ABSTRACT
This chapter discusses parallel communications. The Centronics printer interface transmits eight bits of data at a time to an external device, normally a printer. A 25-pin D-type connector is used to connect to the PC and a 36-pin Centronics interface connector normally connects to the printer. This interface is not normally used for other types of interfacing as the standard interface only transmits data over the data lines in one direction, that is, fi-om the PC to the external device. Some interface devices overcome this problem by using four of the input handshaking lines to input data and then multiplexing using an output handshaking line to multiplex them to produce eight output bits.
