Regardless of what that hipster who lugged an previous Smith Corona to the espresso store will let you know, typewriters aren’t sensible machines in our fashionable world. Even essentially the most primary phrase processing software program is superior in each conceivable approach. In ‘80s, as private computer systems grew to become commonplace, typewriter producers tried to remain related by including new digital options. The Brother AX-25, for instance, had 9kb of inner storage and the power to show saved textual content on a tiny 16-character LCD. YouTuber Artillect had a Brother AX-25 typewriter and determined to convert it right into a paper terminal that connects to a contemporary pc.
This undertaking is just like my very own TI Silent 700 undertaking, by which I linked a classic ‘70s paper terminal to a Raspberry Pi. However Artillect’s undertaking has one main distinction: his typewriter was by no means meant to interface with a pc so as to act as a terminal. The Brother AX-25 is only a fancy (for the time) electrical typewriter. As a substitute of mechanical linkages, the keyboard sends digital indicators to the daisy wheel print head. Except for that and the interior reminiscence, it operates like a standard keyboard. However that digital keyboard turned out to be the important thing to Artillect’s means to interface with this typewriter.
Like a typical pc keyboard, the Brother AX-25 makes use of a keyboard matrix. That might make it attainable to learn key presses by monitoring the matrix’s rows and columns. It additionally makes it attainable to simulate key presses, which is strictly what Artillect did. He linked an Arduino Uno improvement board to the rows’ and columns’ pins via multiplexers. By setting the correct pins to HIGH or LOW, Artillect may use the Arduino to trick the typewriter into considering it acquired a key press. It could then kind the corresponding character, identical to if a person actually did press a key.
Artillect may programmatically management what the typewriter typed, however want one thing to do with that means. So he linked the Arduino to a Raspberry Pi 4 Mannequin B single-board pc’s UART serial output. Something that the Raspberry Pi outputs via the serial port, comparable to terminal prompts and instructions, transmits to the Arduino, which then converts the textual content to simulated key presses that the typewriter prints onto the paper.
The ultimate step within the puzzle was to offer enter to the terminal operating on the Raspberry Pi. I’m undecided why Artillect didn’t simply learn the enter from the typewriter keyboard, however for some motive that wasn’t an choice. As a substitute, he linked his laptop computer to the Raspberry Pi to kind instructions. The typewriter does nonetheless print out these instructions, so the paper roll has a full printed log of the terminal.
The result’s primarily a recreation of the paper terminals made by TI and others within the ‘70s. Artillect even print ASCII artwork!