Abstract: Tag monitoring system for assigning tags to instructions. A memory unit stores instructions to be executed by an execution unit. Before execution an instruction fetch unit decodes the instructions. A register file stores the decoded instructions. A queue having a plurality of slots containing tags which are used for tagging the decoded instructions. A control unit assigns the tags to decoded instructions, monitors the completion of executed instructions, and advances the tags in the queue upon completion of an executed instruction. The register stores a given decoded instruction at an address location in the register file defined by the tag assigned to that instruction. The register file also contains a plurality of read address enable ports and corresponding read output ports. Each of the slots from the queue is coupled to a corresponding one of the read address enable ports.