Hi Joe, This is an ol' problem. There is no easy workaround with this old version o= f MPLAB.=20 The assembler does not rely to the .inc file to decode the CONFIG extended syntax directive (with =3D pairs). It's "hard coded" in the assembler. The symbols in the .inc file purpose is to use the old __config directive form where you use these symbols as ANDed masks. Hopefully MCHP has fixed that in newer versions. (I don't know since when) Check one where the _DEBUG_OFF_4L is present in the .inc file. I would suggest the latest one... =A0=20 Best regards, Philippe=20 -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of IVP Sent: Tuesday, September 6, 2016 3:54 AM To: Microcontroller discussion list - Public. Subject: Re: [PIC] 18F14K22 issues Hi all, I've moved the ISR to past the end of main code, with the ISR vectors programmed, and now see toggling activity in the wait loop. The IRQ system still doesn't respond to an input on INT0 If I call the ISR though it does function as a subroutine and sets the flag bit needed to exit the wait loop Looking around for ideas I notice that other people's config settings include DEBUG =3D OFF. Adding that to my own results in setting "DEBUG" not found for the processor 18F14K22 even when I've edited the .inc file with _DEBUG_OFF_4L EQU H'7F' as my copy of the .inc (for MPLAB 8.56) doesn't mention debug However, introducing a spelling mistake to config options in the .inc doesn't throw up an error. ??? AFAIK there is only one copy of the .inc file, in MPASM Suite, so altering it with a mistake should cause an error message when building the project Can someone have a look in a more recent P18F14K22.inc file to see if it includes anything to turn debug off ? TIA Joe ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.7752 / Virus Database: 4649/12951 - Release Date: 09/05/16 -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .