The Apple II MouseCard (Credit: AppleLogic.org)

The Apple II MouseCard IRQ Is Synced To Vertical Blanking After All

Recently [Colin Leroy-Mira] found himself slipping into a bit of a rabbit hole while investigating why only under Apple II MAME emulation there was a lot of flickering when using the (emulated) Apple II MouseCard. This issue could not be reproduced on real (PAL or NTSC) hardware. The answer all comes down to how the card synchronizes with the system’s vertical blanking (VBL) while drawing to the screen.

The Apple II MouseCard is one of the many peripheral cards produced for the system, originally bundled with a version of MacPaint for the Apple II. While not a super popular card at the time, it nevertheless got used by other software despite this Apple system still being based around a command line interface.

According to the card’s documentation the interrupt call (IRQ) can be set to 50 or 60 Hz to match the local standard. Confusingly, certain knowledgeable people told him that the card could not be synced to the VBL as it had no knowledge of this. As covered in the article and associated MAME issue ticket, it turns out that the card is very much synced with the VBL exactly as described in The Friendly Manual, with the card’s firmware being run by the system’s CPU, which informs the card of synchronization events.

The Nuclear War You Didn’t Notice

We always enjoy [The History Guy], and we wish he’d do more history of science and technology. But when he does, he always delivers! His latest video, which you can see below, focuses on the Cold War pursuit of creating transfermium elements. That is, the discovery of elements that appear above fermium using advanced techniques like cyclotrons.

There was a brief history of scientists producing unnatural elements. The two leaders in this work were a Soviet lab, the Joint Institute of Nuclear Research, and a US lab at Berkeley.

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Antique Mill Satisfies Food Cravings

Everyone knows what its like to get a hankering for a specific food. In [Attoparsec]’s case, he wanted waffles. Not any waffles would do, though; he needed waffles in the form of a labyrinth. Those don’t exist, so he had to machine his own waffle maker.

Antique pantograph mill
When computers were the size of rooms, these stood in where we’d use CNC today.

Most of us would have run this off on a CNC, but [Attoparsec] isn’t into CNCing–manual machining is his hobby, and he’s not interested in getting into another one, no matter how much more productive he admits it might make him. We can respect that. After a bit of brain sweat thinking of different ways to cut out the labyrinth shape, he has the opportunity to pick up an antique Deckle pantograph mill.

These machines were what shops used to do CNC before the ‘computer numeric’ part was a thing. By tracing out a template (which [Attoparsec] 3D prints, so he’s obviously no Luddite) complex shapes can be milled with ease. Complex shapes like a labyrnthine wafflemaker. Check out the full video below; it’s full of all sorts of interesting details about the machining process and the tools involved.

If you don’t need to machine cast iron, but are interested in the techniques seen here, a wooden pantorouter might be more your speed than a one-tonne antique. If you have a hankering for waffles but would rather use CNC, check out these design tips to help you get started. If pancakes are more your style, why not print them?

Shoutout to [the gambler] for sending this into the tip line. We think he struck the jackpot on this one. If you have a tip, don’t be shy. Continue reading “Antique Mill Satisfies Food Cravings”

Inside A Selective Voltmeter

[Martin Lorton] has a vintage Harmon 4200B selective voltmeter that needed repair. He picked it up on eBay, and he knew it wasn’t working, but it was in good condition, especially for the price. He’s posted four videos about what’s inside and how he’s fixing it. You can see the first installment below.

The 4200B is an RMS voltmeter and is selective because it has a tuned circuit to adjust to a particular frequency. The unit uses discrete components and has an analog meter along with an LCD counter.

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A Single Chip Computer For The 8051 Generation

The Intel 8051 series of 8-bit microcontrollers is long-discontinued by its original manufacturer, but lives on as a core included in all manner of more recent chips. It’s easy to understand and program, so it remains a fixture despite much faster replacements appearing.

If you can’t find an original 40-pin DIP don’t worry, because [mit41301] has produced a board in a compatible 40-pin format. It’s called the single chip computer not because such a thing is a novelty in 2025, but because it has no need for the support chips which would have come with the original.

The modern 8051 clone in use is a CH558 or CH559, both chips with far more onboard than the original. The pins are brought out to one side only of the board, because on the original the other side would interface with an external RAM chip. It speaks serial, and can be used through either a USB-to-serial or Bluetooth-to-serial chip. There’s MCS-BASIC for it, so programming should be straightforward.

We can see the attraction of this board even though we reach for much more accomplished modern CPUs by choice. Several decades ago the original 8051 on Intel dev boards was our university teaching microcontoller, so there remains here a soft spot for it. We certainly see other 8051 designs, as for example this Arduino clone.

Supercon 2024: An Immersive Motion Rehabilitation Device

When you’ve had some kind of injury, rehabilitation can be challenging. You often need to be careful about how you’re using the affected parts of your body, as well as pursue careful exercises for repair and restoration of function. It can be tedious and tiring work, for patients and treating practitioners alike.

Juan Diego Zambrano, Abdelrahman Farag, and Ivan Hernandez have been working on new technology to aid those going through this challenging process. Their talk at the 2024 Hackaday Supercon covers an innovative motion monitoring device intended to aid rehabilitation goals in a medical context.

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Hackaday Podcast Episode 320: A Lot Of Cool 3D Printing, DIY Penicillin, And An Optical Twofer

This week, Hackaday’s Elliot Williams and Kristina Panos met up across the universe to bring you the latest news, mystery sound, and of course, a big bunch of hacks from the previous week.

In Hackaday news, the 2025 Pet Hacks Contest rolls on. You have until June 10th to show us what you’ve got, so head over to Hackaday.IO and get started today!

On What’s That Sound, Kristina actually got it this time, although she couldn’t quite muster the correct name for it, however at Hackaday we’ll be calling it the “glassophone” from now on. Congratulations to [disaster_recovered] who fared better and wins a limited edition Hackaday Podcast t-shirt!

After that, it’s on to the hacks and such, beginning with a complete and completely-documented wireless USB autopsy. We take a look at a lovely 3D-printed downspout, some DIY penicillin, and a jellybean iMac that’s hiding a modern PC. Finally, we explore a really cool 3D printing technology, and ask what happened to typing ‘www.’.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download in DRM-free MP3 and savor at your leisure.

Continue reading “Hackaday Podcast Episode 320: A Lot Of Cool 3D Printing, DIY Penicillin, And An Optical Twofer”