RetroGaming

i once met the dev team of the "stella" atari 2600 emulator at a C3 conf. they were competing to make the smallest possible demo for the console, and they'd made a thing that fit into 14 bytes. it just drew some colors, nothing fancy, but still. to demo it there was a real 2600 and a pcb with a compatible edge connector. the only thing on the board was sixteen 8-position DIP-switches, which the dev set by hand to the code of the demo. ran exactly as well on actual hardware.

sidenote, stella is a neat little emulator because not only can you see and edit all those 128 bytes of ram at once during runtime, it also has a "beam display" that shows you where the electron gun in the actual tv would be pointing at any moment in your program. since the 2600 is so barebones you basically have to compute pixels on the fly exactly when the beam passes over the correct position on the tv. they call it "racing the beam". there's a whole book about it.