Hardware Reference
In-Depth Information
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
solutions are available.
One option is to keep a spare floppy drive in your toolkit and temporarily connect it during 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 to actually mount the
drive in the chassis because you will only need to read the disk once 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 compatibility
mode, but you might be missing out on the performance offered by the advanced capabilities your
hard drives support.
Although the first two options can work in most situations, I think the best overall solution is to
simply create a custom Windows XP installation disc that already has the SATA AHCI (and even
RAID) drivers preinstalled. This can be accomplished via a somewhat tedious manual integration
process for each set of drivers, but to make things really easy you can use the menu-driven BTS
DriverPacks from
www.driverpacks.net
to integrate virtually all the popular mass storage drivers
directly into your Windows XP install disc. The DriverPacks allow you to easily add all kinds of
drivers to your Windows XP installation discs. For example, in addition to the mass storage drivers, I
like to integrate the various processor, chipset, and network (both wired and wireless) drivers
because all of these still fit on a CD. If you are willing to move to a DVD instead of a CD, you can fit
Windows XP and all of the available XP DriverPacks on a single DVD.
Non-Volatile Memory Express (NVMe)
The Advanced Host Controller Interface (AHCI) has long been the preferred software interface for
SATA devices. AHCI can be used with conventional SATA as well as SATA Express devices,
allowing both to use the same software interface and therefore the same drivers. While using AHCI
mode with SATA Express allows for maximum compatibility, it does not allow for maximum
performance when interfacing with low-latency devices like solid-state drives (SSDs), which
internally behave more like RAM than a spinning disk. To improve the performance of SSDs
connected via high-speed PCI Express-based interfaces like SATA Express, a new software
interface called the Non-Volatile Memory Host Controller Interface (NVMHCI) was first defined in
2007 by the NVMHCI Workgroup (
www.nvmexpress.org
), a group including more than 75 major
companies from the computing and storage industries. Owing to its intention on being used in
combination with PCIe and SATA Express devices, the NVMHCI specification was subsequently
named NVM Express (NVMe), and the NVMe specification 1.0 was published in 2011.
Like AHCI before it, NVMe is a software interface specification that defines the commands and
