Yes, you are correct, "pretty horrid" isn't the most logical argument. However, I seem to remember having to select different modes and nothing was straight forward and had to be achieved in some convoluted way. Maybe it's just my fading memory but I do recall finding the 6522 very easy to use in comparison to the 8255.
Hope you too have a happy and prosperous new year.
Sorry to disagree, the 8255A IMO makes a suitable port expander, for 8 data lines and 5 control lines from a MCU it can provide an additional 14 I/O pins.
By any definition I would call that port expansion....
Sorry to disagree, the 8255A IMO makes a suitable port expander, for 8 data lines and 3 control lines from a MCU it can provide an additional 16 I/O pins.
By any definition I would call that port expansion....