On Wed, 3 Dec 1997 13:52:12 -0800 WF AUTOMACAO writes: >John A. Craft wrote: >> >> Are the 14000 and 12C50 the only PIC's that contain internal 4Mhz >clocks? >> >> And how acurate are they? I think so. I don't know about the 14000, but the 12C50X is rated to about +-5% using the calibration value supplied by Microchip and pre-programmed into each chip. I've only used it once and didn't care too much about the accuracy at all. Experience reported by some to this list has been that it's not quite accurate enough to send or receive 8-bit async data reliably (which theoretically requires about +-5% accuracy from the clock).