About The Serial Ata Interface - Seagate BARRACUDA XT SERIES SATA ST32000641AS Product Manual

1.1

About the Serial ATA interface

The Serial ATA interface provides several advantages over the traditional (parallel) ATA interface. The primary advan-
tages include:
• Easy installation and configuration with true plug-and-play connectivity. It is not necessary to set any jumpers or other
configuration options.
• Thinner and more flexible cabling for improved enclosure airflow and ease of installation.
• Scalability to higher performance levels.
In addition, Serial ATA makes the transition from parallel ATA easy by providing legacy software support. Serial ATA was
designed to allow you to install a Serial ATA host adapter and Serial ATA disk drive in your current system and expect all
of your existing applications to work as normal.
The Serial ATA interface connects each disk drive in a point-to-point configuration with the Serial ATA host adapter. There
is no master/slave relationship with Serial ATA devices like there is with parallel ATA. If two drives are attached on one
Serial ATA host adapter, the host operating system views the two devices as if they were both "masters" on two separate
ports. This essentially means both drives behave as if they are Device 0 (master) devices.
Note. The host adapter may, optionally, emulate a master/slave environment to host software where two devices on
separate Serial ATA ports are represented to host software as a Device 0 (master) and Device 1 (slave)
accessed at the same set of host bus addresses. A host adapter that emulates a master/slave environment
manages two sets of shadow registers. This is not a typical Serial ATA environment.
The Serial ATA host adapter and drive share the function of emulating parallel ATA device behavior to provide backward
compatibility with existing host systems and software. The Command and Control Block registers, PIO and DMA data
transfers, resets, and interrupts are all emulated.
The Serial ATA host adapter contains a set of registers that shadow the contents of the traditional device registers,
referred to as the Shadow Register Block. All Serial ATA devices behave like Device 0 devices. For additional information
about how Serial ATA emulates parallel ATA, refer to the "Serial ATA International Organization: Serial ATA Revision 2.6".
The specification can be downloaded from www.sata-io.org.
2 Barracuda XT Series SATA Product Manual, Rev. C