Serial ATA or SATA is the newest version of the ATA interface. SATA supports all the traditional ATA functions but does it over an interface cable with only 7 wires (instead of the normal 40 wires for traditional parallel ATA interfaces). Three of the wires are ground signals. The other 4 are two pairs of differential signals - one pair in each direction. SATA is using the transceiver technology used by Fiber (Fibre) Channel. Today's hardware runs at 1.5GHz, 3GHz and 6GHz. ATA commands, status and data are transmitted in packets on this interface.
SATA supports a single device per SATA cable. A SATA cable can be longer than a parallel ATA cable (limited to 1.5 feet), perhaps up to 2 or 3 feet long.
The most common SATA host controller is called AHCI. Most x86 motherboards will have AHCI controllers that support 2, 4 or 6 SATA interfaces. Note that there is only one device per SATA interface (unlike PATA and allowed 2 devices per interface).
While PATA had a version of "Tagged Command Queuing" (TCQ), similar to SCSI TCQ, it was never widely implemented. SATA has a version of TCQ called Native Command Queuing (NCQ). NCQ is widely implemented and used by today's host systems and SATA HDD and SSD devices.
The SATA interface is defined by the SATA-I/O specifications published by the SATA-I/O committee.
The specification for the AHCI host controller can be found at the Intel web site.
Page updated 21 Feb 2015.