[sciguy125]

I wasn't as concerned about how much data, but rather how fast I can get the data I want. (say encoders that need to be read at a known time) After thinking about it more, it's probably alright.

For a parallel bus, the data and address lines would probably have to be shared to minimize the number of I/Os it eats. This means that it takes two bus operations to read/write data. The ports have an RC constant of 6.8us. We'd probably have a settling time of ~25us for solid operation. So, access time is ~50us. That's an enternity in processor terms, but it might still work. How long is the access time for the analog ports?

A large amount of data may be a problem. However, a loop running in the background (triggered by a timer set to interrupt) could work on transfering data in a buffer. For anything that is time sensative, there could be a "do this now, I'm waiting" function.