INT 62 u - FGDRIVER v3.03 - "FG_SETHPAGE" - SET HIDDEN VIDEO PAGE
        AX = 0091h
        BX = new hidden page (0000h to 003Fh)
Notes:  For FGDRIVER v1.10, this function was "FG_PLAYING" (see AX=0075h);
          "FG_SETHPAGE" was AX=0041h
        The specified page must be a physical page or a virtual page
SeeAlso: AX=0037h,AX=0095h,AX=0098h

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