INT 13H (0x13) Function 20H (0x20 or 32) Get Current Media Format (Compaq ATAPI Removable Media Device) 21H (0x21 or 33) Read Multiple Disk Sectors 22H (0x22 or 34) Write Multiple Disk Sectors (PS and PS/2, Hard Disks) 22H (0x22 or 34) Enable/Disable Cache (QuickCache II v4.20)

INT 13H (0x13)

Function 20H (0x20 or 32) --> Get Current Media Format (Compaq ATAPI Removable Media Device)

Call with: AH = 20H
DL = drive number

Return: If Function Successful,
Carry Flag = clear
AL = media type
AH = 00H

If Function Unsuccessful,
CF = set
AH = error code

Comments:

This Function is used to get the current media format. Values for Compaq/ATAPI diskette media type have been given in the following table:

INT 13H (0x13)

Function 21H (0x21 or 33) --> Read Multiple Disk Sectors (PS and PS/2, Hard Disks)

Call with: AH = 21H
AL = number of sectors to Read
CH = low byte of 12-bit cylinder number
CL = starting sector (bits 0 to 5) and bits 8
and 9 of cylinder (bits 6 and 7)

DH = head number (bits 0 to 5) and bits 10
and 11 of cylinder (bits 6 and 7)
DL = drive number
ES:BX = Data buffer to be read

Return: If Function Successful,
Carry flag = clear
ES:BX = Filled Data Buffer

If Function Unsuccessful,
Carry flag = set
AH = status

Comments:

The Function is used to read the multiple Disk sectors Using Multiple Block Mode, which generates an interrupt only after the end of transferring a group of sectors rather than after each sector.

INT 13H (0x13)

Function 22H (0x22 or 34) --> Write Multiple Disk Sectors (PS and PS/2, Hard Disks)

Call with: AH = 22H
AL = number of sectors to be written
CH = low byte of 12-bit cylinder number
CL = starting sector (bits 0 to 5) and bits 8
and 9 of cylinder (bits 6 and 7)
DH = head number (bits 0 to 5) and bits 10
and 11 of cylinder (bits 6 and 7)
DL = drive number
ES:BX = buffer containing data to be written

Return: If function Successful,
Carry Flag = clear
AH = 01H

If function Unsuccessful,
Carry Flag = Set
AH = Status

Comments:

The Function is used to write the multiple Disk sectors using Multiple Block Mode, which generates an interrupt only after the end of transferring a group of sectors rather than after each sector.

INT 13H (0x13)

Function 22H (0x22 or 34) --> Enable/Disable Cache (QuickCache II v4.20)

Call with: AH = 22H
AL = new state (00H, if disabled and 01H,
if enabled)

Return: If Function Successful,
AX = 0000H

If Function Unsuccessful,
AX = status

Comments:

This Function Enables and/or disables caching of all drives. If the function is successful the AX register is 0000H else returns the status.

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