System and method for determining attributes and coupling characteristics of components by comparatively observing provided reference signal

A system and method for determining the physical presence, proper electrical coupling and predetermined identifying characteristics and attributes of various computer system elements and components, including both fixed and removable modules such as field replaceable units ("FRUs"), utilizing a minimum number of signal lines per component. In a preferred embodiment, a voltage divider is established between a first resistance in an environmental monitoring unit ("EMU") and a second resistance in an associated FRU wherein a voltage level taken intermediate the first and second resistances is indicative of a particular FRU attribute.