Comment by YZF

I used the parallel port extensively. I've had the IBM PC AT Technical Reference that had a complete reference to the parallel port. I've read it many times.

But alas, it was decades ago, so it's possible I'm wrong ;)

This is the closest reference I can find: https://www.sfu.ca/phys/430/datasheets/parport.html

The card does have an interrupt but only the ACK signal can interrupt. Not the Data lines. ACK makes sense since it would be part of the printing protocol, you'd send another byte each interrupt.