The serial ATA is a
relatively new interface that effectively improves data transfer rate of
hard disk drives. The SATA data cable has one data pair for differential transmission of data to the device, and one pair for differential receiving from the device, just like EIA-422. That requires that data be transmitted serially. Similar differential signaling system is used in RS485, LocalTalk, USB, Firewire, and differential SCSI.
The major brands of SATA 2 hard drives are Western Digital and Seagate.