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BIOS Description
The Aw ard BIOS supports 3 HDD modes: NORMAL, LBA and LARGE.
NORMAL
Generic access mode in w hich neither the BIOS nor the IDE controller w ill make any trans-
formation during access ing. The maximum number of c ylinder s, heads and sectors for
NORMAL mode are 1024,16 and 63.
If the user sets his HDD to NORMAL mode, the maximum accessible HDD size w ill 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 show n in setup may not be the number physically contained
in the HDD.
During HDD accessing, the IDE controller w ill transform the logical address described by
sector, head and cy linder number into its ow n physical address inside the HDD. The
maximum HDD size supported by LBA mode is 8.4 Gigabytes.
LARGE mode
Some IDE HDDs contain more than 1024 cylinder w ithout LBA suppor t (in s ome cases,
users do not w ant LBA). The Aw ard BIOS provides another alternative to support these
kinds of HDD.
BI O S tricks DOS (or other OS) into di v ising the number of cylinders is less than 1024 by di v idi n g
it by 2. At the same time, the number of heads is multipl i ed by 2. A reverse transformation
process w ill be made insi d e I N T13h in order to access the ri g ht HDD address.
If using Auto detect, the BIOS w ill automatically detect the IDE hard disk mode and set it as
one of the three modes.
Remark
To support LBA or LARGE mode of HDDs, there must be some softw ares involved w hich
are located in Aw ard HDD Service Routine(INT13h). It may fail to access a HDD w ith LBA
(LARGE) mode selected if you are running under an Operating System w hich replaces the
w hole INT 13h.
Manual for WinneX 3E
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