EPoX Computer KP6-FX2 Computer Hardware User Manual


 
KP6-FX 2 3-19
The maximum number of cylinders, head & sectors for NORMAL mode are.
1024, 16 & 63.
no. Cylinder (1024)
x no. Head ( 16)
x no. Sector ( 63)
x no. per sector ( 512)
528 Megabytes
If user set his HDD to NORMAL mode, the maximum accessible HDD size
will 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 & 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. Cylinder (1024)
x no. Head ( 255)
x no. Sector ( 63)
x bytes 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 transformation process will be made inside INT 12h in order to
access the right HDD address!