Hardware Reference
In-Depth Information
member that the media transfer rate is far more important than the interface transfer rate
when selecting a drive, because the media transfer rate is the limiting factor.
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 parts of the standard were published in 2008 and
2009. Other parts are still in progress and continue to be revised. 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.
The primary features added to ATA-8 include the following:
• The replacement of read long/write long functions
• Improved HPA management
• 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 for future writes
As the development of ATA progresses, it is expected that newer features designed by the
SATA-IO committee will be incorporated, including the faster SATA 3Gbps and 6Gbps
transfer speeds.
PATA
PATA has unique specifications and requirements regarding the physical interface,
cabling, and connectors compared to SATA. The following sections detail the unique fea-
tures of PATA.
PATA I/O Connector
The PATA interface connector is normally a 40-pin header-type connector with pins
spaced 0.1 inch (2.54mm) apart. Generally, it is keyed to prevent the possibility of in-
stalling it upside down (see
Figures 7.2
and
7.3
). To create a keyed connector, the manu-
facturer usually removes pin 20 from the male connector and blocks pin 20 on the female
