Acronym for Tagged Command Queuing
TCQ is present in SCSI disks. TCQ allows a disk to reorder some commands if doing so would cause fewer seeks. Metadata is added to the requests so that the returned data is associated to the correct request.
NCQ is a SATA-II standard, which performs essentially the same task.
Some SATA drives such as Western Digital's Rapto series actually implement TCQ.
See Also:
Part of CategoryHardware
2 pages link to TCQ: