Seven Views of Computer Systems
C. GORDON BELL, J. CRAIG MUDGE, and JOHN E. McNAMARA
A computer is determined by many factors, including architecture, structural properties, the technological environment, and the human aspects of the environment in which it was de signed and built. In this book various authors reflect on these factors for a wide range of DEC computers - their goals, their architectures, their various implementations and realizations, and occasionally on the people who designed them.
Computer engineering is the complete set of activities, including the use of taxonomies, theories, models, and heuristics, associated with the design and construction of computers. It is like other engineering, and the definition that Richard Hamming (then at Bell Laboratories) gave is especially appropriate: engineers first turn to science for answers and help, then to mathematics for models and intuition, and finally to the seat of their pants.
In the few decades since computers were first conceived and built, computer engineering has come from a set of design activities that were mostly seat-of-the-pants based to a point where some parts are quite well understood and based on good models and rules of thumb, such as technology models, and other parts are completely understood and employ useful theories such as circuit minimization.
In this chapter, seven views are presented that the authors have found useful in thinking about computers and the process that molds their form and function. They are intentionally independent; each is a different way of looking at a computer. A computer scientist or mathematician sees a computer as levels-of-interpreters. An engineer sees the computer on a structural basis, with particular emphasis on the logic de sign of the structure. The view most often taken by a buyer is a marketplace view. While these people each favor a particular view of computers, each typically understands certain aspects of the other views. The goals of Chapter 1 are to increase this understanding of other views and to increase the number of representations used to describe the object of study and, hence, improve on its exposition. Thus, "The Seven Views of Computer Systems" forms a useful background for the subsequent chapters on past, present, and future computers.