jpx72 wrote:
I was wondering, when using a 32kB eprom on an SKROM board, where there are inputs on MMC1 for chrA15 and chrA16
I think you mean outputs. And the rule your thinking about only applies to inputs.
The MMC1 is driving those pins low or high depending on what the NES is writing the to MMC1. You don't really know what those values are. So shorting them to gnd/vcc would create high current in that pin (bad).
If you're not using an output just leave it floating, which is what you should do in this case.