Int 21H [3.2] Function 44H (68) Subfunction 0EH (14) IOCTL: get logical drive map

Returns the logical drive code that was most recently used to access the specified block device.

Call with:

AH = 44H

AL = 0EH

BL = drive code (0 = default, 1 = A, 2 = B, etc.)

Returns:

If function successful

Carry flag = clear

AL = mapping code

00H if only one logical drive code assigned to the

block device

01H—1AH logical drive code (1 = A, 2 = B, etc.) mapped

to the block device

If function unsuccessful

Carry flag = set

AX = error code

Note:

If a drive has not been assigned a logical mapping with Function 44H Subfunction 0FH, the logical and physical drive codes are the same.

Example:

Check whether drive A has more than one logical drive code.

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mov ax,440eh ; function & subfunction

mov bl,1 ; drive 1 = A

int 21h ; transfer to MS-DOS

jc error ; jump if function failed

or al,al ; test drive code

jz label1 ; jump, no drive aliases

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