Compatibility: 3.2+
Expects: AX    440eH
BL    drive in question (0=default, 1=A, 2=B, etc.)
                                                                  
Returns: AX    error code  if CF is set to CY
AL    00H:  the drive has only one drive number (if no error)
else: drive number currently being used to refer to this
physical drive.
                                                                  
Info: This tells the device driver that its "drive alias" will be used
in subsequent read/write access.

Notes:   The phantom floppy concept is used by DOS on systems which have
a single diskette drive.  In that case, when you attempt to
access drive B, DOS prompts with:

Insert diskette for drive B.
Press any key when ready.

Programs may use this function to ell that driver that the
"disk for drive B" is already in place--and thus avoid having
DOS issue this prompt.

  Phantom floppies are also created by the Driver.Sys installable
device driver.

See Also: Fn 44H (IOCTL)
Fn 440eH (query logical drive map)
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DOS Fn 440fH: IOCTL Set Logical Drive Map