Thanks to all for your suggestions on my Port B problem, now sorted.

Next:

Using MPLAB to run through my program, I need to define a starting point
from within the program. Let me explain:

The program consists of a number of subroutines running from the main
program for the control of lights. These are controlled by timing loops
that are timed via an interrupt routine using the RTCC.

This ISR reads and denounces several inputs, the need for this being
that a steady signal of 4 - 500 ms must be read from a very noisy
source.

The problem is that for testing the ISR I need to get to the beginning
of it and step through it in MPLAB, but how?

TIA,
--
Philip Martin   ----------------------------------------------------------------
Royal Quays             If at first you don't succeed, try again. Then quit:
North Shields.          no use being a damn fool about it !
                                                        W.C. Fields
email philip@philmart.demon.co.uk