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1.2 / STRUCTURE AND FUNCTION 11

Operating environment
(source and destination of data)

Data
movement
apparatus

Control
mechanism

Data Data
storage processing
facility facility

Figure 1.1 A Functional View of the Computer

Function
Both the structure and functioning of a computer are, in essence, simple. Figure 1.1
depicts the basic functions that a computer can perform. In general terms, there are
only four:
• Data processing
• Data storage
• Data movement
• Control
The computer, of course, must be able to process data.The data may take a wide
variety of forms,and the range of processing requirements is broad.However,we shall
see that there are only a few fundamental methods or types of data processing.
It is also essential that a computer store data. Even if the computer is processing
data on the fly (i.e., data come in and get processed, and the results go out immedi-
ately),the computer must temporarily store at least those pieces of data that are being