Wheeler,
The 6602 can physically run without any thing wired up, but it will not be "simulation" mode. Basically, you can use the internal timebase as a source or gate. For example if you are doing simple event counting, you can count the edges of the internal timebase. If you are doing pulse width measurement, or period measurement you can measure the internal 100kHz timebase. You will also be able to run the pulse train generation programs with the default setting of the internal timebase as the source.
The real answer to your question is that you do not need inputs wired up, but you do need to measure a signal (internal timebase) to get valid readings. So you can not do true simulation mode, but you can still program and test your program without your
intended input signals.
