0040h:003Eh           Diskette Drive Recalibrate Status

    Length: 1 byte

    This byte indicates whether or not a diskette drive needs to be
    recalibrated.


                Diskette Drive Recalibrate Status

                7 6 5 4 3 2 1 0
                x . . . . . . .      Interrupt Flag
                . x . . . . . .      Reserved
                . . x . . . . .      Reserved
                . . . x . . . .      Reserved
                . . . . x . . .      Recalibrate Drive 3
                . . . . . x . .      Recalibrate Drive 2
                . . . . . . x .      Recalibrate Drive 1
                . . . . . . . x      Recalibrate Drive 0


    Note that if bits 0 through 3 are 0, the drive needs calibration.

    Recalibration will retract the head to track 0.

    If a drive needs recalibration and a seek is requested, then
    recalibration will be performed before the seek.

    Int 13h, Service 00h, will set bits 0 through 3 to 0, thereby
    forcing a recalibration.