Serial binary adder
The serial binary adder is a digital circuit that performs binary addition bit by bit. The serial full adder has three single bit inputs for the numbers to be added and the carry in. There are two single bit outputs for the sum and carry out. The carry in signal is the previously calculated carry out signal. The addition is performed by adding each bit, lowest to highest, once each clock cycle.
Serial Binary Addition
Serial Binary addition is done by, in simplest terms, a flip-flop and a full adder as stated above. However, there are slight nuances to the addition that can be confusing. When a serial adder performs its addition, it is partially dependent on the clock cycle as a flip-flop is asynchronous and the full adder is not. Thus, when a timing diagram is done, the sum output will change as the inputs are changed, relative to the previous clock cycle which was used to determine the carry in bit. In a serial binary adder of for example 8 bits one bit each of data is loaded and given to the full adder during one clock cycle and the resulting sum is stored in a register.In this way the 8 bit sum is obtained after 8 clock cycles . Design is divided in two parts controller and architecture .The controller part consists of control signal like load inputs .A counter should also be used in the architecture that tells that 8 clock cycles are over and the resulting sum is obtained .
Serial binary subtracter
The serial binary subtracter operates the same as the serial binary adder, except the subtracted number is in 2's complement.
Example of operation
- Denary
- 5+9=14
- X=5, Y=9, Sum=14
- Binary
- 0101+1001=1110
- Addition of each step
| Inputs | Outputs | |||
|---|---|---|---|---|
| Cin | X | Y | Sum | Cout |
| 0 | 1 | 1 | 0 | 1 |
| 1 | 0 | 0 | 1 | 0 |
| 0 | 1 | 0 | 1 | 0 |
| 0 | 0 | 1 | 1 | 0 |
*addition starts from lowest
- Result=1110 or 14