Hi Darrel,

Thanks just got your reply, although I using the comparators to feed the CCp modules. As you say the cmp interrupt is on *any change on either comparator*

so i am using the cmp as a sort of interrupt on change on both analog pins. It is then inportant to disable the cmp interrupt as soon as possible. I did have one comaparator output (the one i felt most probable to set) linked to portb internal interrupt but it oscillated like crazy, I get little or no bounce using this setup. I had been disabling the cmp_int "inside" it own handler routine but felt that this was bad practice (any thought?)which I why I try to keep the sub routines as simple as posible ie Z=1 or Z=2.

I have tried introducing delays without using pause (small count loops) to allow the interrupt disable to settle.

but I guesss that whilst I have been concentrating on timer0 as the culprit I should be back looking at CMP_INT to see if there is any way this could be responsible. But this loopback is happening 206ms after I have disabled CMP.

I also check that Z variable that I use as a progress gate is not corrupted, that is to say that even though Z = 1 the program is passing through a conditional IF's that should prevent it, confused........ I am totally.