The out-of-order execute section
When the ?ops flow into the ROB, they effectively take a place in program order.
?ops also go to the RSU which forms a central instruction window with 20 reservation stations (RS), each capable of hosting one ?op.
?ops are issued to the FUs according to dataflow constraints and resource availability, without regard to the original ordering of the program.
After completion the result goes to two different places, RSU and ROB.
The RSU has five ports and can issue at a peak rate of 5 ?ops each cycle.