When a physical block device is aliased to more than one logical drive code, this function can be used to inform the driver which drive code will next be used to access the device.Sets the next logical drive code that will be used to reference a block device.
Call with:
AH = 44H
AL = 0FH
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:
When a physical block device is aliased to more than one logical drive code, this function can be used to inform the driver which drive code will next be used to access the device.
Example:
Notify the floppy-disk driver that the next access will be for logical drive B.
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mov ax,440fh ; function & subfunction
mov bl,2 ; drive 2 = B
int 21h ; transfer to MS-DOS
jc error ; jump if function failed
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