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The maximum HDD size supported by the LBA mode is 8.4 gigabytes. It
is obtained by the following formula.
no. Cylinders
(1024)
x no. Heads
( 225)
x no. Sectors
( 63)
x bytes per sector
( 512)
8.4 gigabytes
Large Mode
The Large mode is the extended HDD access mode supported by the
G486VPC system board. Some IDE HDDs have more than 1024 cylin-
ders without LBA support (in some cases, you may not want the LBA
mode). This system board provides another alternative to support these
kinds of HDDs.
The BIOS tells the operating system that the number of cylinders is half
of the actual number and that the number of heads is double the actual
number. During disk access, the reverse conversion is done by the
INT13h routine.
Example of Large mode:
CYLS. HEADS
SECTORS
MODE
1120
16
59
NORMAL
560
32
59
LARGE
Maximum HDD size:
no. Cylinders
(1024)
x no. Heads
( 32)
x no. Sectors
( 63)
x bytes per sector
( 512)
1 gigabyte
