1975 - writing as a coursework assignment a keyboard driver in assembly code for a PDP minicomputer. Pressed keys would set up interrupts, be interpreted, and p

1975 - writing as a coursework assignment a keyboard driver in assembly code for a PDP minicomputer. Pressed keys would set up interrupts, be interpreted, and printed back on the teletype. Got the instructions down to the minimal two metres of paper tape, read it in, and it worked! Worth 5% of one module of a computing course :) The most impressive thing about it all was how fast the paper tape reader has read it in.