A short course of lectures on computer science. Complete lecture notes on computer science. Information and forms of its presentation

Federal Agency for Education

State educational institution of higher professional education

Samara State Technical University

Lectures on computer science

for 1st year full-time students

specialties 1004 and 1805

Samara 2008

LECTURE 6. ALGORITHMS. ALGORITHMIZATION. ALGORITHMIC LANGUAGES 19

LECTURE No. 1 HISTORY OF THE DEVELOPMENT OF COMPUTER ENGINEERING. BASIC CONCEPTS: INFORMATION, COLLECTION, TRANSMISSION, INFORMATION PROCESSING

The first mention of a computer is found in the works of Leonardo da’Vinci (drawings of a “logical machine”). The first implementation of a programmable machine is considered to be a weaving loom (rods and punched tapes for changing the order of weaving threads - the type of fabric).

The first practical use of a computer was the calculation of artillery tables in the 1920-30s. Contactors, a 3-story building, several dozen programmers, about a month of programming, several hours of calculations.

First ELECTRONIC computer - USA, analog machine, programming by connecting blocks into a circuit appropriate to the task.

Further development - computers on radio tubes, domestic - Ural, transistor domestic BESM-4, M-200 (up to 10 6 operations / sec), Western IBM. IBM comes to the USSR from social. countries (Hungary, Bulgaria, East Germany) as an EU-computer. ES-computer is a powerful machine for “collective” use. Teamwork is forced due to the discrepancy between the speed of the CPU and the peripherals.

When multitasking mode with a variable number of tasks appears, terminals and display stations appear. The use of machines is becoming truly communal. Terminals acquire intelligence and sprout into personal computers. Electronics-60,100, Iskra, IBM.

If aviation technology developed as quickly as computing (performance, efficiency, cost-effectiveness, cost reduction), currently (about 10 years ago) anyone could freely buy a Boeing 760 type aircraft, fill a bucket of gasoline and fly around the globe in 20 minutes.

Parallel development of machines for individual use:

PROMIN: 100 steps of programmable memory (pocket calculator Electronics B3-38)

NAIRI: high-level language programming, input/output – electric typewriter 120 characters/min or punched tape.

Development of programming techniques.

Programming in machine codes - programmer-sorcerer. No one knows or understands “how he does it” (mind).

Machine-oriented languages (nairi).

Frequently repeated chains of commands give rise to interpreters and translators.

Universal high-level algorithmic languages FORTRAN, ALGOL, PL-1, BASIC, Pascal.

Problem-oriented programming languages.

Delphi visual program design systems, programming without programming.

Development of information carriers.

Magnetic drum – BESM.

Magnetic tapes, magnetic disks – EU.

5-inch floppy disks from 180 kB - Iskra, up to 720 kB.

7 MB hard drive – Spark.

CDs and DVDs.

Flash memory cards.

Development of input/output tools

Perforated photographic film, cash register tape with numbers in a normalized form, programmer-adjuster console - Ural.

Punched cards, punched tapes, ATsPU – BESM

Same with email. write mash. or system programmer monitor - EC. Later keyboard and monitor display stations.

Exotic: various types of pins for poking special. pencil, multilayer monitor screens for finger poking, light pen.

Printers: matrix, electrothermal, inkjet, laser.

Plotters, plotters: flatbed, roll pen, inkjet.

Monitors and graphics cards: 320x200 monochrome: black, green, red; color 320x200, 640x480, 1024x768, ...; CGA–colorgraphicadapter 4 colors, EGA–enhancedgraphicadapter 12 colors, VGA–videographicadapter 256 colors, SVGA–supervideographicadapter4*10 6 colors.

Term "Informatics"(French) informatique) comes from French words information(information) and automatique(automation) and literally means "information automation".

The English version of this term is also widespread - "Computer science", which literally means "computer science".

In 1978, the International Scientific Congress officially assigned the concept "Informatics" areas related to the development, creation, use and logistical maintenance of information processing systems, including computers and their software, as well as organizational, commercial, administrative and socio-political aspects of computerization - mass implementation computer equipment in all areas of people's lives.

Thus, computer science is based on computer technology and is unthinkable without it.

Computer science is a scientific discipline with a wide range of applications. Its main directions:

development of computer systems and software;

information theory, which studies the processes associated with the transmission, reception, transformation and storage of information;

artificial intelligence methods that allow you to create programs for solving problems that require certain intellectual efforts when performed by a person (logical inference, learning, speech understanding, visual perception, games, etc.);

system analysis, which consists of analyzing the purpose of the designed system and establishing the requirements that it must meet;

methods of computer graphics, animation, multimedia;

means of telecommunications, including global computer networks that unite all humanity into a single information community;

various applications covering production, science, education, medicine, trade, agriculture and all other types of economic and social activities.

Computer science is usually thought of as consisting of two parts:

technical means;

software.

Technical means, that is computer hardware, in English are denoted by the word Hardware, which literally translates as "solid products".

And for software a very successful word was chosen (or rather, created) Software(literally - "soft goods"), which emphasizes the equivalence software and the machine itself and at the same time emphasizes the ability of software to be modified, adapted, and developed.

In addition to these two generally accepted branches of computer science, there is another significant branch - algorithmic tools. For her, Russian academician A.A. Dorodnitsin suggested the name Brainware(from English brain- intelligence). This branch is associated with the development of algorithms and the study of methods and techniques for their construction.

You cannot start programming without first developing an algorithm for solving the problem.

The role of computer science in the development of society is extremely great. The beginning of a revolution in the field of accumulation, transmission and processing of information is associated with it. This revolution, following revolutions in the mastery of matter and energy, affects and radically transforms not only the sphere of material production, but also the intellectual and spiritual spheres of life.

The growth in the production of computer equipment, the development of information networks, and the creation of new information technologies lead to significant changes in all spheres of society: in production, science, education, medicine, etc.

Year of manufacture: 2007

Size: 905 kb

Format: doc

Description:

A good course of lectures on computer science for the 1st year, which will help a freshman in mastering basic concepts about computer science.

1. What is computer science.
This point of the lecture talks about the importance of computer science as a science, talks about information, how it is measured, how it is stored and transmitted over a distance.
2. What does a computer consist of?
Description of the components of a computer and the principles of their operation.
3. Criteria for classifying computers.
A brief historical background on the history of computer technology. Generations of computers.
4. All about number systems.
Description of binary, octal, decimal and hexadecimal number systems and methods of conversion from one system to another.
5. Algebra of logic.
Section of discrete mathematics and logical operations.
6. What is software.
Classification and purpose various programs.
7. Algorithms.
Basics of drawing up graphical and verbal algorithms.

State budgetary educational institution

Secondary vocational education

Zlatoust Medical College

LECTURE COURSE

BY DISCIPLINE

"Computer science"

for students of all specialties

2014

Reviewed

at a meeting of the Central Committee

Protocol No. ____________

From "____" _________ 2013

Chairman of the cycle commission

_____________________________

Approved

methodological advice

Protocol No. ____________

From "____" _________ 2013

Chairman of the Methodological Council

____________

Preface

This manual is intended for students and other users studying the discipline “Computer Science”

The manual includes a preface, introduction, three sections and a conclusion. The first section examines the concept of information, as well as types of information and units of measurement of information. Computer hardware and software are also considered. Fundamentals of computer security. The second section discusses software, application software, describes the MS Excel program and the structure of spreadsheets, provides information about MS Word processors, and describes the technology for working with databases Microsoft Access in design mode. The third section contains information about local and global computer networks, services provided by the Internet, and Internet addressing.

Introduction

The subject “Informatics” is academic discipline, which studies technologies for creating, storing, reproducing and processing data (information) using computer technology, as well as the principles of operation of these tools and methods of managing them.

Studying the discipline “Informatics” has the following goals:

formation of general ideas about the possibilities of using computer technology;

familiarization with the basics of modern information technologies (collection, processing, storage and transmission of information) and trends in their development;

training in the use of modern information technologies in professional activities and analysis of the results obtained,

development of algorithmic thinking skills;

mastering techniques for working with modern standard application software packages (MS Excel, MS Word and MS Access), which provide extensive information processing capabilities.

As a result of studying the discipline, students must:

Know:

device personal computer, peripherals, structure of personal computer software;

fundamentals of using system software products for solving professional problems on electronic computers.

Be able to:

work with different types of information using a computer and other information media And communication technologies;

organize your own information activities and plan their results;

use programs graphic editors electronic computers in professional activities;

work with professional application software packages on electronic computers;

draw up technical documentation for the maintenance and operation of electrical equipment;

Section 1. Fundamentals of information culture.

Topic 1.1. Technical means of information support.

Informatization of society.

Informatization is a complex social process associated with significant changes in the lifestyle of the population. It requires serious efforts in many areas, including eliminating computer illiteracy, creating a culture of using new information technologies, etc.

The driving force behind the development of society should be the production of informational, rather than material, products. In the information society, not only production changes, but also the entire way of life, the value system, and the importance of cultural leisure in relation to material values increases. In the information society, intelligence and knowledge are produced and consumed, which leads to an increase in the share of mental labor. A person will need the ability to be creative, and the demand for knowledge is increasing. The material and technological base of society’s information will be various types of systems based on computer technology and computer networks, information technology, telecommunications.

Informatization of society is an organized social, economic, scientific and technical process of creating optimal conditions for meeting information needs and realizing the rights of citizens, government bodies, local governments, organizations, public associations based on the formation and use of information resources

The information society is a society in which the majority of workers are engaged in the production, storage, processing and sale of information, especially its highest form - knowledge.

The goal of informatization is to improve the quality of life of people by increasing productivity and facilitating their working conditions.

The main criteria for development information society are the following:

Availability of computers;

Level of development of computer networks;

Possession of information culture, i.e. knowledge and skills in the field of information technology.

The emergence and development of computers is a necessary component of the process of informatization of society. Informatization of society is one of the laws of modern social progress. When informatizing society, the main attention is paid to a set of measures aimed at ensuring the full use of reliable, comprehensive and timely knowledge in all types of human activity. To ensure accessibility of communication with a computer in natural language, it will be equipped with multimedia tools, primarily audio and video. In the future, portable computers should become more miniature, while the speed of their microprocessors should be the same as on modern supercomputers. They must have a flat display with good resolution. Their external storage devices - magnetic disks - will be portable and have a capacity of more than 100 GB.

To ensure high-quality and widespread exchange of information between computers, new communication channels will be used:

Infrared channels within line of sight.

TV channels.

Wireless technology of high-speed digital communication at a frequency of 10 MHz.

The most important integral part information culture modern man is a communicative culture using modern information technologies. The development of network information technologies has made the information resources of the global computer network Internet potentially accessible to the majority of humanity. The ability to obtain the necessary information from the network becomes an integral part of a person’s information culture.

Thus, a person has an information culture if:

has an understanding of information and information processes, the structure of a computer and its software;

knows how to use information modeling when solving problems using a computer;

is able to enter information from the keyboard with sufficient speed and work with graphical interface programs using the mouse;

knows how to create and edit documents, including multimedia presentations;

can process numerical information using spreadsheets;

knows how to use databases to store and search information;

knows how to use information resources of a computer network;

complies with ethical standards when publishing information on the Internet and in the process of communicating via the Internet.

Information and forms of its presentation

The concept of information is a fundamental concept in computer science. Any human activity is a process of collecting and processing information, making decisions based on it and implementing them. With the advent of modern computer technology, information began to act as one of the most important resources scientific and technological progress.

A person perceives information using the senses, stores and processes it using the brain and central nervous system. Transmitted information usually concerns some objects or ourselves and is associated with events occurring in the world around us.

Within science, information is a primary and indefinable concept.

The concept of information presupposes the presence of a material carrier of information, a source of information, an information transmitter, a receiver and a communication channel between the source and the receiver. The concept of information is used in all areas: science, technology, culture, sociology and everyday life. The specific interpretation of the elements associated with the concept of information depends on the method of a particular science, the purpose of the study, or simply on our ideas.

The term “information” comes from the Latin informatio - explanation, presentation, awareness. The Encyclopedic Dictionary (M.: Sov. Encyclopedia, 1990) defines information in historical evolution: initially - information transmitted by people orally, in writing or in other ways (using conventional signals, technical means, etc.); since the middle of the 20th century - a general scientific concept, including the exchange of information between people, man and machine, the exchange of signals in the animal and plant world (transfer of characteristics from cell to cell, from organism to organism).

A narrower definition is given in technology, where this concept includes all information that is the object of storage, transmission and transformation.

The most general definition takes place in philosophy, where information is understood as a reflection of the real world. Information as a philosophical category is considered as one of the attributes of matter, reflecting its structure.

In the evolutionary series, matter, energy, information, each subsequent manifestation of matter differs from the previous one in that it was more difficult for people to recognize, isolate and use it in its pure form. It was the difficulty of identifying the various manifestations of matter that probably determined the indicated sequence of knowledge of nature by mankind.

Associated with the concept of information are concepts such as signal, message and data.

A signal (from the Latin signum - sign) is any process that carries information.

A message is information presented in a specific form and intended to be transmitted.

Data is information presented in a formalized form and intended for processing technical means, for example, a computer.

There are two forms of information presentation - continuous and discrete. Since signals are carriers of information, physical processes of various natures can be used as the latter. For example, the process electric current in a circuit, the process of mechanical movement of a body, the process of light propagation, etc. Information is represented (reflected) by the value of one or more parameters of a physical process (signal), or a combination of several parameters.

A signal is called continuous if its parameter, within specified limits, can take on any intermediate values. A signal is called discrete if its parameter, within specified limits, can take on individual fixed values.

It is necessary to distinguish between the continuity or discreteness of the signal in terms of level and time. The figure shows in graph form:

a) continuous signal in level and time;

6) signal Hdn, discrete in level and continuous in time;

c) continuous in level and discrete in time signal HND;

d) signal Hdd, discrete in level and time.

Finally, all the variety of information surrounding us can be grouped according to various criteria, that is, classified by type. For example, depending on the area of origin, information reflecting the processes and phenomena of inanimate nature is called elementary, the processes of the animal and plant world - biological, human society - social.

According to the method of transmission and perception, the following types of information are distinguished: visual - transmitted by visible images and symbols, auditory - by sounds, tactile - by sensations, organoleptic - by smells and taste, machine - issued and perceived by computer technology, etc.

The concept of information quantity

The amount of information is the numerical characteristic of a signal, reflecting the degree of uncertainty (incompleteness of knowledge) that disappears after receiving a message in the form of a given signal. This measure of uncertainty in information theory is called entropy. If, as a result of receiving a message, complete clarity is achieved on some issue, it is said that complete or exhaustive information has been received and the need to obtain additional information No. And, conversely, if after receiving the message the uncertainty remains the same, then no information was received (zero information).

The above considerations show that there is a close connection between the concepts of information, uncertainty and choice. Thus, any uncertainty presupposes the possibility of choice, and any information, reducing uncertainty, reduces the possibility of choice. With complete information there is no choice. Partial information reduces the number of choices, thereby reducing uncertainty.

Example. A person throws a coin and watches which side it lands on. Both sides of the coin are equal, so it is equally likely that one side or the other will come up. This situation is attributed to initial uncertainty, characterized by two possibilities. After the coin falls, complete clarity is achieved and uncertainty disappears (becomes zero).

The given example refers to a group of events in relation to which a “yes-no” question can be posed. The amount of information that can be obtained when answering a yes-no question is called a bit (English bit - short for binary digit - binary unit). A bit is the minimum unit of information, because it is impossible to obtain information less than 1 bit. When receiving information of 1 bit, the uncertainty is reduced by 2 times. Thus, each coin toss gives us 1 bit of information.

Other models for obtaining the same amount of information can be an electric light bulb, a two-position switch, a magnetic core, a diode, etc. The on state of these objects is usually designated by the number 1, and the off state by the number 0. Consider the system resulting from throwing two coins, the results are obtained independently of each other. Let us denote the appearance of “tails” as 1, and the appearance of “heads” as 0. For such a system, the following states are possible:

Questions for assessment:

Basic concepts of computer science. Subject and tasks of computer science.

Informatization of society.

Information technologies in everyday life, in business, in management.

Computer technologies for information processing.

The concept of information, properties of information.

The concept of the amount of information. Units of data volume measurement.

History of the development of computer technology.

Generations of computers.

Computer architecture, von Neumann principle.

Computer device.

Main devices on the motherboard. Clock frequency MP.

Computer RAM and permanent memory. Memory devices.

Compound system unit: motherboard, CPU, controllers, internal memory devices.

Composition of the system unit: HDD, CD drive, floppy drive, flash memory.

Composition of the system unit: expansion cards (video card, sound card, network card).

Peripheral devices: keyboard, manipulators.

Peripheral devices: CRT monitors, LCD monitors, plasma panels.

Peripheral devices: printers, scanners, modems.

Software. Software classification.

Classification of application software.

System software: system software levels, basic system software.

Purpose operating system. OS functions (list).

The concept of Windows OS. Windows OS objects.

Organization of data exchange. Working with Windows OS objects.

Formatting and recording on magnetic disks. Purpose of the FAT table. Defragmentation.

Standard Windows applications.

Data archiving. Archive programs and their capabilities.

Viruses and malware.

Antivirus products.

Graphic editors, main characteristics and purpose.

Raster and vector graphics.

Word processor MS Word. MS Word program interface.

Entering and formatting text in MS Word. Inserting a picture in MS Word.

Creating and formatting tables in MS Word.

Inserting symbols and mathematical formulas in MS Word.

Presentation of data on a chart in MS Word.

Technology for working with styles and templates in MS Word.

MS Excel program interface.

Entering, editing and formatting data in MS Excel spreadsheet cells.

Calculations in MS Excel using formulas.

Calculations in MS Excel using functions.

Drawing graphs in MS Excel.

Creating charts in MS Excel.

The concept of a computer network. Local and global network.

Classification of computer networks (by transmission technology, by size, by management method).

Global Internet.

Internet information resources. Search for information.

Methods and characteristics of Internet connections.

Work principles Email. Mail server services.

MINISTRY OF TRANSPORT OF THE RUSSIAN FEDERATION

DEPARTMENT OF COMMUNICATIONS

KRSNOYARSK INSTITUTE OF RAILWAY TRANSPORT – BRANCH OF GOI VPO "IRKUTSK STATE COMMUNICATION UNIVERSITY"

COURSES ON INFORMATION SCIENCE

Textbook for engineering students

Krasnoyarsk 2012

UDC 681.3.06 BBK 32-973-01

Egorushkin, I.O. Course of lectures on computer science. Part 1: Textbook/I.O. Egorushkin. Krasnoyarsk: Krasnoyarsk Institute of Railway Transport - branch of the State Educational Institution of Higher Professional Education "Irkutsk State Transport University", 2012. 79 p.: ill.

A course of lectures on computer science for 1 semester is presented, developed on the basis of the FEPO standard, including the following disciplinary modules:

a) the concept of information, general characteristics processes of collecting, transmitting, processing and storing information;

b) technical means of implementation information processes; computer hardware;

c) software for implementing information processes; G) information Technology: (text processing technologies and

tabular information).

This course of lectures is intended for mastering the theoretical part of the discipline "Informatics" (lecture course) by engineering students. The manual consists of nine lectures provided for in the 1st semester program, developed on the basis of the FEPO standard.

Il. 15. Bibliography: 3 titles.

Reviewers: Gaidenok N.D. – Doctor of Technical Sciences, Professor of the Department of Electrical Railways

Rogalev A.N. – Ph.D., Associate Professor, Department of Mathematical Modeling and Informatics, IGURE SFU

Published by decision of the methodological council of KrIZhT



LECTURE 1. INFORMATION AND FORMAL PRESENTATIONS.................................
1.1.Messages, data, signals....................................
1.2. Measures and units of presentation, measurement and storage of information...................
1.3.Types and properties of information.................................................... ........................................................
LECTURE 2. GENERAL CHARACTERISTICS OF COLLECTION PROCESSES,
PROCESSING, TRANSMISSION AND ACCUMULATION OF INFORMATION.................................
2.1.Measurement of information.................................................... ........................................................ ......
2.2.Perception of information.................................................... ........................................................ ....
2.3.Collection of information.................................................... ........................................................ .............
2.4. Transfer of information................................................... ........................................................ .........
2.5.Information processing.................................................... ........................................................ ......
INFORMATION AND LOGICAL FOUNDATIONS OF COMPUTER....................................................
2.6.Number systems.................................................... ........................................................ ..............
2.7. Positional number systems............................................................ ....................................
LECTURE 3. INFORMATION AND LOGICAL FOUNDATIONS OF COMPUTERS

3.1.Number systems (end)................................................. ...........................................
3.1.1. Binary number system...........................................................................
3.1.2. Other positional number systems....................................................
3.1.3. Mixed number systems.....................................................................
INFORMATICS AS SCIENCE................................................................. ...................................
3.2. Subject area of computer science as a science.................................................... ..............
3.3. Brief history of the development of computer science.................................................... ......................
3.4. The concept of the information society.................................................... ...........................
3.5.Goals and objectives of the “Informatics” course.................................................... ........................................
LECTURE 4. COMPUTER AS INFORMATION PROCESSING TOOL...................
4.1. History of computer development.................................................... ........................................................ ......
4.2. Main characteristics of the computer.................................................... .......................................
4.3. Classification of computers.................................................... ........................................................ ..........
LECTURE 5. COMPUTER AS INFORMATION PROCESSING TOOL
(ENDING)............................................... ........................................................ ............
5.1. General principles of building modern computers.................................................... ......
5.2.Computer software and functions.................................................... ..........
5.3. Composition and purpose of the main elements of the PC, their characteristics....................................
5.3.1. General information about PCs and their classification ..........................................
5.3.2. Structural scheme PC...............................................................................
5.3.3. External PC devices............................................................................
5.3.4. PC storage devices................................................................

LECTURE 6. OPERATING SYSTEMS. GRAPHICS
WINDOWS OPERATING ENVIRONMENT.................................................... ...............


6.1.MSDOS operating system.................................................... ........................................
6.2.NortonCommander Shell.................................................... ...............................................
6.3. Basic technological mechanisms of Windows.................................................... .......
6.4.Creating objects, managing objects, properties of objects..................................
6.5.Navigation through the file system.Operations with files.Searching for files.
Configuring operating system parameters.................................................................... .
6.6. Overview of Windows applications. Collaboration of applications..................................
6.7.Disk maintenance programs.Data archiving.Programs-
archivers........................................................ ........................................................ ...................................
6.8.FarManager shell.................................................... ........................................................ ........

LECTURE 7. INFORMATION PROCESSING SOFTWARE56

LECTURE 8. INFORMATION PROCESSING SOFTWARE

(ENDING)............................................... ........................................................ ............
8.1.Application programs.................................................... ........................................................ ....
8.2.Programming systems.................................................... ........................................................
8.3.Software classification.................................................... .............
8.4.Problem-oriented PPP.................................................... ...................................
8.5.Integrated IFR.................................................... ........................................................ ......
LECTURE 9. FUNDAMENTALS OF TEXT AND TABLE PROCESSING
INFORMATION................................................... ........................................................ ........
9.1.Microsoft Word text processor.................................................... ...........................
9.1.1. Starting and shutting down Word.............................................................
9.1.2. Main menu and toolbars.........................................................
9.1.3. Opening and saving documents.............................................................
9.1.4. Formatting documents..........................................................................
9.1.5. Printing a document................................................................................................
9.2.MicrosoftExcel spreadsheet processor.................................................... ...........................
9.2.1. Spreadsheet Basics......................................................
9.2.2. MS Excel spreadsheet interface. Main Differences
between Word and Excel ................................................... ........................................................ .......
LITERATURE................................................. ........................................................ ..........

LECTURE 1. INFORMATION AND FORMS OF ITS PRESENTATION

IN Within science, information is a primary and indefinable concept. It presupposes the presence of a material carrier of information, a source of information, an information transmitter, a receiver, and a communication channel between the source and the receiver. The concept of information is used in all areas: science, technology, culture, sociology and everyday life. The specific interpretation of the elements associated with the concept of information depends on the method of a particular science, the purpose of the study, or simply on our ideas.

The term "information" comes from the Latin informatio - explanation, presentation, awareness. The Encyclopedic Dictionary (M.: Sov. Encyclopedia, 1990) defines information in historical evolution: initially - information transmitted by people orally, in writing or in other ways (using conventional signals, technical means, etc.); since the mid-twentieth century - a general scientific concept that includes the exchange of information between people, people

And automatically, exchange of signals in the animal and plant world (transfer of characteristics from cell to cell, from organism to organism).

A narrower definition is given in technology, where this concept includes all information that is the object of storage, transmission and transformation of information.

IN evolutionary series matter → energy → information each

the next manifestation of matter differs from the previous one in that it was more difficult for people to recognize, isolate and use it in its pure form. It was the difficulty of identifying the various manifestations of matter that probably determined the indicated sequence of knowledge of nature by mankind.

1.1. Messages, data, signals

WITH The concept of information is associated with such concepts as signal, message and

A signal (from the Latin signum - sign) is any process that carries information.

There are two forms of information presentation – continuous and discrete. Since signals are carriers of information, physical processes of various natures can be used as the latter.

Information is represented (reflected) by the value of one or more parameters of a physical process, or a combination of several parameters.

A signal is called continuous if its parameter, within specified limits, can take any intermediate values. A signal is called discrete if its parameter, within specified limits, can take certain fixed values.

A message is information presented in a specific form and intended to be transmitted.

From a practical point of view, information is always presented in the form of a message. The information message is related to source of the message, By-

message recipient and communication channel.

The message from the source to the receiver is transmitted in material and energy form (electrical, light, sound signals, etc.). A person perceives messages through the senses. Information receivers in technology perceive messages using various measuring and recording equipment. In both cases, the reception of information is associated with a change in time of some quantity characterizing the state of the receiver. In this sense, an information message can be represented by a function x (t), characterizing the change over time in the material and energy parameters of the physical environment in which information processes are carried out.

The function x (t) takes any real values in the range of changes in time t. If the function x(t) is continuous, then there is a continuous or analog information, the source of which is usually various natural objects (for example, temperature, pressure, air humidity), objects of technological production processes (for example, neutron flux in the core, pressure and temperature of the coolant in the circuits of a nuclear reactor), etc. If the function x (t) discrete, then the information messages used by a person are in the nature of discrete messages (for example, alarm signals transmitted through light and sound messages, language messages transmitted in writing or using sound signals; messages transmitted using gestures, etc.).

IN modern world information is usually processed on computers. Therefore, computer science is closely related to tools - computer.

A computer is a device for converting information by performing a program-controlled sequence of operations. A synonym for computer is a computing machine, more often an electronic computer (computer).

Data is information presented in a formalized form and intended for processing by technical means, for example, a computer.

Therefore, along with the terms information input, information processing, information storage, information retrieval terms used data entry, data processing, data storage, etc.

1.2. Measures and units of presentation, measurement and storage of information

For theoretical computer science, information plays the same role as matter in physics. And just as a substance can be assigned a fairly large number of characteristics (mass, charge, volume, etc.), so for information there is, albeit not so large, but a fairly representative set of characteristics. Both for the characteristics of matter and for the characteristics of information, there are units of measurement, which allows some piece of information to be assigned numbers - quantitative characteristics of information.

Today the most famous following methods measurement information:

volume; entropy; algorithmic.

Volumetric is the simplest and crudest way to measure information. The corresponding quantitative assessment of information can naturally be called the volume of information.

The amount of information in a message is the number of characters in the message.

Because, for example, the same number can be written in many different ways (using different alphabets):

"twenty one" 21 11001

then this method is sensitive to the form of presentation (recording) of the message. IN computer technology all processed and stored information, regardless of its nature (number, text, display), is presented in binary form (using an alphabet consisting of only two characters 0 and 1). This standardization allowed the introduction of two standard units of measurement: bits and bytes. A byte is eight bits. These units of measurement will be discussed in more detail later.

Amount of information is a numerical characteristic of a signal that reflects degree of uncertainty(incompleteness of knowledge), which disappears after receiving the message in the form of this signal. This measure of uncertainty in information theory is called entropy. If, as a result of receiving a message, complete clarity is achieved on some issue, it is said that complete or exhaustive information has been received and there is no need to obtain additional information. And, conversely, if after receiving the message the uncertainty remains the same, it means that no information was received (zero information).

The above considerations show that between the concepts of information

tion, uncertainty and choice there is a close connection. So,

any uncertainty presupposes the possibility of choice, and any information, reducing uncertainty, reduces the possibility of choice. With complete information there is no choice. Partial information reduces the number of choices, thereby reducing uncertainty.

Example. A person throws a coin and watches which side it lands on. Both sides of the coin are equal, so it is equally likely that one side or the other will come up. This situation is attributed to initial uncertainty, characterized by two possibilities. After the coin falls, complete clarity is achieved and uncertainty disappears (becomes zero).

In algorithmic information theory (section of the theory of algorithms) it is proposed algorithmic method evaluation of the information in the message. This method can be briefly characterized by the following reasoning.

Everyone will agree that the word 0101...01 is more complex than the word 00..0, and the word where 0 and 1 are chosen from the experiment - tossing a coin (where 0 is a coat of arms, 1 is a tail) is more complex than both of the previous ones.

The computer program that produces a word from all zeros is extremely simple: print the same character. To get 0101...01 you need a slightly more complex program that prints the symbol opposite to the one just printed. A random sequence that does not have any patterns cannot be produced by any “short” program. The length of the program producing the chaotic sequence must be close to the length of the last one.

The above reasoning suggests that any message can be assigned a quantitative characteristic that reflects the complexity (size) of the program that allows it to be produced.

Since there are many different computers and different programming languages ( different ways tasks of the algorithm), then for definiteness they are given by some specific computing machine, for example a Turing machine, and the assumed quantitative characteristic - the complexity of a word (message) - is defined as the minimum number of internal states of the Turing machine required to reproduce it. Also in algorithmic information theory, other methods of specifying complexity are used.

1.3. Types and properties of information

Let us dwell in more detail on the disclosure of the concept of information. Consider the following list:

genetic information; geological information; weather information; false information (disinformation); full information; economic information; Technical information etc.

Probably everyone will agree that this list does not contain all types of information, just as the given list is of little use. This list is not systematized. For species classification to be useful, it must be based on some system. Usually when

classification of objects of the same nature, one or another property (maybe a set of properties) of objects is used as a basis for classification.

As a rule, the properties of objects can be divided into two large classes: external and internal properties.

Internal properties– these are properties organically inherent in an object. They are usually “hidden” from the student of the object and manifest themselves indirectly during interaction of this object with others.

External properties– these are properties that characterize the behavior of an object when interacting with other objects.

Let us explain this with an example. Mass is an internal property of substance (matter). It manifests itself in interaction or during some process. This is where concepts of physics arise, such as gravitational mass and inertial mass, which could be called external properties of matter.

A similar division of properties can be given for information. For any information, three objects of interaction can be specified: the source of information, the receiver of information (its consumer) and the object or phenomenon that this information reflects. Therefore, we can distinguish three groups of external properties, the most important of which are the properties of information from the point of view of the consumer.

Quality of information– a generalized positive characteristic of information, reflecting the degree of its usefulness for the user.

Level of quality– one of the important positive properties of information (from the consumer’s perspective). Any negative property can be replaced by its opposite, positive.

Most often, quality indicators that can be expressed in numbers are considered, and such indicators are quantitative characteristics of the positive properties of information.

As is clear from the above definitions, in order to determine a set of critical quality indicators, it is necessary to evaluate information from the point of view of its consumer.

In practice, the consumer is faced with the following situations: some information corresponds to his request, his requirements, and such information is called relevant; some does not, and is called irrelevant; all information is relevant, but it is not enough for the needs of the consumer; if the information received is sufficient, then it is natural to call such information complete; the information received is untimely (for example, outdated);

Some of the information recognized as relevant by the consumer may turn out to be unreliable, that is, containing hidden errors (if the consumer detects some errors, then he simply classifies the damaged information as irrelevant); the information is inaccessible;

information is subject to “undesirable” use and change by other consumers; information has a form and volume that is inconvenient for the consumer.

A review of the above situations allows us to formulate the following distribution of information properties.

Relevance is the ability of information to meet the needs (requests) of the consumer.

Completeness is the property of information to exhaustively (for a given consumer) characterize the reflected object and (or) process.

Timeliness– the ability of information to meet the needs of the consumer at the right time.

Reliability is the property of information not to have hidden errors. Availability is a property of information that characterizes the possibility of its

received by this consumer.

Security is a property that characterizes the impossibility of unauthorized use or modification.

Ergonomics is a property that characterizes the convenience of the form or volume of information from the point of view of a given consumer.

In addition, information can be classified in terms of its use into the following types: political, technical, biological, chemical, etc. d. This is essentially a classification of information according to need.

Finally, when generally characterizing the quality of information, the following definition is often used: Logical, adequately reflecting the objective laws of nature, society and thinking - this is scientific information Note that the last definition characterizes not the relationship “information – consumer”, but the relationship “information – reflected object/phenomenon”, that is, this is already a group of external properties of information. The most important here is the property of adequacy.

Adequacy is the property of information to uniquely correspond to the displayed object or phenomenon. Adequacy turns out to be an internal property of information for the consumer, manifesting itself through relevance and reliability.

Among the internal properties of information, the most important are the volume (quantity) of information and its internal organization and structure. According to the method of internal organization, information is divided into two groups:

1. Data or a simple, logically unordered collection of information.

2. Logically ordered, organized sets of data. Data ordering is achieved by imposing some

structures (hence the often used term data structure).

In the second group, information is organized in a special way - knowledge. Knowledge, unlike data, is information not about any single specific fact, but about how all facts of a certain type are structured.

Finally, the properties of information associated with the process of its storage were outside our field of vision. The most important property here is survivability - the ability of information to maintain its quality over time. To this you can also add the property of uniqueness. Information that is stored in a single copy is called unique.

Thus, we have described the main properties of information, and accordingly, we have determined the basis for classifying it by type.