He devised the reservation station and coupled it with register renaming via tag broadcast. In his scheme, the tag of an instruction corresponds to the slot in the reservation station the instruction is placed. When the instruction executes, the tag is broadcast back to instructions waiting in the reservation station, thereby notifying them of the newly ready value. When a branch is mispredicted or an instruction has an exception, we will have to recover architectural state to the point of the branch or exceptional instruction. This is hard because, potentially, instructions after the branch might have already executed.
Many different techniques exist for orchestrating the state recovery process.
Limits the amount of Instruction Level Parallelism we will find.