Editing Parallel port (section)

===IBM===
[[IBM]] released the [[IBM Personal Computer]] in 1981 and included a variant of the Centronics interface— only IBM logo printers ([[Original equipment manufacturer|rebranded]] from [[Epson]]) could be used with the IBM PC.<ref name="durda">{{cite web |url=http://nemesis.lonestar.org/reference/computers/interfaces/centronics.html |title=Centronics and IBM Compatible Parallel Printer Interface Pin Assignment Reference |access-date=2007-10-05 |last=Durda IV |first=Frank |year=2004 |url-status=dead |archive-url=https://web.archive.org/web/20070913082745/http://nemesis.lonestar.org/reference/computers/interfaces/centronics.html |archive-date=2007-09-13 }}</ref>  IBM standardized the parallel cable with a [[D-subminiature|DB25F]] connector on the PC side and the 36-pin Centronics connector on the printer side. Vendors soon released printers compatible with both standard Centronics and the IBM implementation.

The original IBM parallel printer adapter for the IBM PC of 1981 was designed to support limited bidirectionality, with 8 lines of data output and 4 lines of data input.{{citation needed|date=March 2021}} This allowed the port to be used for other purposes, not just output to a printer. This was accomplished by allowing the data lines to be written to by devices on either end of the cable, which required the ports on the host to be bidirectional. This feature saw little use, and was removed in later revisions of the hardware. Years later, in 1987, IBM reintroduced the bidirectional interface with its [[IBM PS/2]] series, where it could be enabled or disabled for compatibility with applications hardwired not to expect a printer port to be bidirectional.