Ricki,

You asked How to program the PPI to make Port A Input, Port B&C as output ?

According to the Data Sheet page 9 writing a MODE WORD of 90H will set Port A to input and B&C to output.

The 82xx series are actually 8080 parts. The 8253 or 8254 are still highly regarded and are found stand alone or within core libraries. Someone has a 20MHz part but i forget who.

The 8255 get it's "bad rap" due to the fact that writing the MODE Word causes a "ZERO" to momentarily exist on the ports. This glitch can scramble logic if you haven't prepared for this eventuality and try to change MODE "on the fly".

Consequently, the 8255 is best used when you can set the MODE WORD at the start of process execution and leave it "in state" forever.

Once you find that you cannot always achieve the port agility you may have selected the part for, it's not uncommon to wish you had used alternate solutions (buffers/latches or clocked serial ports).

Use the CMOS part if you have that option.

regards,
p