Embedded Systems and Computer Architecture

9

Input and output ports

To be useful a computer must be able to read data from the outside world and write data to the outside world. In personal computers, input and output are usually from a keyboard and to a visual display unit or sound generator. Computers which are embedded into products such as photocopiers and industrial process controllers read data from devices such as pressure and temperature sensors and write data to devices such as flow control valves, heaters, and motors. Whatever the computer, data enters the computer via an input port and data leaves the computer via an output port. In this chapter we see how simple input and output ports are constructed and how they are accessed within a program. The design of a programmable ...