Try putting a 4.7K pullup resistor on the output pin. The original version of the 12C508 had an errata in it. Some of the pins were redefined as input after a WDT event . If you are using the original windowed samples, this could be your problem. MicroChip fixed the die and new devices will not have the problem. --- Steve ---------- From: pic microcontroller discussion [SMTP:PICLIST@MITVMA.MIT.EDU] Sent: Monday, January 27, 1997 10:46 AM To: Multiple recipients of list PIC Subject: 12C50x Watchdog timeout, and strangeness on output pin I'm using a 12C508 with one of it's output pins tied directly to the RxD pin on a PC's printer port (i.e. 0..5V levels rather than true RS232 -- but works without problems since minimal cable lengths). Even though I set this output pin to 1 within 10us after reset, I still get s on the PC every time the PIC resets on the WDT (at 9600bps). Why? Frank ------------------------------------------------------------------------ Frank A. Vorstenbosch Phone: +44-181-941 7899 Electronics & Software Engineer Mobile: +44-976-430 569 Eidos Technologies Ltd., Hampton, Middx Fax: +44-181-941 7895