INT 13H (0x13) Read sector Function 02H (0x02) Write sector Function 03H (0x03)

INT 13H (0x13)

Function 02H (0x02)  Read sector

Call with: AH = 02H
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

Comments:

This function reads one or more sectors from disk into memory. On fixed disks, the upper 2 bits of the 10-bit cylinder number are placed in the upper 2 bits of register CL.

INT 13H (0x13)

Function 03H (0x03)  Write sector

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 sector transferred

If function unsuccessful
Carry flag = set
AH = status

Comments:

This function writes one or more sectors from memory to disk. On fixed disks, the upper 2 bits of the 10-bit cylinder number are placed in the upper 2 bits of register CL.

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