You can boot an original IBM PC off the keyboard port. Look for the MFG_BOOT function here: https://www.iee.et.tu-dresden.de/~kc-club/DOWNLOAD/DISK401/ROMBIOS

You can boot an original IBM PC off the keyboard port. Look for the MFG_BOOT function here: https://www.iee.et.tu-dresden.de/~kc-club/DOWNLOAD/DISK401/ROMBIOS.ALL https://www.iee.et.tu-dresden.de/~kc-club/DOWNLOAD/DISK401/R... Basically, the device connected to the keyboard port has to reply with code 0x65 when it's initialized, then the BIOS will read some bytes into memory and jump to it. Not sure whether this was brought forward to newer models or clones, though so it's just some fun trivia...