INT 13H (0x13)
Function 4EH (0x4E or 78) --> Set Hardware
Configuration (IBM/MS INT 13H Extensions v2.1)
Call with: AH = 4EH
AL = Function Number ( See the Table in comments)
DL = Drive number
Return: If Function Successful,
Carry Flag = Clear
AH = 00H
If Function Unsuccessful,
Carry Flag = Set
AH = error code
AL = Status
Comments:
This Function is used to set the hardware configuration. The function numbers for AL to call this Function have been given in the following table:
Value |
Description |
00H |
Enable prefetch |
01H |
Disable prefetch |
02H |
Set maximum PIO transfer mode |
03H |
Set PIO mode 0 |
04H |
Set default PIO transfer mode |
05H |
Enable INT 13H DMA maximum mode |
06H |
Disable INT 13H DMA |
DMA and PIO modes are mutually exclusive therefore selecting DMA disables PIO for either the specified device or all devices on that controller and selecting PIO disables DMA
INT 13H (0x13)
Function 5001H (0x5001) --> Send Packet Command (Enhanced Disk Drive Spec v3.0)
Call with: AX = 5001H
DL = Drive number
ES:BX = Command packet (See the Table in
comments)
Return: If Function Successful,
Carry Flag = Clear
AH = 00H
If Function Unsuccessful,
Carry Flag = Set
AH = error code
Comments:
This function is used to send the packet commands. If the function is successful carry flag is clear and AH register is 00H, else Carry flag is set and AH returns the error code. The Format of Enhanced Disk Drive Spec v3.0 command packet has been given in the following table:
Offset |
Size |
Description |
00H |
WORD |
Signature B055H |
02H |
BYTE |
Length of packet in bytes |
03H |
BYTE |
Reserved (0) |
04H |
N BYTEs |
Formatted packet data |
INT 13H (0x13)
Function 5501H (0x5501) --> Inquiry (Seagate ST01/ST02)
Call with: AX = 5501H
DH = Number of bytes to transfer
DL = Drive Number
ES:BX = Buffer for results
Return:
ES:BX buffer, filled with the Inquiry results.
Comments:
This function is used to send inquiry. The ST01/ST02 BIOS does not return any success or failure indication for the function therefore all the commands must be assumed to have been successful.
The ST01/ST02 BIOS always maps its drives after the previous BIOS drives without changing the BIOS drive count at 0040H:0075H. This command is identical to the SCSI Inquiry command
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