How can we decrement and increment operations
We can implement decrement and increment operations by using a combinational circuit or binary down/up counters. In most of computers multiplication and division are implemented using subtract/add and shift micro-operations. If a digital system has implemented multiplication and division by means of combinational circuits then we can call these as micro-operations for that system. An arithmetic circuit is usually implemented by parallel adder circuits. Each of multiplexers (MUX) of given circuit has two select inputs. This 4-bit circuit takes two inputs of 4-bit data values and carry-in-bit and outputs four resultant data bits and a carry-out-bit.
With different input values we can obtain various micro-operations.
Equivalent micro-operation Micro-operation name
R V R + R1 2 Add
R V R + R +11 2 Add with carry
R V R + R1 2 Subtract with borrow
R V R + 2's1 Subtract
R V R1 Transfer
R VR + 11 Increment
R V R - 11 Decrement