Centronics

Centronics Data Computer Corporation devised the connector around 1970 for its own dot-matrix printers, and the 36-pin coupling quickly became an industry standard. Data went eight bits at a time over parallel wires, with separate handshake signals — a byte per clock tick, far faster than the serial ports of the day. On the PC side the familiar 25-pin D-connector sat at the other end.

The interface was only formally standardised in 1994 as IEEE 1284, which also added bidirectional communication so the printer could report status. USB took over from the late 1990s, but the "printer port" and its wide connector lingered on motherboards well into the 2000s.