Hardware Reference
In-Depth Information
systemcouldusetoaccesstheHPA.ThePARTIESstandardwascompletedandpublished
in 2001 as “NCITS 346-2001, Protected Area Run Time Interface Extension Services.”
The HPA works by using the optional ATA
SET MAX ADDRESS
command to make the drive
appear to the system as slightly smaller. Anything from the new max address (the newly
reported end of the drive) to the true end of the drive is considered the HPA and is access-
ible only using PARTIES commands. This is more secure than a hidden partition because
anydatapasttheendofthedrivesimplycannotbeseenbyanormalapplication,orevena
partitioning utility. Still, if you want to remove the HPA, you can use some options in the
BIOS Setup or separate commands to reset the max address, thus exposing the HPA. At
that point, you can run something such as Parted Magic or Partition Commander to resize
the adjacent partition to include the extra space that was formerly hidden and unavailable.
Starting in 2003, some systems using Phoenix BIOS have included recovery software and
diagnostics in the HPA.
Formoreinformation ontheHPAandwhatmightbestoredthere,
see
“
PrebootEnvir-
ATAPI
ATAPI is a standard designed to provide the commands necessary for devices such as
optical drives, removable media drives such as SuperDisk and Zip, and tape drives that
plug into an ordinary PATA (IDE) connector. The principal advantage of ATAPI hard-
ware is that it's cheap and works on your current adapter. Optical drives have a somewhat
lower CPU usage compared to proprietary adapters, but there's no performance gain oth-
erwise.Fortapedrives,ATAPIcanprovidesuperiorperformanceandreliabilitycompared
to floppy controller-attached tape devices. Although ATAPI optical drives use the hard
diskinterface,theydon'tnecessarilylooklikeordinaryharddisks.Tothecontrary,froma
software point of view, they are a completely different kind of animal. They most closely
resembleaSCSIdevice.AllmodernATAopticaldrivessupporttheATAPIprotocols,and
generally the terms are synonymous. In other words, an ATAPI optical drive is an ATA
optical drive, and vice versa.
Caution
Most systems starting in 1998 began supporting the Phoenix El Torito specification, which
enables booting from ATAPI CD or DVD drives. Systems without El Torito support in the
BIOS can't boot from an ATAPI CD or DVD drive. Even with ATAPI support in the BIOS,
you still must load a driver to use ATAPI under DOS or Windows. Windows 95 and later
(including 98 and Me) and Windows NT (including Windows 2000 forward) have native
ATAPI support. Some versions of the Windows 98 and Me CD-ROMs are bootable, whereas
