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During HDD accessing, the IDE controller will transform the logical address described by
sector, head & cylinder into its own physical address inside the HDD.
The maximum HDD size supported by LBA mode is 8.4 Gigabytes which is obtained by
the following formula:
no. Cylinder
x
no. Head ( 255)
x
no. Sector
x
bytes per sector ( 512)
LARGE mode
Extended HDD access mode supported by Award Software.
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 LARGE mode:
CYLS.
1120
560
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 nultiplied by 2. Reverse transformation
process will be made inside INT 12h in order to access the right HDD address the right
HDD address!
Maximum HDD size:
no. Cylinder
x
no. Head ( 32)
x
no. Sector
x
bytes per sector ( 512)
NOTE:
To support LBA or LARGE mode of HDDs, there must be some softwares involved. All these
softwares are located in the Award HDD Service Routine (1NT 13h). It may be failed to access
a HDD with LBA (LARGE) mode selected if you are running under a Operating System which
replaces the whole INT 13h.
UNIX operating systems do not support either LBA or LARGE and must set to the Standard
mode. UNIX can support drives larger than 528MB.
3-11 SAVE & EXIT SETUP
The "SAVE & EXIT SETUP" option will bring you back to boot up procedure with all the
changes you just made which are recorded in the CMOS RAM.
3-12 EXIT WITHOUT SAVING
The "EXIT WITHOUT SAVING" option will bring you back to normal boot up procedure
without saving any data into CMOS RAM. All of the old data in the CMOS will not be
destroyed.
3-13 I/O & MEMORY MAP
MEMORY MAP
(1024)
(
63)
8.4 Gigabytes
HEAD
SECTOR
16
59
32
59
(1024)
( 63)
1 Gigabytes
MODE
NORMAL
LARGE
35
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