Half Subtractor:-

The half subtractor is also a building block for subtracting two binary numbers. It has two inputs and two outputs. This circuit is used to subtract two single bit binary numbers A and B. The 'diff' and 'borrow' are two output states of the half subtractor.

Block diagram:-

Truth Table:-

The SOP form of the Diff and Borrow is as follows:

Diff= A'B+AB'
Borrow = A'B

Diagram:-

*formed using simulator provided.

Full Subtractor:-

The Half Subtractor is used to subtract only two numbers. To overcome this problem, a full subtractor was designed. The full subtractor is used to subtract three numbers A, B, and C, which are minuend, subtrahend, and borrow, respectively. The full subtractor has three input states and two output states i.e., diff and borrow.

Block diagram:-

Truth Table:-

The SOP form can be obtained with the help of K-map as:-

Diff=xy' z'+x' y' z+xyz+x'yz'

Borrow=x' z+x' y+yz

Diagram:-

*formed using simulator provided.

Instructions: If the LED is blinking, Press the reset button and then only input your values to obtain the difference. The MSB in the output and blinking LED indicate the negative sign.

Implementation of a Full Subtractor using 2 4:1 MUX circuits.

Full Subtractor using NAND Gates

Implementation of a Full subtractor using basic gates

Implementation a Full subtractor using 2 Half Subtractors

2 Stage Adder/Subtractor

Half Subtractor and  Full Subtractor

This circuit shows implementation of Full Subtractor using 1:8 demultiplexer

R-S Flip flop

D flip flop

J-K flip flop

T flip flop

Half Adder

Full Adder

Half Subtractor

Full Subtractor