[Evan] previously experienced a working ADM-3A (a dumb terminal from 1976) but was setting up to eye the equipment hungrily. He had only observed the numpad on Wikipedia and in the guide. So when he uncovered some genuine stackpole numpads on a surplus sale, he grabbed them and transformed them to be ADM-3A suitable.
Seeking at the schematic for the ADM-3A, [Evan] figured out that the numpad was parallel to the keyboard matrix, not adjacent. This meant that pressing a 5 on the keyboard was electrically equivalent to urgent a 5 on the keyboard. So holding shift whilst punching on the numpad prospects to some sudden people for individuals of us utilized to extra contemporary keyboards. Considering the fact that [Evan] only necessary to make one particular or two of these, he soldered wires straight to swap contacts in the matrix that the ADM-3A expects. A 3d printed housing, some rubber toes, and a ribbon cable later, it was performed. Although it seems a little diverse from the initial, the vibe is right, and presented that it is a stackpole switch, it has the identical truly feel. With the spare numpads, he produced a replacement PCB that runs QMK and connects to a a lot more contemporary personal computer by using USB-C. The files for the 3d printed housing are also up on GitHub, along with the PCBs and QMK configuration documents.
If you’re fascinated in what far more you can do with an ADM-3A, why not hook it up to a Raspberry Pi?