It’s hard to believe this was ever high tech, but at one time the teletype was the absolute height of computer communications. What’s even more amazing is that most teletypes will still work with even the most modern computers with little more than a USB-to-serial converter and a little creative wiring.

One step ahead of blinking lights

When computers moved from blinking lights to actual words, operators craved a way to input commands through the use of a typewriter keyboard. It wasn’t until the 1950s that this was possible, and so arose this monstrosity:

Essentially what you see here is an electric typewriter, a phone and some other parts all frankensteined together to form an input device. It typed on long rolls and you could also save your work on long strips of paper tape if you need. This device sat as high as a standalone ATM machine and was about twice as wide. It was called a teletype.

I actually played with one when I was pretty young in a computer facility. I remember it looking an awful lot like what you see in the picture above you. In addition to the dial so you could connect, It also had a paper tape reader, the device on the left. It stored digital data on rolls of thin paper and read the data back in incredibly slowly. That’s a subject for another article, I guess.

The amazing teletype

What was amazing about the teletype was that you could access computers anywhere in the world with them using their rotary dial feature. (I am not making this up.) You dialed the number and then the computer would answer. It wasn’t all as automatic as you might remember dial-up networking, but it was still awesome. What it wasn’t was fast. A good teletype connection could do about 30 words a minute, which translates roughly to .00001Mbps, or one-one-hundred-thousandth as fast as the wired network connection in your home. That was usually fast enough for the average programmer to key in what he needed.

What was even more incredible was the two-way nature of the communication. You typed commands into the computer and it responded. Not, you know, really in any way that normal humans could understand at first, but eventually computers were programmed to respond with something reasonably like english, even though their favorite words were some variation of SYNTAX ERROR. (Computers didn’t understand lower case letters until much later.)

The teletype lives on… sorta

The teletype machine’s simple protocol is still with us as part of the terminal programs built into every Windows, Mac and Linux machine. They’re so simple that they take up practically no space so there’s no reason to remove them. I’m sure some hipster has connected one to his iPad, you just know that happened.

The end of the teletype era

What killed the teletype? It was of course the video display terminal. In the 1970s, video display technology got cheap enough that you could sit in front of a converted TV instead of a converted typewriter, and that made it possible to do things like, you know, actually backspace or move the cursor up and down. (Yeah, those were pretty much impossible with teletypes.) Soon, the clacking of the teletype machine was replaced by the whisper of fans. Computing changed leaving behind the humble teletype, but its echoes still live on.

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 9,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.