Not sure how fast the PC can respond, but for timing the resolution of the PC clock under Windows is about 50ms. I would suggest using a 20MHz PIC timing the pulses and passing the data to the PC. Steve --- On Wed, 26 Feb 1997 13:00:11 -0600 Norm Cramer wrote: I am trying to measure some pulse widths using the PC. I would like to use the printer port interrupt as my timing input. How fast can the PC handle the interrupts (i.e. can it handle them at about a 50usec interval?) This will be under DOS. Also how long does the interrupt pulse need to be to get seen. (i.e. would a 2usec pulse every 50usec get seen by the PC?) The PIC relation is that the pulses are being generated by a PIC. BTW thanks to all who helped with the PC timing info. Thanks, Norm -----------------End of Original Message----------------- ------------------------------------- E-mail: sdavidson@its.bldrdoc.gov Steven Davidson Dept. of Comm. NTIA-ITS.N2 325 Broadway Boulder, CO 80303 W 303-497-3411 FAX 5995 -------------------------------------