Hi All It looks as if the list is always divided into three types of users: those who do know, those who don't and those who don't care! Anyway as one who doesn't know I'd like any help you've got to give, please. I need to measure the width of a pulse which occurs at about 30Hz with a 16c(f)84, the pulse width is variable between 1ms and 2ms and I need as high a resolution as possible(about 7bit should do) on the 1ms difference between the two extremes. As usual the routine needs to use as little as possible processor time. Any code will be most helpful. Thanks Robert