Thanks for your help Brent,
that is all much clearer now! You must have a different datasheet from me
because my 16F84 datasheet doesn't have anything like that on page 9.... I
managed to get it from your explaination fine tho, thanks ;-)

> If in timer mode (T0CS=0) the clock
> pulse will be the oscillator frequency divided by 4 (this is 1
> instruction cycle).

So, is my math right here:
for a 1ms timer....
each instruction (clock) cycle on a 16F84 running at 4Mhz is 1us
so set the TRM0 to 5 so will over flow in 250 ticks
set the prescaler to 4....
4 x 250 =1000 or 1ms?

Thanks again for you help Brent,
it is much appreciated,
regards
James Fitzsimons

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