Two definitions in literature:
- A reservation station is a buffer for a single instruction with its operands (original Tomasulo paper, Flynn's book, Hennessy/Patterson book).
- A reservation station is a buffer (in front of one or more FUs) with one or more entries and each entry can buffer an instruction with its operands (e.g. PowerPC literature).
Depending on the specific processor, reservation stations can be central to a number of FUs or each FU has one or more own reservation stations.
Instructions await their operands in the reservation stations, as in the Tomasulo algorithm.