Hardware Reference
In-Depth Information
the driver level, allowing SATA devices to use the same BIOS-level drivers and software
as legacy PATA devices.
Although the intent of SATA was to allow an easy transition from PATA, it was also de-
signed to allow future growth and expansion of capabilities. To accomplish this, an en-
hanced software interface called the
Advanced Host Controller Interface
(AHCI) was ini-
tially developed by the AHCI Contributor Group, a group chaired by Intel and originally
consistingofAMD,Dell,Marvell,Maxtor,Microsoft,RedHat,Seagate,andStorageGear.
The AHCI Contributor Group released a preliminary version of AHCI v0.95 in May 2003
and released the 1.0 version of the specification in April 2004. You can download the cur-
rent version (1.3) from Intel at
www.intel.com/technology/serialata/ahci.htm
.
AHCI provides an industry-standard, high-performance interface to system driver/OS
software for discovering and implementing such advanced SATA features as command
queuing, hot-plugging, and power management. AHCI was integrated into SATA-sup-
porting chipsets in 2004 and is supported by AHCI drivers for Windows. The main idea
behind AHCI is to have a single driver-level interface supported by all advanced SATA
hostadapters. Thisgreatly simplifies theinstallation ofoperating systems, eliminating the
need for custom SATA drivers for each manufacturer's SATA host adapter. For example,
Windows 7/Vista and later include AHCI drivers and automatically support any advanced
SATA host adapters that are AHCI compatible.
Unfortunately, AHCI drivers are not included by default on the Windows XP and earlier
installation CDs, because AHCI was developed long after XP was released. This means,
for example, that if you install Windows XP on a system with an integrated SATA host
adapter set to AHCI mode, you will probably need to press the F6 key at the beginning
of the installation and provide a floppy disk with the AHCI drivers; otherwise, Windows
XP will not be able to recognize the drives. The implication here is that the system must
include a floppy drive, and you must have copied the drivers to a floppy disk in advance.
But what if your system doesn't even include a floppy drive? Fortunately, several solu-
tions are available.
Oneoptionistokeepasparefloppydriveinyourtoolkitandtemporarilyconnectitduring
the installation. Just open the case, plug in a floppy cable from the floppy drive connector
(FDC) on the motherboard to the drive, and connect power to the drive. There is no need
toactually mount the drive inthe chassis because youwill onlyneed toread the diskonce
at the beginning of the installation.
Another option is to set the SATA host adapter to ATA/IDE compatibility mode (disable
AHCI/RAID) in the BIOS Setup, after which you can boot from a standard Windows XP
CD and install Windows without requiring special drivers. You could leave the adapter in
