; add this clr c ; ---> what if C was set by some previous operation?? mov a,dph cjne a,#075h,Next jnc error ;if c is set, acc must be lower than 75h ;if c is clr, acc is higher or equal to 75 Next: ;if we get here, acc is lower than 75h Error: ;if we get here, acc is higher than 75h