Function writes sectors from memory to disk INT 13H (0x13) Function 0BH (0x0B or 11) Write sector long supported on fixed disks only Function 0CH (0x0C or 12) Seek

This function is supported on fixed disks only. The upper 2 bits of the 10-bit cylinder number are placed in the upper 2 bits of register CL.

INT 13H (0x13)

Function 0BH (0x0B or 11) >> Write sector long

Call with:AH = 0BH
AL = number of sectors
CH = cylinder
CL = sector
DH = head
DL = drive
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

Comments:

This function writes a sector(s) from memory to disk. Each sector’s worth of data must be followed by its 4-byte ECC code. The upper 2 bits of the 10-bit cylinder number are placed in the upper 2 bits of register CL. This function is supported on fixed disks only.

INT 13H (0x13)

Function 0CH (0x0C or 12) >> Seek

Call with:AH = 0CH
CH = lower 8 bits of cylinder
CL = upper 2 bits of cylinder in bits 6-7
DH = head
DL = drive
80H-FFH fixed disk

Returns:If function successful
Carry flag = clear
AH = 00H

If function unsuccessful
Carry flag = set
AH = status

Comments:

This function positions the disk read/write heads to the specified cylinder without transferring any data. The upper 2 bits of the cylinder number are placed in the upper 2 bits of register CL. This function is supported on fixed disks only.

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