Hi Neil With my ISR for the GPS receiver loaded low and the one from a terminal emulator/serial control port loaded high things are working so I have to drive past this one and then turn around and come and pick it up later. I have a trade show next week and I'm a hair's breath from completing the code for a demonstration..........mercifully all it needs to do there is look like it's working. When I return week after next I'll try reading through the code first and if nothing jumps up and bites me which is not likely on my own but maybe with more help like I got in the last couple of days I might get lucky. If I have no luck there I'll cut out everything but what I think is the problem and then start adding stuff till the problem rears its head. Thanks again for all the help I'm very grateful to you and to everyone on the list that offered. Phillip Things should be as simple as possible but no simpler Phillip Coiner CTO, GPS Source, Inc. Your source for quality GNSS Networking Solutions and Design Services, Now! -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Neil Baylis Sent: Wednesday, September 20, 2006 8:40 AM To: Microcontroller discussion list - Public. Subject: Re: Re: RE: Re: RE: RE: RE: FW: [PIC] Trouble getting my ISR high On the other hand, using the ICD, I would trace the first time through the keyboard interrupt, and see what's getting corrupted. Is your compiler generating the correct interrupt return code? There's a special return instruction for that (retfie 1). Neil -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist