IEEE 1284 - bidirectional ECP
  ECP - extended capacity port

  Supports addressing, bidirectional data transfers, channels, commands, 
    status.

  Can access printer and modem simultaneously.

  Controller has dedicated registers for the various functions.

IEEE 1284
  Current systems support IEEE 1284 parallel port.

  Usually CMOS configured for backward compatibility.

  5 modes
    Forward direction.
      Compatibility mode - "Centronics" - forward direction only.

    Reverse.
      Nibble mode.
      Byte mode.

    Bi-directional
      EPP (slightly improved version of original EPP).
      ECP - can use DMA controller to transfer data, 
           up to 4 MBytes/sec allowed but only 2MB/s usual. 

Microsolutions backpack.  1992 Pre-USB external hard drive, floppy, Cd, etc
that interfaced through the parallel printer port.