IEEE 1284 - Computer Definition
An IEEE standard for an enhanced parallel interface (parallel port) for personal computers, superseding the Centronics interface. Introduced in 1994, IEEE 1284 can send addresses, allowing individual components in a multifunction device (printer, scanner, fax, etc.) to be addressed independently. Unlike the Centronics interface, the specifications of the cable are also defined in IEEE 1284, providing a cable length up to 32 feet. A legacy interface today, IEEE 1284 has been superseded by USB and network connections. See Centronics interface, DOT4 and USB. Five Modes of Operation The mode chosen by the software driver is based on the connected device. 1-Compatibility mode supports the Centronics interface at 150 KB/sec. 2-Nibble mode supports Bi-tronics; HP's parallel port variation. 3-Byte mode supports IBM PS/2 personal computers. 4-Enhanced Parallel Port (EPP) provides bidirectional speeds up to 1.5 MB/sec. 5-Enhanced Capability Port (ECP) is similar to EPP but can transfer 2.5 MB/sec using direct memory access (see DMA).