On fixed disks, the upper 2 bits of the 10-bit cylinder number are placed in the upper 2 bits of register CL.Writes one or more sectors from memory to disk.
Call with:
AH = 03H
AL = number of sectors
CH = cylinder
CL = sector
DH = head
DL = drive
00H—7FH floppy disk
80H—FFH fixed disk
ES:BX = segment:offset of buffer
Returns:
If function successful
Carry flag = clear
AH = 00H
AL = number of sectors transferred
If function unsuccessful
Carry flag = set
AH = status (see Int 13H Function 01H)
Notes:
On fixed disks, the upper 2 bits of the 10-bit cylinder number are placed in the upper 2 bits of register CL.
On floppy disk drives, an error may result from the drive motor being off at the time of the request. The ROM BIOS does not automatically wait for the drive to come up to speed before attempting the write operation. The requesting program should reset the floppy disk system (Int 13H Function 00H) and retry the operation three times before assuming that the error results from some other cause.