This is for earliest compact Apple Macintosh systems predating the introduction ADB (Apple Desktop Bus) on Macintosh SE and Apple Macintosh II (and Apple IIgs which technically is not a Macintosh):
[Wayback/Archive] GitHub – trekawek/mac-plus-ps2: Arduino project that allows to connect a PS2 keyboard to Macintosh Plus
Before continuing to an even more impressive keyboard and mouse interfacing project below (basically many kinds of modern keyboard, mice and gamepads to many retro computers) that I found thanks to doing some more research after finding the above one, lets summarise where the above one is still useful for:






