4 bit binary subtractor.

4 bit binary subtractor is a digital circuit which performs substraction of binary numbers in paralled form and produces results in parallel form.

The substraction of two binary number can be done by adding the complement of the subtrahend to the minuend. The logic circuit of a 4 bit binary subtractor is shown in the figure

The minuend bits at A and subtrahend bits of B are designated by subscripts from right to left with subscript 1, representing the lower bit. Ci is the input carry and C4 is the output carry. The output S generates the result bits. The entire circuit of 4 bit binary subtractor is enclosed within an IC. It has four terminals for minuend bits and four terminals for subtrahend bits and two terminals for carries input and output.