With all the hype that do-it-yourself IoT is getting today, we're seing solderless boards connected to computers. That brings back good old memories to me. At the back of my books you can read that I controlled my electric train using an Atari ST. It was HO scale and I used the computer's parallel port connected to some relays. That was circa 1990. Well I don't have pictures of that but then I moved on to controlling a tinier train with a Psion Series 3 circa 1992. Same solderless boards and relays. I don't have pictures from that time either but I do still have the hardware, thanks to my parents: Unfortunately it's disconnected now, but wouldn't require much to get connected again. Between the parallel port and relays there where (one for each output) a transistor and a resistor. 8 relays, 8 resistors, 8 transistors: I managed to control 8 independent outputs. Which allowed me in turn to control the train's movement (forward, backwards), plus rail
Blog from a developper, trainer and writer