logical address by sector, head, and 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. of Cylinder
(1024)
x
No. of Head
(255)
x
No. of Sector
(63)
x
No. per Sector
(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 do 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 multiplied by 2. A reverse process will be
made inside INT 12h in order to access the right HDD address
the right HDD address!
No. of Cylinder
(1024)
x No. of Head
(32)
x No. of Sector
(63)
x
No. per Sector
(512)
1 Gigabytes
3. BIOS SOFTWARE
3-11
IDE HDD Auto Detection (Continue…)
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
44
EP-PV12 User’s Manual
