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Int 10h, 1Ch            Save/Restore Video State                          VGA

    Performs a complete save or restore of the VGA video state.

    ------------------------------------------------------------------
    Return size of buffer needed to save/restore video state

        Entry   AX = 1C00h
                CX = Requested states:
                     Bit 2   1 = DAC state
                     Bit 1   1 = BIOS data
                     Bit 0   1 = Video hardware state

        Return  AL = 1Ch   If function supported
                BX = Save/restore buffer size block count
                     (each block is 64 bytes)

    ------------------------------------------------------------------
    Save video state

        Entry   AX    = 1C01h
                CX    = Save:
                        Bit 2   1 = Save DAC state
                        Bit 1   1 = Save BIOS data
                        Bit 0   1 = Save video hardware state
                ES:BX = Address of buffer

        Return  AL = 1Ch   If function supported

    ------------------------------------------------------------------
    Restore video state

        Entry   AX    = 1C02h
                CX    = Restore:
                        Bit 2   1 = Restore DAC state
                        Bit 1   1 = Restore BIOS data
                        Bit 0   1 = Restore video hardware state
                ES:BX = Address of buffer

        Return  AL = 1Ch   If function supported

    ------------------------------------------------------------------

    This service lets you save or restore the video state. First, you
    must determine the size of the memory buffer you need to store
    video information.

    To get that size, use subservice 0. You need to specify how
    much information you want to store by setting the bits of CX as
    follows:
                Bit 2   1 = Save/restore DAC state
                Bit 1   1 = Save/restore BIOS data
                Bit 0   1 = Save/restore video hardware state

    Subservice 1 saves the state. Pass it the address of the data
    buffer you want to use in ES:BX and set the bits in CX to match
    those parts of the video state you want to save. Note that many
    BIOSes corrupt the video registers when saving the state, so a
    program should restore the state, using subservice 2, immediately
    after saving it (the saved data is uncorrupted).

    Subservice 2 restores the video state. The inputs are the same
    as for subservice 1.