INT 62 u - FGDRIVER v3.03 - "FG_TESTMODE" - CHECK IF VIDEO MODE AVAILABLE
        AX = 00A7h
        BX = desired video mode (00h-17h, also 18h-1Dh after "FG_SVGAINIT")
        CX = required number of video pages (ignore memory size if <= 0)
Return: AX = status
            0000h mode not available with requested number of pages
            0001h mode is available
Note:   For FGDRIVER v1.10, this function was unused;"FG_TESTMODE" was AX=0002h
SeeAlso: AX=0005h,AX=0093h

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