Serial Advanced Technology Attachment (SATA) is an evolution of the Parallel ATA (PATA) interface that was developed for connecting a host system to peripheral devices, such as hard disk drives and optical storage drives. The need for increased data transfer rates drove the move from a parallel bus interconnect to a serial interconnect. With a 16 bit parallel data bus, signal crosstalk, among other things, became a problem. These problems are resolved by using serial architecture with differential signals instead of a parallel bus architecture. The cabling used with a serial interconnect is less complex and is physically smaller than what is used with a 16 bit parallel bus. A 40 pin cable is required for PATA connections compared to a 7 pin cable for SATA connections, and PATA cables have a maximum length of 18 inches compared to meter or more for SATA cables. Since the cabling used for serial connections is physically smaller, it allows more flexibility in system design and allows for more storage devices to be installed in the same location without the concern of large bulky cabling.
SATA 3Gb/s is a second generation SATA interface running at 3.0 Gb/s. The interface supports bandwidth throughput up to 300MB/s and a cable length of up to one meter.
SATA 6Gb/s is a third generation SATA interface running at 6.0Gb/s. The interface supports bandwidth throughput up to 600MB/s, supports a cable length of up to one meter, and is backwards compatible with SATA 3Gb/s interface.
External SATA, or eSATA, uses more robust connectors and supports a cable length of up to two (2) meters.
miniSATA, or mSATA, was introduced in 2009. Applications include netbooks and other devices that require a smaller solid-state drive. The connector is similar in appearance to a PCI Express Mini Card interface and is electrically compatible.
mSATA SSD on top of a 2.5” HDD (photo from notebookreview.com)
A new specification, SATA Express, is being developed by the Serial ATA International Organization and combines SATA software infrastructure with the PCI Express® (PCIe®) interface to deliver high-speed storage solutions. SATA Express enables the development of new devices that utilize the PCIe interface and maintain compatibility with existing SATA applications. The technology will provide a cost-effective means to increase device interface speeds to 8Gb/s and 16Gb/s.