A loss-of-signal detector includes a variable gain amplifier with an input receiving an input signal, a threshold comparator with a first input receiving a signal derived from an output of the variable gain amplifier, a second input receiving a reference level and an output providing a loss-of-signal indication signal. A further capability is that the availability of the individual software components upon which a specific business logic process depends may each be individually and continuously checked, in a combined fashion that is referenced to the specific business logic process, so that the status of the business logic process itself can be continuously determined on an on-going basis. The bus monitor monitors a link between the network interface device and the computer. Said coating is present at a level of at least 1% by weight of the water-swellable material. To this end, ultra-minimization, a micro machining technique fit to a mass production, and a semiconductor device assembly manufacturing process are applied, thereby reducing a component cost and increasing uniformity of components.