TEXT № 4. High-Level LanguagesTASK: Read and translate the following text. Learn the vocabulary by heart. Point out the main idea of the text. Discuss the text in the class. High-level languages were developed because of the difficulty of programming assembly languages. High-level languages are easier to use than machine and assembly languages because their commands resemble natural human language. In addition, these languages are not CPU-specific. Instead, they contain general commands that work on different CPUs. For example, a programmer writing in the high-level Pascal programming language who wants to display a greeting need include only the following command: Write (Hello, Encarta User!'); This command directs the computer's CPU to display the greeting, and it will work no matter what type of CPU the computer uses. Like assembly-language instructions, high-level languages also must be translated, but a compiler is used. A compiler turns a high-level program into a CPU-specific machine language. For example, a programmer may write a program in a high-level language such as С and then prepare it for different machines, such as a Cray Y-MP supercomputer or a personal computer, using compilers designed for those machines. This speeds the programmer's task and makes the software more portable to different users and machines. American naval officer and mathematician Grace Murray Hopper helped develop the first commercially available high-level software language, FLOW-MATIC, in 1957. Hopper is credited for inventing the term bug, which indicates a computer malfunction; in1945 she discovered a hardware failure in the Mark II computer caused by a moth trapped between its mechanical relays. From 1954 to 1958 American computer scientist John Backus of International Business Machines, Inc. (IBM) developed Fortran, an acronym for Formula Translation. It became a standard programming language because it can process mathematical formulas, Fortran and its variations are still in use today. Beginner's All-purpose Symbolic instruction Code, or BASIC, was developed by Hungarian-American mathematician John Kemeny and American mathematician Thomas Kurtz at Dartmouth College in 1964. The language was easier to learn than its predecessors and became popular due to its friendly, interactive nature and its inclusion on early personal computers (PCs). Unlike other languages that require that all their instructions be translated into machine code first, BASIC is interpreted—that is, it is turned into machine language line by line as the program runs. BASIC commands typify high-level languages because of their simplicity and their closeness to natural human language. For example, a program that divides a number in half can be written as 10 INPUT "ENTER A NUMBER," X 20 Y=X/2 30 PRINT "HALF OF THAT NUMBER IS," Y The numbers that precede each line are chosen by the programmer to indicate the sequence of the commands. The first line prints "ENTER A NUMBER" on the computer screen followed by a question mark to prompt the user to type in the number labeled "X." In the next line, that number is divided by two, and in the third line, theresult of the operation is displayed on the computer screen. Other high-level languages in use today include C, Ada, Pascal, LISP, Prolog, COBOL, HTML, and Java. New compilers are being developed, and many features available in one language are being made available in others. (3261) Vocabulary: to develop – развивать because of – из-за to resemble – походить на, иметь сходство с instead – вместо, взамен to follow – следовать to direct – направлять naval officer – морской офицер portable – переносной malfunction – неисправная работа bug – ошибка, помеха moth – моль to trap – заключать, останавливать, задерживать relay – смена predecessor – предшественник inclusion – включение, добавление to typify – служить типичным примером (образцом) to precede – предшествовать to label – приклеивать ярлык, относить к какой-либо категории compiler–компилятор, компилирующая программа available – доступный, пригодный
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