Revision D PCB of Mockingboard with GI AY-3-8913 PSGs.

Something Is Very Wrong With The AY-3-8913 Sound Generator

April 15, 2025 by Maya Posch 14 Comments

The General Instruments AY-3-8910 was a quite popular Programmable Sound Generator (PSG) that saw itself used in a wide variety of systems, including Apple II soundcards such as the Mockingboard and various arcade systems. In addition to the Yamaha variants (e.g. YM2149), two cut-down were created by GI: these being the AY-3-8912 and the AY-3-8913, which should have been differentiated only by the number of GPIO banks broken out in the IC package (one or zero, respectively). However, research by [fenarinarsa] and others have shown that the AY-3-8913 variant has some actual hardware issues as a PSG.

With only 24 pins, the AY-3-8913 is significantly easier to integrate than the 40-pin AY-3-8910, at the cost of the (rarely used) GPIO functionality, but as it turns out with a few gotchas in terms of timing and register access. Although the Mockingboard originally used the AY-3-8910, latter revisions would use two AY-3-8913 instead, including the MS revision that was the Mac version of the Mindscape Music Board for IBM PCs.

The first hint that something was off with the AY-3-8913 came when [fenarinarsa] was experimenting with effect composition on an Apple II and noticed very poor sound quality, as demonstrated in an example comparison video (also embedded below). The issue was very pronounced in bass envelopes, with an oscilloscope capture showing a very distorted output compared to a YM2149. As for why this was not noticed decades ago can likely be explained by that the current chiptune scene is pushing the hardware in very different ways than back then.

As for potential solutions, the [French Touch] project has created an adapter to allow an AY-3-8910 (or YM2149) to be used in place of an AY-3-8913.

Top image: Revision D PCB of Mockingboard with GI AY-3-8913 PSGs.

Continue reading “Something Is Very Wrong With The AY-3-8913 Sound Generator” →

Taking A $15 Casio F91W 5,000 Meters Underwater

February 1, 2025 by Maya Posch 42 Comments

When considering our favorite spy movies and kin that involve deep-sea diving, we’d generally expect to see some high-end watch that costs thousands of dollars and is specially engineered to withstand the immense pressures kilometers below the ocean’s surface. Yet what about a humble Casio F91W that can be bought for about $15 if it’s the genuine article and not one of the millions of fakes? Over at the Watches of Espionage site they figured that they’d dress up one of these famous watches to give it the best possible shot at surviving the crushing pressures at a depth of 5 km.

The actual modification to the F91W was pretty mild, involving nothing but a ‘hydro-mod’ whereby oil is used to replace the air inside the watch case. Since oil is incompressible, nothing bad should happen to the watch. Theoretically at least. The Watch-Under-Test (WUT) was strapped to a US Navy’s CURV 21 remotely operated vehicle and dunked into the ocean before starting its descend into the inky darkness of the deep sea.

Although only hitting a measly 4,950 m, the watch survived just fine, showing that even if you’re a secret US operative on a deep-dive espionage mission, all you really need is one of these Casio watches.

Hackaday Podcast Episode 291: Walking In Space, Lead In The Earth, And Atoms Under The DIY Microscope

October 4, 2024 by Al Williams 2 Comments

What have you missed on Hackaday this week? Elliot Williams and Al Williams compare notes on their favorites from the week, and you are invited. The guys may have said too much about the Supercon badge this year — listen in for a few hints about what it will be about.

For hacks, you’ll hear about scanning tunneling microscopes, power management for small Linux systems, and lots of inertial measurement units. The guys talked about a few impossible hacks for consumer electronics, from hacking a laptop, to custom cell phones.

Of course, there are plenty more long-form articles of the week, including a brief history of what can go wrong on a spacewalk and how to get the lead out (of the ground). Don’t forget to take a stab at the What’s That Sound competition and maybe score a sweet Hackaday Podcast T-shirt.

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!

Use this link to teleport a DRM-free MP3 to your location.

Continue reading “Hackaday Podcast Episode 291: Walking In Space, Lead In The Earth, And Atoms Under The DIY Microscope” →

Building The Unreleased Lemmings Arcade Cabinet From 1991

July 29, 2024 by Maya Posch 7 Comments

Back in the early 90s the world was almost graced with an arcade version of Lemmings, but after a few board revisions it was abandoned in 1991. Now the folk over at UK-based [RMC – The Cave] on YouTube have managed to not only get their mitts on a nearly finished prototype board, but have also designed and built a period-appropriate cabinet to go with it. This involved looking at a range of arcade cabinets created by Data East and picking a design that would allow both for the two-player mode of the game, and fit the overall style.

Arcade cabinets came in a wide range of cabinet styles and control layouts, largely defined by the game’s requirements, but sometimes with flourishes to distinguish the cabinet from the hundred others in the same arcade.

In this particular case the typical zig-zag (Z-back) style was found to be a good fit as on the Data East Night Slashers 1993-era cabinet, which then mostly left the controls (with two trackballs) and cabinet art to figure out. Fortunately there is plenty of inspiration when it comes to Lemmings art, leading to the finished cabinet with the original mainboard, the JAMMA wiring harness with MultiPi JAMMA controller, a 19″ CRT monitor and other components including the 3D printed controls panel.

With more and more new arcades popping up in the US and elsewhere, perhaps we’ll see these Lemmings arcade cabinets appear there too, especially since the ROMs on the prototype board were dumped for convenient MAME-ing.

Continue reading “Building The Unreleased Lemmings Arcade Cabinet From 1991″ →

FLOSS Weekly Episode 791: It’s All About Me!

July 10, 2024 by Jonathan Bennett 1 Comment

This week David Ruggles chats with Jonathan Bennett about his origin story! What early core memory does Jonathan pin his lifelong computer hobby on? And how was a tense meeting instrumental to Jonathan’s life outlook? And how did Jonathan manage to score a squashable brain toy from an equipment manufacturer? Watch the whole show to find out!

Continue reading “FLOSS Weekly Episode 791: It’s All About Me!” →

Building And Testing A 1912-style Radio

June 2, 2024 by Maya Posch 28 Comments

A glimpse at a high-end radio set, for 1912. (Credit: [glasslinger], YouTube)

Doing electronics in the 1910s was rather rough, with the radio probably the pinnacle of hi-tech. Despite this, with some know-how and basic wood- and metal-working skills you could get pretty far with DIY-ing a radio set. As [glasslinger] demonstrates in a YouTube video, you can even build your own set with your own crafted tube-amplifier. With items like a hand-crafted resistor and capacitor – as well as tuning elements and period-correct point-to-point wiring – it definitely has that retro vibe to it.

Such DIY projects used to be very commonly featured in electronics magazine, even after the transistor came onto the scene by the 1950s. The fancier designs use a regenerative design, like this one by [Dick Whipple] which provides not only some background theory, but also the full schematic and how-to in case you feel like giving it a shake yourself.

Even if you’re not into crafting your own basic electronic components, radios like these are a great introduction to a lot of RF theory and amplification basics.

Continue reading “Building And Testing A 1912-style Radio” →

The Chess Computer From 1912

July 3, 2023 by Al Williams 12 Comments

Who was [Leonardo Torres Quevedo]? Not exactly a household name, but as [IEEE Spectrum] points out, he invented a chess automaton in 1920 that would foreshadow the next century’s obsession with computers playing chess.

Don’t confuse this with the infamous Mechanical Turk, which appeared to be a chess computer but was really a guy hiding inside a fake chess computer. The Spanish engineer’s machine really did play a modified end game. The chessboard was vertical, and pegs represented pieces. There were mechanical arms to move the pegs. The device actually dates back to 1912, with a public demonstration in Paris in 1914. Given [Quevedo’s] native language, the machine was called El Ajedrecista.

Continue reading “The Chess Computer From 1912” →