Hardware Reference
In-Depth Information
of signal timing, electromagnetic interference (EMI), and other integrity problems. The
solution is called SATA, which is an evolutionary replacement for the venerable PATA
physical storage interface. When set in non-AHCI/RAID modes (in other words, IDE or
legacy mode), SATA is software-compatible with PATA, which means it emulates all the
commands, registers, and controls so existing software can run without changes. In other
words, the existing BIOSs, operating systems, and utilities that work on PATA also work
with SATA.
Of course, they do differ physically—that is, you can't plug PATA drives into SATA
host adapters, and vice versa, although signal converters make that possible. The physical
changes are all for the better because SATA uses much smaller and thinner cables with
only seven conductors that are easier to route inside the PC and easier to plug in with
smaller, redesigned cable connectors. The interface chip designs also are improved, with
far fewer pins and lower voltages. All these improvements are designed to eliminate the
design problems inherent in PATA.
Figure 7.8
shows the official Serial ATA International Organization working group logo
that identifies most SATA devices.
Figure 7.8
Serial ATA official logo, which identifies SATA devices.
Although SATA didn't immediately replace PATA, most new systems following SATA's
standardization included SATA interfaces alongside PATA interfaces. Over time, SATA
haspredominantlyreplacedPATAasthedefactostandardinternalstoragedeviceinterface
found in PCs. The transition from ATA to SATA has been a gradual one. In this transition,
PATA capabilities continue to be available.
Development for SATA started when the Serial ATA Working Group effort was an-
nouncedattheIntelDeveloperForuminFebruary2000.TheinitialmembersoftheSerial
ATA Working Group included APT Technologies, Dell, IBM, Intel, Maxtor, Quantum,
andSeagate.TheoriginalgrouplaterbecameknownastheSerialATAIIWorkingGroup,
