Three stages of Tomasulo algorithm
1. Issue — get instruction from Instruction Queue
If reservation station free, the Tomasulo algorithm issues the instruction and fetches operands from registers if possible. ? In-order issue!
2. Execution — operate on operands (EX)
When both operands ready then dispatch to FU and execute;if not ready, watch CDB for result (check for RAWs).? Out-of-order dispatch and execution!
3. Write result — finish execution (WB)
Write on Common Data Bus to all awaiting units; mark reservation station available.