Embedded Linux®: Hardware, Software, and Interfacing

Control Using the Parallel Port

The parallel port, sometimes called a printer port, was originally designed to connect a printer to the computer. Over the years, many other devices, such as scanners, removal drives, and copy protection devices, have been connected to PCs via parallel ports. In today's PCs, this port has eight bidirectional data lines, four bidirectional control lines, and five status input lines, and they are accessed through a DB-25 female connector. Since its inception, the parallel port has evolved into four types:

• The standard parallel port (SPP)

• The PS/2-type (simple bidirectional) port

• The enhanced parallel port (EPP)

• The extended capabilities port (ECP)

The IEEE standard 1284, “IEEE Standard Signaling Method for a Bidirectional ...