外文原文：
Microprocessors in Engineers
The development of the microprocessor during the 1970s brought about a revolution
in engineering design. The industrial revolution at the turn of the nineteenth century
heralded the development of the machines which could replace physical drudgery by
mechanical means. Apart from a few exceptions, however, these machines required
manual supervision because the problem of controlling this mechanical power was not at
all straightforward.
Many types of automatic control systems have appeared during the twentieth
century, based on electronic, mechanical, hydraulic and fluidic principles. In each case
the design techniques have been similar because each component of the system usually
contributes a single well defined function to the system behavior.
The microprocessor represents a fundamentally different approach to the design of a
system. Its physical form is quite simple and reliable, consisting of a few general-purpose
elements which can be programmed to make the system function as required. It is the
controlling program which must be designed to give the system the required behavior,
and which will contain “components” and “subassemblies” just like any other kind of
engineering. The program, or software, is just of the engineered system as the physical
hardware, but it is much less susceptible to failure, provided that it is designed properly.
The idea of programmed systems is not new; electronic computers have been in
existence for many decades. However, it has taken the development of the large scale
integrated circuit-the silicon chip-to produce computers which are cheap, rugged, and
reliable enough to be incorporated into engineering designs as components. The
techniques of software design are well known to computer scientists and it is not
surprising that the principles of good engineering design and “software engineering” are
essentially those of good engineering design. We shall see that engineering design using
software allows systems to be designed more easily than using more conventional
techniques.
It is the combination of developments in electronic device technology with those in
computer technology which has enabled the microprocessor to be produced, and these
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