AWARD BIOS 3-17
LBA (Logical Block Addressing) mode:
A new HDD accessing method to overcome the
528 Megabyte bottleneck.
The number of cylinders, heads & 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 & 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. Cyclinder (1024)
x no. Head ( 255)
x no. Sector ( 63)
x bytes per secttor ( 512)
8.4 Gigabytes
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 does not want LBA). The Award BIOS provides another alternative to
support these kinds of LARGE mode:
CYLS. HEADS SECTOR MODE
1120 16 59 NORMAL
560 32 59 LARGE
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. A reverse
transformation process will be made inside INT 12h in order to access the right
HDD address!
Maximum HDD size:
no. Cyclinder (1024)
x no. Head ( 32)
x no. Sector ( 63)
x bytes per sector ( 512)
1 Gigabytes
