at least you won't use it in memory-mapped mode. In port-mapped mode, you still can't operate the LCD any faster, but you can, at least, run everything else that's capable at full speed.

The catch with memory-mapping your I/O is that slow external I/O devices impact EVERYTHING, since standard 805x's have no "wait" signal by means of which you could adjust the cycle length.

Now, some more modern 805x's have the ability to stretch external bus access times, but that impacts ALL external memory mapped devices to the extent that they have to run at the speed of the slowest. In rare cases, it's quick enough to reprogram the MCU SFR's such that the cycle stretch is appropriate for the device(s) that you're going to use next. It quickly becomes a programming headache, though, particularly if you have interrupt-driven I/O routines for some external memory-mapped devices.

RE