The Standard Parallel Port mode in a multi-mode port emulates the original protocol of the original Centronics parallel port. This mode is also called Centronics mode, compatability mode, AT-type, or ISA-compatable. It can only send data in a forward direction at speeds from 50 kbytes per second to 150 kbytes per second. Handshaking signals used in this mode are generated by the PC software driver and the peripheral. Transmission rates are low due to the use of software handshaking instead of having the hardware handle the handshaking.

EPP

The Enhance Parallel Port mode is a relatively new mode defined by the IEEE 1284 standard. An EPP port is bidirectional, can distinguish between addresses and data, and is capable of high speeds. Theoretically, an EPP can write or read a byte of data in one ISA-bus cycle. With handshaking, this requires about 1 microsecond. Transmission rates can approach 1 Mbyte per second with this mode.

ECP

The Extended Capabilities Port is a high-speed mode that provides a number of sub-modes for backwards compatability. However, it utilizes a 16 byte FIFO to hold data to be sent or received.