Ants, Dirt, Rain, And The Commodore 64 That Wouldn’t Quit

October 3, 2018 by Dan Maloney 34 Comments

Some electronics gear is built for the roughest conditions. With rugged steel cases, weatherproof gaskets, and cables passing through sealed glands, these machines are built to take the worst that Mother Nature can throw at them, shrugging off dust, mud, rain, and ice. Consumer-grade computers from the start of the home PC era, however, are decidedly not such machines.

Built to a price point and liable to succumb to a spilled Mountain Dew, few machines from that era that received any kind of abuse lived to tell the tale. Not so this plucky Commodore 64C, which survived decades exposed to the elements. As [Adrian Black] relates in the video below, this machine was on a scrap heap in an Oregon field, piled there along with other goodies by one of those “pickers” that reality TV loves so much. The machine was a disaster. It hadn’t been soaked in oil, but it was loaded with pine needles and an ant colony. The worst part, though, was the rust. The RF shielding had corroded into powder in some places, leaving reddish rust stains all over the place. Undeterred, [Adrian] gave the machine a good bath, first in water, then in isopropanol. Liberal applications of Deoxit helped with header connections, enough to see that the machine miraculously booted. It took some finagling, especially with the 6526 I/O controller, but [Adrian] was eventually able to get everything on the motherboard working, even the sound chip.

Whether this machine survived due to good engineering or good luck is debatable, but it’s a treat to see it come back to life. We hope a full restoration is in the works, not least as a way to make up for the decades of neglect.

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Fixing An IBM 1401 Computer To Get It Printing Again

September 20, 2018 by Steven Dufresne 10 Comments

The IBM 1401 is a classic computer which IBM marketed throughout the 1960s, late enough for it to have used transistors rather than vacuum tubes, which is probably a good thing for this story. For small businesses, it was often used as their main data processing machine along with the 1403 printer. For larger businesses with mainframes, the 1401 was used to handle the slower peripherals such as that 1403 printer as well as card readers.

The Computer History Museum in Mountain View, CA has two working 1401s as well as at least one 1403 printer, and recently whenever the printer printed out a line, the computer would report a “print check” error. [Ken Shirriff] was among those who found and fixed the problem and he wrote up a detailed blog entry which takes us from the first test done to narrow down the problem, through IBM’s original logic diagrams, until finally yanking out the suspect board and finding the culprit, a germanium transistor which likely failed due to corrosion and an emitter wire that doesn’t look solidly connected. How do they know that? In the typical [Ken]-and-company style which we love, they opened up the transistor and looked at it under a microscope. We get the feeling that if they could have dug even deeper then they would have.

If you’re unfamiliar with the work of this team who maintain the machines at the museum, you’ll want to read up on how they recently got a 1401 to run FORTRAN II code.

Electromagnetic Field: Speczilla!

September 15, 2018 by Jenny List 9 Comments

It is a golden rule of the journalist’s art, that we report the news, we don’t make it. But just occasionally we find ourselves in the odd position of being in the right place such that one of our throwaway comments or actions has the unintended consequence of seeding a story. This is one of those moments, so it’s a rare case of use of the first person in a daily piece as your scribe instead of Hackaday’s usual second person.

At the SHA2017 hacker camp in the Netherlands, [Matt “Gasman” Westcott] gave his presentation on composing a chiptune from an audience suggestion. Afterwards my Tweet about never having seen a Sinclair Spectrum as large as the one on the presentation screen grew a life of its own and became the idea for a project, which in turn at Electromagnetic Field 2018 was exhibited as a giant-sized fully working Sinclair ZX Spectrum.

Since much of the work was performed in Oxford Hackspace I saw Matt’s progression, his first experiments with foam rubber keys, then as he refined his two-wire switch mechanism. Early experiments hooking a row of them up to a real Spectrum motherboard weren’t the success he’d hoped for, so he moved to the FUSE emulator on a Raspberry Pi. A huge effort and needlework learning curve plus a lot of help from OxHack’s textile specialists and buying his local furniture store’s entire stock of foam allowed him to perfect a facsimile of the classic Spectrum’s case and blue rubber keys, while its lettering and iconic BASIC keywords were vinyl-cut at rLab in Reading. A Milton Keynes Makerspace member provided transport to the camp where it was united with a huge TV in a gazebo, completing the trio of local spaces.

At the camp, though it suffered a few technical hitches along the way it was rather a success. There were two techniques, kneeling down and pressing keys with the palm of your hand, or dancing on them in socked feet for complex manoeuvres. The trademark single-key-press BASIC keywords took a little while to re-learn though, there was a time when those were instinctive.

We’d normally wrap a piece like this one up with a link or two. To other projects perhaps, or other hacks from the same person. But in this case we have neither another home computer on this scale, nor any hacks from [Matt], as he’s well known in the European arm of our community for something completely different. As [Gasman] he’s a chiptune artist par excellence, as you can see if you watch his set from the 2014 Electromagnetic Field.

TI(ny) Is A New Take On The TI-99/4A

September 12, 2018 by Lewin Day 23 Comments

Way back in the 1980s, in the heyday of the personal computer revolution, Texas Instruments were one of the major players. The TI-99/4A was one of their more popular machines, selling 2.8 million units after an epic price war with the Commodore VIC-20. However once it had been discontinued, fans were left wanting more from the platform. Years later, that led [Fabrice] to produce the TI(ny), his take on an upgraded, more integrated TI-99/4A (Google Translate link).

Having spent many years working on these machines, [Fabrice] was very familiar with the official TI schematics – regarding both their proper use and their errors, omissions and inaccuracies. With a strong underlying knowledge of what makes a TI-99/4A tick, he set out to pen his own take on an extended model. [Fabrice] rolls in such features as Atari-compatible joystick ports, slot connectors for PeBOX expansion cards, and an RGB video output. It’s then all wrapped up in a very tidy looking case of somewhat unclear construction; it appears to be modified from an existing small computer case, and then refinished to look almost stock.

The best detail, though? It’s all made with components available in 1983! We see a lot of retro builds that are the equivalent of throwing a modern fuel-injected V8 into a vintage muscle car, and they are fantastic – but this is a project that shows us what was possible way back when.

Overall it’s a tidy build that shows what the TI-99/4A could have been if it was given a special edition model at the end of its life. If you’re looking to relive the glory days of the machine yourself, what better way then firing up the best demo on the platform? As the saying goes – Don’t Mess With Texas.

[Thanks to g_alen_e for the tip!]

A Switching Power Supply, 1940s-Style

September 8, 2018 by Dan Maloney 26 Comments

“They don’t build ’em like they used to.” There’s plenty of truth to that old saw, especially when a switch-mode power supply from the 1940s still works with its original parts. But when said power supply is about the size of a smallish toddler and twice as heavy, building them like the old days isn’t everything it’s cracked up to be.

The power supply that [Ken Shirriff] dives into comes from an ongoing restoration of a vintage teletype we covered recently. In that post we noted the “mysterious blue glow” of the tubes in the power supply, which [Ken] decided to look into further. The tubes are Thyratrons, which can’t really be classified as vacuum tubes since they’re filled with various gasses. Thyratrons are tubes that use ionized gas – mercury vapor in this case – to conduct large currents. In this circuit, the Thyratrons are used as half-wave rectifiers that can be rapidly switched on and off by a feedback circuit. That keeps the output voltage fixed at the nominal 140V DC required by the teletype, with a surprisingly small amount of ripple. The video below is from a series on the entire restoration; this one is cued to where the power supply is powered up for the first time. It’s interesting to see the Thyratrons being switched at about 120 Hz when the supply is under load.

Cheers to [Ken] and his retrocomputing colleagues for keeping the old iron running. Whether the target of his ministrations is a 1974 scientific calculator or core memory from an IBM 1401, we always enjoy watching him work.

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Detective Work Recovers Atari ST ASIC Designs

September 5, 2018 by Al Williams 28 Comments

[Christian Zietz] wanted to know more about the Atari ST. He found information online from newer Atari machines like the Falcon030 and the Jaguar, but couldn’t find much else. While looking through some archives of old disk images from the Atari headquarters, he found a folder marked “Drawings\4118.” With some detective work and emulation of an old operating system, he was able to recover the schematics for the ST-4118 video shifter ASIC (Application-Specific Integrated Circuit).

Unfortunately, this appeared to be a chip for the unreleased Atari Panther video game console. However, it did show the way to how these older schematics were readable. [Christian] continued searching and found some floppy disk images that were a bit unusual. They didn’t have a proper file system but had been created by a backup program called FastBack for MS-DOS.

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NASA Shows Off Its Big Computer In 1986

August 28, 2018 by Al Williams 55 Comments

Sometimes it is hard to remember just how far computers have come in the last three or four decades. An old NASA video (see below) has been restored with better sound and video recently that shows what passed for a giant computer in 1986. The Cray 2 runs at 250 MHz and had two gigabytes of memory (256 ~~megabytes of~~ million 64-bit words).

Despite the breathless praise, history hasn’t been kind to the Cray 2. Based on ECL, it had 4 processors and –in theory — could reach 1,900 megaFLOPs/second (a FLOP is a floating point operation). However, practical problems made it difficult to get to that theoretical maximum.

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