INT 62 u - FGDRIVER v4.02 - "FG_GETMAXY" - GET MAXIMUM ROW IN SCREEN SPACE
	AX = 004Ah
Return: AX = maximum Y coordinate in screen space
		(or character space if in text mode)
Note:	the FGDRIVER functions are rearranged with each major release, but
	  their parameters do not change (see #03474 at AX=0000h)
SeeAlso: AX=0049h,AX=00C1h