Reservation station
Beginner
A waiting seat where a step sits until all the numbers it needs have arrived.
Novice
A buffer in front of an execution unit where an instruction waits for its operands. Each operand is either a value or a tag naming which instruction will produce it; when that result is broadcast, the station grabs it.
Expert
From Tomasulo’s IBM 360/91 floating-point unit: tag-based operand capture from a common data bus. Modern cores use unified or distributed issue queues with the same wakeup-and-select function.
Explained in Branch prediction and out-of-order execution (Architectures).
See also: Out-of-order execution, Register renaming.