INT 10 - ATI BIOS Extensions - ???

	AX = A000h
	CL = ??? (bits 2-0 may not be 000)
	CH = ??? (81h or ???)
	DX = segment of ??? (if CH=81h)
	???
Return: AX = ???
Program: the ATI BIOS extensions are supported by ATI graphics cards containing
	  the Mach64 or newer graphics chips (Rage Pro, Rage 128, etc.)
SeeAlso: AX=4F10h/BL=00h,AX=A001h