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Date: 29 Apr 2015

Half-subtractor is a combinational circuit capable of subtracting a binary number from another binary number. It produces two outputs: difference and borrow. The borrow output specifies whether a binary number 1 is borrowed to perform subtraction or not.

Graphic symbol of half-subtractor

Figure (a): Graphic symbol of half-subtractor

Figure (a) shows the graphic symbol of half-subtractor. The inputs are A and B. The output D is the result of subtraction of B from A and output B0 is the borrow output.

A B D B0
0 0 0 0
0 1 1 1
1 0 1 0
1 1 0 0

Table 1: Truth Table of harlf-subtractor

Logic diagram of half-subtractor

Figure(b): Logic diagram of half-subtractor