Jumper,
Thanks for the reply.

Actually, I am using an 18F part - the 18F2620. I already managed to modify a Mecanique MicroCode Studio loader by disassembling it, making the code changes, and reassembling it. It now works quite well for my purposes, using the PIC's internal 8MHz clock. The next thing I wanted to try was to modify the code so that there are 2 serial ports - the hardware port dedicated to the loader and a software port for my application. Once I do this, I hope to eliminate the need for a PIC reset in order to reload. I think I should be able to use the dedicated loader port to download new code any time I want to talk to it.

Anyway, in musing about this, I thought it might be easier to do some of the things I wanted if the code was implemented in the PBP environment. However I do recognize that major sections of assembly code are unavoidable.

Joe