INT 10 - VIDEO - MSHERC.COM - INSTALLATION CHECK???
        AH = EFh
Return: DL = video adapter type
            00h original Hercules
            01h ???  \ one is probably Hercules Plus, the other
            02h ???  / Hercules InColor
            FFh non-Hercules
        DH = memory mode byte
            01h "half" mode
            03h "full" mode
Note:   MSHERC.COM is a support program for the Microsoft Quick languages which
          makes their graphics libraries compatible with a Hercules card by
          adding video modes 08h and 88h, and supporting text in the new
          graphics modes.  While in mode 08h or 88h, INT 10 supports the
          Hercules card much like a CGA.