Seagate BarraCuda Product Manual, Rev. A

7

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Introduction

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 users to install a SATA host adapter and SATA disk drive in the current system and expect all of the 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 3.2”. 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.