Abstract machines and software design

Abstract

A recent trend in operating system design [1,2,6,7] is to consider the design as a hierarchy of abstract machines. The problem is viewed as constructing a “users' machine” from a given hardware machine by means of software. Rather than do this in one large step, a progression of abstract machines are defined starting at the hardware machine and ending with the users' machine. Each new machine is “built from” the earlier machines, adding to their capabilities. This approach appears to be a strong positive step toward bringing more discipline to the software development process. Liskov [6, 7] carefully documents the advantages. She also tries to establish formal rules to guide the process and relates this approach to structured programming [3, 8].