Hi Since I want to set three input and one output so my code would be like that: //Configurations sbit READ_1=P1^0; sbit READ_2=P1^1; sbit READ_3=P1^2; sbit SEND=P1^3; READ_1=1; //INPUT READ_2=1; //INPUT READ_3=1; //INPUT SEND=0; //OUTPUT //Main program bit x1,x2,x3; x1=READ_1; x2=READ_2; x3=READ_3; SEND=x1; Is it correct? Arron