ABSTRACT
While the diagrams we have displayed so far don't make this clear, a system need not have only one input and one output. A system can, for example, have three inputs and five outputs, if its physical arrangement and operation dictate this. When this is the case, the definition of transfer function and block diagram must be extended appropriately. In drawing block diagrams and defining transfer functions, we can choose the level of detail which we wish to display, according to our needs. A designer of the E/P transducer of Fig. 1-1 might prefer the detail of Fig. 1-1 b since it makes clear the operation and interconnection of all the components. A user of alreadydesigned units (such as the designer of the system of Fig. 1-2), would on the other hand be unconcerned with such detail and prefer the overall description of Fig. 1-1 c.
