0040h:0091h           Diskette Drive 1 Media State

    Length: 1 byte

    This byte is reserved for the PC, PCjr, PC XT dated 11/8/82, and
    the PC Convertible. For all others, this byte contains the state
    of the floppy diskette drive 1. See the description at address
    0040h:0090h for the format for the Diskette Drive Media State.