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Constellation CS Serial ATA Product Manual, Rev. C 3
www.seagate.com
1.1 About the SATA interface
The Serial ATA (SATA) interface provides several advantages over the traditional (parallel) ATA interface. The primary
advantages 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, SATA makes the transition from parallel ATA easy by providing legacy software support. SATA was designed to
allow you to install a SATA host adapter and SATA disk drive in your current system and expect all of your existing
applications to work as normal.
The SATA interface connects each disk drive in a point-to-point configuration with the SATA host adapter. There is no master/
slave relationship with SATA devices like there is with parallel ATA. If two drives are attached on one SATA 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.
The SATA 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 SATA host adapter contains a set of registers that shadow the contents of the traditional device registers, referred to as the
Shadow Register Block. All SATA devices behave like Device 0 devices. For additional information about how SATA
emulates parallel ATA, refer to the “Serial ATA International Organization: Serial ATA Revision 3.0”. The specification can be
downloaded from
www.sata-io.org.
Note
The host adapter may, optionally, emulate a master/slave environment to host software where two devices on
separate SATA 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 SATA environment.