Информатика, кибернетика и программирование
Electronic circuits work a thousand times more rapidly than nerve cells in the human brain. A problem that takes the human brain 2 years in order to solve it can be solved by a computer in one minute. The heart of the electronic computer is its transistors. In order to work a computer must have instructions...
Electronic circuits work a thousand times more rapidly than nerve cells in the human brain. A problem that takes the human brain 2 years in order to solve it can be solved by a computer in one minute. The heart of the electronic computer is its transistors. In order to work a computer must have instructions; this is called “programming”.
There are two main types of electronic computers: analogue and digital. In analogue computers problems are solved by analogy, the problems which analogue computers can solve are the following: mechanical forces, speeds, rotations, etc. Analogue computers are used for investigation of mechanical processes, in general, they are used for scientific and engineering problems in which great accuracy is not required but answers accurate enough are required quickly.
In digital computers problems are solved by counting. They may be very large and powerful. All the data connected with the problem which must be solved are converted into electrical pulses by very fast electronic switches and these pulses are stored and counted. With modern electronic devices a single switching operation can take place in a few nanoseconds (a nanosecond is a thousand millionth of a second).
What is a microprocessor?
A microprocessor is the central arithmetic and logic unit of a computer, together with its associated circuitry, scaled down so that it fits on a single silicon chip (sometimes several chips) holding tens of thousands of transistors, resistors and similar circuit element. A typical microprocessor chip measures half a centimeter on a side.
The task of the microprocessor is to receive data in the form of strings of binary digits (0s and 1s), to store the data for later processing, to perform arithmetic and logic operations on the data according to the previously stored instructions and to deliver the results to the user through an output mechanism such as an electric typewriter, a cathode ray tube display or a two dimensional plotter. A typical microprocessor would consist of the following units: a decode and control unit (to interpret instructions from the stored program), the arithmetic and logic unit, or ALU (to perform arithmetic and logic operations), registers (to serve as an easily accessible memory for data which are frequently manipulated), an accumulator (a special register closely associated with the ALU), address buffers (to supply the control memory with the address from which to take the next instruction) and input/output buffers (to read instructions or data into the microprocessor or to send them out).
Programming is the process of preparing a set of coded instruction which, when executed by a digital computer, yield the solution of a specific problem or perform specific functions. Each computer and each programming language has its own unique repertoire, method of operation, etc. These should be studied and understood before preparing a program on a specific language for execution by a specific computer.
A computer has the ability to automatically execute a program stored within itself. During execution of the program, the computer performs various digital operations (adding two numbers, moving data in and out of storage, reading in or printing out data, etc.) If the stored program is changed, the actions of the computer change. Thus, the computer actions depend on both the configuration of the computer hardware (the physical computer equipment) and the software (the programs stored within the computer).
A given computer capability can be provided either by hardware alone or by a combination of hardware and software. The choice of a given mixture of hardware and software depends on factors such as cost, speed, ease of maintenance, and flexibility.
There are three nominal levels of programming language: machine language, assembler language, and compiler language.
In the machine language programming level, the programmer writes the program exactly as stored in the computer. Very little programming is done at this level as it is extremely tedious, and when errors are found it is hard to correct them.
The machine language level is useful in the initial operation of a computer when no other techniques are available, in repair of a faulty computer, and in the debugging of programs when other techniques fail and the program must be examined at the machine language level.
What is a computer?
The word computer comes from a Latin word which means to count. A computer is a machine with a complex network of electronic circuits that operate switches or magnetize tiny metal cores. The switches, like the cores, are capable of being in one of two possible states, that is, on and off; magnetized or demagnetized. The machine is capable of storing and manipulating numbers, letters, and characters. The basic idea of the computer is that we can make the machine do what we want by inputting signals that turn certain switches on and turn others off, or that magnetize or do not magnetize the cores.
The basic job of computers is the processing of information. For this reason, computers can be defined as devices which accept information in the form of instructions called a program and characters called data, perform mathematical and/or logical operations on the information, and then supply results of these operations. The program, or part of it, which tells the computers what to do and data, which provide the information needed to solve the problem, are kept inside the computer in a place called memory.
Some of the most common methods of inputting information are to use punched cards, magnetic tape, disks, and terminals. The computers input device (which may be a card reader, a tape drive or disk drive, depending on the medium used in inputting information) reads the information into the computer.
For outputting information, two common devices used are a printer which prints the new information on paper, or a CRT display screen which shows the results on a TV-like screen.
There are different kinds of computers. Some do only one job over and over again. These are special-purpose computers. But there are some computers that can do many different jobs. They are called general-purpose computers. These are the “big brains” that solve the most difficult problems of science. They answer questions about rockets and planes, bridges and ships long before these things are even built. Computers help our space program, our business and industry, medicine and education. They are powerful tools which help to change our life and the world around us.
A computer system is a collection of components that work together to process data. The purpose of a computer system is to make it as easy as possible for you to use a computer to solve problems. A functioning computer system combines hardware elements with software elements. The hardware elements are the mechanical devices in the system , the machinery and the electronics that perform physical functions.
The software elements are the programs written for the system; these programs perform logical and mathematical operations and provide a means for you to control the system. Documentation includes the manuals and listings that tell you how to use the hardware and software.
Collectively these components provide a complete computer system: system hardware + system software + system documentation = computer system. Usually, a computer system requires these basic hardware items: the computer, which performs all data processing; a terminal device, used like a typewriter for two-way communication between the user and the system; and a storage medium for storing programs and data.
Computer systems that that provide (or use) have a magtape device, because magnate device is an industry standard storage device.
Peripheral devices are categorized as input/output (I/O) devices since the functions they perform provide information (input) to the computer, accept information (output) from the computer, or do both. Line printers are output devices because they perform only output operations.
Terminals and storage devices are input/output devices because they perform both input and output operations.
System software is an organized set of supplied programs that effectively transform the system hardware components into usable tools. These programs include operations, functions, and routines that make it easier for you to use the hardware to solve problems and produce results.
For example, some system programs store and retrieve data among the various peripheral devices. Others perform difficult or lengthy mathematical calculations. Some programs allow you to create, edit, and process application programs of your own.
System software always includes an operating systems, which is the “intelligence” of the computer system. Usually the system software includes one or several language processors.