Revolution of Java
READ AND TRANSLATE THE TEXT Computer languages Unfortunately for us. computers can't understand spoken English or any other natural language. The only language they can understand directly is machine code which consists of 1s and 0s (binary code). Machine code is too difficult to write. For this reason, we use symbolic languages to communicate instructions to the computer For example, assembly languages use abbreviations such as ADD, SUB, MPY to represent instructions. The program is then translated into machine code by a piece of software called an assembler. Machine code and assembly languages are called low-level languages because they are closer to the hardware. They are quite complex and restricted to particular machines. To make the programs easier to write, and to overcome the problem of intercommunication between different types of computer, software developers designed high-level languages which are closer to the English language. Here are some examples: FORTRAN was developed by IBM in 1954 and is still used for scientific and engineering applications. COBOL (Common Business Oiented Language) was developed in 1959 and is mainly used for business applications. BASIC was developed in the 1960s and was widely used in microcomputer programming because it was easy to learr Visual BASIC is a modern version of the old BASIC language, used to build graphical elements such as buttons and windows in Windows programs. PASCAL was created in 1971. It is used in universities to teach the fundamentals of programming. C was developed in the 1980s at AT&T. It is used to write system software, graphics and commercial applications. C++ is a version of C which incorporates object-oriented programming: the programmer concentrates on particular things (a piece of text, a graphic or a table, etc.) and gives each object functions which can be altered without changing the entire program. For example, to add a new graphics format, the programmer needs to rework just the graphics object. This makes programs easier to modify. Java was designed by Sun in 1995 to run on the Web. Java applets provide animation and interactive features on web pages. Programs written in high-level languages must be translated into machine code by a compiler or an interpreter. A compiler translates the source code into object code – that is. it converts the entire program into machine code in one go. On the other hand, an interpreter translates the source code line by line as the program is running. It is important not to confuse programming languages with markup languages used to create web documents. Markup languages use instructions, known as markup tags to format and link text files. Some examples include: HTML which allows us to describe how information will be displayed on web pages. XML. which stands for Extensible M.irxup Language. While HTML uses pre-defined tags. XML enables us to define our own tags; it is not limited by a fixed set of tags. VoiceXML. which makes Web content accessible via voice and phone. VoiceXML is used to create voice applications that run on the phone, whereas HTML is used to create visual applications (for example, web pages).
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