INT 62 u - FGDRIVER v1.10 - "FG_GETMAP" - STORE IMAGE AS MODE-INDEPENDNT BITMAP
        AX = 0046h
        ES:BX -> buffer for video mode-independent bitmap
        CX = width of bitmap in bytes
        DX = height of bitmap in pixel rows
Return: each bit in bitmap is set if corresponding pixel is of the current
          color, cleared otherwise
Note:   this call is ignored in text modes
SeeAlso: AX=0048h