The conversion of symbolic languages
As we see, most of the symbolic languages are oriented toward the particular application areas of business or science (math). The one problem with all symbolic languages is that none of them can be understood by a computer. The symbolic languages may say AP, ADD,or use a "plus" sign to indicate an addition step, but the only thing that means addition to a computer is its binary machine code. Wfe have symbolic programs that are relatively easy for humans to understand, but they cannot be understood by computers. On the other hand, we have machine code that is understood by the computer, but it is difficult for humans to use. The solution is a translator that translates the symbolic program into machine code. The translator allows the human to work with relatively easy-to-understand symbolic languages and it allows the computer to follow instructions in machine code. The translation of symbolic instructions to machine code is accomplished through the use of a program called a language processor. There are three types of language processors. They are called assemblers, compilers, and interpreters. Each translates symbolic instructions to machine code, but each does it differently.
(The translator is a program itself. It is part of a group of programs, called the operating systems, that help us to use the computer.)
Running the computer program
The operating system is a collection of program provided by the computer's manufacturer that allows us to shedule jobs for the computer, to translate source programs into object programs, to sort data stored on secondary storage devices, and to copy data from any input device to any output device. These programs are called control programs, language programs and utility programs.
The control program (often called the supervisor, monitor, or executive) is a main-storage-resident program. Its functions are to schedule jobs, shedule input and output for our programs, and to monitor the execution of our programs.
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The language processors are programs that translate source programs into object programs. There are three types of language processors: assemblers, compilers, and interpreters. Each language has its own language processor.
The service programs are programs that are commonly used in all data processing centers. They have functions that are required by everyone using a computer. Examples of service programs include linkage editors to prepare object programs for execution, a librarian to catalog programs into a library area on magnetic disc, utility programs to transfer data from device to device, and sort-merge programs for sorting data on magnetic tape or disk.
3. Testing the computer program
There are two kinds of errors or bugs with which programmers must deal. The first type is the coding error. Such errors are syntax errors that prevent the language processor from successfully translating the source program to object program code. The language processor identifies the nature and the location of the error on the source program listing, so these errors are relatively easy to find and correct. The second type of bug is the logic error. The computer program can be successfully translated, but the program does not produce the desired results. These errors are generally much more difficult to find and to correct than are coding errors. Logic errors can be avoided through careful planning of the program logic, but it is the programmer's responsibility to test thoroughly all of the program's functions, in order to verify that the program performs according to specifications.
There are many tools provided to the programmer to help in debugging the program logic. These tools are called debug packages or tracing routines. They assist the programmer in following the logic by printing out calculation results and field values used in making logic decisions in the program. In a few cases it may be necessary to use a memory dump — a printout of the instructions and date held in the computer's memory — in order to find the cause of logic errors.
1. Подберите вместо пропусков подходящее по смыслу
1. The most common____ for planning the program logic
are flowcharting and pseudocode.
a) technologies; b) technics; c) techniques
2.______ was designed for dealing with the complicated
mathematical calculations of scientists and engineers, a) COBOL; b) FORTRAN; c) PL/I
3.______ is the foundation of any programming languages.
a) a set of rules; b) a group of numbers; c) a lot of instructions
4. I / О______ match the physical and electrical charac
a) interchanges; b) interfaces; c) interpretations
5. Letter-quality, dot-matrix and ink-jet printers are all
a) line; b) page; c) character
6. The most common device used to transfer information
a) keyboard; b) printer; c) modem
7. Input-output units link the computer to its external
a) requirement; b) development; c) environment
8. I / О devices can be classified according to their speed,
a) high-speed; b)medium-speed; c) low-speed
2. Согласуйте слова в левой колонке с их интерпретаци
1. Computer a) an electronic device accepting data pro-
cessing results from the computer system;
2. Input b) the unit performing arithmetic opera-
tions called for in the instructions;
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3. Output с) the unit coordinating all the activities of
various components of the computer. It reads information, enterpretes instructions, performs operations, etc.;
4. Software d) a set of programs designed to control the
operation of a computer;
5. Hardware e) lists of instructions followed by the con-
trol unit of the CPU:
6. Storage f) an electronic device keying information
into the computer;
7. CPU g) the unit holding all data to be processed,
intermediate and final results of processing;
8. CU h) visible units, physical components of a
data processing system;
9. ALU i) the unit that directs the sequence of sys-
tem operations, selects instructions and interpretes them;
10. Program j) a device with a complex network of elec-
tronic circuits that can process information, make decisions, and replace people in routine tasks.
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