Conversions of 8bit computers into something more modern using a Raspberry Pi board aren’t unheard of, but how far can you go back? How about 19th-century technology, in the form of a typewriter? That’s precisely what GitHub user Riley, AKA Artillect, has done, as reported on Hackaday. However, the choice of typewriter is more 1980s than 1880s.
"Who doesn't love the sound of an old typewriter?" begins the introduction to the project, eliciting an unstoppable tooth-grind from those of us who remember. For the uninitiated, imagine everyone in your office typing at ridiculous speeds on a mechanical gaming keyboard with the clickiest switches imaginable, and you'll have something of the right idea. Add in someone sitting in the corner tearing up newspapers through Dave Mustaine's guitar amp, to emulate the sound of dot-matrix printers, and you're closer to the original sound.
With its rudimentary paper-based display technology, the typewriter isn't really suitable for a GUI or WIMP environment - it doesn't even have a mouse! - but what it can do is print the output from a Terminal window, which is where the Raspberry Pi comes in. Artillect originally wanted to replace the typewriter's mechanism with a screen but changed their mind.
The tricky part was getting the signal from the keyboard to the Pi and out again to direct the print head. The keys plug into an 8x11 matrix, which Artillect was able to connect to the Pi using two flexible cables with the requisite number of pins. By following the traces on the matrix, the keys could be matched up to pairs of inputs. These are then connected to two multiplexers, one for the horizontal and one for the vertical. There's an Arduino involved too, and a detailed video, embedded above, that tells you how it all plugs together.
The Brother AX25 uses a daisy-wheel printer instead of a dot matrix, but the sound it makes is still pretty distinctive. Artillect's project still needs some tidying up, and we'll be interested to see what they do next to turn it into a 'proper' computer. There's still a laptop connected over a serial link, for one thing, that we suspect will be the first thing to go. If you're interested in the project or fancy having a go yourself, all code and materials are detailed on GitHub.
Let me know if you have any questions!