[Graphic representation on microcomputers. An example of interface construction].

Personal computers are generally used in laboratories as programmable calculators, data base organizers or word processors. With the addition of appropriate interfaces, they can also be used in data acquisition, analysis, and automatic control of experiments. In this paper the basic principles of operation of input and output devices are described, to serve as a guide to the construction of these interfaces. This description is specifically dedicated to the S-100 8-bit computer bus, with detailed explanation of the several signals involved in input-output machine cycles. Complete schematics and software driver for an interface to display analog signals on an oscilloscope or X-Y plotter is included as an example. Applications of this interface to the analysis of currents from membrane ionic channels are also discussed.