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Momentus 5400.3 PSD SATA Product Manual, Rev. A
The Serial ATA 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 normally 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 AT A makes the transitio n from pa ral lel ATA easy by providing legacy software support. S erial
ATA was designed to allow you to install a Serial ATA host adapter and Serial ATA disc drive in your current
system and expect all of your existing applications to work as normal.
The Serial ATA interface connects each disc 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 operatin g 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 ada pter cont ains a set of registers that shadow the contents of the traditional device regis-
ters, referred to as the Shadow Register Block. All Serial ATA devices behave like Device 0 devices. For addi-
tional information about how Serial ATA emulates parallel ATA, refer to the “Serial ATA: High Speed Serialized
AT Attachment” specification. The specification can be downloaded from http://www.serialata.org.
1.2 Non-volatile cache (NVC )Momentus 5400.3 PSD SATA include a non-volatile cache feature. For a user to see the benefits of NVC, the
host operating system must support the “Non-volatile cache” commands (B6h) and associated subcommands
as specified in the ATA-8 specification. See Section 4.3 for the list of commands supported by Momentus
5400.3 PSD SATA drives (including the Non-volatile cache commands).
Non-volatile cache is designed to:
• Improve performance
• Provide power savings and battery life (in notebook systems)
• Improve reliability
• Reduce acoustic noise in some read/write operations
Improve performance
The non-volatile cache (NVC) improves performance by writing and reading to the non-volatile cache rather
than waiting for the rotating media to complete spinning-up from sleep, standby, and hibernate modes. Perfor-
mance improvements may also be seen from minimizing disc seeks and enabling more I/Os per second. The
non-volatile cache also improves cold boot performance when used with operating systems designed to take
advantage of this cache.