Micro-operation Categories (2 Marks)

A micro-operation is an elementary operation performed on data in registers during one clock pulse. Four categories:

1. Register Transfer: Moves data between registers or between register and memory, without alteration. e.g. R1 ← R2, MAR ← PC, MDR ← M[MAR]. Triggered by control signals and bus.

2. Arithmetic Micro-operations: Performed by ALU. e.g. R3 ← R1 + R2, R1 ← R1 + 1 (increment), R2 ← R2 - 1 (decrement), Add with carry, Subtract.

3. Logic Micro-operations: Bitwise operations on registers. e.g. R1 ← R1 ∧ R2 (AND), R1 ← R1 ∨ R2 (OR), R1 ← not R1 (COMPLEMENT), XOR. Used for masking/clearing.

4. Shift Micro-operations: Shift/rotate register contents. e.g. R1 ← shl R1 (logical shift left), shr, ashl/ashr (arithmetic preserves sign), cir/cil (circular rotate). Used for serial transfer & multiply/divide by 2^n.