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parallel port Last modified: Monday, July 21, 2003

A parallel interface for connecting an external device such as a printer. Most personal computers have both a parallel port and at least one serial port. On PCs, the parallel port uses a 25-pin connector (type DB-25) and is used to connect printers, computers and other devices that need relatively high bandwidth. It is often called a Centronics interface after the company that designed the original standard for parallel communication between a computer and printer. (The modern parallel interface is based on a design by Epson.) A newer type of parallel port, which supports the same connectors as the Centronics interface, is the EPP (Enhanced Parallel Port) or ECP (Extended Capabilities Port). Both of these parallel ports support bi-directional communication and transfer rates ten times as fast as the Centronics port. Macintoshes have a SCSI port, which is parallel, but more flexible.

History of the parallel port This page, from Warp Nine Engineering, provides a history of the PC parallel port. There are tables that provide SPP signal and register definitions, as well as a description of transfer modes. IEEE 1284 Parallel Port information page Contains links to an introduction to the IEEE 1284 standard and operating modes, parallel port standards information, activities and news, FAQs, compatible products and links, and the IEEE standards organization home page. Integrated Peripherals Describes the settings that control system integrated peripherals. This page is from "The PC Guide". Parallel port central Contains a collection of links and resources for the PC parallel port including ECP, EPP, bidirectional, and IEEE-1284 modes. Parallel port FAQ Provides answers to specific, technical questions relating to programming, interfacing and using the parallel port. Troubleshooting Peripheral I/O Ports Discusses troubleshooting of peripheral I/O ports on the PC including serial and parallel I/O port connections. This page is from "The PC Guide."