Hi,
I missed the fact that the interrupt was declared as ASM. In that case, as you say, there's not that much overhead but it's also risky business since the actual handler IS written in PBP - if you don't know what you're doing here you're likely to run into trouble.

And, with the above in mind, perhaps adding the "extra" reload code for accuracy isn't a good idea (and not needed since there's much less overhead) since it might use some PBP system variables and then the whole thing is a mess.

I wasn't trying to say that it couldn't run at a higher oscillator speed than 4Mhz. I was trying to say that I don't think it'll be able to interrupt much faster when running AT 4Mhz, in fact that IS what I said ;-) But that was before you enlightned me of the fact that he has the ISR declared as ASM.

bwaxing,
You do realise the difference of declaring the interrupt as type ASM as oppesed to type PBP and what impact it might have on your code if you declare it as ASM but write the handler in PBP?

/Henrik.