You think using 8255's is bad! A friend is doing an engineering course where they teach 6809!! I did explain to him that they were discontinued some time ago but nevertheless he had to do his assignment. I wonder if they still teach sc/mp?

As for poor Lisa, she's asked a reasonable question and just because a 8255 is involved the forum has erupted into something off topic! And the problem isn't due to the poor innocent 8255!

As for old, I seem to recall the 8051 was (c)Intel 1978. I still pine for my old sc/mp (pmos of course!) with no stack pointer and instructions like XPAL,XPAH,XPPC.............