Line Printer Does Its Best Teletype Impression

December 3, 2019 by Tom Nardi 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.

Upgrade Board Turns Typewriter Into A Teletype

November 14, 2019 by Tom Nardi 24 Comments

It may come as little surprise to find that Hackaday does not often play host to typewriter projects. While these iconic machines have their own particular charm, they generally don’t allow for much in the way of hardware modification. But then the IBM Wheelwriter 1000 isn’t exactly a traditional typewriter, which made its recent conversion to a fully functional computer terminal possible.

A product of the Computer History Museum’s [IBM 1620 Jr. Team], this modification takes the form of a serial interface board that can be built at home and installed into the Wheelwriter. The board allows the vintage electronic typewriter to speak RS-232 and USB, so it can be connected to whatever vintage (or not so vintage) computer you can imagine. The documentation for the project gives a rough cost of $150, though that does assume you’ve already got a Wheelwriter 1000 kicking around.

The GitHub repository includes everything you need to create your own board, and there’s even a highly detailed installation guide that goes over the case modifications necessary to get the new hardware installed. It also explains that you’ll want to get a new keycap set for your Wheelwriter if you perform this modification, as the original board doesn’t have all of the ASCII characters.

So why adapt an old electric typewriter to function as a teletype? As explained by the [IBM 1620 Jr. Team], there are projects out there looking to recreate authentic 1960s-era computing experiences that need a (relatively) affordable paper terminal. The originals are too rare to use in modern recreations, but with their adapter board, these slightly less archaic input devices can be used in their place.

Once you’ve built your new teletype, or in the somewhat unlikely event you already have one at the ready, we’ve seen a couple of projects that you might be interested in to put it to use.

AI-Enabled Teletype Live Streams Nearly Coherent Conversations

May 23, 2019 by Dan Maloney 17 Comments

If you’ve got a working Model 33 Teletype, every project starts to look like an excuse to use it. While the hammering, whirring symphony of a teleprinter going full tilt brings to mind a simpler time of room-sized computers and 300 baud connections, it turns out that a Teletype makes a decent AI conversationalist, within the limits of AI, of course.

The Teletype machine that [Hugh Pyle] used for this interesting project, a Model 33 ASR with the paper tape reader, is a nostalgia piece that figures prominently in many of his projects. As such, [Hugh] has access to tons of Teletype documentation, so when OpenAI released their GPT-2 text generation language model, he decided to use the docs as a training set for the model, and then use the Teletype to print out text generated by the model. Initial results were about as weird as you’d expect for something trained on technical docs from the 1960s. The next step was obvious: make a chat-bot out of it and stream the results live. The teletype can be seen clattering away in the recorded stream below, using the chat history as a prompt for generating text responses, sometimes coherent, sometimes disturbing, and sometimes just plain weird.

Alas, the chat-bot and stream are only active a couple of times a week, so you’ll have to wait a bit to try it out. But it looks like a fun project, and we appreciate the mash-up of retro tech and AI. We’ve seen teleprinters revived for modern use before, both for texting and Tweeting, but this one almost has a mind of its own.

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Texting With A Teletype

April 23, 2019 by Brian Benchoff 13 Comments

How do you get the kids interested in old technology? By connecting it to a phone, obviously. Those kids and their phones. When [Marek] got his hands on an old-school teletype, he hooked it up to a GSM network, with all the bells and whistles including a 40mA current loop running at an impressive 50 baud.

The teletype in question here is a vintage T100 teletype manufactured in Czechoslovakia sometime in the ’70s. This was a gift to [Marek]’s workplace, the museum of Urban Engineering in Cracow, and this project is effectively an experiment to investigate the possibility of running this teletype as an interactive exhibit rather than an artefact from the age of current loops and phone systems.

The current loop is, or was, the standard way of connecting a teletype to anything, so all [Marek] had to do was construct a box that translated the signals from a GSM modem to this current loop. For the prototype, the microcontroller in question is an old AT89C2051 (as that’s what was sitting in the parts drawer). This was moved over to a PIC32 microcontroller and a SIM800 GSM module. This is housed in a two-part enclosure, with the GSM interfaced housed in one half, with the current loop generator consisting of a simple DC power supply housed int the other half.

This interface is capable of receiving and sending messages from the keyboard to a GSM network, so it is theoretically possible you could text your friends using an old-school teletype. This functionality hasn’t been implemented yet, but it is just about the coolest thing you could possibly imagine. You can check out a video of the teletype in action below. Continue reading “Texting With A Teletype” →

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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Ancient Teletype Revived In Labor Of Retrocomputing Love

August 2, 2018 by Dan Maloney 19 Comments

Readers with not too many years under their belts may recall a time when the classic background sound effect for radio and television news programs included a staccato mechanical beat, presumably made by the bank of teletype machines somewhere in the studio, clattering out breaking stories onto rolls of yellow paper. It was certainly true that teletypes were an important part of the many communications networks that were strung together over the 20th century, but these noisy, greasy beasts had their day and are now largely museum pieces.

Which is exactly where the ancient Model 19 Teletype machine that [CuriousMarc] and company are restoring is destined. Their ongoing video series, six parts long as of this writing, documents in painstaking detail how this unit worked and how they are bringing it back to its 1930s glory. Teletypes were made to work over telephone lines with very limited bandwidth, and the hacks that went into transmitting text messages with a simple 5-bit encoding scheme are fascinating. The series covers the physical restoration of the machine, obviously well-loved during its long service with the US Navy. Of particular interest is the massive power supply with its Thyratron tubes and their mysterious blue glow.

The whole series is worth a watch if you’re even slightly interested in retrocomputing. We’re particularly taken with the mechanical aspects of these machines, though, which have a lot in common with mechanical calculators. [Al Williams] recently covered the non-replacement of the power supply caps for this unit, which is an interesting detour to this restoration.

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Bringing A Teletype Into The 21st Century

July 3, 2016 by Brian Benchoff 9 Comments

Before modern CRTs with ancient VGA connectors, and before fancy video terminals, the display for computers large and slightly smaller was the Teletype. While many of these Teletypes were connected directly, they were designed to be a remote terminal, connected through Ma Bell’s network. [NeXT] over on the Vintage Computer Forums is bringing the iconic ASR33 Teletype into the 21st century by giving this old display a modern way to connect to the outside world.

If you ever see a Teletype in action, it will be connected to a local machine. This was certainly not always the case. The Teletype was designed to connect to remote systems. [NeXT]’s Teletype came with a Call Control Unit designed for Telex lines, which do not exist anymore. Modems for the ASR33 existed, but good luck finding one. Lucky for [NeXT], nearly every modem ever made is backwards-compatible with the Bell Dataphone, one of the standard ways of plugging a Teletype into a phone line. All [NeXT] had to do was put a modem inside this Teletype.

With relays, transistors, LEDs, and a lot of perfboard, [NeXT] successfully built a circuit that would interface the Teletype’s Call Control Unit to a Hayes Smartmodem tucked away inside the stand. Believe it or not, this is an exceptionally useful build; if you ever find a Teletype tucked away in the back of an old office, in a surplus shop, or on Craigslist, odds are it won’t be compatible with any modern electronics. That’s not to say land lines are particularly modern, but since there’s a microcontroller included in the new circuitry, it’s relatively easy to add a USB port to this ancient terminal.