Hardware Reference
In-Depth Information
ATA/ATAPI-7 (ATA with Packet Interface-7)
Work on ATA-7, which began late in 2001, was completed and officially published in 2004. As with
the previous ATA standards, ATA-7 is built on the standard that preceded it (ATA-6), with some
additions.
The primary additions to ATA-7 include the following:
• Ultra-DMA (UDMA) Mode 6 was added. This allows for 133MBps transfers (called
UDMA/133, Ultra-ATA/133, or just ATA/133). As with UDMA Mode 5 (100MBps) and
UDMA Mode 4 (66MBps), the use of an 80-conductor cable is required.
• Added support for long physical sectors. This allows a device to be formatted so that there are
multiple logical sectors per physical sector. Each physical sector stores an ECC field, so long
physical sectors allow increased format efficiency with fewer ECC bytes used overall.
• Added support for long logical sectors. This enables additional data bytes to be used per sector
(520 or 528 bytes instead of 512 bytes) for server applications. Devices using long logical
sectors are not backward compatible with devices or applications that use 512-byte sectors,
such as standard desktop and laptop systems.
• SATA 1.0 incorporated as part of the ATA-7 standard. This includes the SATA physical
interconnection as well as the related features and commands.
• The ATA-7 document split into three volumes. Volume 1 covers the command set and logical
registers, which apply to both Serial and Parallel ATA. Volume 2 covers the parallel transport
protocols and interconnects (PATA), and Volume 3 covers the serial transport protocols and
interconnects (SATA).
The ATA/133 transfer mode was originally proposed by Maxtor, and only a few other drive and
chipset manufacturers adopted it. Among the chipset manufacturers, VIA, ALi, and SiS added
ATA/133 support to their chipsets, prior to moving on to SATA, but Intel decided from the outset to
skip ATA/133 in its chipsets in lieu of adding SATA (150MBps or 300MBps). This means the
majority of systems that utilize PATA do not support ATA/133; however, all ATA/133 drives do
work in ATA/100 mode.
ATA/ATAPI-8
Work on ATA-8 began in 2004, and some initial parts of the standard were published in 2006 and
2008. Other parts are still in progress and continue to be revised as of 2013. As with the previous
ATA standards, ATA-8 is built on the standard that preceded it, with some additions. As with the
previous version, ATA-8 includes SATA but adds the newer 2.x and 3.x versions of the SATA
specification.
The primary features added to ATA-8 include the following:
• The inclusion of SATA 2.x and 3.x for serial transport (physical) and command set functions
• The replacement of read long/write long functions
• Improved HPA management via additional HPA-related commands
• Defined
IDENTIFY DEVICE
word 217 to report drive rotational speed (rpm), where a value
of 1 indicates nonrotating media (solid-state drive)
• Addition of the
TRIM
command for flash-based solid-state drives (SSDs). This allows the
system to inform an SSD which blocks are no longer in use so they can be erased in preparation
