ABSTRACT
An interface is a system consisting of hardware, software, or both that allows two dissimilar components to interact. Consider, for example, the problem of connecting a special type of printer system manufactured on the planet Mars with a PC on the Earth. The manufacturer of the printer has provided complete specifications for the input signals, but these specifications unfortunately do not correspond to either the RS-232 port or the Centronics printer port attached to the PC. To interface this Martian printer with the earthbound PC, you must do two things. First, you must build suitable hardware that can connect the PC to the printer and generate all the signals required by this printer. The signals generated by the PC should meet the timing as well as the voltage level (or current level) requirements of the printer. Second, you must provide suitable software routines and drivers that will translate user commands such as
into signals that the printer will understand.
