Interfacing an 8255 with the Parallel Port

This discussion shows how a PC printer port may be interfaced with an 8255 Programmable Peripheral Interface to provide 24 outputs. It is an easy way to expand the number of parallel port outputs and at $3.00 for an 8255, it is inexpensive.

Note that all bits on Ports A, B and C are configured as outputs. The input capability of the 8255 is not used.

The arrangement uses all eight Data outputs and all four Control outputs on the parallel port.

The five inputs on the Status port are not used and are available for other uses.

Please e-mail me if you use this or if you find any errors.