Hai, I'm currently creating a ISA board with a PIC18x442 on top of it. This isa board will do some IO to other chips (AD converters, DA motor controller, counters and digital IO lines) Host system is build around Windows NT 4.0. That's for my setup. I want to enable in-circuit programming so I can update the firmware of the PIC without opening the computer and replacing the pic's. My questions are: 1) Do I really only need Vpp, Vss, pData and pClock? 2) Where can I find an example schematic? 3) What's the data structure to send to the PIC? Happy pic programming Ries (see subject line) Can I make double tags?