As far as I know the only use of 82C55s are in classroom lab projects and new-hire electrical engineer projects.

I guess Intel figured that out long ago with their sales volume... engineers quickly realized 244s and 373s etc were a better bargain and more trouble free.

Intel's original 8080 peripheral chips were as pathetic as their multibus board designs were at that time. One of my most treasured documents the first two years working as a design EE out of college was titled "How the 82XX *REALLY* Works".

Someone had documented all the chip performance errors and Intel documentation errors on this chip and circulated it among contacts.

I had discovered about half the gotchas while designing a multibus disk controller in 1980. The company sold Wicat (now defunct) non-exclusive rights to it and I was told to spend a week lecturing a group of their engineers on the circuitry and firmware. As I began me section warning of the diabolical Intel 82XX, they said they had run into that before and would mail me a document they acquired through someone else.

That's how haphazard information sharing was before the internet. :)

aka j