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Arithmetic Micro-operations

In general, the Arithmetic Micro-operations deals with the operations performed on numeric data stored in the registers.

The basic Arithmetic Micro-operations are classified in the following categories:

1. Addition
2. Subtraction
3. Increment
4. Decrement
5. Shift

Some additional Arithmetic Micro-operations are classified as:

1. Add with carry
2. Subtract with borrow
3. Transfer/Load, etc.

The following table shows the symbolic representation of various Arithmetic Micro-operations.

Symbolic Representation	Description
R3 ← R1 + R2	The contents of R1 plus R2 are transferred to R3.
R3 ← R1 – R2	The contents of R1 minus R2 are transferred to R3.
R2 ← R2′	Complement the contents of R2 (1’s complement)
R2 ← R2′ + 1	2’s complement the contents of R2 (negate)
R3 ← R1 + R2′ + 1	R1 plus the 2’s complement of R2 (subtraction)
R1 ← R1 + 1	Increment the contents of R1 by one
R1 ← R1 – 1	Decrement the contents of R1 by one

Note: The increment and decrement micro-operations are symbolized by ‘+ 1’ and ‘? 1’ respectively. Arithmetic operations like multiply and divide are not included in the basic set of micro-operations.