Fig. 5. Hierarchy of components used in logical design of a sequential multiplier.
structural scheme of description, we specify seven exact operations and then say everything can be built by combining them, here we specify seven functions and say everything can be decomposed into systems whose components are also only of these seven types.
HOW TO CONNECT COMPONENTS INTO SYSTEMS
Each component, of whatever type, has a number of ports. Each port permits the transmission, in or out (sometimes both) of a set of bits that play some role in the operation of the component. To construct a system one connects the ports of one component with the ports of another. Conceptually, they become identical: two connected ports always have identical bit values.