T13/2132-D Revision 3

June 23, 2010

8.14 Check Extensions Present (FN 41h)

This function shall be used to check for the presence of INT 13h extensions. If CF=1b, the extensions are not supported for the requested device. If CF=0b, BX shall be checked to confirm that it contains the value AA55h indicating that the extensions are present. If BX = AA55h, the value of CX shall be checked to determine what subsets of this interface are supported for the requested device. At least one subset shall be supported. The version of the extensions shall be 30h. This indicates that the INT 13h extensions are compliant with this standard.

Entry

AH 41h

BX 55AAh

DL BIOS device number

Exit

Carry Clear Function completed without error

AH Version of extensions. Shall be set to 30h

AL Vendor Specific

BX AA55h

CX Interface support bit map (see table 21)

Carry Set Function completed with an error

AH Shall be set to the error code 01h (Invalid Command)

Table 21 — Interface Support Bit Map

Bit

Description

0If the content of this bit is one, then the Fixed disk access subset shall be supported.

1If the content of this bit is one, then the Device locking and ejecting subset shall be supported.

2This bit shall be set to one to indicate that the Enhanced disk drive support subset is present.

3If the content of this bit is one, then the 64-bit extensions are present. When the 64-bit extensions are present, the fields starting at offset 10h in the Device Address Packet are valid.

15:4 Reserved.

42

Working Draft Enhanced Disk Drive - 4 (EDD-4)

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Western Digital T13/2132-D manual Check Extensions Present FN 41h, Interface Support Bit Map Description