Int 2F Fn 1510  - Cd-rom V2.10+ - Send Device Driver Request               [d]

   AX = 1510h
   CX = CD-ROM drive letter (0 = A, 1 = B, etc)
   ES:BX -> CD-ROM device driver request header (see #2284 at AX=0802h)

Return: CF clear if device driver has been called (check the request header's
         status word to determine whether an error has occurred)
       ES:BX request header updated
   CF set if device driver has not been called
       AX = error code (000Fh = invalid drive, 0001h = invalid function)
       ES:BX request header unchanged

Notes: MSCDEX initializes the device driver request header's subunit field
     based on the drive number specified in CX
   MSCDEX v2.21 through v2.25 (at least) return error code AX=0001h if
     nested calls are attempted
BUGS:  Novell DOS 7 NWCDEX prior to the 12/13/94 update did not initialize
     the subunit field
   Windows95 sets CF if CX isn't a CD-ROM drive but leaves CF unchanged
     if the drive is in fact a CD-ROM

See Also: AX=0802h