How To Restore A Musical Amiga

December 24, 2022 by Bryan Cockfield 21 Comments

Despite the huge strides in computing power and functionality that have been achieved in the past few decades, there are still some things that older computers can do which are basically impossible on modern machines. This doesn’t just include the ability to use older hardware that’s now obsolete, either, although that is certainly a perk. In this two-part restoration of an Amiga 500, [Jeremy] shows us some of these features like the ability to directly modify the audio capabilities of this retro machine.

The restoration starts by fixing some damage and cleaning up the rest of the machine so it could be powered up for the first time in 30 years. Since it was in fairly good shape he then started on the fun part, which was working with this computer’s audio capabilities. It includes a number of amplifiers and filters in hardware that can be switched on or off, so he rebuilt these with new op-amps and added some new controls so that while he is using his MIDI software he can easily change how it sounds. He also restored the floppy disk drives and cleaned up the yellowing on the plastic parts to improve the overall appearance, as well as some other general improvements.

These old Amigas have a lot going for them, but since [Jeremy] is a musician he mostly focused on bringing back some of the musical functionality of his childhood computer, although he did build up a lot of extra features in this machine as well. These types of audio circuits are not something found in modern computers, though, so to get a similar sound without using original hardware you’ll need to build something like this NES audio processing unit programmed in Verilog.

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Hackaday Links: November 13, 2022

November 13, 2022 by Dan Maloney 6 Comments

Talk about playing on hard mode! The news this week was rife with stories about Palmer Luckey’s murder-modified VR headset, which ostensibly kills the wearer if their character dies in-game. The headset appears to have three shaped charges in the visor pointing right at the wearer’s frontal lobe, and would certainly do a dandy job of executing someone. In a blog post that we suspect was written with tongue planted firmly in cheek, Luckey, the co-founder of Oculus, describes that the interface from the helmet to the game is via optical sensors that watch the proceeding on the screen, and fire when a certain frequency of flashing red light is detected. He’s also talking about ways to prevent the removal of the headset once donned, in case someone wants to tickle the dragon’s tail and try to quickly rip off the headset as in-game death approaches. We’re pretty sure this isn’t serious, as Luckey himself suggested that it was more of an office art thing, but you never know what extremes a “three commas” net worth can push someone to.

There’s light at the end of the Raspberry Pi supply chain tunnel, as CEO Eben Upton announced that he foresees the Pi problems resolving completely by this time next year. Upton explains his position in the video embedded in the linked article, which is basically that the lingering effects of the pandemic should resolve themselves over the next few months, leading to normalization of inventory across all Pi models. That obviously has to be viewed with some skepticism; after all, nobody saw the supply chain issues coming in the first place, and there certainly could be another black swan event waiting for us that might cause a repeat performance. But it’s good to hear his optimism, as well as his vision for the future now that we’re at the ten-year anniversary of the first Pi’s release.

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A small green circuit board with a tiny OLED display

An Oscilloscope Trigger For Vintage Video Processors

October 18, 2022 by Chris Wilkinson 8 Comments

Working on retro computers is rarely straightforward, as [ukmaker] recently found out while designing a new display interface. Their oscilloscope was having trouble triggering on the video signal produced by older video circuitry, so they created the Video Trigger for Retrocomputers.

The Texas Instruments TMS9918 video display controller was used across a range of 1980s game consoles and home computers, from the well-known ColecoVision to Texas Instruments’ own TI-99/4. Substantial retro computing heritage notwithstanding, the video output from this chip was (for reasons unknown) not quite compatible with the Hantek DSO1502P oscilloscope. And without a better understanding of the video signal, it was difficult to use the chip with newer TFT displays, being designed for CRT televisions with more forgiving NTSC tolerances.

Maybe a different scope would have solved the problem, but [ukmaker] had a feeling that the ‘scope needed an external trigger signal. The Video Trigger project uses a LM1881 sync separator to tease out the horizontal and vertical sync signals from the vintage video chip, with the output piped into an ATmega 328P. Along with a smattering of discrete components, the ATmega aids the user in selecting which line to frame a trigger on, and the slope of the horizontal sync signal to align to. A tiny OLED display makes configuration easy.

If this has piqued your interest, [ukmaker] also has a great write-up over on GitHub with all the gory details. Maybe it will help you in your next vintage computing caper. Having the right tool can make all the difference, like this homebrew logic meter for hobby electronics troubleshooting. Or if you want to know more about the mystical properties of analog NTSC video, we’ve covered that, too.

A small keyboard form factor retrocomputer with blue keys on a black background sits in front of a display and a LEGO model of the Space Shuttle. There are a number of jumper wires and a breadboard coming from an open panel on the right side of the machine.

Aqua PCB Is A Big Upgrade For The Mattel Aquarius

October 15, 2022 by Navarre Bartz 9 Comments

In case you weren’t around in the 80s, or you happened to blink, you may have missed the Mattel Aquarius computer. [Nick Bild] has a soft spot in his heart for the machine though and built the Aqua cartridge to make the Aquarius into a more usable machine.

Originally equipped with a mere 4 KB of RAM and a small, rubbery keyboard, it’s not too surprising that the Aquarius only lasted five months on the market. [Nick] decided on the cartridge slot to beef up the specs of this little machine given the small number of expansion ports on the device. Adding 32 KB of RAM certainly gives it a boost, and he also designed an SD card interface called Aqua Write that connects to the Aqua cartridge for easily transferring files from a more modern machine.

The Aqua Write uses an Arduino Mega 2560 to handle moving data between the SD card and the system’s memory. This is complicated somewhat because a “PLA sits between the Z80 and data bus that XORs data with a software lock code (initialized to a random value on startup).” [Nick] gets around this by running a small program to overwrite the lock code to zero after startup.

Getting data on and off retrocomputers can certainly be a challenge. If you’re trying to get files on or off another old machine, check out this Simple Universal Modem or consider Using a Raspberry Pi as a Virtual Floppy Drive.

Why Learn Ancient Tech?

October 15, 2022 by Elliot Williams 69 Comments

The inner orbits of the Hackaday solar system have been vibrating with the announcement of the 2022 Hackaday Supercon badge. The short version of the story is that it’s a “retrocomputer”. But I think that’s somehow selling it short a little bit. The badge really is an introduction to machine language or maybe a programming puzzle, a ton of sweet blinky lights and clicky buttons, and what I think of as a full-stack hacking invitation.

Voja Antonic designed the virtual 4-bit machine that lives inside. What separates this machine from actual old computers is that everything that you might want to learn about its state is broken out to an LED on the front face, from the outputs of the low-level logic elements that compose the ALU to the RAM, to the decoder LEDs that do double-duty as a disassembler. You can see it all, and this makes it an unparalleled learning aid. Or at least it gives you a fighting chance.

So why would you want to learn a made-up machine language from a non-existent CPU? Tom Nardi and I were talking about our experiences on the podcast, and we both agreed that there’s something inexplicably magical about flipping bits, calling the simplest of computer operations into action, and nonetheless making it do your bidding. Or rather, it’s anti-magical, because what’s happening is the stripping away of metaphors and abstractions. Peering not just behind, but right through the curtain. You’re seeing what’s actually happening for once, from the bottom to the top.

As Voja wrote on the silkscreen on the back of the badge itself: “A programmer who has never coded 1s and 0s in machine language is like a child who has never run barefoot on the grass.” It’s not necessary, or maybe even relevant, but learning a complex machine in its entirety is simultaneously grounding and mind-expanding. It is simply an experience that you should have.

Building A Replica Of An Obscure Romanian Computer

September 29, 2022 by Lewin Day 5 Comments

We’ve all seen emulated Apple II and Commodore 64 boards about the place. Few of us have heard of the Romanian ZX Spectrum clone known as the Cobra, let alone any efforts to replicate one. However, [Thomas Sowell] has achieved just that, and has shared the tale with us online.

The Cobra was named for its origins in the city of Brasov – hence, COmputer BRasov. The replica project was spawned for a simple reason. Given that sourcing an original Romanian Cobra would be difficult, [Thomas] realized that he could instead build his own, just as many Romanians did in the 1980s. He set about studying the best online resources about the Cobra, and got down to work.

The build started with board images sourced from Cobrasov.com, and these were used to get a PCB made. [Thomas] decided to only use vintage ICs sourced from the Eastern Bloc for authenticity’s sake, too. Most came from the former USSR, though some parts were of East German, Romanian, or Czechoslovakian manufacture. The project took place prior to the Russian invasion of Ukraine, so there weren’t any hassles shipping across borders.

With everything hooked up and the EEPROMs given a real Cobra ROM image, the computer burst into life. There were some hiccups, with an overheating video IC and some memory glitches. However, with some nifty tweaks and replacements subbed in, the computer came good. Other work involved adding a custom keyboard and modifying 3.5″ floppy drives to work with the system.

Overall, the build is a faithful tribute to what was an impressive piece of engineering from behind the Iron Curtain. [Thomas]’s work also embodies the DIY ethos behind many homebrew Cobra computers built back in the day.

If all this talk has got you curious about the full history of the Cobra and Romania’s underground computer movement, we have everything you’re looking for right here!

Tiny Dongle Brings The Hard Drive’s Song Back To Updated Retrocomputers

September 26, 2022 by Dan Maloney 28 Comments

Back in the “beige box” days of computing, it was pretty easy to tell what your machine was doing just by listening to it, because the hard drive was constantly thrashing the heads back and forth. It was sometimes annoying, but never as annoying as hearing the stream of Geiger counter-like clicks stop when you knew it wasn’t done loading a program yet.

That “happy sound” is getting harder to come by, even on retro machines, which increasingly have had their original thrash-o-matic drives replaced with compact flash and other solid-state drives. This HDD sound simulator aims to fill that diagnostic and nostalgic gap on any machine that isn’t quite clicky enough for you. Sadly, [Matthias Werner] provides no build details for his creation, but between the longish demo video below (by a satisfied customer) and the details of the first version, it’s easy enough to figure out what’s going on here. An ATtiny and a few support components ride on a small PCB along with a piezoelectric speaker. The dongle connects to the hard drive activity light, which triggers a series of clicks from the speaker that sound remarkably like a hard drive heading seeking tracks. A demo starts at 7:09 in the video below; the very brave — or very nostalgic — might want to check out the full defragmentation that starts at 13:11.

Sure, this one is perhaps a bit over-the-top, but in the retrocomputing world, no price is too high to pay in the name of nostalgia. And it’s still far from the most ridiculous hard drive activity indicator we’ve seen.

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