INT 13h, 19h (25)      Park Heads                                PS/2

     Parks disk heads. You should do this before moving a drive.

             On entry:         DL          Drive ID number (bit 7 = 1
                                                   for hard disks. 0 origin)

             Returns:          AH          Status of operation (see
                                                   Service 01h)
                               CF          = 1 . Failure

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     This service parks the heads of PS/2 disk drives. You should do this
     before moving a drive. Place the number of the disk to park in DL (0
     origin), and set bit 7 of DL to 1 for hard disks.

     On return, AH holds the status code (see Service 01h for the meaning of
     the codes). If the carry flag is set, the operation failed.