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Chapter 1: General Description of the Commercial Translator System

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Introduction and Plan of the Manual

This manual has been written to be useful to two different groups of readers. Chapters 2 through 4 present a comprehensive description of the Commercial Translator language. The reader with experience in data processing may therefore begin immediately with Chapter 2. The present chapter contains a brief discussion of the essential characteristics of data processing systems (language questions aside), an indication of the motivation that led to the Commercial Translator language, and a number of relatively simple graded examples. These examples introduce the fundamentals of the Commercial Translator language without attempting to be complete.

This chapter then is intended to be of assistance to the new user who has had little or no experience in data processing.

Designing Data Processing Programs

Suppose you have been assigned to a team that is to set up a data processing system for some application in payroll, or inventory control, or utility billing, or insurance, or even in an area of science or engineering. What do you need to know about data processing in order to use the Commercial Translator language on such a job?

To begin with, we can mention a few areas of knowledge that are not needed. You need no knowledge of electronics. You need no knowledge of mathematics beyond high school algebra (unless, of course, the problem itself is mathematical). With the Commercial Translator language you do not even need a detailed knowledge of how your particular computer system works. However, you do need to know certain facts about data processing, and eventually, if you work with the subject for a while, you will pick up certain detailed facts about your particular computer—but you do not need these now. For now, the general ideas which you should have are discussed below.

What Is a Data Processing System?

A data processing system is composed functionally of five parts, as shown in Figure 1. The input section accepts information "from the outside," and converts it into the electronic form in which it is manipulated and stored internally. Externally, information is typically recorded on punched cards, punched paper tape, or magnetic tape. In some applications, printed characters can be read directly. Presently-used business machines cannot recognize handwriting or speech. The output section of a computer has the obvious function of converting from the internal representation to some convenient external form, such as printing, punched cards, magnetic tape, punched paper tape, or a variety of specialized media. Though the speeds of all of these devices are much greater than those of manual devices, they are still generally quite slow compared to speeds of internal electronic manipulation. The kind and number of input and output devices naturally depends on the particular machine and its application.

The storage section of a computer serves two important purposes. The obvious function is to hold the data on which we wish to operate. A function less obvious to the newcomer is to hold coded instructions which we place there to specify the procedure we wish to follow.