On Fri, 23 Jul 2010 00:44:31 +0930 "Roger Weichert" wrote: > Does anyone have any suggestions for techniques for narrowing down this > sort of fault? Thanks. If you have the SIO connected to some terminal, you could replace the EPROM with one which has a debug monitor in it, so you can test the other parts one by one. John -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist