The increment micro-operation adds one binary value to the value of binary variables stored in a register. For instance, a 4-bit register has a binary value 0110, when incremented by one the value becomes 0111.
The increment micro-operation is best implemented by a 4-bit combinational circuit incrementer. A 4-bit combinational circuit incrementer can be represented by the following block diagram.
Note: The 4-bit binary incrementer circuit can be extended to an n-bit binary incrementer by extending the circuit to include n half-adders. The least significant bit must have one input connected to logic-1. The other inputs receive the number to be incremented or the carry from the previous stage.