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