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Most chips like that are interfaced in hardware much like external memory. But I can remember interfacing an old 8255 (i think that is the port chip but if it's the timer chip what can I say, it's been a long time) to the parallel port. Why not just use some 74374 latches that are selected with a 74138 encoder? 3 lines allow you to select 8 ports. With an inverter like a 7406 or 7405 and six pins from the pic, you can control 64 374 latches. You can even wire the 374's up to make it serial i/o, then just use one line for data and one line for a clock. Or just use the sync serial port built into most pics (forget the 84, it's 8 years out of date - use the 628 instead and have a look at the most amazing micro I've ever seen, the 20 pin pic16f90) The only advantage the 8255 has is you can make the ports (within reason) bi-directional.
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