Parallel port

The parallel port uses a sub-d 25 connector to provide a 8-bit data bus. It is commonly used by printers. There are 3 kinds of parallel ports: Standard Parallel Port (SPP), Enhanced Parallel Port (EPP) and Extended Capabilities Parallel Port (ECP). iirc they are all part of IEEE Standard 1284, or is it just the second two?

Registers & Common Address

Common base addresses are:

• LPT1: 0x3BC/0x378
• LPT2: 0x278

Data Register

Address = Base Address + 0

Any byte writen to this register is put on pins 2 through 9 of the port. Any read from this register reflects the state of the port.

Status Register

Address = Base Address + 1

Control Register

Address = Base Address + 2