TABLE OF CONTENTS This chapter explains microcomputers and how they are used in instrumentation and control systems. Topics include microcomputer fundamentals, microcomputer equipment, microcomputer inputs and outputs, computerized instrumentation, and computerized control systems. The specific automotive applications of microcomputers are explained in later chapters.
A digital computer represents each variable in terms of binary numbers.
In digital computer-based systems, physical variables are represented by a numerical equivalent using a form of the binary (base 2) number system. In the previous chapter it was shown that transistor circuits can be constructed to have one of two stable states: saturation and cutoff. These two states can be used to represent a 0 (zero) or a 1 (one) in a binary number system. To be practically useful, there must be groups of such circuits that are arranged in the form of a place position, binary number system.
By contrast, an analog system has a single lead with a voltage (relative to ground) that is proportional to the relevant physical variable. A digital system will have a group of leads, each one of which can have only two voltage levels representing 0 or 1 (as discussed in Chapter 3). It is common practice for a digital computer to have the number of voltages representing the binary digits (bits) be a multiple of 8. For example, early automotive engine control computers used 8 bits to represent data, which means that 256 (2 8) possible levels can be represented. In early twenty-first-century...
