Hi, please specify the problem. Otherwise, at least one error has been found. It is marked below. On Tue, 3 Aug 1999, felix centeno wrote: > Hi Friend I'm working in an serial adquisition system for a PC with an 16C71 > but the PIC software is not working this is the code: > > > ;********************************************************* > ; > ; A/D ADQUISITION SERIAL FOR PC ------- snip --------- > ; > CLRF OPTION_REG ; SET CONFIG. > CLRF INTCON ; NO INTERRUPS > MOVLW B'00000000' ; > MOVWF TRISA ; ALL PORTA IS INPUT --- snip --- Bingo! The constant zero makes all PORTA to output, rather than input. I hope this helps. Imre