Neil, The PIC18Fxx2 data sheet, at http://www.microchip.com/download/lit/pline/picmicro/families/18fxx2/39564b.pdf shows context save/restore code in section 8.9, on page 85; you might want to try using that. Note that you can also use the built-in hardware context save/restore, which only requires you to return from your ISR with the retfie FAST instruction. No other save/restore code is required, unless you're using prioritized interrupts. For those who are busily arguing over the virtues of putting complete information in message bodies and not relying on subject lines to convey critical information, I would point out that Neil did indicate, in the body of his message, which processor he was referring to: Neil Bradley wrote... >I have the quintessential guide to the PIC, but it's a 16F in the book >which contains assembly syntax that won't work on the 18F. ;-| I'm hoping >my translation is correct - please advise me if it isn't. Thanks! At least that was enough indication for me... Dave D. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.