Tickets for computer science and ICT. Modeling methods and technologies
Ticket No. 1
1. The concept of information. Types of information. The role of information in wildlife and in people's lives.
2. Practical task. In the environment educational performer Kangaroo needs to construct the word SON using a linear algorithmic structure.
Ticket No. 2
1. Measuring information: content and alphabetical approaches. Units of information measurement.
2. Practical task. Dial next text(take from the teacher), using the given font and paragraph parameters. Delete and insert specified fragments (blocks of text). Check your spelling. Insert a picture.
Ticket number 3
1. Discrete representation of information: binary numbers; binary encoding of text in computer memory. Information volume of the text.
2. Practical task. Create the suggested drawing in Paint using the rectangle, circle, straight line and curved line tools. Using standard Windows programs adjust the photo: brightness, contrast. Scanning a photo.
Ticket number 4
1. Discrete representation of information: coding of a color image in a computer (raster approach). Presentation and processing of sound and video images. Multimedia concept.
2. Practical task. File system: creation, copying, renaming, deleting. Windows desktop customization, customization antivirus program, using an archiver.
Ticket number 5
1. The process of information transmission, source and receiver of information, information transmission channel. Information transfer speed.
2. Creating a multimedia presentation of the answer to the first question of the ticket. Design based on templates. Selecting the type of slide layout, applying a design template, color schemes and animation effects. Show a presentation using automatic change slides.
Ticket number 6
1. The concept of an algorithm: linear, branched, cyclic. Algorithm executor. System of performer commands (using the example of educational performer Kangaroo). Properties of the algorithm. Methods for writing algorithms; flowcharts.
2. Practical task. Database creation " Computer school" Determining the database structure: number and types of fields, filling out tables (or using ready-made ones).
Ticket number 7
1. Basic algorithmic structures: following, branching, loop; image on block diagrams.
2. Practical task Working with the “Family Budget” spreadsheet. Creating a table in accordance with the task conditions, using functions. Constructing charts and graphs using tabular data.
Ticket number 8
1. Quantities: constants, variables, types of quantities. Assignment, input and output of values. Linear algorithms for working with quantities.
2. Practical task Searching for information on the Internet using query language. Search engines.
Ticket number 9
1. Logical quantities, operations, expressions. Boolean expressions as conditions in branching and cyclic algorithms.
2. Practical task Formatting a text document. Setting page parameters, inserting page numbers, headers, footers, hyperlinks, changing font and paragraph parameters.
Ticket number 10
1. Introduction to Programming: Language Pascal programming; examples of simple programs with linear, branching and cyclic structure.
2. Practical task Working with winrar archivers, zip. Creating a folder archive, unzipping. Antivirus programs. Using and configuring anti-virus programs.
Ticket number 11
1. The main components of a computer, their functional purpose and operating principles. Program principle computer operation.
2. Practical task Construction of an algorithm for processing quantities with implementation in the Pascal programming language. Search highest value of three given variables.
Ticket number 12
1. Computer software, composition and structure. Purpose of the operating system. Team interaction between user and computer. Graphic user interface.
2. Practical task Creating a multimedia presentation of the answer to the first question. Selecting the type of slide layout, applying a design template, color schemes and animation effects. Show slides using control buttons.
Ticket number 13
1. The concept of a file and file system for organizing data (folder, hierarchical structure, file name, file type, file parameters). Basic operations with files and folders performed by the user. The concept of archiving and virus protection.
2. Practical task Creation of a “Computer School” database. Organization of information search in databases. Creating queries of varying complexity.
Ticket number 14
1. Information resources of society. Basics information security, ethics and law.
2. Practical task Working with a spreadsheet. Solving a problem using a spreadsheet for changing initial data for the Family Budget problem.
Ticket number 15
1. Technologies for working with text documents. Text editors and processors: purpose and capabilities. Basic structural elements text document. Fonts, styles, formats. Basic techniques for editing a document. Embedded objects. The concept of hypertext.
2. Practical task Constructing an algorithm for the problem of finding the perimeter of a square if its side is known. Implementation of the program in Pascal. Debugging the program and getting the result for different conditions tasks.
Ticket number 16
1. Technologies for working with graphic information. Raster graphics in Photoshop and vector graphics in Paint. Graphics editor, basic tools and operating modes.
2. Practical task Solving a problem on the topic “Number systems” using the standard “Calculator” program. Converting numbers from the decimal number system to the binary system and vice versa. Check using the Calculator.
Ticket number 17
1. Tabular databases (DB): basic concepts (field, record, primary key of a record); data types. Database management systems and principles of working with them. Search, delete and sort data in the database. Search conditions (logical expressions); order and sort keys.
2. Practical task Construction of an algorithm for calculating the area of 5 squares with sides varying from 0 to 15 in a cycle. Debugging the program, obtaining results.
- Searching for information using a computer. Information and search systems.
- Download the word processor Word. Using the built-in vector editor create and fill out the table “Population and flags of states.”
State | Population | Flag |
|||
Russia | 145 000 000 | ||||
Japan | 127 000 000 | ||||
Sweden | 9 500 000 | ||||
Panama | 16 000 000 | ||||
______________________________
EDUCATIONAL INSTITUTION OF THE REPUBLIC OF CRIMEA
"KERCH POLYTECHNIC COLLEGE"
- MSEXCEL. Diagrams. Types of charts. Types of diagrams. Chart objects.
- Download the program PowerPoint . Create a two-slide presentation:
- Title slide -Data storage;
- Slide 2 objects (First slide – Magnetic storage media).
- Insert pictures of information carriers into the text of the presentation using information search engines on the Internet.
Presentation text.
Title slide title.
Data storage.
Subtitle.
- Paper media;
- Magnetic storage media (hard disk drive – Winchester);
- External media for PC on flash key fobs;
- Optical (laser) storage media.
First slide. Magnetic storage media.
The first PCs used floppy disks. Since the 1980s, PCs began to use built-inhard disk drives, or HDD . They are also called hard drives . Winchester diskis a package of magnetic disks placed on a common axis, which is in constant rotation when the computer is running. Each magnetic surface of the disk pack has its own magnetic head in contact.
- Download Excel spreadsheet processor. On Sheet 1 of the book, create a table “Computer sales” and build 3 types of diagrams:
- Stacked histogram;
- Bar chart with grouping;
- Normalized stacked histogram.
Sales of computers |
||||
I quarter | II quarter | III quarter | IV quarter |
|
Sycamore | ||||
Plus | ||||
___________________________
Task 1 is worth 1 point
Task 2 is worth 2 points
Task 3 is worth 2 points
Teacher's signature _________________
STATE BUDGET PROFESSIONAL
EDUCATIONAL INSTITUTION OF THE REPUBLIC OF CRIMEA
"KERCH POLYTECHNIC COLLEGE"
- Email. Address email box. Electronic Communication Etiquette.
- Download PowerPoint program. Create a slide presentation in the form of a greeting card:
- Title slide – Greeting card;
- Slide 2 objects ( The first slide is the text of the greeting card);
- Choose the slide design at your discretion;
- Insert attributes of congratulations (drawing, photo, clip, etc.) into the presentation text using information and search engines on the Internet.
Presentation text.
Title slide title.
Greeting card for Teacher's Day.
First slide. Congratulatory poem.
Thanks for the wonderful lessons,
For the light of a smile and for the wisdom of words,
That you are warm and attentive to everyone
And believe in your students.
"Table 3.2":
- Fill the table cells with formulas and perform calculations;
- Set boundaries according to the sample.
Table 3.2
Mathematical formula | Formula in Excel | Result |
||
=(1+A2) / (4*B2) | 0,416667 |
|||
0,352941 |
||||
5,93548 |
___________________________
Task 1 is worth 1 point
Task 2 is worth 2 points
Task 3 is worth 2 points
Teacher's signature _________________
STATE BUDGETARY PROFESSIONAL EDUCATIONAL INSTITUTION OF THE REPUBLIC OF CRIMEA "KERCH POLYTECHNIC COLLEGE"
| |||||
=(7*A3 – 12*B3^3)/(45 – 2*C3) | |||||
Task 1 is worth 1 point
Task 2 is worth 2 points
Task 3 is worth 2 points
Teacher's signature _________________
Tickets for the state (final) certification in computer science in oral form for the course of basic general education are compiled on the basis of the federal component of the state standard of basic general education (order of the Ministry of Education of Russia dated March 5, 2004 No. 1089). At the same time, they take into account the content of the currently existing Mandatory minimum content of basic general education (Order of the Ministry of Education of Russia dated May 19, 1998 No. 1236) and the Mandatory minimum content of secondary (complete) general education (Order of the Ministry of Education of Russia dated June 30, 1999 No. 56), which are almost completely implemented in primary school.
The sets of tickets fully reflect the federal component of the state standard of basic general education and also include some well-established topics in the computer science course, which continue in high school and are subsequently traditionally present at entrance exams to colleges and universities. The examination material presented is independent of the specific implementation of the subject content in existing textbooks. The kit can be considered universal, since the content of the theoretical part is focused on the federal component of the state standard of basic general education, and the content of the practical part involves testing the level of competence in the field of ICT. This implies that when solving a specific problem in a computer science course or any related field of knowledge, it is necessary to rely on theoretical knowledge and practical skills in the field of information and communication technologies.
The set consists of 20 tickets.
The content of the exam questions is developed on the main topics of the course in computer science and information technology, combined in accordance with the state educational standard for the subject in the sections: "Information processes" and " Information Technology". The content of the section "Information Processes" is divided into the following topics: "Presentation of information", "Transmission of information", "Information processing. Algorithms", "Computer", "Information processes in society". The content of the section "Information technologies" consists of the following topics: "Text processing technology", "Graphics processing technology", ""Processing technology numerical information", "Technology for storing, searching and sorting information and databases", "Telecommunication technologies".
A set of tickets for computer science has the following structure: each ticket contains two parts - theoretical and practical. The theoretical part involves an oral response from students with a possible demonstration on the computer of the illustrative part necessary for the answer. This can be a description of the objects of study, their essential features, properties, connections between them, i.e. revealing the essence of the studied object. The qualitative characteristics of assimilation of the studied material may differ. In some cases, this is the completeness and consistency of the generated knowledge, and in other cases, it is the strength and effectiveness of students’ knowledge; there may be a case of independent and prompt application of knowledge by students. The described qualitative characteristics are criteria for assessing student learning outcomes.
The practical part contains a task that must be completed on a computer. The main goal of this section of the exam is to check the graduate’s level of competence in the field of ICT (the ability to operate with theoretical knowledge and studied software, the ability to use it to solve practical problems).
Each of the tasks is focused on testing the ability to perform a certain set of operations with a specific software package, but it also demonstrates general knowledge and skills in the field of “Computer Science and ICT”: launching programs for execution, reading and writing data files, choosing the optimal storage and presentation format objects. Setting this format allows us to identify the degree of mastery of information and communication technologies sufficient to continue education. Thus, both special (subject) skills that are formed in the process of studying specific educational material and rational skills are tested. educational activities, i.e. the ability to plan educational work, organize it rationally, and control its implementation.
- Construction of algorithms:
- to control the training executor (basic algorithmic structures);
- for processing quantities with implementation in a programming language (branch, loop, array or auxiliary algorithms).
- Working with the file system, with a graphical interface. Organization of individual information space. Working with archivers and anti-virus programs.
- Creating and editing text documents, including those that include objects (tables, images, etc.).
- Creation of graphic images using a graphics editor. Input an image through a scanner or from a digital camera. Digital image processing.
- Database creation. Organization of information search in databases.
- Working with a spreadsheet. Constructing charts and graphs using tabular data. Conducting a computational experiment in a spreadsheet environment.
- Create a multimedia presentation based on templates.
- Searching for information on the Internet using query language.
The set of tickets includes applications with practical tasks on given topics.
Preparing and conducting the exam and evaluating the answers.
The approximate preparation time for students to answer the tickets can range from 10 to 40 minutes. The response time for a ticket should generally not exceed 15 minutes.
Evaluating the examinee's response expert (consists of several opinions of members of the examination commission).
The examination committee is recommended to first accept the practical task, which is assessed dichotomously: passed/fail. The practical part for the selected ticket accepted by the commission means that the student can already qualify for a grade of “3” or satisfactory. Then, when answering the theoretical part of the ticket orally, the student can add one or two more points to the existing points, depending on the quality of preparation. Thus, a cumulative assessment system is used, corresponding to the traditional five-point scale.
The answer to the ticket as a whole is rated as “4” if, when answering the theoretical part of the ticket, minor errors were made, sometimes the sequence of presentation was violated, or some insignificant elements of content were missing.
The answer to the ticket as a whole is graded “5” if the student, when answering the theoretical part of the ticket, demonstrated systematic, complete knowledge and was smart on the question posed. The student presented the content of the question coherently, in a brief form, consistently revealed the essence of the studied material, demonstrating the strength and applied orientation of the acquired knowledge and skills, and did not allow it in terminology;” errors and factual inaccuracies.
Ticket 1
- Concept of information. Types of information. The role of information in both wildlife and people's lives. Language as a way of presenting information: natural and formal languages. Basic information processes: storage, transmission and processing of information.
- In the educational executor environment, draw a rectangular frame along the edge of the screen (drawing margin) using an auxiliary algorithm (procedure).
Ticket 2
- Measuring information: content and alphabetical approaches. Units of information measurement.
- Prepare a poster for the play "Pinocchio", prepared by the theater studio "Yunost". When preparing a text document, use various sizes, styles and types of fonts. Prepare a list of characters and performers using a table. Use embedded objects: picture, symbol, WordArt.
Ticket 3
- Discrete representation of information: binary numbers; binary encoding of text in computer memory. Information volume of the text.
- In the Paint graphic editor, open the dog.jpg file. Complete the doghouse and any other missing details. Color the resulting drawing.
Ticket 4
- Discrete representation of information: coding of color images in a computer (raster approach). Presentation and processing of sound and video images. Multimedia concept.
- Create a folder named NEW in the C:\EXAMEN folder. Copy the LORA folder and the gramota.doc uspev.xls files to the created NEW folder from the C:\WORK folder. Go to the C:\EXAMEN folder and rename the LORA folder to the STAR folder. Move the STAR folder to the C:\WORK folder. Remove the NEW folder from the C:\EXAMEN folder, and the STAR folder from the C:\WORK folder. Empty trash. Display the contents of the folder C:\WORK\TEST\DATA in full form (Table), sorting it by file size (descending) Determine which file in the folder C:\WORK\TEST\DATA has the largest size. Display the contents of the folder C:\WORK\TEST\DATA in full form (Table), sorting it by the time the files were created (ascending). Create a folder named ARJ in the C:\EXAMEN folder. Zip all files from the DATA folder and place the archive in the ARJ folder.
Ticket 5
- The process of information transmission, source and receiver of information, information transmission channel. Information transfer speed.
- Prepare based on ready-made template presentation on the topic “Computer devices”, consisting of at least 5 slides. Apply animation effects to objects. Set up automatic slide show.
Ticket 6
- The concept of an algorithm. Algorithm executor. System of performer commands (using the example of a training performer). Properties of the algorithm. Methods for writing algorithms; flowcharts.
- Create database table structure Students, containing the following fields: last name, first name, class, address, date of birth, weight. Determine the primary key of the table. In table mode, enter 10 records about students from your school into the database (field values can be set arbitrarily). Add a “height” field to the table structure after the “date of birth” field. Remove the "weight" field from the structure. Fill in the “height” field in the table (optional). Display the fields “Last names”, “First name”, “Class for students whose height is above 175 cm (use a query), sorting them in alphabetical order of last names. Remove from the table information about students with the name “Vladimir”.
Ticket 7
- Basic algorithmic structures: following, branching, loop; image on block diagrams. Breaking a task into subtasks. Auxiliary algorithms.
- Working with a spreadsheet. A deposit of size N was made to the bank at P% per annum. Determine the annual increase in the contribution and the amount of the contribution in Chern K years.
Ticket 8
- Quantities: constants, variables, types of quantities, Assignment, fruit and output of quantities. Linear algorithms for working with quantities.
Find answers to questions using the search server Rambler (www.rambler.ru) or Yandex (www.yandex.ru) Indicate the address of the information source.
1) Where and when was the last All-Russian Olympiad in Informatics held? Who became the winner of the Olympics?
2) Where and when was the last international Olympiad in Informatics held? What is the composition of the Russian team and its result?
Ticket 9
- Logical values, operations, expressions. Logical expressions as conditions in branching and cyclic algorithms.
- Develop a hypertext document “Video Library”, which contains a list of video films (at least three) and links to information about the actors and directors of the films. In turn, the actor and director pages contain links to film summaries.
Ticket 10
- Introduction to programming: programming language (using the example of one of the high-level languages); examples of simple programs with linear and branching structure.
- Create your own folder in the exam folder. Copy several text documents from the My Documents folder into it. Archive all text files to the archive type RAR.Create a self-extracting archive of the same files in your folder. Compare the volume of two created archives. Extract the files from the first archive into the newly created ARCHIVE folder. Use an antivirus program to check for viruses in the Exam folder.
Ticket 11
- The main components of a computer, their functional purpose and operating principles. The software principle of computer operation.
- Write an algorithm in Pascal programming language to find the circumference of a circle. Explain the progress of the algorithm, its purpose main commands programs.
Ticket 12
- Computer software, composition and structure. Purpose of the operating system. Team interaction between user and computer. Graphical user interface.
- Develop a “Video Library” presentation containing hyperlinks that contain a list of video films (at least three) and links to information about actors and directors of films. In turn, the actors' and directors' pages contain links to film annotations.
Ticket 13
- The concept of a file and file system for organizing data (folder, hierarchical structure, file name, file type, file parameters). Basic operations with files and folders performed by the user. The concept of archiving and virus protection.
- Open the SPORT database. Change the size of the "Country" field to 20. Create a request to display the last name and country for athletes from the USA. Create a request to display the number, last name, scores for the rings and crossbar for athletes who received a score of at least 9.500 on the rings.
Ticket 14
- Information resources of society. Fundamentals of information security, ethics and law.
10 districts of the Moscow region were selected to conduct the experiment. The sown areas and the average yield in the region are known.
| District name | Crop area (m) | Average yield (t/ha) |
|---|---|---|
| Dmitrovsky | 93 | 12 |
| Domodevsky | 65 | 17 |
| Klinsky | 98 | 15 |
| Lytkarinsky | 64 | 17 |
| Lyubertsy | 102 | 17 |
| Maryinsky | 155 | 14 |
| Mytishchinsky | 207 | 16 |
| Orlovsky | 307 | 19 |
| Reutovsky | 134 | 21 |
| Semenovsky | 45 | 14 |
Determine the amount of crop harvested in each district and in the experimental districts of the region as a whole, as well as the average yield for all districts. Identify areas with the lowest and highest yields.
Ticket 15
- Technologies for working with text documents. Text editors and processors: purpose and capabilities. The main structural elements of a text document. Fonts, styles, formats. Basic techniques for editing a document. Embedded objects. The concept of hypertext.
- Create an algorithm in Pascal to find the amount of a deposit in a bank after N years, if the initial deposit amount is M. Explain the progress of the algorithm and the assignment of the main program commands. Draw up a block diagram of the algorithm.
Ticket 16
- Technologies for working with graphic information. Raster and vector graphics. Hardware input and output of graphic images. Application programs for working with graphics. Graphics editor. Basic tools and operating modes.
- Convert the number 24110 to hexadecimal, octal and binary number systems. Add the numbers 1101112 and 1110002. Perform the test. Multiply the numbers 10102 and 11102. Perform the test.
Ticket 17
- Tabular databases (DB): basic concepts (field, record, primary key of a record); data types. Database management systems and principles of working with them. Search, delete and sort data in the database. Search conditions (logical expressions); order and sort keys.
- Write an algorithm in Pascal to find the largest of three numbers entered from the keyboard. The numbers entered are different. Draw up a block diagram of the algorithm. Explain the progress of the algorithm and the purpose of the main program commands.
Ticket 18
Ticket 19
- Basic principles of organization and functioning of computer networks. Internet. Information resources and services of computer networks: World Wide Web, file archives, interactive communication. Purpose and capabilities of e-mail. Searching for information on the Internet.
- Processing digital photos in a graphics editor. Elimination of defects. Launch the Gimp graphics editor. Upload a photo file suggested by the teacher. Correct any defects in the photograph. Save the image code with a different name.
Ticket 20
Please enable JavaScript to view the comments powered by Disqus. 1 ticket –beginning-
I generation, 1945-1954
The use of vacuum tube technology, the use of memory systems on mercury delay lines, magnetic drums, cathode ray tubes(Williams tubes).
Punched tapes and punched cards, magnetic tapes and printing devices were used for data input and output.
The concept of a stored program was implemented.
II generation, 1955-1964 Replacement of vacuum tubes as the main components of a computer with transistors. Computers have become more reliable, their performance has increased, and energy consumption has decreased. With the advent of memory on magnetic cores, its operating cycle decreased to tens of microseconds.
The main principle of the structure is centralization.
High-performance devices for working with magnetic tapes and memory devices on magnetic disks appeared.
III generation, 1965-1974 Computers were designed on the basis of integrated circuits of low degree of integration (MIS - 10 - 100 components per chip) and medium degree of integration (SIS - 10 -1000 components per chip).
An idea arose, which was implemented, of designing a family of computers with the same architecture, which was based mainly on software.
In the late 60s, minicomputers appeared. In 1971, the first microprocessor appeared.
IV generation, after 1975 The use of large integrated circuits (LSI - 1000 - 100,000 components per chip) and ultra-large integrated circuits (VLSI - 100,000 - 10,000,000 components per chip) in the creation of computers.
The beginning of this generation is considered to be 1975 - Amdahl Corp. released six AMDAHL 470 V/6 computers, which used LSI as an elemental base.
High-speed memory systems on integrated circuits began to be used - MOS RAM with a capacity of several megabytes. If the machine is turned off, the data contained in the MOS RAM is saved by automatic transfer to disk. When the machine is turned on, the system starts using a boot program stored in ROM (read-only memory), which unloads the operating system and resident software into the MOS RAM.
The first personal computers appeared in the mid-70s.
V generation The main emphasis when creating computers is on their “intelligence”; attention is focused not so much on the elemental base, but on the transition from an architecture focused on data processing to an architecture focused on knowledge processing.
Knowledge Processing - Use and Processing knowledge computer, which a person uses to solve problems and make decisions.
1 ticket –continued-
Development of computer technology. Its development is noted background And four generations of computers. The backstory begins in ancient times from various devices for counting (abacus, abacus), and the first calculating machine appeared only in 1642. It was invented by a French mathematician Pascal. Built around gears, it could add decimal numbers. All four arithmetic operations were performed by a machine created in 1673 by a German mathematician Leibniz. It became the prototype of adding machines, used from 1820 to the 60s of the 20th century. The idea of a program-controlled calculating machine with an arithmetic unit, control, input and printing devices (albeit using a decimal number system) was first put forward in 1822. English mathematician Babbage. His project was ahead of the technical capabilities of its time and was not implemented. Only in the 40s of the XX century. succeeded in creating a programmable calculating machine, based on electromechanical relays that can be in one of two stable states: “on” and “off.” This is technically simpler than trying to implement ten various conditions, relying on information processing based on a decimal rather than a binary number system. In the second half of the 40s, the first electronic computers appeared, element base which were vacuum tubes. Main characteristics of the computer different generations are given in table. 1
With each new generation of computers, the speed and reliability of their operation increased while their cost and size decreased, and information input and output devices were improved. In accordance with the interpretation of the computer - as a technical model of the human information function - input devices are approaching the natural perception of information for humans (visual, audio) and, therefore, the operation of entering it into the computer becomes more and more convenient for humans.
A modern computer is a universal, multifunctional, electronic automatic device for working with information. Computers in modern society have taken over a significant part of the work related to information. By historical standards, computer information processing technologies are still very young and are at the very beginning of their development. Not a single state on Earth has yet created an information society. There are still many flows of information not involved in the scope of computers. Computer techologies today they are transforming or replacing the old ones, pre-computer information processing technologies. The current stage will end with the construction in industrialized countries of global networks for storing and exchanging information, accessible to every organization and every member of society. You just have to remember that you should let computers do what they can do. better than man, and not to use to the detriment of a person or society.
2 ticket
Informatization of society- a global, civilization-wide process of active formation and large-scale use of information resources. In the process of informatization of society, the traditional technological method of production and way of life is transformed into a new post-industrial one, based on the use of cybernetic methods and means.
Information society- a society in which the majority of workers are engaged in the production, storage, processing and sale of information, especially its highest form - knowledge
In the actual practice of the development of science and technology in advanced countries at the end of the 20th century. The picture of the information society created by theorists is gradually taking on visible shape. It is predicted that the entire world space will transform into a single computerized and information space. community of people living in electronic apartments and cottages. Any home is equipped with all kinds of electronic devices and computerized devices. Human activities will be focused primarily on information processing, while material and energy production will be entrusted to machines.
Local computer network(LAN)- a group of computers and peripheral equipment united by one or more autonomous high-speed digital data transmission channels within one or more nearby buildings. There are:
Depending on the data transmission technology: local networks with data routing and local networks with data selection;
Depending on the physical means of connection used: cable local networks and wireless local networks.
Telecommunications network is a general concept of a data transmission medium. This includes computer, telephone and some other networks.
A) Computer network- same as LAN
B) Telephone network - a communication network designed for speech transmission and consisting of:
From automatic telephone exchanges(switching nodes); And
From telephones and other devices (subscriber systems).
IN) Television network– designed to transmit moving images and their sound.
3 ticket
Computer- programmable electronic device, capable of processing data and performing calculations, as well as performing other symbol manipulation tasks. There are two main classes of computers:
Digital computers (computers) that process data in the form of numeric binary codes;
Analog computers that process continuously changing physical quantities that are analogues of calculated quantities.
Backbone-modular principle.
The architecture of modern PCs is based on the backbone-modular principle. Modular principle allows the consumer to assemble the computer configuration he needs and, if necessary, upgrade it. The modular organization of the system is based on the backbone (bus) principle of information exchange. A highway or system bus is a set of electronic lines that link together the processor, memory and peripheral devices for memory addressing, data transfer and service signals. Data via the data bus can be transferred from the processor to any device or, conversely, from the device to the processor, i.e. The data bus is bidirectional.
Principles background Neumann - general principles underlying modern computers:
-1- the principle of program control, according to which a program consists of a set of commands that are executed by the processor one after another in a certain sequence;
-2- the principle of memory homogeneity, according to which programs and data are stored in the same memory;
-3- the principle of addressing, according to which the main memory consists of renumbered cells and any cell is available to the processor at any time.
4 ticket
Main components of a computer. The role of everyone in the information processing process.
The main components of a computer include:
1. Central processor
3. System bus
4. Controllers and devices for input/output and information storage.
The role of each of them in the processing process:
* The main part of an Electronic Computer is definitely CPU. It reads data and commands from memory and performs the required operations on this data (and the number of operations is a priori f
fixed and represents the so-called machine code). After which, if necessary, it writes the results of its work into memory. It also controls input/output and information storage devices via
rollers.
* The main role of memory is to remember, store and provide stored information to the processor. Memory stores both data and processor instructions. The memory is connected to the central processing unit via the system bus. The unit of storing information in memory is a byte. Moreover, a byte in most modern machines consists of eight bits. A bit is the minimum logical structure of a sufficient system for describing two
states. Memory is divided into RAM and ROM by type. RAM - Random Access Memory - is a temporary memory in which data is not saved when there is no power. ROM - Read Only Memory is a type of memory in which data is stored permanently until it is overwritten or erased.
* The system bus is a device that allows you to transfer data between the central processing unit, memory and controllers.
* A controller is a special device that allows you to communicate with peripheral devices, a kind of interface to the central processor. Controllers allow the central processing unit to manage input/output and storage. Input-Output devices are special devices that are used to enter data and/or commands into a computer or output work results. An example of an input/output device is touchscreen, modem etc.
5 ticket
Composition of the system unit. Purpose of each device.
1. Motherboard
2. Processor
Motherboard- the main board of the computer on which the electronic components, defining the processor architecture.
CPU- the main working component of a computer, which:
Performs arithmetic and logical operations, specified by the program;
Manages the computing process; And
Coordinates the operation of all computer devices.
In general, the central processor contains:
Arithmetic-logical unit;
Data buses and address buses;
Registers;
Command counters;
Very fast, small cache memory;
Mathematical floating point coprocessor.
A fast storage device directly connected to the processor and designed to write, read, and store executing programs and data.
HDD- a magnetic disk in which the information carriers are round aluminum plates (platters), both surfaces of which are coated with a layer of magnetic material. This plate or group of coaxially arranged plates, together with the read/write unit, are placed in a sealed box to protect them from dust, moisture and dirt.
6 ticket
Types of memory. Basic characteristics of memory. Properties of memory.
Read Only Memory- non-volatile memory, used to store data that will never need to be changed. The contents of persistent memory are “hardwired” into the device during its manufacture for permanent storage. ROM can only be read.
IN permanent memory record a program for controlling the operation of the processor itself, programs for controlling the display, keyboard, printer, external memory, programs for starting and stopping the computer, and device testing programs.
Random Access Memory- a fast storage device directly connected to the processor and designed for writing, reading and storing executable programs and data.
Characteristics: capacity, speed.
Properties: permanent, rewritable.
7 ticket
Infopmation. Properties of information. Unitsamount of information.
Concept of information. The term information comes from the Latin informatio, which means explanation, information, exposition. The concept of “information” has many meanings and therefore cannot be strictly defined. In a broad sense information - this is a reflection of the real (material, objective) world, expressed in the form of signals and signs.
In computer science, the concept of “information” means information about objects and phenomena environment, their parameters, properties and condition, which reduce the degree of uncertainty and incomplete knowledge about them.
Properties of information (information requirements). At the same time, in order for information to contribute to making correct decisions based on it, it must be characterized by such properties as reliability, completeness, relevance, usefulness, understandability. Let us also pay attention to such a property of information as adequacy - a certain level of correspondence of the image created with the help of the received information to a real object, process, phenomenon, etc., which allows us to talk about the possibility of clarifying, expanding the volume of information, and bringing it closer to greater reliability in the process of cognition.
Unit of information called bit (bit) - an abbreviation for the English words binary digit, which means binary digit.
8 ticket
Computer peripherals. TheirroleVprocessinginformation.
Peripherals are designed for external data processing, ensuring their preparation, input, storage, management, protection, output and transmission over a distance via communication channels.
Basically, peripheral devices play the role of terminals from which the information processing process is controlled.
9 ticket
Computer software. Types of software. Ppikladnoeprogpammo provision.
Software - a set of programs:
Ensuring the processing or transmission of data;
Designed for repeated use and application by different users.
Based on the types of functions performed, software is divided into system, application and instrumental.
Application software software - software consisting of:
Individual application programs and application software packages designed to solve various user problems; And
Automated systems created on the basis of these (packages of) application programs.
10 ticket
Purpose. Operation NN th system(OS) - ensures the holistic functioning of all computer components, and also provides the user with access to the computer’s hardware capabilities.
OS composition. The OS structure consists of the following modules:
basic module(OS kernel) - controls the operation of programs and the file system, command processor- deciphers and executes user commands received primarily through the keyboard;
peripheral device drivers - software ensures consistency between the operation of these devices and the processor additional service programs(utilities) - make the process of communication between the user and the computer convenient and versatile.
Loading the OS. The files that make up the OS are stored on disk, That's why the system is called disk operating system (DOS). It is known that in order to execute them, programs - and, therefore, OS files - must be located in random access memory (RAM). However, in order to write the OS into RAM, you need to create a boot program, which is not in RAM immediately after turning on the computer. The way out of this situation is to follow and those linen, step-by-step loading of the OS into RAM.
The first stage of loading the OS. In the system unit of the computer there is read only memory(ROM, permanent memory,ROM - Read Only Memory - memory with read-only access), which contains programs for testing computer units and the first stage of loading the OS. They begin to execute with the first current pulse when the computer is turned on (this is possible because the information in ROM is stored in the form electronic circuits, which allows it to be saved even after the computer is turned off, that is, it has the property energy independence). At this stage, the processor accesses the disk and checks for the presence of a very small boot program at a certain location (at the beginning of the disk). If this program is detected, it is read into RAM and control is transferred to it.
The second stage of loading the OS. The loader program, in its own queue, looks for the base OS module on the disk, overwrites its memory and gives it control.
The third stage of loading the OS. The base module includes a main bootloader that searches for other OS modules and reads them into RAM. After the OS has finished loading, control transmitted command processor and the system prompts you to enter user commands.
Replace them with what is in RAM while working computer the base OS module must be present and commanding th processor. Therefore, there is no need to load all OS files into RAM at the same time. Device drivers and utilities can be loaded into RAM as needed, reducing the required amount of RAM allocated to system software.
11 ticket
operating room Windows system: purpose, advantages, disadvantages.
Windows operating system is a single-user operating system developed by Microsoft for personal computers.
Windows OS is multitasking and multithreaded, characterized by a windowed graphical interface.
12 ticket
The concept of an algorithm. Properties of the algorithm. Algorithm executor.
An algorithm is an accurate and understandable instruction to the performer to perform a sequence of actions aimed at solving a given problem. The name “algorithm” comes from the Latin form of the name of the Central Asian mathematician al-Khwarizmi - Algorithmi. Algorithm is one of the basic concepts of computer science and mathematics.
Algorithm properties:
1. Certainty
Each command must be clear and not subject to interpretation.
2. Discreteness
The algorithm should be broken down into simple steps (stages)
3. Effectiveness
The algorithm must lead to a solution to a given problem in a finite number of steps.
4. Mass participation
The algorithm is developed for a certain class of problems that differ only in the initial data.
Executor– an abstract or real system capable of executing the commands of an algorithm. The performer is characterized by: environment, elementary actions, command system, failures.
13 ticket
Types of algorithms
Sequence is the arrangement of actions one after another.
An algorithm in which there is a BRANCHING structure is called BRANCHING.
Branching is the choice of action depending on the fulfillment of some condition.
An algorithm that has a LOOP structure is called CYCLIC.
A cycle is the repeated repetition of some action.
14 ticket
Stages of solving problems on a computer.
Programming is a theoretical and practical activity related to the creation of programs. Solving problems on a computer includes the following main steps, some of which are carried out without the participation of a computer.
1. Formulation of the problem:
collecting information about the task;
formulation of the problem conditions;
determining the final goals of solving the problem;
determination of the form for issuing results;
description of data (their types, ranges of values, structure, etc.).
2. Analysis and study of the problem, model:
analysis of existing analogues;
analysis of hardware and software;
development of a mathematical model;
development of data structures.
3. Algorithm development:
choosing an algorithm design method;
choosing the form of recording the algorithm (flowcharts, pseudocode, etc.);
selection of tests and testing method;
algorithm design.
4. Programming:
choosing a programming language;
clarifying ways to organize data;
recording the algorithm in the selected language
programming.
5. Testing and Debugging:
syntax debugging;
debugging semantics and logical structure;
test calculations and analysis of test results;
improvement of the program.
15 ticket
Sequential detailing method.
The process of solving a complex problem quite often comes down to solving several simpler subproblems. Accordingly, when developing a complex algorithm, it can be divided into separate algorithms, which are called auxiliary ones. Each such auxiliary algorithm describes the solution to a subtask.
The process of constructing an algorithm using the sequential refinement method is as follows. First, the algorithm is formulated in “large” blocks (commands), which may be incomprehensible to the performer (not included in his command system) and are written as calls to auxiliary algorithms. Then detailing occurs, and all auxiliary algorithms are described in detail using commands that are understandable to the performer.
16 ticket
Programming systems
Programming system - software system, intended for developing programs in a specific programming language. The programming system provides the user special means program development: translator, (special) program text editor, libraries of standard routines, software documentation, debugger, etc.
17 ticket
Text editor. Purpose and main functions.
Text editor - a program for entering and changing text data: documents, books, programs, etc. The editor provides modification of lines of text, contextual search and replacement of parts of text, automatic page numbering, processing and numbering of footnotes, paragraph alignment, checking the spelling of words, building tables of contents, printing text on a printer, etc.
18 ticket
Spreadsheet. Purpose and main functions
Spreadsheets - computer program, which supports the presentation of data in the form of tables consisting of rows and graphs, at the intersection of which cells (table cells) are located. The value in a numeric cell of the table is either specified explicitly or calculated using the formula associated with the cell. Spreadsheets are a tool for analyzing (financial) information.
19 ticket
Database management systems
Database management system is a set of software and linguistic tools for general or special purposes that supports the creation of databases, centralized management and organizing access to them for various users in the conditions of the adopted data processing technology.
The DBMS is characterized by the model used, means of administration and development of application processes.
The DBMS provides:
Description and compression of data;
Data manipulation;
Physical placement and sorting of records;
Failure protection, data integrity support and recovery;
Working with transactions and files;
Data security.
The DBMS defines the data representation model.
20 ticket
General principle 1: to convert a number to some number system with base M (digits 0, ..., M-1), in other words, to M-ary SS, you need to represent it in the form:
C = an * Mn + an-1 * Mn-1 + ... + a1 * M + a0.
a1..n - digits of a number from the corresponding range. an is the first digit, a0 is the last.
Compare this notation with the representation of a number, for example, in the decimal system.
From a system with a larger base to a system with a smaller one
Obviously, to find such a representation one can
1. divide the number by M, the remainder is a0.
2. take the quotient and do step 1 with it, the remainder will be a1...
The desired number will be written in the new number system using the resulting digits.
General principle 2: If the base of one system is the degree of another, for example, 2 and 16, then the translation can be made based on the table:
2 -> 16: we collect fours (16 = 2 4) numbers from the end of the number, each four is one of the digits in hexadecimal. Example below.
16 -> 2 - vice versa. We create fours according to the table.
From a smaller base to a larger one:
We simply calculate C = an * Mn + an-1 * Mn-1 + ... + a1 * M + a0, where M is the old base. Calculations, naturally, proceed according to the new number system.
For example: from 2 to 10: 100101 = 1*25 + 0*24 + 0*23 + 1*22 + 0*21+1=32+4+1=37.
Generally speaking, you can do a lot of clever tricks - they are in the example implementations :)
Many questions are asked regarding fractions and negative numbers.
Negative - the module of the number does not change when moving to another SS, therefore: remember the sign, apply the standard method - put the sign. Next I will talk about positive numbers
Decimal fractions - I move the comma, remembering by what power of the base I multiplied.
For example, moving a comma from the 4th place from the end in a ternary number is the same as multiplying it by 34
121201,2112 * 34 = 1212012112.
After the standard procedure with positive numbers, divide the resulting fraction by this factor. If you get a periobic fraction, that means this is your destiny. Remember: in the 3-digit system 1/3 = 0.1, and in the decimal system - 0.(3). It is a thankless task to operate with decimal fractions.
Ordinary - the correctness of the fraction is preserved relative to transformations, which means the same - the standard for the numerator and denominator.
21 tickets
File system. Files and folders. File name and type. File properties and attributes. Actions with files and folders.
File system- part of the operating system that provides writing and reading files on disk media.
The file system defines the logical and physical file structure, identification and associated file data.
File- a set of related records (clusters) stored in the external memory of a computer and considered as a single whole. Typically, a file is uniquely identified by specifying the file name, its extension, and the path to the file. Each file consists of attributes and content. There are text, graphic and sound files.
Folder – directory with files.
File Properties – size, creation date, location address, file type, summary.
Attributes 1.Read only 2.Hidden 3.Archive.
Actions with files and folders.
1. Open 2. Close 3. Cut 4. Copy 5. Paste 6. Send 7. Delete 8. Create a shortcut 9. Perform some action with another program (anti-virus scan).
22 ticket
Elements of algebra of logic. Logical expressions. Logical operations. Truth tables.
A logical expression is an expression in which the operands are objects on which logical operations are performed.
The result of executing a logical expression is one of two logical values: either True or False.
How to create a truth table?
According to the definition, the truth table of a logical formula expresses the correspondence between all possible sets of variable values and the values of the formula.
For a formula that contains two variables, there are only four such sets of variable values:
(0, 0), (0, 1), (1, 0), (1, 1).
If a formula contains three variables, then there are eight possible sets of variable values:
(0, 0, 0), (0, 0, 1), (0, 1, 0), (0, 1, 1),
(1, 0, 0), (1, 0, 1), (1, 1, 0), (1, 1, 1). The number of sets for a formula with four variables is sixteen, etc.
In general, for a formula containing n variables, the number of possible sets of variable values is always 2n.
A convenient form of recording when finding the values of a formula is a table that contains, in addition to the values of variables and formula values, also the values of intermediate formulas.
23 ticket
External memory computer. Various types of storage media.
Under external memory Computers usually mean both storage media (that is, devices where it is directly stored) and devices for reading/writing information, which are most often called drives. As a rule, each storage medium has its own storage device.
Winchester is installed inside the system unit and externally is a sealed metal box, inside which there are several disks combined into one package, magnetic read/write heads, a mechanism for rotating the disk and moving the heads. The main characteristics of the hard drive are:
Capacity, that is, the maximum amount of data that can be written to the medium;
Performance, determined by the time of access to the necessary information, the time of reading/writing it and the data transfer rate;
Uptime, which characterizes the reliability of the device.
Disk drives for working with laser (optical) discs - drives CD-ROM(Compact Disk Read Only Memory) - used for using various types of CDs.
Drives optical disks are divided into three types:
Non-writable (CD-ROM - read-only memory on a CD);
Write once and read many times (CD-WORM);
Rewritable (CD-RW, CD-E).
Work principles.
When recording, a CD is processed by a laser beam (without mechanical contact), which burns out the area that stores a logical one, and leaves intact the area that stores a logical zero. As a result, small depressions, so-called pits, are formed on the surface of the CD. When reading, a laser beam of lower intensity is directed onto the surface of the disk, the change in the characteristics of the reflected beam is analyzed, which are converted into a digital code.
The main characteristics of the CD are:
Capacity, which is 500-700 MB;
The data transfer speed from the media to the RAM is, depending on the drive, from 150 to 4800 KB/s;
The average access time required for the drive to locate the required data on the storage medium. Depending on the drive, it ranges from 80 to 400 ms.
Tickets for computer science
Information and information processes in nature, society, technology. Human information activity.
Object-oriented programming technology. Objects and their properties.
Practical task on carrying out calculations using a spreadsheet.
Information and management. Purpose and functions feedback.
Logic programming technology. Difference between logical programming languages and algorithmic programming languages.
The task of determining the result of executing an algorithm according to its block diagram or recording on algorithmic language.
Language and information. Natural and formal languages.
Technology algorithmic programming. Basic types and methods of organizing data (variables, arrays, lists, etc.)
P
practical task on plotting a function using spreadsheets.
Binary number system. Writing numbers in the binary number system.
Backbone-modular principle of computer construction.
The task is to develop an algorithm for execution of the Robot or Turtle type.
Binary coding of information.
The main characteristics of the computer (line width, amount of RAM and external memory, clock frequency and etc.).
A practical task on creating, converting, storing and printing a drawing using a graphic editor.
Amount of information. Units for measuring the amount of information.
External computer memory. Various types information carriers (information capacity, speed, etc.).
Practical task on working with files (copying, renaming, deleting, etc.).
Basic computer devices, their functions and reciprocity.
Basics of hypertext markup language (HT).
Practical task on finding files.
Software control of computer operation. Computer software.
Basic logical operations. Logical multiplication, addition, negation.
Practical task on working with disks (formatting, creating a system floppy disk, etc.).
Files (type, name, location). File system. Basic operations with files.
Logical expressions and their transformations. Truth tables.
Practical task on “treating” a floppy disk from viruses using GUI.
Legal protection of programs and data. Data protection.
Basics of computer logical devices (adder).
Practical task on creating, editing, saving and printing text using text editor.
modeling as a method of scientific knowledge. Material and information models.
The main logical devices of a computer (register).
Practical task to search for information in a database using specified parameters.
Formalization. Construction of mathematical models.
Multimedia technology (hardware and software).
A practical task on sorting information in a database according to specified parameters.
technology for solving problems using a computer. Technological chain: model construction – formalization – algorithm – program – computer experiment.
Computer software (its composition and purpose).
Problem to convert a decimal number to binary number.
concept of an algorithm. Properties of algorithms. Possibility of automation of human activities.
Computer operating system (purpose, composition, loading).
Branching algorithms. Branch command.
Positional and non-positional number systems. Writing numbers in positional number systems.
The task of determining the truth of a compound statement.
Cyclic algorithms. Repeat command.
Perform arithmetic operations in the binary number system.
The task is to determine the units of measurement of the amount of information.
Development of algorithms using the method of sequential detailing. Auxiliary algorithms.
Information Modeling. Main types of information models (tabular, hierarchical, network).
Binary addition problem.
Programming language basics (alphabet, operators, data types, etc.).
Static information models (state models). Dynamic information models (behavior models).
The task of constructing a query when searching for information on the Internet.
Text editor. Purpose and main functions. Encodings of Russian letters.
Information models of management processes.
Practical installation task software product.
Graphics editor. Purpose and main functions. Graphic file formats.
Formal logical models and mathematical models.
Spreadsheets. Purpose and main functions.
Programming systems. Interpretations and compilation.
The task of building an information model.
Database. Purpose and main functions. Database management systems (DBMS).
Computer viruses: distribution methods, charging prevention.
Practical tasks for developing a Web page using the tool.
Global network Internet and its information resources ( Email, teleconferences, file archives, World Wide Web).
Information. A probabilistic approach to measuring the amount of information.
The task of constructing a block diagram of a simple algorithm written in natural language.
Hypertext. WWW (World Wild Web) technology.
Fundamentals of object-oriented programming.
Practical task to determine the information capacity of various media.
Informatization of society. Main stages of development computer technology.
Structure of the global computer network Internet. Addressing to the Boarding School.
Practical task on converting a graphic file format.
Technology. Human information activity.
Information is a fundamental concept, so it is impossible to define it exhaustively through some simpler concepts. Each option for defining information has some incompleteness. In a broad sense, information is a reflection of the real (material, objective) world, expressed in the form of signals and signs. Signals reflect physical (physical - chemical) characteristics various processes and objects.
Actions performed with information are called information processes. Information processes can be divided into three components: storage, transmission and processing of information.
The combination of the concepts (information) and (management) led N. Wiener in the 40s. to the creation of cybernetics, which, in particular, for the first time pointed to the commonality of information processes in technology, society and living organisms. Objects of living nature, unlike inanimate ones, have the ability to exchange information and respond to it. For example, mountains are susceptible to erosion due to the adverse effects of wind, sun, rain, but they cannot take this information into account and use it for survival, unlike, for example, hares, which change their color to white after receiving information from the surrounding world about the onset of winter. A bee flies to the smell of a flower, which is information for it; bats navigate in space, receiving information using ultrasonic location. The dog has excellent communication abilities. She receives and processes the following information: if she performs the actions that the owner requires of her, he rewards her. To achieve what he wants, the dog must select external information necessary for further actions. She, for example, associates the concept (one's own) with members of the owner's family and the concept (stranger) with all other people.
The use of the concept of information has had a significant impact on the development of modern biology, especially its branches such as neurophysiology and genetics.
In technology, software-controlled machines operate, guided by the information embedded in them - the program of their work; the machine at the entrance to the subway, having received information about whether the token is lowered or not, accordingly allows or does not allow a person to pass; the autopilot controls the aircraft in accordance with the programmed him with the program.
But only for a person, information received from the outside world can become information that is the object of conscious storage, exchange and transformation. Information processes have always played an important role in the life of society. People exchange oral messages, notes, messages. They pass on requests, orders, progress reports to each other, publish advertisements and scientific articles, keep old letters, think for a long time about the news they receive, or immediately rush to carry out the instructions of their superiors. Of great importance for the preservation and development of culture is the transmission from generation to generation of fairy tales, traditions, legends, and the creation of works of painting.
A person’s entire life is constantly connected with receiving, accumulating and processing information. Information is the subject of human intellectual activity, the product of this activity. Information for a person is the knowledge that he receives from various sources. Everything everyone knows special person, he once learned from parents, teachers, from books, personal practical experience and kept it in his memory. In turn, everything that is written in books, magazines, newspapers reflects the knowledge of the authors of these texts, and therefore this is also information.
The question of knowledge classification is a complex scientific problem. One approach to such a classification is to divide KNOWLEDGE into declarative and procedural.
Declarative (from the word (declaration), which means (statement), (message)) includes knowledge about certain phenomena (the Earth revolves around the Sun), events (Pushkin was born in 1799), its objects (Baikal is the deepest freshwater lake in the world lake), dependencies (the square of the hypotenuse is equal to the sum of the squares of the legs).
Procedural knowledge includes knowledge about the actions that need to be taken to achieve a goal (how to assemble a radio, how to solve a square control, how to grow tomatoes, how to cure a cold).
People began to deal with the three components of information processes - storage, transmission and processing of information - a long time ago, long before the advent of computers.
A person stores information either in his own memory (sometimes they say “in the mind”) or on some external media. Most often, on paper. The information that a person remembers is always available to him. Every person remembers his home address, telephone number, as well as the addresses and telephone numbers of loved ones. If you need an address and phone number that you don’t remember, a notebook or telephone directory will help.
A person’s own memory can be called operative memory. Here the word (operative) is synonymous with the word (quick). Memorized knowledge is reproduced by a person instantly. One’s own memory can also be called internal memory, since its carrier, the brain, is located inside the human body.
Notebooks, reference books, encyclopedias, magnetic recordings, in relation to a person, are external repositories of information. To use information from an external source, you first need to make it operational (read the phone number), and then use it for its intended purpose (dial the number on the device). A person may forget operational information. Information on external media is stored more reliably. Books and records can be considered as an extension of human memory, as our external memory.
A person constantly has to participate in the process of transmitting information. Transfer can occur during direct conversation between people, through correspondence, using technical means, communications: telephone, radio, television. Such means of communication are called information transmission channels.
During the transmission process, information may be distorted or lost if the information channels are of poor quality or there is interference (noise) on the communication line. Many people know how difficult it is to communicate with poor telephone connections.
The process of information transfer is always two-way: there is a source and there is a receiver of information. The source transmits (sends) information, and the receiver receives (perceives) it. When reading a book or listening to a teacher, a student is a receiver of information. Each person constantly moves from the role of a source to the role of a receiver of information.
A person has to process information almost continuously. Here are some processing options:
Obtaining new information from given information through mathematical calculations or logical reasoning (for example, solving a mathematical problem, revealing by an investigator based on collected evidence);
Changing the form of information presentation + without changing its content (for example, translating text from one language to another, encryption (encoding) of text);
Organizing (sorting) information (for example, arranging class lists alphabetically by student last name, arranging train schedules by departure time);
Searching for the necessary information in some information array (for example, searching for a phone number in a phone book, searching for a translation of a foreign word in a dictionary, searching for information about an airplane flight in an airport schedule).
A person perceives information from the surrounding world using his senses. There are five of them: vision, taste, smell, touch.
More than 90% of information comes to us through vision and hearing. But smells, taste and tactile sensations also carry information. For example, when you smell something burning, you find out that the lunch you forgot about was burned in the kitchen. You can easily recognize familiar food by taste, familiar objects by touch, even in the dark.
Information perceived by a person in speech or written form is called (or sign) information. Indeed. Written text contains letters, punctuation, numbers, and other symbols. Oral speech is also made up of signs. Only these signs are not written, but sound, they are called phonemes. Phonemes make up words, words make up phrases. There is a direct connection between written signs and sounds, since writing is recorded on paper by human speech. Individual letters or a combination of letters indicate speech sounds, and punctuation marks indicate pauses and intonation.
Human speech and writing are closely related to the concept of language. Language is a sign system for representing information. Colloquial languages have a national character. There are Russian, English, Chinese, French and others. They are called natural languages.
In addition to natural languages, there are formal languages. As a rule, these languages are some kind of profession or field of knowledge. For example, mathematical symbolism can be called the formal language of mathematics, and musical notation can be called the formal language of music.
Natural languages have a national character and have oral and written forms. Formal languages are, as a rule, artificial languages of professional communication.
We can give examples of methods of linguistic exchange of information that replace speech. For example, deaf people use gestures instead. The conductor's gestures convey information to the musicians. The referee on the sports ground uses a certain sign language that is understandable to the players.
Smells, taste and touch sensations cannot be reduced to any signs and cannot be conveyed using signs. Of course, they carry information, since we remember them and recognize them. Such information is called figurative information. Figurative information also includes information perceived through vision and hearing, but not reduced to languages (the sound of the wind, birdsong, pictures of nature).
Although information is associated with a material medium, and its transmission requires energy, the same information can be stored on various material media (on paper, in the form of a photograph, on magnetic tape) and transmitted with different energy costs (by mail, by telephone) , with a courier), and the consequences (including material ones) of damaged information are completely independent of the physical costs of its transmission. For example, a slight press of a button lowers a heavy theater curtain or blows up a large building, a red traffic light stops a train, and unexpected unpleasant news can cause a heart attack. Therefore, information processes cannot be reduced to physical ones, and information, along with matter and energy, is one of the fundamental entities of the world around us.
Advances in technology in the 18th and 19th centuries. were almost entirely associated with the successes of physics and chemistry. Thanks to them, various converters of matter and energy were created and successfully distributed: engines for metallurgical and chemical production, electric generators. The efficiency of their work is described using physical concepts: power, load capacity, amount of energy generated. In the 20th century With the development of technology, a different kind of device appeared: a means of communication, an automation device, and since the 40s. – computer technology. Since the last third of the 20th century. They began to talk about (information explosion), using these words to describe the rapid growth of volumes and flows of information. As a means for storing, processing and transmitting information, scientific and technological progress offered society a computer (electronic - computer, E.V.M).
The operation of a computer imitates (models) the information function of a person. From the above it follows that there are four main human information functions:
Reception (input) of information;
Storing information (memory);
Thinking process (information processing);
Transfer (output) of information. The computer contains devices that perform these functions of a thinking person:
Input device;
memory device;
CPU;
output device.
This composition of computer devices was first proposed in the last century by Charles Babbage. All of them were included in the design of his Analytical Engine. The computer, which appeared in the mid-20th century, retained the same composition of devices. Charles Babbage was the first to put forward the idea of program control of a computer. The program contains instructions for the processor, which solves the problem by executing them sequentially.
A modern computer is a universal (multifunctional) electronic program-controlled device for working with information. The computer in modern society has taken control of a significant part of the work related to information. By historical standards, computer information processing technologies are still very young and are at the very beginning of their development. That's why they are called new information technologies - NIT. Not a single state on Earth has yet created an information society. There are many more flows of information not involved in the scope of computers. Computer technologies today are transforming or replacing old, pre-computer information processing technologies. The current stage ends with the construction in industrialized countries of global networks for storing and exchanging information, accessible to every organization and every member of society. You just need to remember that computers should be trusted to do things better than humans, and not be used to the detriment of humans and society.
Object-oriented approach in information technology.
Encapsulation is the union of an object's properties and possible operations (methods) on it.
Encapsulation. An object, on the one hand, has certain properties that characterize its state at a given moment in time, and, on the other hand, operations are possible on it that lead to changes in these properties.
The object-oriented approach allows you to combine a static model that describes the properties of an object and a dynamic model that describes their changes.
With this approach, access to changing the properties of an object is possible only through methods belonging to this object. Methods "surround" the properties of an object; properties are said to be "encapsulated" in an object.
Thus, in object-oriented programming, a central place is occupied by objects that combine into one whole (encapsulate) the properties of an object and the operations (methods) possible on it.
Speaking figuratively, objects are nouns. The object is, for example, the graphic primitive Circle. Properties of the object, i.e. its qualities and characteristics (eg coordinates, color, radius) are adjectives. Object methods, i.e. a set of operations that it can perform (for example, move, change color) - these are verbs; objects that encapsulate the same list of properties of operations are combined into classes. Every single object is an instance of a class. Instances of a class can have different property values.
For example, a computer's file system may contain hundreds or thousands of files. All files have the same set of properties (name, position in the file system, etc.) and operations (renaming, moving or copying, etc.) and form the file object class.
Each individual file is an instance of this class and has specific property values (name, location, etc.)
Inheritance defines the relationship between classes; objects of a descendant class have all the properties and operations of objects of a parent class.
Inheritance. In vector graphics editors, an image is constructed from graphic primitives (point, line, circle, etc.).
Operation properties (methods)
Coordinates (x, y) movement
Color change color
One of the graphic primitives is the point object class. In the point class, each object has certain properties (coordinates, color), on which corresponding operations (moving, changing color) are possible. The point object class can be specified by a table,From a point feature class, you can get a new circle feature class by adding a new radius property and an operation to change the radius.
All objects of the Circle class inherit the properties and operations of the class. The point is called the parent class, and the Circle class is the child class.
Polymorphism translated from Greek means “many forms.” The same operation on objects of different classes can be performed by different methods.
Polymorphism. A situation often occurs when the same operations can be performed on objects of different classes.
So, in the example discussed above, you can perform the same Move operation on objects of different classes Point and Circle.
Most classes of objects in the Windows &Office environment (folders, documents, symbols, etc.) are also characterized by a set of the same operations (renaming, moving, copying, deleting, etc.). Such uniformity is very convenient for the user.
However, it is obvious that the mechanisms for implementing these operations are not the same for different classes. For example, to copy a folder, you need to perform a sequence of actions to change the file system, and to copy a symbol, make changes to the document. These operations will be performed by various programs that are available, respectively, in the Windows operating system and in the Word text editor/
In this way, polymorphism is implemented, i.e., the possibility of performing the same operations on objects belonging to different classes, while maintaining individual methods for their implementation for each class.
The practical implementation of the object-oriented approach will be considered when studying the technology of object-oriented programming in the Visual Basic language
Object-oriented programming languages.
Object-oriented programming is currently the most popular programming technology. Object-oriented programming is a development of structured programming technology, but has its own characteristic features.
The basic unit in object-oriented programming is an object, which contains and encapsulates both the data that describes it (properties) and the means for processing this data (methods).
Object-oriented programming at its core is the creation of applications from objects, just as houses are built from blocks and various parts. Some objects have to be created entirely on your own, while others can be borrowed ready-made from various libraries.
Events occupy an important place in object-oriented programming technology. Events can be a mouse click on an object, pressing a certain key, opening a document, etc. As a reaction to events, it calls a specific procedure that can change the properties of an object, call its methods, etc.
Object-oriented programming systems typically use a graphical interface to visualize the programming process. It becomes possible to create objects, set their properties and behavior using the mouse.
The most common object-oriented visual programming systems are Microsoft Visual Basic and Borland Delphi.
In the Windows &Office environment, applications, documents, etc. can act as software objects. Each of these objects can be an executor of algorithms. Commands to an object (executor) can be given either by other objects operating in a given system or by a computer user.
In order for an object in the Windows &Office environment (for example, the Word application) to automatically execute an algorithm, it is necessary to write it in the formal language that this object “understands”. Such a language is the Visual Basic for Application (VBA) programming language, which is the core of the object-oriented Visual Basic programming language.
Objects and their properties
Objects that have the same sets of properties and methods form a class of objects. So, in the Word application there is a class of objects called Documents, which has such properties as name, location (File Name), etc. Objects of this class also have a certain set of methods, for example, opening a document, printing a document, saving document, etc.
An object class can contain many different documents (instances of the class), each of which has its own name. For example, one of the documents may be named Sample. Doc
Objects in an application form some kind of hierarchy. At the top of the object hierarchy is the application. Thus, the hierarchy of Word application objects includes the following objects: application, document, document fragment, symbol, etc.
A full reference to an object consists of a series of names of objects nested sequentially. The separators for object names in this row are dots; the row starts with the highest-level object. For example, a link to a sample document. Doc in Word application will look like this,
Application. Documents (“Proba. Doc”)
However, it is not necessary to make a full reference to the object every time. An object reference can be omitted if the object is active. For example, if the Word application is active, it is enough to make a relative link to the document itself, documents (“sample. doc”).
Information and management. Closed and open-loop control systems, feedback purposes.
In 1948, a book by the American mathematician Norbert Wiener (cybernetics, or control and communication in animals and machines) was published in the USA, which proclaimed the birth of a new science - cybernetics. It is no coincidence that the emergence of this scientific direction coincided with the creation of the first computers. N. Wiener foresaw that the use of computers for control would become one of their most important applications, and this would require a deep theoretical analysis of the control process itself. From the standpoint of kyvernetics, the interaction between the controlling and controlled objects is considered from information point vision. From this position, it turned out that a wide variety of management processes occur in a similar way and are subject to the same principles.
Let's discuss what management is from a cybernetic point of view.
MANAGEMENT is the purposeful influence of the control object on the control object, carried out to organize the functioning of the control object according to a given program.
The simplest situation is two objects: one is the manager, the other is the controlled one. For example, a person and a TV, an owner and a dog, a traffic light and a car. To a first approximation, the interaction between such objects can be described by the following diagram:
Control object
Managed object
Control action
In the above programs, the control action is performed in different forms: a person presses a key or turns the TV control knob, the owner gives a command to the dog with his voice, a traffic light in different colors controls the movement of cars at an intersection.
From a cybernetic point of view, all options for control actions should be considered as control information transmitted in the form of commands. In the example with a TV, commands like (turn on - turn off), (switch channel) are transmitted through technical controls. The owner gives commands to the dog by voice. The driver perceives traffic light signals as commands.
The definition given above says that management is a purposeful process; commands are not given randomly, but with a very specific purpose. In the simplest case, the goal can be achieved after executing one command. To achieve a more complex goal, it may be necessary to execute a sequence (series) of commands. A sequence of commands leading to a predetermined goal is called an algorithm. In the above examples, the TV, the dog, the car are the executors of the algorithm, aimed at very specific goals (watch a program of interest, complete certain tasks of the owner, drive through an intersection favorably).
So, we see that the cybernetic approach combines both material and information processes in which management takes place.
If you carefully consider the examples under consideration, you come to the conclusion that strictly in accordance with the diagram in Fig. 1 only the system (traffic light - cars) works. The traffic light (without looking) controls the movement of cars, not paying attention to the situation at the intersection. The process of controlling a TV or a dog is completely different. Before giving the next command, a person looks at the state of the control object, at the result of the previous command. If he does not find the desired program on a given channel, he will switch the TV to the next channel; if the dog does not comply with the command (lie down), the owner will repeat this command. From these examples we can conclude that the manager not only issues commands, but also receives information from the control object about its state. This process is called feedback.
Feedback is the process of transmitting information about the state of a control object to the control object.
Control action
Control object
Managed object
Feedback control corresponds to the following circuit:
Control systems with feedback are called closed-loop control systems, and control systems that do not have corrective feedback are called open-loop.
In the open-loop control option, the algorithm can only be a single-valued sequence of commands. For example, the traffic light algorithm:
Red – yellow – green – red – yellow – green, etc.
This algorithm is linear, or sequential.
With feedback, the algorithm can be more flexible, allowing for alternatives and iterations. At the same time, the manager himself must be sufficiently (intelligent) to, having received feedback information, analyze it and make a decision on the next command. In all cases where the manager is a person, this condition is met.
If a police traffic controller works at a traffic light at a road intersection, then traffic control will become more rational. The traffic controller monitors the accumulation of cars on intersecting roads and gives the green light in the direction in which it is most needed at the moment. Often, due to the (brainless) management of traffic lights, (traffic jams) arise on the roads, and here the traffic controller certainly comes to the rescue.
Thus, with feedback and an (intelligent) manager, control algorithms can have a complex structure containing alternative commands (branching) and repeating commands (loop).
Systems in which the role of manager is assigned to a computer are called automatic program-controlled systems. For the functioning of such a system, firstly, direct and feedback communication must be provided between the computer and the control object, and secondly, a control program (an algorithm written in a programming language) must be stored in the computer’s memory. Therefore, this control method is called program control.
Let us once again formulate the essence of the cybernetic approach to the management process:
there is control information interaction between the control object and the control system;
control information is transmitted via direct communication in the form of control commands;
information about the state of the control object is transmitted via the feedback line;
the sequence of control commands is determined by the control algorithm;
Without taking into account feedback, the algorithm can only be linear; with feedback, the algorithm can have a complex structure containing branches and cycles.
Cybernetics, according to this scheme, describes controls in technical systems, in a living organism, and even in human society.
Logic programming technology. Difference between logical programming languages and algorithmic programming languages.
Understanding Logic Models
Our life is a continuous chain of large and small logical problems. Through reasoning and conclusions we make a decision, i.e. We model our future behavior.
Logical models help solve not only everyday, but also scientific problems.
Logical models are models in which a decision is made based on the analysis of various conditions.
Thus, logical models are based on reasoning and operations with it. In this case, it goes without saying that indisputable truths are also taken into account: day follows night, a person cannot be in two places at the same time, a son is always younger than his father, etc.
Scientists and researchers are often faced with the task of drawing certain conclusions based on a multitude of disparate data and facts. And here logical models do not help them.
Usually a working hypothesis is put forward, which is tested by comparisons, comparisons of initial data and intermediate data and intermediate results, using logical reasoning. If theoretical conclusions contradict the initial facts, indisputable truths or stated conditions, then another hypothesis is put forward and the reasoning is repeated again and again until eventually the correct decision is made or an unambiguous answer is formulated.
Logical statements and conditions.
Human speech consists of reasoning (statements). Statements carry specific semantic content (what they say). But we can look at them from the point of view of veracity, whether what is being said is true. In this case, a statement can take two meanings, “true” and “false”. For example, the statement “The earth consists of three pillars” is false, but the statement “The earth turns” is true. Statements considered from the point of view of their truth and falsity are called logical statements. Even ancient philosophers reflected on the rules for constructing logical, correct reasoning.
Our further behavior often depends on the correctness or falsity of a statement. For example, the expression “it’s raining outside” can be both true and false, so in a specific situation it implies different actions, “if it’s raining outside, take an umbrella.” Naturally, if there is no rain, then there is no need to take an umbrella. Reasoning, we are faced with what in ordinary life is called the condition, “if you finish the quarter well, then you will go hiking,” “if the average daily air temperature is below 80C, it’s time to start periodically heating the premises.” In the examples given, after the word “if” the condition on which the decision is made is indicated. Thus, by analyzing conditions, one can build one or another model of behavior.
A condition is a logical statement that can take two meanings, true and false. Depending on its value, the further course of action is determined.
In mathematics and technology, the conditions are formulated more strictly and contain special comparison operations (greater than, less than, equal to) examples of using conditions in mathematics, “if X>0, then the modulus of the number is equal to the number itself,” “if in a linear function y=kx+b coefficient b=0, then the straight line passes through the origin of coordinates.”
Analysis of conditions is used in various fields of technology, “if the water temperature is 1000C, then the water goes into a gaseous state,” “if the density of a body is more than 1000 kg/m3, then it sinks in water.”
So, to make a choice, you need to analyze the condition. In general, the scheme may look like this: “if the condition is satisfied, then” or “if the condition is satisfied, then... otherwise...”
To find out whether a condition is true or false, it is convenient to formulate it in the form of a question that can be answered briefly and precisely, “yes” or “no”. For example, to the question “is the selected ball white?” You should answer “yes” only if the ball is white. In any other case (the ball is red, green, grey-brown-crimson) you should answer “no”.
There should be no ambiguity in the formulation of the question. The question is, “do you disapprove of the administration’s activities?” is incorrect because It’s not clear how to answer it, “yes! I approve!” or not! I don’t approve!”
Logical operations
The condition is simple if it is immediately fashionable to answer the question unambiguously - “yes” or “no”. But there are also complex conditions, consisting of several simple ones, each of which can be true and false.
In life, we often take advantage of difficult conditions. For example, a child sets conditions for parents, “if you buy me a bicycle and roller skates, I will try to study well.”
It is absolutely clear that the child promises to study well only if two conditions are met simultaneously (if there is both a bicycle and roller skates).
Another example is that to successfully pass an exam you need knowledge or luck.
From this example it follows that success in the exam is ensured if a person is well prepared, or he is “lucky,” or both.
Thus, in life, simple conditions are often combined into more complex ones using the conjunctions AND, OR. By analogy with life, the most common logical operations are the operations “OR” (logical addition) and “AND” (logical multiplication).
Language and information. Natural and formal languages.
Like any instrument, the tongue requires proper handling. Only in this case can you guarantee that you will receive the necessary and reliable information with its help.
Suppose one person is telling another the contents of a movie. His interlocutor does not know the content of this film or, in other words, its subject area. From the narrator he learns only the names of the objects in question. His task is to understand what this movie is about or, in other words, to match the name with certain objects. If he cannot do this, then he will either not understand what the interlocutor is telling him, or will misunderstand. This depends on many reasons, in particular on how well the interlocutors speak the language, how clearly they understand the meaning of individual words. It may also happen that the interlocutor is not at all familiar with the subject of the story. For example, try to explain to a person who has never seen a TV, and you explain to him the construction of his system.
The most important method in transmitting information is its encoding and decoding. Currently, there are several universal techniques for encoding information. One of the most important techniques that plays a big role in computer science and computer technology is coding using “0” and “1”. This method is so universal that it can be used to encode, for example, pictures; we denote the cells in which the picture falls as “1”, and everything else as “0”.
The result is a drawing code that can be represented in the computer's memory.
It is so important that the interlocutor understands you correctly. This becomes especially important when the “interlocutor” is a computer that cannot “think through” anything and understands all the information presented; the computer must be able to process it, that is, be able to perform certain actions.
Natural languages are mainly of a national nature.
Formalized languages. Understanding the world around us, a person gives objects and phenomena names. This leads to the fact that in people’s minds the object is replaced by a name, from which only one thing is required, to help identify the named object.
The possibility of a fundamental separation of an object and its name is the main thesis of formalization. It can be illustrated with a very simple example. If we write the word “cow”, then it is not at all the same as the animal known to everyone. You can erase the letter “a” from this word and this will not mean that the cow’s tail was cut off. Today this idea seems almost obvious. However, it took centuries to reach her.
The emergence of the very idea of a computer became possible only after the meaning of the main thesis of formalization was fully realized. Until quite recently, people believed that a name is inseparable from the object it denotes.
The possibility of a fundamental separation of the object being studied and its name (sign) allows us to consider language (a system of languages) as a universal modulating environment. Natural language provides the greatest opportunities for modeling. However, the ambiguity of understanding many language constructions often creates difficulties. For example, if the job is given in Russian “to take a big red ball,” then he can act in two ways, take the given red ball or start sorting through the available red balls. Consequently, in order to use a language to build models, especially those that will be further studied using a computer, it must first be clarified, or, in other words, formalized.
binary coding of information.
A number system is a set of rules for naming and representing numbers using a set of symbols called numbers. The number system is divided into positional and non-positional. An example of a non-positional number system is Roman; positional number systems include binary, decimal, octal, and hexadecimal. Here, any number is written as a sequence of digits from the corresponding alphabet, and the meaning of each digit depends on the place (position) it occupies in this sequence. For example, in the entry 555, made in the decimal number system, one digit 5 is used, but depending on the place it occupies, it has a different quantitative value - 5 units, 5 tens, 5 hundreds. Therefore, the equalities are valid (subscripts are used to indicate in which number system the number is written).
555,5 10 =5*10 2 +5*10 1 +5*10 0 +5*10 -1 ,
11,01 2 =1*2 1 +1*2 0 +0*2 -1 +1*2 -2
Let's consider arithmetic operations in the binary number system. First, note that 1 2 +1 2 =10 2. Why? First, let us remember how the entry 10 appeared in the usual decimal number system. To the quantity indicated by the highest digit of the decimal alphabet 9, we add 1. The result is a quantity for which there are no more numbers left in the alphabet to indicate one digit. For the resulting quantity, you have to use a combination of two digits of the alphabet, that is, represent this quantity as the smallest of the two-digit numbers: 9 10 +1 10 =10 10. A similar situation arises in the case of the binary number system. Here the quantity indicated by the leading digit 12 of the binary alphabet is increased by one. In order to represent the resulting quantity in one number system, you also have to use two digits. For the smallest two-digit number, the only option here is 102. Secondly, it is important to understand that 10 2 10 10. strictly speaking, in the binary number system this should be read not as “ten”, but as “one zero”. The correct ratio is 10 2 =2 10. Here, to the left and to the right of the equal sign, different symbols for the same quantity are written. This quantity is simply written using the alphabets of different number systems - binary and decimal. It seems like we say “apple” in Russian, and “apple” in English about the same object, and we will be right in both cases.
Addition in the binary number system. After these preliminary considerations, we will write down the rule for performing arithmetic addition of single-digit numbers in the binary number system,
0+0=0 1+0=1 0+1=1 1+1=10.
WITH 
Therefore, using the well-known mental memorization when transferring the overflow to the most significant digit, we obtain,
Subtraction in the binary number system. Based on the fact that subtraction is the inverse action of addition, we write the rule for the arithmetic subtraction of single-digit numbers in the binary number system,
0-0=0 1-0=1 1-1=0 10-1=1.
Using this rule you can check the correctness of the above
addition is the subtraction of one of the terms from the resulting sum. At the same time, in order to calculate one from zero in any digit, it is necessary to “occupy” the missing amount in the adjacent high-order digits (just as in the decimal number system one does when subtracting a large number from a smaller one).
Multiplication in the binary number system. The rules for multiplying single-digit binary numbers are most obvious,
0*0=0 1*0=0 0*1=0 1*1=1.
IN 
In this case, the process of multiplying two multi-bit binary numbers is written in a column, we get the following result,
Then, when solving this example, it was necessary to find the sum of four single-digit binary numbers in each digit. At the same time, we took into account that in the binary number system.
1+1+1+1=11+1=100.
D 
division in the binary number system is carried out in the same way as in the decimal number system, using multiplication and subtraction,
Converting a number from the decimal number system to binary (method 1). It is known that in the decimal number system 1+1+1=3, and 1+1+1+1=4, therefore,
3 10 =11 2 , 4 10 =100 2 .
Obviously, adding one at a time to find the binary representation of any decimal number is irrational. Without giving justifications and general rules for converting the representation of a number from one positional number system to another, we will limit ourselves to brief examples.
Translation of integers. Let it be required to find a representation of the number 12 10 in the binary number system (the task can be formulated as follows: convert the number 12 from the decimal to the binary number system, or 12 10 X 2, where X is the required representation).
P 
We proceed as follows, dividing, starting from 12, each resulting quotient by the base of the system into which we transfer the number, that is, by 2. We get.
Then, in the direction indicated by the arrow, starting from the last quotient (in our case it will always be equal to 1), written in the most significant bit of the generated binary representation, we fix all the remainders. As a result, we get the answer 12 10 =1100 2. .
P 
Conversion of decimal fractions less than one. If the specified translation needs to be carried out for a number less than one, for example for 0.25, then the scheme of our actions will change,
For convenience, we will draw a vertical line separating the whole part from the fractional part. Let's multiply the fractional part on the left by 2. Write the result on the next line, and leave as many digits to the right of the vertical as the original fractional part had. Since in this case the product is equal to 50, then the digit to the left of the vertical is written 0. We repeat the process of multiplying by 2 the number to the right of the vertical. The result of multiplication is 50*2=100. Consequently, when writing the result in the next line, the diagram ends up with two zeros to the right of the vertical, and the one is transferred to the digit to the left of the vertical. This completes the process of multiplying by 2 in this example, since we have already received the exact answer. The answer forms a number read to the left of the vertical in the direction indicated by the arrow (from top to bottom). Obviously, if we continued the multiplication further, we would have to multiply by 2 the zeros to the right of the vertical and, therefore, write only zeros to the left of the vertical in each line. These would be insignificant zeros in the resulting fraction. Therefore, having received, as a result of a series of multiplications by 2, only zeros to the right of the vertical, we complete the process of converting a decimal fraction less than one into the binary number system and write the answer 0.25 10 = 0.01 2.
P 
It is clear that much more often we come across such an initial decimal fraction, when multiplying by 2 the numbers to the right of the vertical will not lead to the appearance of only zeros there. Let, for example, according to the conditions of the problem, it is required to convert the decimal fraction 0.3 into the binary number system. We proceed as described above,
In this case, an exact answer cannot be obtained, since the translation process has to be interrupted and the approximate answer must be written down with a certain specified accuracy (specifically in this example, up to those decimal places), 0.3 10 ≈0.010 2.
Converting decimal fractions greater than one. In this case, it is necessary, having separated the integer and fractional parts in the original decimal number, to carry out an independent translation for each of them into the binary number system in the indicated way. Let's look at two examples using the results already obtained:
A) 12.25 10 =12 10 +0.25 10 =1100 2 +0.01 2 =1100.01 2
B) 12.3 10 =12 10 +0.3 10 ≈1100 2 +0.010 2 ≈1100.010 2
In example a) the answer is accurate, while in example b) due to the approximate translation of the fractional part, the final answer will also be approximate.
Finally, let's look at the advantages and disadvantages of using the binary number system compared to any other positional number system. Disadvantages include the length of the record representing the binary number. The main advantages are the simplicity of the operations performed, as well as the ability to automatically process information, realizing only two states of computer elements.
Backbone-modular principle of computer construction.
A computer is a universal multifunctional electronic program-controlled device for storing, processing and transmitting information.
Computer architecture is a general description of the structure and function of a computer at a level sufficient to understand the operating principles and system of computer commands. The architecture does not include a description of the details of the technical and physical structure of the computer (4).
The main components of a computer architecture: processor, internal (main) memory, external memory, input devices, output device.
The most widespread types of computers: processes internal (main) memory, external memory, input devices, output devices.
The most popular type of computer in our time is the personal computer (PC). A PC is a small-sized computer designed for individual user work and equipped with user-friendly (friendly) software.
Almost all models of modern PCs have a mainline type of architecture (including the world's most common IBM PC and Apple Macintosh). Below is a diagram of the design of computers built on the backbone principle.
CPU
Internal wrinkle.
Information highway (data bus + address bus + control bus)
drive
keyboard
Peripherals
Processor purpose:
perform information processing operations.
Computer memory is divided into internal and external. The internal memory of a PC includes random access memory (RAM) and read-only memory (ROM).
RAM – fast, semiconductor, volatile memory. RAM stores the currently executing program and the data with which it directly works.
RAM is memory used for both reading and writing information. When the power is turned off, the information in RAM disappears (volatility).
ROM is fast, non-volatile memory. ROM is read-only memory. Information is entered into it once (usually at the factory) and stored permanently (when the computer is turned on and off). ROM stores information that is constantly required on the computer, usually operating system components (hardware monitoring programs, computer boot program, etc.).
Information communication between computer devices is carried out through the information highway (another name is the common bus). A trunk is a cable consisting of many wires. One group of wires (data bus) transmits the processed information, and then it transmits control signals (for example, a signal for the device to be ready for operation, a signal for the device to start operating, etc.). The number of bits simultaneously transmitted over the bus is called the bus width. Any information transmitted from the processor to other devices via the data bus is accompanied by an address transmitted via the address bus (just as a letter is accompanied by an address on an envelope). This can be an address cell in RAM or the address (number) of a peripheral device.
The modern PC implements the principle of open architecture. This principle allows you to change the composition of the PC device (modules). Additional peripheral devices can be connected to the information highway, and some device models can be replaced by others. It is possible to increase the internal memory or replace the microprocessor with a more advanced one. The hardware connection of the peripheral device to the bus is carried out through a special controller unit (other names - adapter). Software control of the device is carried out through a driver program, which is a component of the operating system. Therefore, to connect a new peripheral device to a computer, you must use the appropriate controller and install the appropriate driver in the OS.
main characteristics (bit capacity, address space, etc.) of the computer processor.
The processor is the central device of the computer.
Processor purpose:
manage the operation of the computer given program;
perform information processing operations.
A microprocessor (MP) is an ultra-large integrated circuit that implements the functions of a PC processor. A microprocessor is created on a semiconductor chip (or several chips) using complex microelectronic technology.
The capabilities of a computer as a universal performer for working with information are determined by the processor command system. This command system is a machine command language (MCL). Computer control programs are compiled from NMC commands. A separate command defines a separate operation (action) of the computer. In NMC, there are commands by which arithmetic and logical operations are performed, operations for controlling the sequence of command execution, data operations from one memory device to another, etc.
The processor includes the following devices: control unit (CU), arithmetic-logical unit (ALU), processor memory registers.
The control unit controls the operation of all computer devices according to a given program. (The function of the control device can be compared to the work of a conductor who controls an orchestra). (A program is a kind of “score” for the control unit).
ALU is a computing tool of the processor. This device performs arithmetic and logical operations on program commands.
Registers are the internal memory of the processor. Each of the registers serves as a kind of draft, using which the processor performs calculations and stores intermediate results. Each register has a specific purpose. The program counter register (S. Ch. K) contains the address of the computer memory cell in which the next executable command of the program is stored. This command is placed in the command register (RC) for the duration of its execution. The result obtained can be rewritten from the register to a RAM cell.
Processor characteristics.
clock frequency.
The processor works in close contact with a chip called a clock generator (CG). The GTC produces periodic pulses that synchronize the operation of all computer nodes. This is a kind of metronome inside the computer. The processor works in the rhythm of this matron. Clock purity is equal to the number of clock cycles per second. A beat is the time interval between the start of the current pulse and the start of the next one. The processor is allocated a certain number of clock cycles to perform each operation. It is clear that if the metronome beats faster, then the processor works faster. Clock frequency is measured in megahertz-MHz. A frequency of 1 MHz corresponds to a million clock cycles per second. Here are some typical microprocessor clock frequencies: 40 MHz, 60 MHz.
processor bit capacity.
Bit capacity is the maximum number of double code bits that can be processed or transmitted by the processor simultaneously. The processor capacity is determined by the capacity of the registers in which the processed data is placed. For example, if the register is 2 bytes in size, then the processor bit size is 16(8*2).
A cell is a group of consecutive bytes of RAM that contains information available for processing by a separate processor command. The contents of a memory cell are called a machine word. Obviously, the size of the memory cell and machine word is equal to the processor capacity. The exchange of information between the processor and internal memory is carried out in machine words.
The address of a memory cell is equal to the address of the low byte (the lowest numbered byte) included in the cell. Addressing both bytes and memory cells starts from zero. Cell addresses are multiples of the number of bytes in a machine word (change after 2, or after 4, or after 8). Let us emphasize once again: a cell is a container of information, a machine word is information in a cell.
Address space.
Via the address bus, the processor transmits an address code - a binary number indicating the address of the memory or external device to which information is sent via the data bus. Address space is the range of addresses (set of addresses) that the processor can access using an address code.
If the address code contains n bits, then the size of the address space is 2n bytes. Typically, the size of the address code is equal to the number of lines in the address bus (address bus width). For example, if the computer has a 16-bit address bus, then the address space is 2 16 =64 KB, and with a 32-bit address space it is 2 32 =64 KB.
Examples of microprocessor characteristics:
MP intel-80386: space - 232 bytes = 4GB, bit depth - 32, clock frequency - from 25 to 40 MHz;
MP Pentium: address space - 232 bytes = 4GB, bit capacity - 64GB, clock frequency - from 60 to 100 MHz.
amount of information, unit of measurement of the amount of information.
Already in the process of the emergence of human society, the need arose to coordinate joint actions (obtaining food, hunting, repelling enemies, etc.), which presupposes a means of communication between members of collective actions. At first it was gestures, facial expressions, individual sounds, and then oral and written speech, means of communication. People began to have the opportunity to exchange information, experience and knowledge among themselves, as well as transfer all this, which today is called information, from generation to generation. We receive information from the world around us through our senses and by processing it with our brain.
Messages and information are central concepts in computer science. Although in everyday life these concepts are used as synonyms, in a more strict understanding there are certain differences between them. These differences are already evident in the phrase, “I did not receive any information from this message.”
Therefore, the following relationships between these concepts can be defined: information is transmitted through a message. It should be noted that the concept of “information” is quite broad. And therefore it is difficult to define it, in a strict sense, through a broader concept. In this case, understanding a concept comes through a description of its properties and relationships with other concepts.
Everything a person does is in one way or another connected with the use of information, and the volumes of information that a person needs to process have increased dramatically (information explosion). The need to process large volumes of information with great efficiency (speed) required the creation of special devices - electronic computers (computers). The science that studies the laws and methods of obtaining, processing, storing, and transmitting information using a computer is called computer science.
However, animals, insects, and birds also have information flows. The study of the laws of transmission and use of information in biological, technical, social, and other systems is dealt with by another science - cybernetics, which is closely related to computer science.
To determine the amount of information, the unit of measurement used is the bit (from the English Bit, derived from the combination binary digit). One bit is the amount of information contained in a “yes” or “no” message (in binary code “1” and “0”).
Since a bit is the smallest amount of information, larger units of measurement are used to measure larger volumes. The relationship between the units is as follows.
1 byte - 8 bits
1 kilobyte (KB) - 2610 bits == 1024 bytes
1 megabyte (MB) - 1024 KB
1 gigabyte (GB) - 1024 MB
"kilo" in the SI measurement system means the number 1000, but in computing it is 1024 bytes. Therefore, if they say “64 KB”, then this means 64 * 1024 or 65536 bytes. A megabyte, in turn, means 1024*1024 or 1048576 bytes. The amount of memory in a computer is also measured in these same units (namely, byte, KB, MB, GB).
External computer memory, storage media (floppy and hard drives, CD-ROM drives).
Preserving information for its subsequent use or transmission to other people has always been of decisive importance for the development of human civilization. Before the advent of computers, people learned to use a great variety of means for this purpose: books, photographs, tape recordings, etc., which increased by the end of the 20th century. flows of information, the need to store it in large volumes and the advent of computers contributed to the development and use of information media that provide the possibility of long-term storage in a more compact form. Such media include flexible and hard magnetic disks and so-called CD-ROM disks. Their indicators, such as information capacity, access time to information, reliability of its storage, and basic operation time, are essential.
Devices that provide recording of information on media, as well as its search and reading into RAM, are called storage devices (disk drives).
The basis for recording, storing and reading information is based on two principles - magnetic and optical, which ensure the preservation of information even after the computer is turned off.
Magnetic recording is based on digital information (in the form of zeros and ones) converted into alternating electric current, which is accompanied by an alternating magnetic field. The magnetic coating of the disk consists of many tiny areas of spontaneous magnetization (domains). Electrical impulses, arriving at the drive head, create an external magnetic field, under the influence of which the domains’ own magnetic fields are oriented in accordance with its direction. After removing the external field, zones of residual magnetization remain on the surface of the disks as a result of recording information, where the magnetized area corresponds to 1, and the non-magnetized area corresponds to 0. When reading information, magnetized areas of the media cause a current pulse in the drive head (the phenomenon of electromagnetic induction).
Among disk magnets (MD), flexible and rigid ones are used.
Flexible MDs (FMDs) are designed for transferring documents and programs from one computer to another, storing archival copies (ticket No. 6) and information that is not constantly used on the computer. A flexible MD with a diameter of 5.25 inches (133mm) can currently store up to 1.2 MB of information. These discs are double-sided, with increased recording density. The rotation speed of the disk, located in a thin plastic envelope, is 300-360 rpm. HMDs with a diameter of 3.5 inches (89mm) have a capacity of 1.4MB. Protection of the magnetic layer is especially important, so the disk itself is hidden in a durable plastic case, and the contact area of the heads with its surface is protected from accidental touches by special curtains, which are automatically retracted only inside the drive.
The drive controller turns on the rotation motor, checks whether the cutout prohibiting write operations is closed or open, and installs the read/write head in the desired place.
A hard magnetic disk (HMD), or hard drive, is designed for permanent storage of information used when working with a computer: operating system programs, frequently used software packages, text editors, etc. Modern LMDs have a rotation speed of 3600 to 7200 rpm . This can be a glass disk (with a metal surface film, such as cobalt), not sensitive to temperature, with a recording density 50% higher than that of an aluminum disk. The latest developments allow for a recording density of 10 Gbit per square inch, which is 30 times higher than usual. When rotating, the head is located above the disk at a distance of 0.13 microns (in 1980 - 1.4 microns). Hard magnetic disks are often several disks on one axis, the read/write heads move across all surfaces at once. Information capacity - up to 800 MB - 9 GB.
Any magnetic disk is not initially ready for work. To bring it into working condition, it must be formatted, i.e., a disk structure must be created. The structure of the GMD is magnetic concentric tracks, divided into sectors, marked with magnetic marks, and the LMD also has cylinders - a set of tracks located one above the other on all working surfaces of the disks. All magnetic disk tracks on the outer cylinders are larger than on the inner ones. Therefore, with the same number of sectors on each of them, the recording density on the internal tracks should be greater than on the external ones. The number of sectors, sector capacity, and therefore the information capacity of the disk depends on the type of drive and formatting mode, as well as on the quality of the disks themselves.
CD-ROM (Compact disk read memory) disks have a capacity of up to 3GB, high reliability of information storage, and durability (their predicted service life if performed well is 30-50 years). The diameter of the disk can be either 5.25 inches or 3.5. The manufacturing process consists of several stages. The beginning prepares information for the master disk (the first sample), produces it and a replication matrix. The principle of recording and reading is optical. The encoded information is applied to the master disk with a laser beam, which creates microscopic depressions on its surface, separated by flat areas. The digital information represents an alternation of depressions (non-reflective spots) and light-reflecting islands. Copies of the master disc negative (matrix) are used to press the CDs themselves. A replicated CD consists of a polycarbonate base, reflective and protective layers. Finely sprayed aluminum is usually used as a reflective surface. Unlike magnetic disks, whose tracks are concentric circles, a CD-ROM has only one physical track in the shape of a spiral, running from the outer edge of the disk to the inner.
Reading information from a CD occurs using a laser beam, which hits a reflective island and is deflected to a photodetector, which interprets it as a binary unit. The laser beam entering the cavity is scattered and absorbed - the photodetector records a binary zero.
While all magnetic disks rotate at a constant number of revolutions per minute i.e. With a constant angular speed, the CD-ROM rotates at a variable angular speed to ensure a constant linear speed when reading. Thus, reading the internal sectors is carried out at a higher number of revolutions than reading the external ones. This explains the rather low data access speed for reading a CD-ROM (from 150 to 400ms at a rotation speed of up to 4500 rpm) compared to a hard drive.
The data transfer speed, determined by the rotation speed of the disk and the density of the data recorded on it, is at least 150 kb/s and reaches 1.2 MB/s.
To load a CD into the drive, you use either one of the varieties of a sliding panel or a special transparent cassette. They produce external devices that allow you to independently burn special CDs. Unlike ordinary ones, these discs have a reflective layer of gold. These are the so-called rewritable CD-Rs. Such discs usually serve as master discs for further replication or creation of archives.
Reserve for increasing capacity - increasing recording density by reducing the laser wavelength. This is how compact discs appeared capable of storing almost 4.7 GB of information on one side and 10 GB of information on two sides. It is also planned to create a two-layer recording system, i.e. when on one side of the media there are two surfaces spaced apart in depth with recorded data. In this case, the information capacity of the CD will increase to 8.5 GB on one side. One of the most viable devices for storing data may be magneto-optical disks. The fact is that CD-ROMs, and when working with it, they turn out to be slower than hard magnetic disks. For this reason, information is usually copied from CDs onto MDs, with which they work. Such a system is not suitable if the work is related to databases, which, due to their large information capacity, are more profitable to place on a CD-ROM. In addition, CDs currently used in practice are not rewritable.
Magneto-optical disks do not have such disadvantages. The achievements of magnetic and optical technologies are combined here. You can write information to them and quickly read it. They retain all the advantages of GMD (portability, the possibility of separate storage, increased computer memory) with enormous information capacity.
software control of computer operation. Computer software.
You already know how widely computers are used. With their help, you can print books, make drawings and drawings, you can create computer reference books on any topic, make calculations, and even talk with a computer on a certain topic if you store a knowledge base in the relevant subject area in its memory.
Now we will talk about another important application of computer technology - the use of computers for control.
N. Wiener foresaw that the use of computers for control would become one of their most important applications, and this would require a deep theoretical analysis of the control process itself. It is no coincidence that the emergence of cybernetics coincided with the creation of the first computers.
From the point of view of cybernetics, the interaction between managers and managed objects is considered as an information process. From this position, it turned out that a wide variety of management processes occur in a similar way and are subject to the same principles. Let's discuss what control is from a cybernetic point of view.
Management is the purposeful interaction of objects, one of which is the manager, the other is the managed. The simplest situation is two objects, one is the manager, the second is the controlled one. For example, a person and a TV, an owner and a dog, a traffic light and a car. To a first approximation, the interaction between such objects can be described by the following scheme,
Control object
Managed object
Manager
impact
In the examples given, the control action is performed in different forms: a person presses a key or turns the TV control knob, the owner gives a command to the dog with his voice.
From a cybernetic point of view, all options for control actions should be considered as control information transmitted in the form of commands.
In the example with a TV, codes of the following type are transmitted through technical controls: “turn on-off” “increase or decrease volume”. The definition given above says that management is a purposeful process, that is, commands are not given randomly, but with a very specific purpose. In the simplest case, the goal can be achieved after executing one command. To achieve a more complex goal, it may be necessary to execute a sequence (series) of commands. A sequence of commands to control an object, leading to a predetermined goal, is called a control algorithm.
In this case, the control object can be called the executor of the control algorithm. This means that in the above examples, the TV, the dog, the car are the executors of control algorithms aimed at very specific goals (find a program of interest, complete a certain task of the owner, safely drive through an intersection).
If you carefully consider the examples under consideration, you come to the conclusion that only the traffic light-car system works strictly in accordance with the diagram. The traffic light controls the movement of cars without looking, not paying attention to the situation at the intersection. The process of controlling a TV or a dog is completely different. Before giving the next command, a person looks at the state of the control object, at the result of the previous command. If he does not find the desired program on a given channel, he will switch the TV to the next channel; if the dog does not comply with the “lie down” command, the owner will repeat this command. From these examples we can conclude that the manager not only issues commands, but also receives information from the control object about its state. This process is called feedback.
Feedback is the process of transmitting information about the state of a control object to the manager.
U Control object
Managed object
The following circuit corresponds to feedback control.manager
impact
Feedback
In the open-loop control option, the algorithm can only be a single-valued (linear) sequence of commands.
Here is an example of how a traffic light works:
RED-YELLOW-GREEN-YELLOW-RED-YELLOW-GREEN, etc.
This algorithm is called linear or sequential.
With feedback, the algorithm can be more flexible, allowing for branching and repetition.
At the same time, the manager himself must be intelligent enough to, having received feedback information, analyze it and make a decision on the next command. In all cases where the manager is a person, this condition is met.
If a cop works instead of a traffic light, then traffic control will become more rational. The traffic controller monitors the accumulation of cars at the intersection and gives the “green lane” in the direction in which it is most needed. Often, due to the “brainless” management of traffic lights, “traffic jams” occur on the roads. And the traffic controller certainly comes to the rescue.
Thus, in the presence of feedback and an “intelligent” manager, control algorithms can have a complex structure containing alternative commands (branching) and repeating commands (cycles).
Systems in which the role of manager is entrusted to a computer are called automatic program-controlled systems.
\for the functioning of such a system, firstly, direct and feedback communication must be provided between the computer and the control object, and secondly, a control program (an algorithm written in a programming language) must be stored in the computer’s memory. Therefore, this control method is called program control.
Basic logical operations. Logical multiplication, addition negation
Logical operations OR (logical addition) (disjunction).
Mom dictates a difficult condition to you: if you clean your room or wash all the dishes after dinner, you will go to the disco. The condition can be written as follows: “Have you cleaned the room?” or “did you wash the dishes?”
Each of the two simple questions can be answered “yes” and “no.” The decision is made depending on the answer to these questions.
Cleaned the room? Did you wash the dishes? Will you go to the disco?
No (false). Yes (true). Yes (true).
Yes (true). No (false). Yes (true).
Let us use a table to present all possible decision-making options.
Such a table is usually called a truth table. From it we can conclude that the OR operation gives you three different options for making a positive decision on the issue, or cleaning, or washing the dishes, or doing both.
Making a decision on this complex condition has the following form: if the complex condition is true, then you can go to the disco (otherwise, obviously, you will have to sit at home).
Logical operation AND (logical multiplication) (conjunction).
You came to apply for a job based on an advertisement, which stipulates that you are required to have computer knowledge and work experience in your specialty. The condition can be formulated as follows: “Do you have work experience?” And “do you know a computer?” Each of the two simple questions can be answered with both “yes” and “no”.
Do you have work experience? Do you know a computer? You will be hired
No (false). No (false). No (false).
No (false). Yes (true). No (false).
Yes (true). No (false). No (false).
Yes (true). Yes (true). Yes (true).
possible combinations of answers to make a decision,From the table we can conclude that the AND operation gives you only one option for making a positive decision, having work experience and knowing a computer at the same time.
Making a decision on this complex condition has the same standard form: if the condition is true, then you are hired (otherwise, obviously, you are not accepted).
It should be noted that analyzing a complex condition requires precision and understanding. If there is no confidence in the correctness of the inputs, then a complex condition can always be replaced by a sequential analysis of simple conditions. Let us illustrate this idea with a simple “garden” example. To prevent the development of diseases, tomatoes and cucumbers are sprayed with Bordeaux mixture - a mixture of solutions of copper sulfate and lime. The main condition when using such a liquid is that the solution should not be acidic. This is checked with litmus paper. There are three possible reaction options: the paper turns red (acidic reaction), turns blue (alkaline) or does not change color (neutral).
The following options for the logical decision-making model are possible.
Behavior algorithm (option 1)
Mix the solutions.
Dip litmus paper into the liquid.
If the paper turns blue or does not change color,
It can be sprayed
Otherwise add lime
And repeat the steps starting from point 2.
End of the algorithm
This model contains a condition that is true in all cases, except for the simultaneous falsity of two initial expressions; the piece of paper does not turn blue and does not retain its color.
Logical negation (inversion)
Logical negation (inversion) makes a true statement false and, conversely, a false statement true.
Attaching the particle “not” to a statement is called the operation of logical negation.
Let A = “two multiplied by two equals four” be a true statement, then the statement F, formed using the operation of logical negation, “two multiplied by two does not equal four” is false.
Inversion over a logical statement A is usually denoted by Ā. Let us form a statement F, which is the logical negation of A.
The truth of such a statement is given by the truth table of the logical negation function.
The truth of a statement formed using the operation of logical negation can be easily determined using a truth table. For example, the statement “two times two is not equal to four” is false (A = 0), and the statement “two times two is equal to four” obtained from it as a result of logical negation is true (F = 1).
Files (type, name, location). Working with files.
A file is a collection of information that is homogeneous in its purpose, stored on disk and has a name.
The rules for forming file names and combining files into file systems depend on the specific operating system. Let us outline these rules using the MS-DOS 6.0 operating system as an example.
The file name consists of two parts: the name itself and the name extension (i.e., the file type). The actual file name consists of no more than eight characters. You cannot use symbols of arithmetic operations, spaces, relations, or punctuation. Names that are device names in MS-DOS, for example con, ipt1, ipt2, are prohibited as file names. The name extension can consist of no more than three characters, including none. If there are extensions, then they are separated from the main name by a dot, for example ris. Bmp, mart. Txt, doc.doc. By the name of the file you can judge its purpose, since a certain convention has been established for extensions that fixes the type of file processing for the OS. The com or exe extension contains program files designed to be executed upon user call; doc files with documents prepared in the Microsoft World text editor; bak – backup copies; bas files with program texts in BASIC.
A list of file names stored on a given disk is located in a directory (directories) along with information about its type, size, and creation time. The capacity of floppy magnetic disks, and even more so of hard disks and compact disks, is such that an impressive number of files can be stored on one disk. Therefore, working with a directory that has a linear structure is extremely inconvenient when there are a large number of files.
MS-DOS allows you to organize file names into several directories, placing file names in one directory, united by some characteristic. Directory names are written using the restrictions already mentioned. Typically, the name extension is not used for directories. A directory can contain any reasonable number of file names; it may also contain other directories, called subdirectories in this situation, etc. This creates a hierarchical structure, a “tree” of directories, the “root” of which is the main (root) directory, the “branches” are subdirectories, and the “leaves” are file names.
Two files or two subdirectories located in two different directories can have the same name. Therefore, to uniquely identify a file (directory) on a disk, you must specify the path (route) to access it. The access path consists of a drive name and a list of directory names. The first directory in the list is a subdirectory of the root directory, each subsequent directory is a subdirectory of the previous one, the last directory in this list contains the searched file. List elements are separated by backslashes (\).
For example:
C:\qbasic\basic1\qbasic.exe
C:\qbasic\basic2\qbasic.exe
A compound (full) file name consists of the path to the file and its name. It uniquely identifies an area on the disk with that name. A certain area is allocated on the disk, in which a special table is placed containing sequences of block (sector) numbers for each file. This table is constantly updated, and is completely erased along with the root directory when the disk is formatted.
Files are often divided into two categories - text and binary. Text files are intended to be read by humans. They consist of strings of characters. Text files store document texts, program texts in programming languages, etc.
The files are not text, they are called binary. They have a form that is “understandable” only to a computer; they are often structured in such a way that it is convenient to “read” them for a specific program.
When using a computer, for a variety of reasons, damage or loss of information on magnetic disks is possible. In order to reduce losses in such situations, you should have backup copies of the files you use and systematically update copies of the files you change. To create archives, programs are used - archivers (packers), which, through the use of special information compression methods, make it possible to create smaller copies of files and combine copies of several files into one archive file, which is conveniently stored on a floppy disk. Examples of archiver programs – pkzip, arj, etc.
In addition to archiving files, you can perform the following actions (the corresponding MS-DOS commands are indicated in brackets):
Creation (using a text editor);
Delete(del);
Rename(ren);
Copying from one directory to another;
Locating on disk by file name and the string of characters it contains (the filefind program from the Norton Utilites package);
In some cases, recovery if a file is accidentally deleted (unarase program from the Norton Utilites package).
These actions can be performed on individual files or on a group of files.
Logical expressions and their transformations. Truth tables.
Logical expressions. Each compound statement can be expressed in the form of formulas (logical expressions), which will include logical variables denoting statements and signs of logical operations denoting logical functions.
To write compound statements in the form of logical expressions in a formal language (the language of logical algebra0), in a compound statement it is necessary to identify simple statements and logical connections between them.
Let us write the compound statement “2*2=5 or 2*2=4 or 2*24” in the form of a logical expression and analyze the compound statement. It consists of two simple statements,
A= “2*2=5” - false (0)
B = “2*2-4” - true (1).
Then the compound statement can be written in the following form,
"A or B and Ā or B."
Now it is necessary to write the statement in the form of a logical expression, taking into account the sequence of logical operations. When performing logical operations, the following order of their execution is defined: inversion, conjunction, disjunction. Shackles can be used to change the specified order.
The truth or falsity of compound statements can be determined purely formally, guided by the laws of propositional algebra, without referring to the semantic content of the statements.
P
Let us leave the values of logical variables in the logical expression and, using the truth tables of basic logical operations, we obtain the value of the logical function.
Truth tables. For each compound statement (logical expression), it is possible to construct a truth table that determines its truth or falsity for all possible combinations of the initial values of simple statements (logical variables).
When constructing truth tables, it is advisable to be guided by a certain sequence of actions.
First, it is necessary to determine the number of rows in the truth table, which is equal to the number of possible combinations of the values of the logical variables included in the logical expression. If the number of logical variables is n, then the number of lines =2 n .
Each Boolean function has two arguments and four possible sets of argument values. Using the formula, we can determine how many different logical functions of two arguments can exist,
T 
Thus, there are 16 different logical functions of two arguments, each of which is specified by its own truth table.
In everyday and scientific speech, in addition to the basic logical connectives “and”, “or”, “not”, some others are also used, “if...then”, “then...and only when...” and others. Some of them have their own name and its symbol and they correspond to certain logical functions.
Logical consequence (implication). Logical consequence (implication) is formed by combining two statements into one using the figure of speech “if..., then...”.
A compound statement formed using the operation of logical consequence (implication) is false if and only if a false conclusion (second statement) follows from a true premise (the first statement).
However, the operation of logical implication is somewhat different from the usual understanding of the word “should.” If the first statement (premise) is false, then regardless of the truth or falsity of the second statement (conclusion), the compound statement is true. This can be understood in such a way that anything can follow from a false premise.
In propositional algebra, all logical functions can be reduced by logical transformations to three basic ones, logical multiplication, logical addition and logical negation. Let us prove by methods of comparison of truth tables that the operation of implication A→B is equivalent to the logical expression ĀB.
A compound statement formed using the logical operation of equivalence is true if and only if both statements are simultaneously either false or true.
Consider, for example, two statements A = “the computer can perform calculations” and B = “the computer is turned on.” A compound statement obtained by the equivalence operation is true when both statements are either true or false.
“a computer can perform calculations if and only if the computer is turned on.”
“a computer cannot perform calculations if and only if the computer is not turned on.”
A compound statement obtained using the equivalence operation is false when one statement is true and the other is false,
“A computer can perform calculations if and only if the computer is not turned on.”
“The computer cannot perform calculations if and only if the computer is turned off”
Ticket 10
Legal protection of programs and data. Data protection
Changes taking place in the economic life of Russia - the creation of a financial and credit system, enterprises of various forms of ownership, etc. - have a significant impact on information security issues. For a long time, in our country there was only one property - state property, so information and secrets were also only state property, which were protected by powerful special services.
Information security problems are constantly aggravated by the penetration of technical means of data processing and transmission, and especially computer systems, into almost all areas of society. This gives grounds to raise the problem of computer law, one of the main aspects of which is the so-called computer encroachments. The relevance of the problem is evidenced by the extensive list of possible methods of computer crimes.
The objects of encroachment can be the technical means themselves (computers and peripherals), such as material objects, software and databases, for which the technical means are the environment.
In this sense, a computer can act both as an object of attack and as a tool. If we separate the last two concepts, then the term computer crime as a legal category does not have much meaning. If the computer is only the object of an attack, then the classification of the offense can be made according to existing rules of law. If it is only a tool, then only such a sign as “the use of technical means” is sufficient. It is possible to combine these concepts when the computer is both a tool and an object. In particular, this situation includes the theft of machine information. If the theft of information is associated with the loss of material and financial assets, then this fact can be classified as a crime. Also, if this fact is associated with violations of national security interests or authorship, then criminal liability is directly provided for in accordance with the laws of the Russian Federation.
Each failure of a computer network is not only “moral” damage for enterprise employees and network administrators. As electronic payment technologies, “paperless” document flow and others develop, a serious failure of local networks can simply paralyze the work of entire corporations and banks, which leads to significant material losses. It is no coincidence that data protection in computer networks is becoming one of the most pressing problems in
modern computer science. To date, three basic principles of information security have been formulated, which should ensure:
data integrity - protection against failures leading to loss of information, as well as unauthorized creation or destruction of data.
confidentiality of information and, at the same time, its
It should also be noted that certain areas of activity (banking and financial institutions, information networks, public administration systems, defense and special structures) require special data security measures and place increased demands on the reliability of the functioning of information systems, in accordance with the nature and importance of the tasks they solve .
Computer crime
In none of the criminal codes of the Union republics will it be possible to find a chapter entitled “Computer crimes”. Thus, computer crimes as specific crimes in the legal sense do not exist.
Let us try to briefly outline the phenomenon that, as a sociological category, is called “computer crime.” Computer crimes can be conditionally divided into two large categories - crimes related to interference with the operation of computers, and crimes using computers as necessary technical means.
Let us list the main types of crimes related to interference with computers.
1. Unauthorized access to information stored on a computer. Unauthorized access is carried out, as a rule, by using someone else's name, changing the physical addresses of technical devices, using information remaining after solving problems, modifying software and information, stealing a storage medium, installing recording equipment connected to data transmission channels.
Hackers are “electronic corsairs”, “computer pirates” - these are the names of people who gain unauthorized access to other people’s information networks for fun. Dialing one number after another for luck, they wait patiently until someone else's computer answers at the other end of the line. After this, the phone is connected to the signal receiver in its own computer, and the connection is established. If
Now if you guess the code (and the words that serve as a password are often banal), you can infiltrate someone else’s computer system.
Unauthorized access to files of a legitimate user is also achieved by finding weaknesses in the system's security. Once discovered, the attacker can slowly examine the information contained in the system, copy it, and return to it many times, just as a buyer examines goods in a display case.
Programmers sometimes make errors in programs that cannot be detected during debugging. Authors of large, complex programs may overlook some weaknesses in the logic. Vulnerabilities are sometimes found in electronic circuits. All these negligence and mistakes lead to the appearance of “gaps”.
Usually they are still identified when checking, editing, and debugging the program, but it is impossible to completely get rid of them.
It happens that someone breaks into a computer system by posing as a legitimate user. Systems that do not have means of authentic identification (for example, by physiological characteristics: fingerprints, retinal patterns, voice, etc.) are left without protection against this technique. The simplest way to implement it:
Receive codes and other identifying ciphers of legitimate users.
This can be done:
By acquiring (usually bribing staff) a list of users with all the necessary information;
The discovery of such a document in organizations where there is no established
sufficient control over their storage;
Eavesdropping through telephone lines.
It sometimes happens, as with erroneous telephone calls, that a user from a remote terminal connects to someone else's system, being absolutely sure that he is working with the system he intended. The owner of the system to which the actual connection occurred, by generating plausible responses, can maintain this delusion for a certain time and thus obtain some information, in particular codes.
Any computer center has a special program that is used as a system tool in case of failures or other deviations in the operation of the computer, a kind of analogue of the devices placed in vehicles under the inscription “break glass in case of an accident.” Such a program is a powerful and dangerous tool in the hands of an attacker.
Unauthorized access may occur as a result of a system failure. For example, if some of the user's files are left open, he may gain access to parts of the data bank that do not belong to him. Everything happens as if a bank client, entering the room allocated to him in the vault, notices that the vault does not have one wall. In this case, he can break into other people's safes and steal everything that is stored in them.
2. Entering “logic bombs” into the software, which are triggered when certain conditions are met and partially or completely disable the computer system.
A “time bomb” is a type of “logic bomb” that goes off when a certain point in time is reached.
The “Trojan horse” method consists of secretly introducing such commands into someone else’s program, which allow the implementation of new functions that were not planned by the owner of the program, but at the same time maintaining the previous functionality.
Using a Trojan horse, for example, criminals transfer a certain amount from each transaction to their account.
Computer program texts are usually extremely complex. They consist of hundreds, thousands, and sometimes millions of teams. Therefore, a “Trojan horse” consisting of several dozen commands is unlikely to be detected, unless, of course, there is suspicion about it. But even in the latter case, it will take many days and weeks for expert programmers to find it.
There is another type of “Trojan horse”. Its peculiarity is that in a harmless-looking piece of program, not commands that actually do the “dirty” work are inserted, but commands that form these commands and, after execution, destroy them. In this case, a programmer trying to find a “Trojan horse” needs to look not for the Trojan horse itself, but for the commands that form it. Taking this idea further, we can imagine teams creating teams, etc. (an arbitrarily large number of times), creating a “Trojan horse”.
In the United States, a form of computer vandalism has become widespread, in which a “Trojan horse” destroys, after a certain period of time, all programs stored in the machine’s memory. Many computers that go on sale contain a “time bomb” that “explodes” at the most unexpected moment, destroying the entire data library. One should not think that “logical bombs” are exotic, unusual for our society.
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