divisor is subtracted from the remaining highest order bits of the dividend this subtraction in the first step of the process is a forced subtraction the result of this subtraction the sum of the highest order bits of the dividend which remain after the left shift and the twos complement of the divisor may produce a carryout value of one or may not produce a carryout value a zero it should be noted that the carryout bit produced is inverted in the case of a subtraction which produces a negative number indicating that the divisor is greater than the upper bits of the dividend an exclusive nor xnor operation is carried out using the carryout value and the most significant bit of the dividend stored before the subtraction the result of the xnor operation determines the first bit of the quotient and the next operation to be performed if the xnor operation produces a one value this indicates that the quotient is to be a one and that the next operation should be a subtraction if the xnor operation produces a zero value this indicates that the quotient is to be a zero and that the next operation should be an addition as may be seen when this operation is performed with the most significant digit of the dividend and the carryout of the first forced step of the operation in the example an xnor result of zero is obtained consequently the divisor is greater than the remaining upper order bits of the dividend the first quotient bit is a zero and the next operation to be performed is an addition the partial remainder which resulted from the first subtraction operation is concatenated with the unused lower order.