Ok... well, I think you're saying what I've already thought of and discarded, but perhaps not. I program my pic chips using PicBasic. There are two foreseeable problems with interrupts: 1) I don't know how to create them, and once created, I'd have to dust off my ASM skills in order to use them; 2) if there was an interrupt while the PIC was in the process of executing a SEROUT, it would likely screw up the serial stream, wouldn't it? Then I get a crashed RC.
As for a 555 timer, in my original post, I'd been intending on using that as the source of the pulses. I've used them before. I just need a dedicated pulse counter with serial output. If parallel is the only option, I suppose I could be persuaded to dedicate a PIC to translating the parallel to serial
