A method is provided that includes transmitting a video stream to a set-top box. The method further includes comparing, by the host, the first authentication information with the second authentication information. This information allows stores to be sorted into those which can see price aggression, those which cannot, and those which are likely to respond to promotions. Circuits are achieved to create a frequency reference and a capacitance reference using said method Additionally a method is introduced to create a capacitance reference in integrated circuits using said MOSFET capacitors. The hard disk cage is fixedly connected to the fixing portions and above the tray, and has a hole corresponding to a hole of the front board.