Data Processing Techniques and Systems

 Data processing is any computer process that converts data into information. The processing is usually assumed to be automated and running on a mainframe, minicomputer, microcomputer, or personal computer. Because data are most useful when well-presented and actually informative, data processing systems are often referred to as information systems to emphasize their practicality. Nevertheless, both terms are roughly synonymous, performing similar conversions; data-processing systems typically manipulate raw data into information, and likewise information systems typically take raw data as input to produce information as output.

 More generally, the term data processing can apply to any process that converts data from one format to another, although data conversion would be the more logical and correct term. From this perspective, data processing becomes the process of converting information into data and also the converting of data back into information. The distinction is that conversion doesn't require a question (query) to be answered. For example, information in the form of a string of characters forming a sentence in English is converted or encoded from a keyboard's key-presses as represented by hardwareoriented integer codes into ASCII integer codes after which it may be more easily processed by a computer—not as merely raw, amorphous integer data, but as a meaningful character in a natural language's set of graphemes—and finally converted or decoded to be displayed as characters, represented by a font on the computer display. In that example we can see the stage-by-stage conversion of the presence of and then absence of electrical conductivity in the key-press and subsequent release at the keyboard from raw substantiallymeaningless integer hardware-oriented data to evermore-meaningful information as the processing proceeds toward the human being.  

 Input, Processing and output  Processing

 Whenever a computer is used it must work its way through three basic stages before any task can be completed. These are input, processing and output. A Computer works through these stages by running a program. A program is a set of step-by-step instructions which tells the computer exactly what to do with the input in order to produce the required output.  

  Input   Processing  

 The input stage of computing is concerned with getting the data needed by the program into the computer. Input devices are used to do this. The most commonly used input devices are the mouse and the keyboard.  The program contains instructions about what to do with the input. During the processing stage the compute follows these instructions using the data which has just been input. What the computer produces at the end of this stage, the output, will only be as good as the instructions given in the program. In other words if garbage has been put in to the program, garbage is what will come out of the computer. This is known as GIGO, or Garbage In Garbage Out.  

 Output   

 The output stage of computing is concerned with giving out processed data as information in a form that is useful to the user. Output devices are used to do this. The most commonly used output devices are the screen, which is also called a monitor or VDU and the printer.  

                                                      INTRODUCTION TO COBOL  

 In contrast to administrative data processing, scientific computing generally involves a lower volume and diversity of input data, small or nonexistent files, less complex processing logic but more extensive mathematical manipulation, and more limited report production needs. Because administrative data processing has characteristics different from those of scientific computing, a special programming language i.e. COBOL (Common Business Oriented Language) has been developed to fulfill the particular needs associated with such processing of data. Now, the COBOL has persisted as the most widely used language for administrative data processing 

 HISTORY OF COBOL  

 In the 1950s there was a growing need for a high-level programming language suitable for business data processing. To meet this need, the Dept. of Defense (DoD) of USA (in 1958) formed a “short-term work” group. In 1959, the short-term committee gave the idea of a new language named COBOL (COmmon Business Oriented Language).  In 1960, the board of directorate of the short-term group, known as CODASYL (Conference on DATA System Language) established a COBOL maintenance committee to keep the COBOL up-to-date. On May 5, 1961, COBOL-61 was published with some revisions. The users started writing programs in COBOL when the first COBOL compiler became available in early 1962. In 1965, the next version with some new additions was published .In August 1968 a standard version of the language was approved by the American National Standards Institute (ANSI) known as ANSI-68 COBOL or COBOL-68. COBOL-74, the next revised official standard was introduced in 1974. This version is currently implemented in almost every machine. However, in 1985 a revised standard was introduced known as COBOL-85 that is the latest version of COBOL. COBOL is self-documenting language. One of the design goals for COBOL was to make it possible for non-programmers such as supervisors, managers and users, to read and understand COBOL code. As a result, COBOL contains such English-like structural elements as verbs, clauses, sentences, sections and divisions. As it happens, this design goal was not realized. Managers and users nowadays do not read COBOL programs. Computer programs are just too complex for most laymen to understand them, however familiar the syntactic elements. But the design goal and its effect on COBOL syntax has had one important side effect. It has made COBOL the most readable, understandable and self-documenting programming language in use today. It has also made it the most verbose. When programs are new, both the in-program comments and the external documentation accurately reflect the program code. But over the time, as  more and more revisions are applied to the code, it gets out of the step with the documentation. Ultimately, the documentation actually becomes a hindrance to maintenance rather than help. The self-documenting nature of COBOL means that this problem is not as severe with COBOL programs as it is with other languages Readers who are familiar with C or C++ or Java might want to consider how difficult it becomes to maintain programs written in these languages. C programs that you have written yourself are difficult enough to understand when you come back to them six months later. Consider how much more difficult it would be to understand a program that had been written fifteen years previously by someone else, and which had since been amended and added to by so many others that the documentation no longer accurately reflects the program code. This is a nightmare still awaiting maintenance programmers of the future COBOL is a simple language (no pointers, no user defined functions, no user defined types) with a limited scope of function. It encourages a simple straightforward programming style. Curiously enough though, despite its limitations, COBOL has proven itself to be well suited to its targeted problem domain (business computing). Most COBOL programs operate in a domain where the program complexity lies in the business rules that have to be encoded rather than in the sophistication of the data structures or algorithms required. And in cases where sophisticated algorithms are required COBOL usually meets the need with an appropriate verb such as the SORT and the SEARCH.  

 Advantages of COBOL 

 1) Its main advantage is advancement of communication i.e. it reduces the communication gap between the programmers and decision makers.

 2) No need of any symbolic and machine instructions by the programmers.  

 3) Pre-tested modules of input and outputs are included in the COBOL processor. Hence it reduces the tedious job of writing and test them. 

4) The programmer is writing in a language that is familiar to him/her and hence reduces the documentation. 

5) While COBOL is not completely portable but with a little modification in a program you can make a COBOL program portable. 

6) A COBOL program is a set of different DIVISIONS there fore different divisions can handle using the modular programming approach.

 7) During the completion phase, a COBOL processor generates a list of diagnostics (list of errors other then logical)  

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