Nov 9, 2012

COMPUTER LANGUAGE

COMPUTER LANGUAGE: Computer can not understand text or written in English or other language.There is a special type of
language use for computer system known as computer language.



               Types of computer languages are ----

1. LOW LEVEL LANGUAGE:
    The term low level means closeness to the way in which machine understand.

         The low level languages are ---
A. Machine Language: This is the language (in the form of 0's and 1's, called binary numbers)understood directly by the computer. It is machine dependent.It is difficult to learn and even more difficult to write programs.

B. Assembly Language: This is the language where the machine codes comprising of 0's and 1's are substituted by symbolic codes (called mnemonics) to improve their understanding. It is the first step to improve programming structure.

Assembly language programming is simpler and less time consuming than machine level programming , it is easier to locate and correct errors in assembly language than in machine language programs.It is also machine dependent. Programmers must have knowledge of the machine on which the program will run.

COMPUTER LANGUAGE


2. HIGH LEVEL LANGUAGE:

    You know that low level language requires extensive knowledge of the hardware since it is machine dependent. To overcome the limitation,high level language has been evolved which uses normal English like,easy to understand statements to solve any problem. Higher level languages are computer independent and programming becomes quite easy and simple.
                
            The high level languages are-----
A. Basic(beginners all purpose symbolic instruction code): Prof. John Kemeny and Thomas Kurtz developed the BASIC language. BASIC is the short form of beginners all purpose symbolic instruction code. This language is very easy to learn. To use this language, it is necessary to learn some grammatical rules which are very easy to understand.

                         BASIC is an interpreter based language. Interpreters are used in microcomputer systems to translate BASIC instructions into machine language. After entering a statement, the same is checked for syntax error and the error, if there be any, can be corrected immediately. Due to this reason, BASIC has gained tremendous popularity. BASIC is a quite flexible and reasonably powerful language. It can be equally applied to business applications and scientific applications. This language has not yet been standardised. Hence, the language varies significantly from one computer system to another and a BASIC program written on one computer, may not work on another computer without modification. 

B. Cobol(common business oriented language):  COBOL is a high level language developed specially for business data processing. It is the most widely used business oriented programming language. COBOL is the short form of common business oriented language. During 1959-1960, members of CODASYL(conference on data system language) outlined the structure of this language. In 1968, ANSI COBOL standard was formulated. The COBOL program can be used in any computer system using ANSI COBOL compiler.


                        All COBOL programs must have four divisions,  a> the identification division, b> the environment division, c> the data division  and  d> the procedure division. It is a self-documenting language requiring no much explanation for proper understanding. 

C. Fortran(formula translation):  FORTRAN is one of the oldest and popular high level language. FORTRAN is the short abbreviation of FORmula TRANslation. This high level language has been developed by IBM in 1957. Original version of FORTRAN has been upgraded at different times. Two earlier versions of FORTRAN are FORTRAN II and FORTRAN IV. In 1966, American National Standards Institute(ANSI) standardised FORTRAN IV version for using the same in all types of computer system. During 1977, ANSI developed another version named as FORTRAN 77 where more structural approach to programming has been introduced. FORTRAN was developed for solving scientific and engineering problems. For mathematical modelling and solving algebra based problems, this language is most appropriate.


                       FORTRAN program consists of a series of statements. Through the statements, input, output, arithmetic, logic and other instructions can be given to the computer. Some FORTRAN instructions are READ, WRITE, DO, STOP etc. Whose meanings can easily be understood. 

D.  C :  During 1960, an international committee developed a computer language ALGOL 60. But it could not become so popular because it was too abstract language, known as Combined Programming Language(CPL) developed at the Cambridge University. The difficulty of the CPL is that, it is too difficult to learn and implement. To avoid this, Martin Richard at Cambridge University developed Basic Combined Programming Language(BCPL) in 1967. Unfortunately it was less powerful and its application was too specific. At the same time another language, known as 'B' was developed by Ken Thompson at AT&T's Bell Laboratory in 1970 to avoid the limitation of BCPL. Like BCPL, 'B' also was found to be too specific. In 1972, considering the features of BCPL and 'B' and adding some additional features, Dennis Ritchie at AT&T's Bell Laboratory developed a powerful computer language known as 'C' .


                           Today, AT&T's (Bell Lab's patent) markets a 'C' compiler and UNIX operating system tools as a single software package. There are many other versions of  'C' that run on PC's and larger machines.

                           Although 'C' is a general purpose high level language, it also allows programmers to write low level machine instructions. It supports machine and assembly language. It is thus a favourite language of professional programmers who write operating system and other software packages for machines of all sizes and it is used to create graphics and special effects.

E.  C++:  Later on Turbo C and C++ were evolved using the capability of C. Turbo C was developed by Boreland International in 1989 and it contains an interactive environment with menu-driven compiler. Turbo C programs are typically smaller, compiled and linked faster and these execute faster as compared to any ANSI compiler. Turbo C programmer may use either the menu or command line methods or both. Turbo C compiler offers some new functions that address text handling, memory management, interface with DOS files. C++ was evolved to add further enhancement to C's capability.



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