IEEE 1284 Parallel Interface Standard

IEEE 1284 is a standard used for parallel and a point-to-point communication between a computer and its devices. IEEE 1284 transmits 8 bits at a time and provides fast throughput and bidirectional communication with high data transfer rates (DTR) (up to 4 MBps).

IEEE 1284 is available with five different functional modes that allow devices to transfer data in the following directions:

• Forward: From computer to printer/device
• Backward: From printer/device to computer
• Bidirectional: Both directions simultaneously

The five functional modes are:

• Compatibility: Original parallel mode. Compatible with other modes and used for older laser and dot matrix printers.
• Byte: Used to control data speed. Uses software drivers to disable other data line controlling drivers
• Enhanced capability port (ECP): Allows high DTRs. Used for printers and scanners with different functions, such as first in, first out (FIFO) for printing queues and data compression for images. Has advanced channel addressing that allows each fax, scanner or printer to use the computer modem for simultaneous data transmission.
• Nibble: Excellent for printers. Allows the communication system to retransfer data to the computer.
• Enhanced parallel port (EPP): Launched by Intel and other data systems to provide a highly efficient parallel interface and may be used with a standard interface. Allows devices to transfer data at rates ranging from 500 Kbps to 2 Mbps. Bidirectional and ideally suited to portable hard drives, network adapters and other similar devices.