A Tricky Commodore PET Repair And A Lesson About Assumptions

April 14, 2025 by Maya Posch 11 Comments

The PET opened, showing the motherboard. (Credit: Ken Shirriff)

An unavoidable part of old home computer systems and kin like the Commodore PET is that due to the age of their components they will develop issues that go far beyond what was covered in the official repair manual, not to mention require unconventional repairs. A case in point is the 2001 series Commodore PET that [Ken Shirriff] recently repaired.

The initial diagnosis was quite straightforward: it did turn on, but only displayed random symbols on the CRT, so obviously the ICs weren’t entirely happy, but at least the power supply and the basic display routines seemed to be more or less functional. Surely this meant that only a few bad ICs and maybe a few capacitors had to be replaced, and everything would be fully functional again.

Initially two bad MOS MPS6540 ROM chips had to be replaced with 2716 EPROMs using an adapter, but this did not fix the original symptom. After a logic analyzer session three bad RAM ICs were identified, which mostly fixed the display issue, aside from a quaint 2×2 checkerboard pattern and completely bizarre behavior upon running BASIC programs.

Using the logic analyzer capture the 6502 MPU was identified as writing to the wrong addresses. Ironically, this turned out to be due to a wrong byte in one of the replacement 2716 EPROMs as the used programmer wasn’t quite capable of hitting the right programming voltage. Using a better programmer fixed this, but on the next boot another RAM IC turned out to have failed, upping the total of failed silicon to four RAM & two ROM ICs, as pictured above, and teaching the important lesson to test replacement ROMs before you stick them into a system.

The host stands in his electronics lab with the image of four remote controls overlaid.

Introducing Infrared Remote Control Protocols

April 13, 2025 by John Elliot V 23 Comments

Over on his YouTube channel [Electronic Wizard] has released a video that explains how infrared (IR) remote controllers work: IR Remote Controllers protocol: 101 to advanced.

This video covers the NEC family of protocols, which are widely used in typical consumer IR remote control devices, and explains how the 38 kHz carrier wave is used to encode a binary signal. [Electronic Wizard] uses his Rigol DS1102 oscilloscope and a breadboard jig to sniff the signal from an example IR controller.

There is also an honorable mention of the HS0038 integrated-circuit which can interpret the light waves and output a digital signal. Of course if you’re a tough guy you don’t need no stinkin’ integrated-circuit IR receiver implementation because you can build your own!

Before the video concludes there is a brief discussion about how to interpret the binary signal using a combination of long and short pulses. If this looks similar to Morse Code to you that’s because it is similar to Morse Code! But not entirely the same, as you will learn if you watch the video!

The ProStar: The Portable Gaming System And Laptop From 1995

April 13, 2025 by Maya Posch 5 Comments

Whilst recently perusing the fine wares for sale at the Vintage Computer Festival East, [Action Retro] ended up adopting a 1995 ProStar laptop. Unlike most laptops of the era, however, this one didn’t just have the typical trackpad and clicky mouse buttons, but also a D-pad and four suspiciously game controller looking buttons. This makes it rather like the 2002 Sony VAIO PCG-U subnotebook, or the 2018 GPD Win 2, except that inexplicably the manufacturer has opted to put these (serial-connected) game controls on the laptop’s palm rest.

Though branded ProStar, this laptop was manufactured by Clevo, who to this day produces generic laptops that are rebranded by everyone & their dog. This particular laptop is your typical (120 MHz) Pentium-based unit, with two additional PCBs for the D-pad and buttons wired into the mainboard.

Unlike the sleek and elegant VAIO PCG-U and successors, this Clevo laptop is a veritable brick, as was typical for the era, which makes the ergonomics of the game controls truly questionable. Although the controls totally work, as demonstrated in the video, you won’t be holding the laptop, meaning that using the D-pad with your thumb is basically impossible unless you perch the laptop on a stand.

We’re not sure what the Clevo designers were thinking when they dreamed up this beauty, but it definitely makes this laptop stand out from the crowd. As would you, if you were using this as a portable gaming system back in the late 90s.

Our own [Adam Fabio] was at VCF East this year as well, and was impressed by an expansive exhibit dedicated to Windows 95.

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Hackaday Links: April 13, 2025

April 13, 2025 by Dan Maloney 9 Comments

It’s been a while since we’ve dunked on an autonomous taxi foul-up, mainly because it seemed for a while there that most of the companies field testing driverless ride-sharing services had either ceased operation or curtailed them significantly. But that appears not to be the case after a Waymo robotaxi got stuck in a Chick-fil-A drive-through. The incident occurred at the chicken giant’s Santa Monica, California location at about 9:30 at night, when the autonomous Jaguar got stuck after dropping off a passenger in the parking lot. The car apparently tried to use the drive-through lane to execute a multi-point turn but ended up across the entrance, blocking other vehicles seeking their late-evening chicken fix. The drive-through-only restaurant ended up closing for a short time while Waymo figured out how to get the vehicle moving again.

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An attractive orange CNC mill sitting ona bench.

3D Printed Milling Machine Is Solid As A Rock

April 13, 2025 by Tyler August 59 Comments

There are no shortage of CNC machines in the DIY space these days, but sometimes you just need to do things your own way. That’s what [Chris Borges] decided when he put together this rock-solid, concrete-filled CNC milling machine.

The concrete body of this machine is housed inside a 3D printed shell, which makes for an attractive skin as well as a handy mold. Within the concrete is a steel skeleton, with the ‘rebar’ being made of threaded rods and a length of square tubing to hold the main column. You can see the concrete being poured in around the rebar in the image, or watch it happen in the build video embedded below.

An image of the main column of [Chris]'s CNC mill as the concrete is added. The steel reinforcement is clearly visible. — In goes the concrete, up goes the rigidity.

All three axes slide on linear rails, and are attached to lead screws driven by the omnipresent NEMA 17 steppers. The air-cooled spindle, apparently the weak-point of the design, is attached to a pivoting counterweight, but make no mistake: it is on rails. All-in-all, it looks like a very rigid, and very capable design — [Chris] shows it cutting through aluminum quite nicely.

Given that [Chris] has apparently never used a true mill before, this design came out remarkably well. Between the Bill of Materials and 45 page step-by-step assembly instructions, he’s also done a fantastic job documenting the build for anyone who wants to put one together for themselves.

This isn’t the first concrete-filled project we’ve highlighted from [Chris], you may remember seeing his lathe on these pages. It certainly isn’t the first CNC mill we’ve covered, either.

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A slide from a talk about Spade language with a diagram about how it fits in with Verilog, VHDL, and HLS.

The Spade Hardware Description Language

April 13, 2025 by John Elliot V 15 Comments

Spade is an open-source hardware description language (HDL) developed at Linköping University, Sweden.

Other HDLs you might have heard of include Verilog and VHDL. Hardware engineers use HDLs to define hardware which can be rendered in silicon. Hardware defined in HDLs might look like software, but actually it’s not software, it’s hardware description. This hardware can be realized myriad ways including in an FPGA or with an ASIC.

You have probably heard that your CPU processes instructions in a pipeline. Spade has first-class support for such pipelines. This means that design activities such as re-timing and re-pipelining are much easier than in other HDLs where the designer has to implement these by hand. (Note: backward justification is NP-hard, we’re not sure how Spade supports this, if it does at all. If you know please enlighten us in the comments!)

Spade implements a type system for strong and static typing inspired by the Rust programming language and can do type inference. It supports pattern matching such as you might see in a typical functional programming language. It boasts having user-friendly and helpful error messages and tooling.

Spade is a work in progress so please expect missing features and breaking changes. The documentation is in The Spade Book. If you’re interested you can follow development on GitLab or Discord.

So now that you know about the Spade language, are you planning to take it for a spin? You will find plenty of Verilog/VHDL designs at Hackaday which you could re-implement using Spade, such as an easy one like Breathing LED Done With Raw Logic Synthesized From A Verilog Design (see benchmarks) or a much more challenging one like Game Boy Recreated In Verilog. If you give Spade a go we’d love to see what you come up with!

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Satisfy Your High-Voltage Urges With This Printable Flyback Transformer

April 13, 2025 by Dan Maloney 11 Comments

Sick of raiding old TVs and CRT monitors for flyback transformers to feed your high-voltage addiction? Never fear; if you’re careful, a 3D-printed flyback might be just the thing you’re looking for.

To be fair, it’s pretty easy to come by new flyback transformers, so building your own isn’t strictly necessary. But [SciTubeHD] was in the market for a particularly large flyback, in a good-natured effort to displace [Jay Bowles] from his lofty perch atop the flyback heap. And it’s also true that this project isn’t entirely 3D-printed, as the split core of the transformer was sourced commercially. The secondary coil, though, was where most of the effort went, with a secondary form made from multiple snap-together discs epoxied together for good measure. The secondary has about a kilometer of 30-gauge magnet wire while the primary holds just ten turns of 8-gauge wire covered with silicone high-voltage insulation.

To decrease the likelihood of arcing, the transformer was placed in a plastic container filled with enough mineral oil liquid dielectric to cover the secondary. After degassing in a vacuum chamber for a day, [SciTubeHD] hooked the primary to a couple of different but equally formidable-looking full-bridge inverters for testing. The coil was capable of some pretty spicy arcs — [SciTubeHD] measured 20 amps draw at 35 volts AC input, so this thing isn’t to be trifled with. STL files for the core parts are coming up soon; we trust schematics for the power supply will be available, too.

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