A system and method for single instance backup. The housing shell is cut from a quartz monocrystal which is a suitable material for the insulating housing shell due to its resistivity and dielectric strength properties. Also, a method for easily and accurately testing a two-port RAM is disclosed, allowing a stable implementation of an internal memory in an ASIC device. The light from the light transreflective member is provided through a TFT substrate to a user as an image.