Abstract: A small-size electronic apparatus includes a plurality of units each having a circuit board and an independent housing accommodating various functional components on a function to function basis. Desired ones of the units can be interconnected by a connector or connectors which may be in the form of a cable having a connector elements at its two ends with which interface portions of the units are inter-connected, or a connector pair having a male connector element and a female connector element which permit direct interconnection for the units to be layered one on top of another. The connectors permits the removal or assembling of the units without requiring any tools, and the provision of additional units with no limitation being imposed on the number of units.

Abstract: A product terminal incorporated in a product sends using state information for each configuring unit in real time to the host computer. The host computer estimates QCD of collected product considering possibility of reuse of each unit of the product, and shares the information with a warehouse center terminal, a factory terminal, and a collection terminal to effectively produce products.