Vintage IBM 1403 Printer Problem Evades an Easy Fix

The Computer History Museum in Mountain View has two operational IBM 1401 mainframes, which use IBM 1403 high-speed printers. They aren’t some decades-old notion of “high speed” that barely looks sluggish today, either. These monsters slam out ten lines per second thanks to a rotating chain of type slugs and an array of electromagnetic hammers. Every 11.1 microseconds, a character in the chain would be lined up with a hammer, and if the control circuitry identified it as a character that needed to be printed, the hammer behind the paper would drive the paper into the print ribbon and the slug, putting an imprint of the character onto the paper. When one of these printers failed with a sync error, it kicked off some serious troubleshooting to diagnose the problem.

The IBM 1403’s type chain has a repeating set of characters that spins around at high speed. Unlike a typewriter or label maker, the hammers are not inside this unit. The hammers are on the outside, and work by pressing the paper onto the type slugs as the required characters line up.

Investigation of the problem ultimately led to an intermittent connection in a driver card due to a broken PCB trace, but by then some fuses had been blown as well. In the end the printer was brought back online, but possibly with a slightly damaged coil on one of the hammers.

[Ken]’s writeup on the repair process is highly detailed and walks through the kind of troubleshooting and repairs involved when solving problems with vintage electronics. Electrical fundamentals might be the same, but a deep understanding of not only the architecture but also the failure modes of vintage hardware is needed in order to troubleshoot effectively.

If IBM 1401 mainframes and fixing 1403 printers sounds familiar, it’s because a printer fix has been done before. That was due to a different problem, but still a challenging task to narrow down and fix.

“DB” = Abbreviated Microcontroller Debugging

We’ve all been there. When debugging a microcontroller project, we just want to put in a print statement to figure out what’s going on with the microcontroller in real time. However, advanced embedded programmers know that printf statements are verboten: they’re just too SLOW. While not fixing this plight entirely, [Atakan Sarioglu] has come up with a clever way to create readable debug messages with minimal runtime overhead.

[Atakan Sarioglu]’s innovation, called BigBug (Github), is a dynamically-generated codebook. The codebook translates abbreviated messages sent over serial (UART here) to longer-form human-readable messages. To generate the codebook, BigBug automatically parses your comments to create a lookup between an abbreviation and the long-form message. When you are running your program on the microcontroller, BigBug will translate the short codes to long messages in real-time as you send log/debug data over serial. Continue reading ““DB” = Abbreviated Microcontroller Debugging”

A Scratch Instrument For Ants

If you think that this scratch instrument looks as though it should be at least… three times larger in order to be useful, you’d be wrong. This mighty pocket-sized instrument can really get the club hopping despite its diminuitive size. Despite that, the quality of the build as well as its use of off-the-shelf components for almost every part means that if you need a small, portable turntable there’s finally one you can build on your own.

[rasteri] built the SC1000 digital scratch instrument as a member of the portabilist scene, focusing on downsizing the equipment needed for a proper DJ setup. This instrument uses as Olimex A13-SOM-256 system-on-module, an ARM microprocessor, and can use a USB stick in order to load beats to the system. The scratch wheel itself uses a magnetic rotary encoder to sense position, and the slider is miniaturized as well.

If you want to learn to scratch good and learn to do other things good too, there’s a demo below showing a demonstration of the instrument, as well as a how-to video on the project page. All of the build files and software are open-source, so it won’t be too difficult to get one for yourself as long as you have some experience printing PCBs. If you need the rest of the equipment for a DJ booth, of course that’s also something you can build.

Continue reading “A Scratch Instrument For Ants”

Behold The WT-220: A ‘Clever’ VT-220 Terminal

[John Whittington] failed to win a bid for an old VT-220 serial terminal on eBay, so he decided to make his own version and improve it along the way. The result is the Whitterm-220 (or WT-220) which has at its core a Raspberry Pi and is therefore capable of more than just acting as a ‘dumb’ serial terminal.

Rear of the WT-220 with paint-filled laser engraving and all necessary connectors.

The enclosure is made from stacked panels of laser-cut plywood with an acrylic plate on the back for labels and connectors, where [John] worked paint into the label engravings before peeling off the acrylic’s protective film. By applying paint after laser-engraving but before peeling off the film, it acts as a fill and really makes the text pop.

Near the front, one layer of clear acrylic among the plywood layers acts as a light guide and serves as a power indicator, also doing double duty as TX/RX activity lights. When power is on, that layer glows, serving as an attractive indicator that doesn’t interfere with looking at the screen. When data is sent or received, a simple buffer circuit tied to the serial lines lights up LEDs to show TX or RX activity, with the ability to enable or disable this functionality by toggling a GPIO pin. A video overview is embedded below, where you can see the unit in action.

Continue reading “Behold The WT-220: A ‘Clever’ VT-220 Terminal”

Woodworker Goes from 3D-Printing Skeptic to Believer

If there’s one place where the old ways of doing things live a longer life than you’d otherwise expect, it’s the woodshop. Woodworkers have a way of stubbornly sticking to tradition, and that usually works out fine. But what does it take to change a woodworker’s mind about a tool that seems to have little role in the woodshop: the 3D-printer?

That’s the question [Marius Hornberger] asked himself, and at least for him, there are a lot of woodworking gadgets that can be 3D-printed. [Marius] began his journey into additive manufacturing three years ago as a skeptic, not seeing how [Benchy] and friends could be of any value to his endeavors. But as is often the case with a tool that can build almost anything, all it takes is a little ingenuity to get started. His first tool was a pair of soft jaws for his bench vise. This was followed by a flood of useful doodads, including a clever center finder for round and square stock, custom panels for electrical switches, and light-duty pulleys for some of the machines he likes to build. But [Marius] obviously has an issue with dust, because most of his accessories have to do with helping control it in the shop. The real gem of this group is the hose clamp for spiral-reinforced vacuum hose; standard band clamps don’t fit well on those, but his clamps have an offset that straddles the wire for a neat fit. Genius!

[Marius] has kindly made all his models available on Thingiverse, so feel free to dig in and start kitting out your shop. Once you do maybe you can start building cool things like his all-wood scissors lift.

Continue reading “Woodworker Goes from 3D-Printing Skeptic to Believer”

Kitty Yeung On Tech-Fashion Designs and the Wearables Industry

If there is a field which has promise verging on a true breakout, it is that of wearable electronics. We regularly see 3D printing, retrocomputing, robotics, lasers, and electric vehicle projects whose advances are immediately obvious. These are all exciting fields in which the Hackaday community continually push the boundaries, and from which come the astounding pieces of work you read on these pages daily. Of course the projects that merge textiles and electronics are pushing boundaries in the same way, except for that it’s often not obvious at first glance. Why is that?

Wearables are a field in which hard work and ingenuity abound, but pulling off the projects that stand out and go beyond mere ordinary garments adorned with a few twinkly LEDs or EL wire is hard. Wearables have a sense of either still seeking its killer application or its technological enabler, and it was this topic that physicist, textilist, and artist Kitty Yeung touched upon in her talk at the recent Hackaday Superconference.

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Incredibly Heavy Ornament Likely Inappropriate To Hang On Tree

It’s that time of year again, and the Christmas hacks are flooding in thick and fast. To get into the Christmas spirit,  the FoxGuard team wanted a custom ornament to hang from the tree. They may have gotten more than they bargained for.

It’s a simple build that demonstrates the basic techniques of working with DACs and scopes in a charming holiday fashion. A Tektronix T932A analog oscilloscope is pressed into service as a display, by operating in XY mode. A Teensy 3.5 was then chosen for its onboard digital to analog converters, and used to output signals to draw a Christmas tree and star on the screen.

Old-school coders will appreciate the effort taken to plot the graphics out on graph paper. While the hack doesn’t do anything cutting edge or wild, it’s impressive how quick and easy this is thanks to modern development methods. While the technology to do this has existed for decades, a hacker in 1998 would have spent hours breadboarding a PIC microcontroller with DACs, let alone the coding required. We’ve come a long way.

It’s a bit of fun, but we highly recommend you don’t try and hang an analog scope off your tree at home. These WiFi-controlled ornaments are perhaps more suitable. Video after the break. Continue reading “Incredibly Heavy Ornament Likely Inappropriate To Hang On Tree”