Full-Subtractor
Full subtractor is a combinational circuit capable of performing subtraction on two bits namely minuend and subtrahend. It accepts three inputs: minuend, subtrahend and a borrow bit. It produces two outputs: difference and borrow. The borrow output tells whether the minuend bit needs to borrow a binary bit 1 from the next higher minuend bit or not.
Graphic symbol of full-subtractor
| Inputs | Outputs | |||
|---|---|---|---|---|
| A | B | Bin | BD | Bout |
| 0 | 0 | 0 | 0 | 0 |
| 0 | 0 | 1 | 1 | 1 |
| 0 | 1 | 0 | 1 | 1 |
| 0 | 1 | 1 | 0 | 1 |
| 1 | 0 | 0 | 1 | 0 |
| 1 | 0 | 1 | 0 | 0 |
| 1 | 1 | 0 | 0 | 0 |
| 1 | 1 | 1 | 1 | 1 |
| Truth table for full-subtractor | ||||
One bit full subtractor circuits can be cascaded to perform subtraction of tow multiple bit binary numbers.
Applications
Full subtractors are used in ALU to subtract.
These are used to do substraction in calculators and digital devices.
These are used in microcontrollers