teletype

22 Articles

Selectric Typewriter Goes From Trash Can To Linux Terminal

July 25, 2023 by 19 Comments

If there’s only lesson to be learned from [alnwlsn]’s conversion of an IBM Selectric typewriter into a serial terminal for Linux, it’s that we’ve been hanging around the wrong garbage cans. Because that’s where he found the donor machine for this project, and it wasn’t even the first one he’s come across in the trash. The best we’ve ever done is a nasty old microwave.

For being a dumpster find, the Selectric II was actually in pretty decent shape. The first couple of minutes of the video after the break show not only the minimal repairs needed to get the typewriter back on its feet, but also a whirlwind tour of the remarkably complex mechanisms that turn keypresses into characters on the page. As it turns out, knowing how the mechanical linkages work is the secret behind converting the Selectric into a teletype, entirely within the original enclosure and with as few modifications to the existing mechanism as possible.

Keypresses are mimicked with a mere thirteen solenoids — six for the “latch interposers” that interface with the famous whiffletree mechanism that converts binary input to a specific character on the typeball, and six more that control thinks like the cycle bail and control keys. The thirteenth solenoid controls an added bell, because every good teletype needs a bell. For sensing the keypresses — this is to be a duplex terminal, after all — [alnwlsn] pulled a page from the Soviet Cold War fieldcraft manual and used opto-interrupters to monitor the positions of the latch interposers as keys are pressed, plus more for the control keys.

The electronics are pretty straightforward — a bunch of MOSFETs to drive the solenoids, plus an AVR microcontroller. The terminal speaks RS-232, as one would expect, and within the limitations of keyboard and character set differences over the 50-odd years since the Selectric was introduced, it works fantastic as a Linux terminal. The back half of the video is loaded with demos, some of which aptly demonstrate why a lot of Unix commands look the way they do, but also some neat hybrid stuff, like a ChatGPT client.

Hats off to [alnwlsn] for tackling a difficult project while maintaining the integrity of the original hardware.

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Typewriter Mashup Becomes 120-Year-Old Teletype

April 5, 2023 by 13 Comments

Vintage typewriters can be beautiful and elegant devices. But there’s a limit to their value if, as with the 1903 Remington owned by [Daniel Ross], they are fire-damaged and have a seized mechanism. What did he do with what was essentially a piece of scrap metal? Produce an unholy mashup of the vintage machine and a 1988 Sharp daisy wheel typewriter to make a steampunk-style teletype, of course!

Stripping down both machines was evidently no easy task, and the result he’s achieved has the Sharp’s printer mechanism at 90 degrees to its original orientation sitting below the roller in the space once occupied by the Remington’s type bars. We’re sad to see that the keyboard on the older machine appears to be inoperable, but on the other hand each letter does light up as it’s typed.

Meanwhile at the electronics side the components from the Sharp have been transferred to a custom PCB, and the whole can be driven from a 300-baud serial line. As can be seen from the video below the break, the result is an unholy love-child of two typewriters that could scarcely be more different, but somehow it works to make an impressive whole.

If this project looks a little familiar to Hackaday readers, it’s because we’ve mentioned it in passing before. It’s hooked up to his COSMAC Elf retrocomputer, and we saw it in passing a couple of years ago at a much earlier stage of construction before the custom PCB and light-up keyboard.

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Retrotechtacular: A 1960s Look At The 21st Century Home

December 15, 2022 by 29 Comments

If you only watch the first 60 seconds of 1967’s “At Home, 2001,” you’ll be forgiven for thinking that the film is riddled with missed predictions. And to be sure, the cold open is rife with them, from disposable paper furniture to seashell-shaped houses that look like they’re extruded from concrete. Really, the only clear winner from that first tranche of predictions is the rise of the microwave oven, which given the expense of magnetrons in 1967 and the complexity of the electronics needed to drive them was a non-obvious development.

But pushing beyond that opening to the meat of this film reveals a fair number of domestic trends that actually did manage to come true, at least partially, and if not by 2001 then shortly thereafter. The film is an educational piece hosted by iconic American newsman Walter Cronkite, who lends his gravitas to the proceedings. The film opens with “Uncle Walter” sonorously pontificating on the unsustainability of the “ticky tacky” spawl of the suburbs and how the situation simply must change.

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Converting An 80s Typewriter Into A Linux Terminal

August 4, 2022 by 26 Comments

Typewriters may be long past their heyday, but just because PCs, word processor software, and cheap printers have made them largely obsolete doesn’t mean the world is better off without them. Using a typewriter is a rich sensory experience, from the feel of the keys under your fingers that even the clickiest of PC keyboards can’t compare with, to the weirdly universal sound of the type hitting paper.

So if life hands you a typewriter, why not put it back to work? That’s exactly what [Artillect] did by converting an 80s typewriter into a Linux terminal. The typewriter is a Brother AX-25, one of those electronic typewriters that predated word processing software and had a daisy wheel printhead, a small LCD display, and a whopping 8k of memory for editing documents. [Artillect] started his build by figuring out which keys mapped to which characters in the typewriter’s 8×11 matrix, and then turning an Arduino and two multiplexers loose on the driving the print head. The typewriter’s keyboard is yet used for input, as the project is still very much in the prototyping phase, so a Raspberry Pi acts as a serial monitor between the typewriter and a laptop. The video below has a good overview of the wiring and the software, and shows the typewriter banging out Linux command line output.

For now, [Artillect]’s typewriter acts basically like an old-school teletype. There’s plenty of room to take this further; we’d love to see this turned into a cyberdeck complete with a built-in printer, for instance. But even just as a proof of concept, this is pretty great, and you can be sure we’ll be trolling the thrift stores and yard sales looking for old typewriters.

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Almost-Modern TeleType Is Silent

December 8, 2021 by 25 Comments

If you’ve ever used a real TeleType machine or seen a movie with a newsroom, you know that one TeleType makes a lot of noise and several make even more.[CuriousMarc] acquired the silent replacement, a real wonder of its day, the TI Silent 703. The $2,600 machine was portable if you think hauling a 25-pound suitcase around is portable. In 1971, it was definitely a step up.

The machine used a thermal printer, could have a built-in acoustic coupler for talking over the phone. You could also get a dual tape drive that acted like a mostly silent paper tape reader and punch.

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Logging Into Linux With A 1930s Teletype

April 15, 2020 by 47 Comments

Buried deep within all UNIX-based operating systems are vestiges of the earliest days of computing, when “hardware” more often than not meant actual mechanical devices with cams and levers and pulleys and grease. But just because UNIX, and by extension Linux, once supported mechanical terminals doesn’t mean that getting a teletype from the 1930s to work with it is easy.

Such was the lesson learned by [CuriousMarc] with his recently restored Model 15 Teletype; we covered a similar Model 19 restoration that he tackled. The essential problem is that the five-bit Baudot code that they speak predates the development of ASCII by several decades, making a converter necessary. A task like that is a perfect job for an Arduino — [Marc] put a Mega to work on that — but the interface of the Teletype proved a bit more challenging. Designed to connect two or more units together over phone lines, the high-voltage 60-mA current loop interface required some custom hardware. The testing process was fascinating, depending as it did on an old Hewlett-Packard serial signal generator to throw out a stream of five-bit serial pulses.

The big moment came when he used the Teletype to log into Linux on a (more or less) modern machine. After sorting out the mysteries of the stty command, he was able to log in, a painfully slow process at 45.5 bps but still a most satisfying hack. The ASCII art — or is it Baudot art? — is a nice bonus.

We love restorations like these, and can practically smell the grease and the faint tang of ozone around this device. We’re not thrilled by the current world situation, but we’re glad [CuriousMarc] was able to use the time to bring off a great hack that honors another piece of our computing history.

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Line Printer Does Its Best Teletype Impression

December 3, 2019 by 22 Comments

Back in the early days of computing, user terminals utilized line printers for output. Naturally this took an incredible amount of paper, but it came with the advantage of creating a hard copy of everything you did. Plus it was easy to annotate the terminal output with nothing more exotic than a ballpoint pen. But once CRT displays became more common, these paper terminals (also known as teleprinters, or teletypes) quickly fell out of style.

A fan of nostalgic hacks, [Drew DeVault] recently tried to recreate the old-school teletype experience with (somewhat) more modern hardware. He picked up an Epson LX-350 line printer, and with a relatively small amount of custom code, he was able to create a fairly close approximation of what it would have been like to use one of these terminals. He’s published all the source code, so if you’ve got an old line printer and a Linux box, you too can learn what it was like to measure your work day in reams of paper.

This is made possible by the fact that the modern Linux virtual terminal is simply a userspace emulation of those physical terminals of yore. [Drew] just need to write some code that would essentially spawn a shell on the Linux USB line printer device, plus sprinkle in some quality of life improvements such as using Epson’s proprietary ANSI escape sequences to feed the paper out far enough so the user can see what it says before pulling it back in to write the next interactive line.

Of course, the experience isn’t perfect as the printer naturally doesn’t have a keyboard attached to it. If you’re looking for something a bit more authentic, you could always convert an old electric typewriter into a modern-ish teletype.