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Generic access mode in which neither the BIOS nor the IDE controller
will make any transformation during accessing. The maximum number of
cylinders, heads and sectors for NORMAL mode are 1024,16 and 63.
If user sets his HDD to NORMAL mode, the maximum accessible HDD
size will be 528 megabytes even though its physical size may be greater
than that.
LBA (Logical Block Addressing) mode
A new HDD accessing method to overcome the 528 Megabyte bottleneck.
The number of cylinders, heads and sectors shown in setup may not be
the number physically contained in the HDD.
During HDD accessing, the IDE controller will transform the logical
address described by sector, head and cylinder number into its own
physical address inside the HDD. The maximum HDD size supported
by LBA mode is 8.4Gigabytes.
LARGE mode
Some IDE HDDs contain more than 1024 cylinder without LBA support
(in some cases, user do not want LBA). The Award BIOS provides
another alternative to support these kinds of HDD.
BIOS tricks DOS (or other OS) that the number of cylinders is less than 1024
by dividing it by 2. At the same time, the number of heads is multiplied by 2.
A reverse transformation process will be made inside INT13h in order to
access the right HDD address.
Auto detect
If using Auto detect, the BIOS will automatically detect IDE hard disk
mode and set it to one kind of HDD modes.
3. Remark
To support LBA or LARGE mode of HDDs, there must be some software
involved which are located in Award HDD Service Routine(INT13h).It
maybe fail to access a HDD with LBA (LARGE) mode selected if you are
running under an Operating System which replaces the whole INT 13h.
Power-On Boot
If you have made all the changes to CMOS values and the system can
boot with the CMOS values selected in Setup, restart the system by turning it
Chapter 4
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