Steve,

The T51 has timers and a UART that are implemented in SFR space. There's no example of memory-mapped-I/O in it. You've probably noted that there are fewer instructions available once they have it implemented.

If they want a good grade on their effort, they need to do it well. Throwing away quite a bit of flexibility and performance, just to make it a little easier would not get them that excellent grade in my class. This is an academic exercise, after all. If they do the external-memory-mapped version poorly, they have to take full responsibility. OTOH, if they map it into SFR space and the professor doesn't like it, well, they can say, "... but this follows the pattern the T51 author set, and it works just as it should."

RE