Not all MIDI cables are created equal! The formal MIDI spec doesn’t actually use all five of the pins on the DIN connector. On some older gear, having all five wires in the MIDI cable hooked up and functioning can actually cause problems. Two problem items that immediately come to mind are the Casio CZ-101, and the Atari 1040st computer. The 1040st, in particular, had its MIDI out jack wired as both a MIDI out, and a MIDI thru; both these functions could be accessed simultaneously with a properly wired MIDI "Y" cable. Using a five-wire MIDI cable with this non-spec connector caused a variety of hard to trace MIDI weirdness…