INT 41H and INT 46H: Hard Disk Parameter Pointers
These vectors (0:0104 and 0:0118) are pointers to hard disk operating
parameter structures on AT-class and better computers.
See Hard Disk Parameter Table for a layout of the data at these vectors.
XT: Depending upon switch settings, one of four addresses are copied to
AT: At Boot time, the AT BIOS reads the CMOS Memory to learn which type(s)
of hard disk drives are attached. It then points the vectors...
INT 41H --> first hard disk
INT 46H --> second hard disk
...to tables in ROM. Many recent BIOSes are able to handle "user-defined"
hard-disk types. They store the necessary parameters in non-volatile RAM
and copy them into memory at boot time.
See Also: BIOS Data Area