Centronics printer One of the most used printer interfaces in the past. Now replaced by IEEE1284-B / USB.
ECP Parallel LPT port (IEEE-1284A) This port is found in some old PC computers. ECP = Extended Capabilities port. ECP is an extension of the EPP design.
IEEE1284-B (centronics) printer IEEE1284-B connector (also called Centronics) is widely used in parallel interface printers (except some HP's).
Parallel port (LPT) Loopback Used to verify the port is functional.
PC parallel LPT port One of the most used printer interfaces (in the past), since every Intel/DOS/Windows based Personal Computer was equipped with D-Sub-25 female connector which was called LPT1