellow laser is peaking at 153 mJ, more than double the original output. That’s even better than the 30-50% [Les] expected, but he reckons it is because the old YAG is, well, old. The coatings break down over time, and UV light from the flashbulbs degrades the crystals too. That’s another benefit of tossing cerium in there, as apparently it acts as sunscreen for your laser rod. It lasts longer and works better, making it a no-brainer of an upgrade.

We’ve seen [Les]’s laser-based hacking before, like this  diode-laser PSU and we’re always glad to take a look with our remaining eye. We also featured his tattoo removal laser back when he started working on it, along with less-lasery projects like his crystal-growing rig.

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A Versatile PDP-11/70 Emulator

August 3, 2026 by 6 Comments

The PDP-11 was a 16-bit minicomputer that was very influential in its time. That’s what inspired [vanheusden] to start working on an emulator for the machine in 2018, which has since been developed to run on a wide variety of platforms. 

The emulator, named “Kek,” is quite capable, able to run Unix 5 up to an d including Unix 7 in multi-user mode, along with BSD 2.11 Unix depending on what it’s running on. It also supports classic hardware like RK05, RL02, RP06, and RP07 disks, the KW11-L line time clock, and the DC-11 serial line interface. The emulator can also run on a wide variety of platforms. It’s possible to run it on a standard Linux machine if so desired, or you can run it on BSD, MacOS, or Windows if so desired. Beyond that, you can even get it going on a Teensy 4.1 or an ESP32 if that’s more your jam. Modern microcontrollers are just that powerful that emulating a PDP-11/70 just isn’t a challenge anymore.

We love seeing old machines emulated and brought back to life. It’s funny to see how often it’s done on microcontrollers instead of full-scale PCs these days, too. Video after the break.

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