Converting an Old Typewriter Into a Computer Terminal

YouTuber Artillect had a Brother AX-25 electronic typewriter and converted it into a paper terminal that connects to a modern computer.

Cameron Coward
12 days agoRetro Tech

Despite what that hipster who lugged an old Smith Corona to the coffee shop will tell you, typewriters are not practical machines in our modern world. Even the most basic word processing software is superior in every imaginable way. In ‘80s, as personal computers became commonplace, typewriter manufacturers attempted to stay relevant by adding new electronic features. The Brother AX-25, for example, had 9kb of internal storage and the ability to display stored text on a tiny 16-character LCD. YouTuber Artillect had a Brother AX-25 typewriter and decided to convert it into a paper terminal that connects to a modern computer.

This project is similar to my own TI Silent 700 project, in which I connected a vintage ‘70s paper terminal to a Raspberry Pi. But Artillect’s project has one major difference: his typewriter was never meant to interface with a computer in order to act as a terminal. The Brother AX-25 is just a fancy (for the time) electric typewriter. Instead of mechanical linkages, the keyboard sends electronic signals to the daisy wheel print head. Aside from that and the internal memory, it operates like a normal keyboard. But that electronic keyboard turned out to be the key to Artillect’s ability to interface with this typewriter.

Like a standard computer keyboard, the Brother AX-25 utilizes a keyboard matrix. That would make it possible to read key presses by monitoring the matrix’s rows and columns. It also makes it possible to simulate key presses, which is exactly what Artillect did. He connected an Arduino Uno board to the rows’ and columns’ pins through multiplexers. By setting the proper pins to HIGH or LOW, Artillect could use the Arduino to trick the typewriter into thinking it received a key press. It would then type the corresponding character, just like if a user really did press a key.

Artillect could programmatically control what the typewriter typed, but need something to do with that ability. So he connected the Arduino to a Raspberry Pi 4 Model B single-board computer’s UART serial output. Anything that the Raspberry Pi outputs through the serial port, such as terminal prompts and commands, transmits to the Arduino, which then converts the text to simulated key presses that the typewriter prints onto the paper.

The final step in the puzzle was to provide input to the terminal running on the Raspberry Pi. I’m not sure why Artillect didn’t just read the input from the typewriter keyboard, but for some reason that wasn’t an option. Instead, he connected his laptop to the Raspberry Pi to type commands. The typewriter does still print out those commands, so the paper roll has a full printed log of the terminal.

The result is essentially a recreation of the paper terminals made by TI and others in the ‘70s. Artillect even print ASCII art!

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