A digital signal processing circuit, such as a digital-to-analog converter having multiple cascaded processing stages, some of which are selectably placed in a low-power non-operating state according to a lower-power operating mode of the digital signal processing circuit and are placed in an operating state according to another higher-performance operating mode of the circuit. In one embodiment the method and apparatus is used to authenticate the contents of a removable media. The device can be configured to be worn around the head, the neck, or body of the user. A plurality of historical parameters corresponding to one or more previous states of the at least one weather phenomenon is associated with the current state of the at least one weather phenomenon if at least one previous state of the at least one weather phenomenon has been identified. The invention improves upon prior art systems and relates to a system whereby both a silk screen squeegee unit and a quartz flash unit are slidably mounted on a common set of rails, in order to allow each to be easily placed and removed from the silk screening platform.