Basics of storage of information in the computer. Storage of data in the memory of the computer the foundations of the organization of storage in computer

The tasks of accumulation (storage), processing and transmitting information stood before humanity at all stages of its development. Each stage corresponds to a certain level of development of information work, the progress of the development of which every time gave the human society a new quality. Previously, the main stages of information handling, and they are common to all sciences when processing information using computers. A scientific foundation for their solution was such a science as informatics.

Informatics - comprehensive scientific and technical discipline engaged in the study of the structure and common properties information, information processes, development on this basis information technology and technology, as well as solving scientific and engineering problems of creating, implementation and effective use Computer equipment and technology in all spheres of social practice.

The origins of computer science can be sought in the depths of centuries. Many centuries ago the need to express and remember the information led to the emergence of speech, writing, accounts. People tried to invent, and then improve the methods for storing, processing and disseminating information. Until now, evidence of attempts to our distant ancestors have been preserved - primitive rock paintings, records on birch crust and clay powders, then handwritten books.

The appearance of a printing machine in the XVI century made it possible to significantly increase the ability of a person to process and store the necessary information. This was an important stage in human development. Information in printed form was the main way of storage and exchange and continued to remain up to the middle of the twentieth century. Only with the advent of EMM there were fundamentally new, much more efficient ways of collecting, storing, processing and transmitting information (Fig. 1.1).

Figure 1.1. Development of information storage methods

Methods for transferring information. A primitive way to transfer the messages from a person to a person was replaced by a more progressive postal tie. Postal connection gave a fairly reliable way to exchange information. However, we should not forget that only messages written on paper could be transmitted in this way. And most importantly, the transfer rate was commensurate only at the speed of movement of a person. The invention of the telegraph, the phone gave fundamentally new features of processing and transmitting information.

The emergence of electronic computing machines made it possible to process, and subsequently and transfer information at a rate of several million times greater than the processing speed (Fig. 1.2) and information transmission by man (Fig. 1.3).

Figure 1.2. Development of information processing methods

Figure 1.3. Development of information transfer methods

The basis of modern informatics form three components, each of which can be considered as relatively independent scientific discipline (Fig. 1.4).

Theoretical informatics is part of informatics engaged in the study of the structure and general properties of information and information processes, the development of general principles for the construction of information technology and technology. It is based on the use of mathematical methods and includes such basic mathematical sections as the theory of algorithms and automata, the theory of information and the theory of coding, the theory of formal languages \u200b\u200band grammatics, survey operations, etc.).

Informatization (technical and software) - section involved in the general principles for building computing devices and data processing and data systems, as well as issues related to the development of software systems.

Information systems and technologies - section of informatics associated with the decision of the analysis of information flows, their optimization, structuring in various complex systems, with the development of the principles of implementation in these systems of information processes.

Computer science is widely used in various fields of modern life: in the production, science, education and other fields of human activity.

The development of modern science involves the conduct of complex and expensive experiments, such as, for example, when developing thermonuclear reactors. Computer science allows you to replace real experiments with machinery. It saves colossal resources, makes it possible to process the results obtained by the most modern methods. In addition, such experiments occupy much less time than real. And in some areas of science, for example, in astrophysics, the real experiment is simply impossible. Here, in general, all studies are carried out through computing and model experiments.

Figure 1.4. Informatics structure as a scientific discipline

Further development of informatics, like any other science, entails new achievements, discoveries, and consequently, new applications that may be difficult to assume today.

Computer science is a very wide sphere of scientific knowledge that arose at the junction of several fundamental and applied disciplines.

As an integrated scientific discipline, the informatics is connected (Fig. 1.5):

With philosophy and psychology - through the doctrine of information and the theory of knowledge;

With mathematics - through the theory of mathematical modeling, discrete mathematics, mathematical logic and the theory of algorithms;

With linguistics - through the doctrine of formal languages \u200b\u200band on iconic systems;

With cybernetic - through the theory of information and the theory of management;

With physics and chemistry, electronics and radio engineering - through the "material" part of the computer and information systems.

Figure 1.5. Communication informatics with other sciences

The role of informatics in the development of society is extremely large. It is a scientific foundation of the Company's informatization process. It is associated with a progressive increase in computer equipment, development information networks, Creation of new information technologieswhich lead to significant changes in all spheres of society: in production, science, education, medicine, etc.

The main function of computer science is to develop methods and means of converting information using a computer and in applying them when organizing the technological process of information conversion.

Performing your function, informatics solves the following tasks:

Examines information processes in social systems;

Develops information technology and creates newest technologies transformation of information based on the results obtained during the study of information processes;

Solves scientific and engineering problems of creating, implementing and ensuring the effective use of computer equipment and technology in all spheres of human activity.

1.2. The concept of information. The overall characteristics of the processes of collection, transmission, processing and accumulation of information

The whole life of a person is somehow connected with the accumulation and processing of information that he receives from the surrounding world, using five senses - vision, hearing, taste, smelling and touch. As the scientific category "Information" is a subject of study for a wide variety of disciplines: informatics, cybernetics, philosophy, physics, biology, communication theory, etc. Despite this, strict scientific definition, what information is, so far does not exist, And instead, it usually uses the concept of information. The concepts differ from the definitions of the fact that different disciplines in different areas of science and technology invest different meaning in it so that it is most of the subject and objectives of a specific discipline. There are many definitions of the concept of information - from the most common philosophical (information is the reflection of the real world) to the most private application (information has information that are processing object).

Initially, the meaning of the word "information" (from lat. Informatio - clarification, the presentation) was interpreted as something inherent only by human consciousness and communication: "knowledge, information, messages, news transmitted by people oral, written or in another way."

Information is neither matter or energy. Unlike them, it can occur and disappear.

The feature of the information is that it is manifested only in the interaction of objects, and the exchange of information may be carried out at all between any objects, but only between those of them, which represent an organized structure (system). Not only people can be elements of this system: the exchange of information can occur in the animal and the plant world, between living and inanimate nature, people and devices.

Information is the most important resource of modern production: it reduces the need for land, labor, capital, reduces the consumption of raw materials and energy, causes new production to life, is a product, and the seller does not lose it after the sale can accumulate.

The concept of "information" usually assumes the presence of two objects - the source of information and the "receiver" (consumer, addressee) of information.

Information is transmitted from the source to the receiver in the material and energy form in the form of signals (for example, electrical, light, sound, etc.), distributed in a specific environment.

Signal (from lat. Signum - sign) - physical process (phenomenon), carrying message (information) on event or condition of observation object.

Information can flow in analog (continuous) form or discretely (as a sequence of individual signals). Accordingly, the analog and discrete information is distinguished.

The concept of information can be viewed from two positions: in the broad sense of the word - this is the world around us, sharing information between people, the exchange of signals between living and inanimate nature, people and devices; In the narrow sense of the word information is any information that can be saved, convert and transmit.

Information is a specific attribute of a real world, which is its objective reflection in the form of a set of signals and manifested when interacting with the "receiver" of information, allowing to allocate, register these signals from the world and by this or that criterion to identify them.

From this definition it follows that:

Information is objective, since this property of matter is reflected;

Information is manifested in the form of signals and only when the objects interact;

The same information can be interpreted differently by various recipients depending on the "configuration" "receiver".

A person perceives signals through the senses that are "identifies" by the brain. Receivers of information in the technique perceive signals using different measuring and recording equipment. In this case, a receiver with greater sensitivity when registering signals and more perfect algorithms for their processing allows you to obtain large amounts of information.

Information has specific functions. The main ones are:

Cognitive - receiving new information. The function is implemented mainly through such stages of information conversion as:

- Its synthesis (production)

- performance

- storage (time transmission)

- perception (consumption)

Communicative - the function of communication of people implemented through such stages of information conversion as:

- Transmission (in space)

- Distribution

Management - formation of expedient behavior of a managed system receiving information. This feature of information is inextricably linked with cognitive and communicative and implemented through all the main stages of circulation, including processing.

Without information, life cannot exist in any form and any information systems created by a person cannot function. Without it, biological and technical systems are pile of chemical elements. Communication, communication, the exchange of information is inherent in all living beings, but in a special extent person. Being accumulated and processed from certain positions, information gives new information, leads to a new knowledge. Obtaining information from the surrounding world, its analysis and generation make up one of the main functions of a person who distinguishes it from the rest of the living world.

In the general case, the role of information may be limited to emotional impact on a person, but most often it is used to generate control effects in automatic (purely technical) and automated (human-machine) systems. In such systems, separate stages (phases) of information conversion can be distinguished, each of which is characterized by certain actions.

The sequence of actions performed with information is called the information process.

The main information processes are:

- collection (perception) of information;

- preparation (transformation) of information;

- information transfer;

- processing (transformation) of information;

- data storage;

- Display (play) information.

Since the material carrier is a signal, it is realistic to be the stages of circulation and conversion of signals (Fig. 1.6).

Figure 1.6. Basic information processes

At the stage of information perception, targeted extraction and analysis of information about any object (process) is carried out, as a result of which the image image is formed, its identification and evaluation are carried out. The main task at this stage is to separate useful information From the interfering (noise), which in some cases is associated with significant difficulties.

At the stage of preparation of information, its primary transformation is carried out. At this stage, operations such as normalization, analog-digital conversion, encryption are carried out. Sometimes the preparation phase is considered as auxiliary at the perception stage. As a result of perception and preparation, a signal is obtained in a form, convenient for transmission, storage or processing.

At the transfer stage, the information is sent from one place to another (from the sender to the recipient - the addressee). Transmission is carried out through the channels of various physical nature, the most common of which are electrical, electromagnetic and optical. Removing the signal at the outlet of the channel exposed to the action of noise, is the nature of the secondary perception.

At the processing stages, its general and significant interdependencies are detected, which are of interest to the system. Converting information at the processing stage (as well as other steps) is carried out either by means of information technology or by a person.

Under the processing of information is understood to be any of its transformation conducted under the laws of logic, mathematics, as well as informal rules based on "common sense", intuition, generalized experience, the prevailing and behavior standards. The result of processing is also information, but either represented in other forms (for example, ordered by some signs), or containing answers to the questions set (for example, solving some task). If the processing process is formalized, it can be performed by technical means. Cardinal shifts in this area have occurred thanks to the creation of a computer as a universal information converter, and therefore the concepts of data and data processing appeared.

Data is called facts, information presented in formalized form (encoded), listed on those or other carriers and allowing processing using special technical means (first of all computers).

Data processing involves the production of various operations on them, primarily arithmetic and logical, to obtain new data that are objectively necessary (for example, in the preparation of responsible decisions).

At the storage stage, information is recorded in a storage device for subsequent use. Semiconductor and magnetic media are used to store information.

The information display step must precede the stages associated with the participation of a person. The purpose of this stage is to provide a person with the information they need with the help of devices capable of influencing his senses.

Any information has a number of properties that, together, determine the degree of its compliance with the needs of the user (quality of information). There are many diverse properties of information, as each scientific discipline considers those properties that it is most important. From the point of view of computer science, the most important are the following:

The relevance of the information is the property of information to maintain value for the consumer over time, i.e. not to be exposed to "moral" aging.

Fullness of information is the property of information characterized by a measure of sufficiency to solve certain tasks. The fullness of information means that it ensures the adoption of the correct (optimal) solution. It is estimated to be a relatively definite task or group of tasks.

Information adequacy is a property consistent with substantive information of the state of the object. Violation of identity is associated with technical aging of information, in which the difference in real signs of objects and the same features displayed in the information occurs.

The safety of information is the property of information characterized by the degree of readiness of certain information arrays to the target application and the definable control and protection and protection ability to ensure the continued availability and timely provision of the information array necessary for the automated solution of the target and functional tasks of the system.

The accuracy of the information is the property of information characterized by the degree of compliance of real information units to their true meaning. The required level of confidence of information is achieved by introducing methods for monitoring and protecting information at all stages of its processing, improving the reliability of a complex of technical and software information systems, as well as administrative and organizational measures.

Information society

Modern society is characterized by a sharp increase in the amount of information circulating in all spheres of human activity. This led to the informatization of society.

Under the informationalization of society, the organized socio-economic and scientific and technical process of creating optimal conditions for meeting the information needs and the realization of the rights of physical and legal entities Based on the formation and use of information resources - documents in different form of submission.

The purpose of informatization is to create an information society when most people are engaged in manufacturing, storage, processing, implementation and use of information. To solve this problem, new directions arise in the scientific and practical activities of members of society. So the informatics and information technologies arose.

Characteristic features of the information society are:

1) the absence of the problem of the information crisis, eliminating the contradiction between information avalanche and information hunger;

2) the priority of information before other resources;

3) the creation of an information economy as the main form of development of society;

4) the formation of automated generation, storage, processing and use of knowledge using the latest information technology and technology.

5) information technology, acquiring global nature, cover all spheres of human social activities;

6) the formation of the information unity of the whole human civilization;

7) the implementation of the free access of each person to the information resources of the entire civilization;

8) the decision of the humanistic principles of society management and environmental impact.

In addition to the listed positive results of the process of informatization of society, negative trends accompanying this process are possible:

1) excessive influence of the media;

2) the invasion of information technologies into a person's privacy;

3) the difficulty of adapting some people to information society;

4) the problem of quality selection of reliable information.

At the moment, the closer to all countries to the information society are located in the United States, Japan, England, Western European countries.

1.3. Number systems

The number system is a method for recording numbers with set set Special characters (numbers).

There are positional and non-pricing systems.

In non-phase surgery, the weight of the weight does not depend on the position that it takes place. Thus, for example, in the Roman number system, the XXXII (thirty-two two), the weight of the x in any position is simply ten.

In positional surgery systems, the weight of each digit varies depending on its position in the sequence of numbers depicting the number.

Any positional system is characterized by its base. The base of the positioning system is the number of different characters or characters used for the image of the numbers in this system.

For the basis, you can take any natural number - two, three, four, sixteen, etc. Consequently, an infinite set of positional systems may be possible.

Decimal number system

Came to Europe from India, where it appeared no later than the VI century n. e. In this system 10 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, but information carries not only a digit, but also the place on which the number is worth (that is, its position). In the decimal number system, the number 10 and its degrees play a special role: 10, 100, 1000, etc. right figure The numbers show the number of units, the second right is the number of tens, the following is the number of hundreds, etc.

Binary number system

In this system, only two digits - 0 and 1. A special role is played here 2 and its degrees: 2, 4, 8, etc. The very right figure of numbers shows the number of units, the following digit - the number of two, the following is the number of fours and etc. The binary number system allows you to encode any natural number - to present it as a sequence of zeros and units. In binary form you can represent not only numbers, but any other information: texts, pictures, movies and audio recordings. Engineers binary coding attracts that it is easily implemented technically.

Octal number system

In this number system 8 digits: 0, 1, 2, 3, 4, 5, 6, 7. The figure 1, indicated in the youngest discharge, means, as in the decimal number, simply one. The same figure 1 in the next discharge means 8, in the following - 64, etc. The number 100 (octal) is nothing but 64 (decimal). To translate into a binary system, for example, the number 611 (octal), it is necessary to replace each digit equivalent to it binary triad (three digits). It is easy to guess that to transfer a multi-valued binary number to the octal system, you need to break it on the triads to the right and replace each triad with an appropriate octal digit.

Hex number

The record of the number in the octaous number system is compact enough, but it is even more compact in the hexadecimal system. As the first 10 of 16 hexadecimal digits, familiar figures 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 9, but as the remaining 6 digits use the first letters of the Latin alphabet: a, b, c, D, E, F. Figure 1, recorded in the youngest discharge, means just a unit. The same figure 1 in the following - 16 (decimal), in the following - 256 (decimal), etc. The figure of F, specified in the youngest discharge, means 15 (decimal). Transfer from a hexadecimal system to binary and back is made similarly to how this is done for the octal system.

Table 1. Compliance between the first few natural numbers of all three number systems

1.4. Information coding

Currently, information is submitted in all computing machines using electrical signals. At the same time, two forms of its representation are possible - as a continuous signal (using a similar value - analogue) and in the form of several signals (using a voltage set, each of which corresponds to one of the numbers of the presented value).

The first form of information representation is called analog, or continuous. The values \u200b\u200bpresented in this form can take fundamentally any values \u200b\u200bin a specific range. The number of values \u200b\u200bthat such a value can take is infinitely large. Hence the names - a continuous value and continuous information. The word continuity distinctly allocates the basic property of such values \u200b\u200b- the absence of breaks, the gaps between the values \u200b\u200bthat this analog value can take. When using an analog form to create a computing machine, a smaller number of devices will be required (each value is one, and not several signals), but these devices will be more difficult (they should distinguish a significantly larger number of signal states). The continuous form of representation is used in analog computing machines (AVM). These machines are intended mainly to solve problems described by the system of differential equations: studies of the behavior of moving objects, modeling processes and systems, solving problems of parametric optimization and optimal control. Continuous signal processing devices have higher speeds, they can integrate a signal, perform any of its functional transformation, etc. However, due to the complexity of the technical implementation of the logic operation devices with continuous signals, long-term storage of such signals, their accurate measurement of AVM cannot effectively solve problems related to storage and processing of large amounts of information.

The second form of information representation is called discrete (digital). Such values \u200b\u200bthat take all possible, but only quite definite values \u200b\u200bare called discrete (intermittent). Unlike continuous magnitude, the number of discrete values \u200b\u200bwill always be finite. The discrete form of the presentation is used in digital electronic computers (computers), which easily solve problems related to storage, processing and transmission of large amounts of information.

To automate computer work with information related to various typesIt is very important to unify their presentation form - for this, coding is usually used.

Coding is a signal representation in a specific form, convenient or suitable for subsequent use of the signal. Speaking is stricter, this rule describing the display of one set of characters to another set of signs. Then the displayed set of signs is called the original alphabet, and the set of signs that is used to display, coded alphabet, or alphabet for coding. In this case, coding is subject to both individual symbols of the initial alphabet and their combination. Similarly, for the construction of the code, both individual characters of the code alphabet and their combinations are used.

The set of code alphabet characters used to encode one character (or one combination of symbols) of the original alphabet is called a code combination, or, in short, the symbol code. In this case, the code combination may contain one character of the code alphabet.

The symbol (or combination of characters) of the original alphabet, which corresponds to the code combination, is called the source symbol.

The combination of code combinations is called code.

The relationship of characters (or symbol combinations, if not separate symbols of the initial alphabet) of the original alphabet with their code combinations are encoded with their code compliance table (or code table).

As an example, you can bring the system for recording mathematical expressions, the Alphabet of Morse, the marine flank alphabet, the braille system for the blind, etc.

In computing technology, there is also its own coding system - it is called binary coding and is based on the data presentation by the sequence of only two characters: 0 and 1 (used binary number system). These signs are called binary numbers, or bits (Binary Digital).

If you increase the number of discharges in the binary coding system, then doubles the number of values \u200b\u200bthat can be expressed in this system. To calculate the number of values, the following formula is used:

where n is the number of independently encoded values,

a M is the discharge of binary coding adopted in this system.

For example, what number of values \u200b\u200b(n) can I code 10 discharges (m)?

To do this, we build 2 to 10 degree (M) and we obtain N \u003d 1024, i.e., in the binary coding system, 1024 can be encoded, 1024 independently encoded values.

Coding text information

To encode text data, specially developed encoding tables are used based on comparison of each alphabet symbol with a certain integer. Eight binary discharges are sufficient for coding 256 different characters. This is enough to express all the symbols of English and Russian, both lowercase and capital, as well as punctuation marks, symbols of major arithmetic actions and some generally accepted by various combinations of eight bits. special symbols. But not everything is so simple, and there are certain difficulties. In the first years of the development of computing technology, they were associated with the lack of necessary standards, and at present, on the contrary, caused by the abundance of simultaneously operating and contradictory standards. For almost all languages \u200b\u200bcommon on the globe, their code tables are created. In order for the whole world to encode text data equally, we need single coding tables, which still has not yet become possible.

Coding graphic information

The encoding of graphical information is based on the fact that the image consists of the smallest points forming a characteristic pattern called a raster. Each point has its own linear coordinates and properties (brightness), therefore, they can be expressed using integers - raster coding allows you to use binary code to present graphics information. Black and white illustrations are presented in the computer in the form of combinations of points with 256 grades of gray - for encoding the brightness of any point of a sufficiently eight-bit binary number.

For encoding color graphic images, the principle of decomposition (decomposition) of arbitrary color on the main components is used. In this case, various methods for encoding color graphics information can be used. For example, in practice it is believed that any color visible by the human eye can be obtained by mechanically mixing the main colors. Three main colors are used as such components: red (RED, R), Green (Green, G) and Blue (Blue, B). Such a coding system is called the RGB system.

On the color encoding of one point of color image, it is necessary to spend 24 discharge. At the same time, the coding system provides an unambiguous definition of 16.5 million different colors, which is actually close to the sensitivity of the human eye. Presentation mode of color graphics using 24 binary discharges is called full color (True Color).

Each of the main colors can be put into line with an additional color, that is, the color that complements the main color to the white. Accordingly, additional colors are: Blue (CYAN, C), purple (Magenta, M) and yellow (Yellow, Y). This coding method is accepted in printing, but the fourth paint is also used in printing - black, black, k). This encoding system is denoted by CMYK, and to represent color graphics in this system you need to have 32 binary discharge. This mode is called full color (True Color).

If you reduce the number of binary discharges used to encode the color of each point, then the amount of data can be reduced, but the range of encoded colors is noticeably reduced. Coding color graphics 16-bit binary numbers is called High Color mode.

Coding sound information

Receptions and methods for encoding sound information came into computing techniques the most late and still far from standardization. Many individual companies have developed their corporate standards, although you can distinguish two main directions.

The FM method (Frequency modulation) is based on the fact that theoretically, any complex sound can be decomposed on the sequence of simple harmonious signals of different frequency, each of which represents the correct sinusoid, and therefore, it can be described by numeric parameters, that is, the code. In nature, the sound signals have a continuous spectrum, that is, are analog. Their decomposition into harmonic rows and representation in the form of discrete digital signals perform special devices - analog-digital converters (ADC). Reverse conversion To play sound encoded by numerical code, digital-analog converters (DAC) are performed. With such transformations, some of the information is lost, so the sound recording quality is usually not completely satisfactory and corresponds to the quality of the sound of the simplest electro musical instruments With "Color", characteristic of electronic music.

Method of table-wave synthesis (Wave-Table) better corresponds to the modern level of development of technology. There are pre-prepared tables in which samples of sounds are stored for many different musical instruments. In the technique, such samples are called samples. Numeric codes express the type of tool, its model number, tone height, duration and intensity of sound, the dynamics of its change. Since "real" sounds are used as samples, the sound quality obtained as a result of synthesis is very high and approaches the quality of the sound of real musical instruments.

Data measurement units

The smallest unit of measurement of information is byte equal to eight bits. One byte can encode one of 256 values. There are also larger units such as kilobyte (KB), megabytes (MB), gigabytes (GB) and Terabyte (TB).

1 byte \u003d 8 bits

1 KB \u003d 1024 byte

1 MB \u003d 1024 Kb \u003d 2 20 bytes

1 GB \u003d 1024 MB \u003d 2 30 byte

1 TB \u003d 1024 GB \u003d 2 40 byte

test questions

1. What is the computer science?

2. How did the methods for collecting, storing and transferring information developed?

3. What is the structure of modern computer science?

4. What is information?

5. What functions do the information performs?

6. Give the characteristic basic information processes.

7. What is the main difference between data from information?

8. What properties has the information?

9. What is understood by the informatization of society?

10. What characteristic features of the information society has?

11. What is a number system and what are they? Give examples.

12. Give the characteristic of the main positional viewing systems.

13. In which two types of information can be presented? Describe them and give examples.

14. What is coding? Give examples of coding from life.

15. What is the main unit of reporting in computer?

16. How are different types of information in computer encoded?

17. With which units measure information?

3.1. Representation of data in computer

When conducting mathematical calculations, the number inside the computer can be represented using the natural and normal forms of recording.

An example of recording in a natural form can be the number 456.43. To record such a number, the machine word (operand) is divided into two fixed fields (parts). The first field is assigned to record the whole part, and the second is to write a fractional part of the number. Senior digit is intended to indicate the sign of the number.

In computing technology, it is customary to separate the whole part of the number from the fractional part of the point. Since in this case the position of the point between the whole and fractional part is clearly defined, then such a representation of numbers is called the representation with fixed point. Below in fig. 3.1 shows the machine word 16 digits (2 bytes).

Machine wordit is a structural unit of computer information. With the help of machine words, they write numbers, symbols and commands. In modern computers, the length of the machine words is 32 ... 128 discharges. Physically, each discharge of the machine word is a separate memory element (trigger or storage capacitor).

Fig. 3.2. Presentation of an integer

The normal form of the number of numbers has the following form:

where m - mantissa numbers; P - order; D - base Number system.

The order indicates the location among the point separating the integer part of the number from the fractional. Depending on the order, the point moves (floats) on the mantissa. This form of numbers representation is called a form with floating point. Fig. 3.3 illustrates the form of a floating point number on the example of a 32-bit machine word.

For example, let m \u003d 0.3, d \u003d 10, and the order will be different:

0.3 · 10 -1 \u003d 0.03; 0.3 · 10 -2 \u003d 0.003; 0.3 · 10 2 \u003d 30; 0.3 · 10 3 \u003d 300.

From the above example, it can be seen that due to the change in the order, the dot moves (floats) on the mantissa. At the same time, if the order is negative, the point shifts on the Mantissa to the left, and if positive, then to the right.

31

…

…

Fig. 3.3. Pose of a floating point number

In this case, the machine word is divided into two main fields. In one field, the mantissa of the number is recorded, in the second - the order of the number is indicated. The range of the presentation of the floating point numbers is much larger than the number of numbers representation with a fixed point. However, the speed of the computer during the processing of a floating point numbers is much lower than when processing numbers with a fixed point.

3.2.Resert teams in computer

The computer's work program consists of a sequence of commands.

Under team It is understood as information that ensures the generation of control signals generated in the processor control device to perform a variable action machine.

The command field consists of two parts: operational and address. The operating part indicates the operation code (CP). The code determines the action that the computer must execute (arithmetic - addition, subtraction, logical - inversion, etc.).

The address part of the command contains the addresses of operands (numbers or symbols) involved in the operation. Under address It is understood by the RAM or ROM cell number, where the information necessary for executing the command is recorded.

Thus, the computer (more precisely, the processor) performs an action that is determined by the code of the operation, above the data, the location of which is indicated in the address part of the command.

The number of addresses specified in the address command may be different. Depending on the number of addresses, the following formats of commands distinguish: single, two and three-ripen. There are also chaasadres. In fig. 3.4 Presented the structure of various commands.

Cop	A1.
Cop	A1.	A2.
Cop	A1.	A2.	A3.

Operating Address Part Team

part of the team

Fig. 3.4. Team structure

Trekhadres teamPerforming, for example, the addition operation should contain the addition of the addition operation and three addresses.

Actions performed by this command are described by the following sequence of operations.

1. Take the number stored at the first address A1.

2. Take the number stored in the second address A2, and folded with the first number.

3. The result of adding to write down the third address A3.

In the case of a two-chade command, the third address is absent, and the result can be recorded either at the second address (with a loss of information that was recorded there), or leave in the register of the adder, where the operation was performed. Then, an additional command of the rewriting command for the desired address is required to release an adder register. When organizing the addition of two numbers stored at A1 and A2 addresses with the result of the result in A3 using unicast teamsThe three teams are already required.

1. A call to the adder (Allu) of the number stored at A1.

2. A call of the number stored at A2 and addition of it with the first number.

3. Record the result at A3.

Thus, the smaller the addresses contains the command, the greater the number of commands are required to compile the same machine operation program.

By increasing the number of addresses in the team, you have to increase the length of the machine word to take the necessary fields in it for the address part of the commands. With an increase in the memory capacity, the length of the field required to specify one address increases. At the same time, not all commands fully use address fields. For example, for the recording command of the number at a specified address, only one address field is required. An unjustified increase in the length of the machine word for using multicast teams leads to a decrease in computer performance, because It is necessary to process the fields of greater length.

There are non-addresse commands that contain only the operation code, and the necessary data is placed in advance in certain processor registers.

Modern computers automatically perform several hundred different commands. All machine commands can be divided into groups by types of operations:

· Data transfer operations;

· Arithmetic operations;

· Logical operations;

· Operations of access to external computer devices;

· Management transmission operations;

· Servicing and auxiliary operations.

When designing new processors, developers have to solve the complex task of selecting the length of the command and defining the list of necessary commands (command systems). Contradictory command configuration requirements led to the creation of processors with various formats of command formats (CISC and RISC architecture).

3.3.Kodova table

Code table - This is an internal (encoded) presentation in the machine of letters, numbers, characters and control signals. So, the Latin letter A in the code table is represented by a decimal number of 65D (inside the computer, this number will be represented by binary number 01000001B), Latin letter C - number 67D, Latin letter M - 77D, etc. Thus, the word "Samara" written by capital Latin letters will circulate inside the computer in the form of numbers:

67D-65D-77D-65D-80D-65D.

If we speak more precisely, then inside the computer, this word is stored and used in the form of binary numbers:

01000011V-01000001B-01001101B-01000001B-0101000V-01000001V

The numbers are similarly encoded (for example, 1 - 49d, 2 - 59d) and symbols (for example,! - 33D, + - 43D).

Along with alphanumeric symbols, control signals are encoded in the code table. For example, the code 13D causes the printer's print head to return to the beginning of the current line, and the 10D code moves the paper that is charged into the printer to one line forward.

The code table can be represented not only with the power of a decade, but also with the help of hexadecimal SS. Note once again that the signals presented in the binary number system circulate inside the computer, and in the code table for greater convenience of reading the user - in a decimal or hexadecimal SS.

Each letter, digit, punctuation sign or control signal is encoded by an eight-bit binary number. Using an eight-bit number (single "number), you can presented (encode) 256 arbitrary characters - letters, numbers and any graphic images.

All over the world, the ASCII code table is accepted as a standard (American Standard Code for Information Interchange - American Standard Codes for Information Exchange). The ASCII table regulates (strictly determines) exactly half of the possible characters (Latin letters, Arabic numbers, punctuation marks, control signals). For their encoding, codes from 0d to 127d are used.

The second half of the ASCII code table (with codes from 128 to 255) is not defined by the American standard and is intended to place the symbols of the national alphabets of other countries (in particular, Cyrillic - Russian letters), pseudographic symbols, some mathematical signs. In different countries, on various models EUM, various operating systems can also use different options for the second half of the code table (they are called ASCII extensions). For example, a table that is used in the MS-DOS operating system is called CP-866. Using this table for encoding the words "Samara", recorded by Russian letters, we obtain such codes:

145D-128D-140D-128D-144D-128D.

When working in the operating room windows system The CP-1251 codes table is used, in which the Latin letter encoding coincides with the CP-866 and ASCII table encoding, and the second half of the table has its own layout (encoding) of characters. Therefore, the word "Samara", written in capital Russian letters, will have a different presentation inside computer:

209D-192D-204D-192D-208D-192D.

Thus, externally the same word (for example, "Samara") inside the computer can be represented in various ways. Naturally, it causes certain inconveniences. When working on the Internet, the national text sometimes becomes unreadable. The most likely reason in this case is the mismatch of the encoding of the second half of the code tables.

The general disadvantage of all single-byte code tables (eight-bit binary numbers are used for encoding) is the lack of any information in the code code, which prompts the machine, which in this case uses the code table.

Community firms Unicode. A different symbol encoding system is proposed as standard. In this system, two bytes (16 bits) are used in this symbol (16 bits), and this allows you to enable information about how the character belongs to the symbol code and how it needs to be played on the monitor screen or on the printer. Two bytes allow you to encode 65,536 characters. True, the amount of information occupied by the same text will double. But the texts will always be "readable" regardless of the national language and operating system.

3.4.Ganization of data storage on magnetic disks

3.4.1. Disks

Disks - Devices for constant storage of information. Any computer has a hard magnetic disk drive, designed to read and write to a fixed hard magnetic disk (Winchester), and a drive (or drive) for flexible magnetic disks used to read and write to flexible magnetic discs (floppy disks). In addition, there may be drives for working with CDs, magneto-optical discs, etc.

Any hard disk or magneto-optical disc can be divided into several parts, which will look at the user on the screen as well as physically existing discs. These parts are called logical disks. Each logical disk has a name (letter) by which you can contact it. Thus, the logical disk is part of the usual hard diskhaving your own name. For example, a 3 GB hard disk can be divided into two logical disks: drive C: volume of 2 GB and disk D: 1 GB.

The disc on which the operating system is recorded, called systemic (or bottling) Disk. As boot disk Most often used hard drive C:.

In DOS and Windows operating systems, each disk can additionally give names (label - label), which reflect their content, for example: system, graphics, texts, distributions, etc.

3.4.2. Files

Information on disks (hard drives, floppy disks, magneto optical disks, CDs, etc.) is stored in files.

File - This is a set of interrelated data perceived by the computer as a single integer having a common name on a disk or other media of information. The files may store programs, documents ready for program execution, drawings, etc.

In order for the operating system and other programs to contact files, the files must have designations. This designation is called file name. The file name usually consists of two parts. - Actually name (in a DOS from 1 to 8 characters, in Windows - from 1 to 254 characters) and expansion up to 3 characters long. The name and expansion are separated from each other. Often the name and expansion together are also called the name. File names:

vova.doc tetris.exe doc.arj config.sys

The name and expansion may consist of capital and lowercase latin letters (Russian letters), numbers and symbols, except control characters and symbols \\ /: * are possible?< > ; , + \u003d. Russian letters in file names should be used with caution - some programs do not "understand" names with Russian letters. File names may include characters "-" (hyphen), "_" (underscore), "$" (dollar), "#" (lattice), "&" (ampersand, typographic "and" in English countries), " @ "(" Dog "),"! ","% ", Brackets, quotes," ^ "(" cover ")," '"(apostroph)," ~ "(tilda or" wave ").

The file name extension is optional. It, as a rule, describes the content of the file, so the use of expansion is very convenient. Many programs establish a specific extension of the file name, and you can find out what program has created a file. In addition, many programs (for example, a shell program) allow you to invite the file name to invaluate the appropriate program and immediately load this file into it. Examples of typical extensions:

cOM, EXE - Find files (ready for program execution); If you select a file with such an extension and press the Enter key, the program will immediately start working;

bAT - Command (Batch) files;

tXT, DOC, WP, WRI - Text Files (Documents). DOC extension gives its documents MS Word, WP - WordPerfect, WRI - MS Write. In files with the extension TXT, the text is usually without any design (text-only, only text);

bak - latest version text (backup);

tIF, PCX, BMP, PIC, GIF, JPG, CDR - graphic files of different formats;

aRJ, ZIP, LZH, RAR - Sucked (archived) files;

hLP - help files, prompts to different programs;

drV, EGA, VGA, SYS, DLL and a number of others - service programs and program drivers, with which the computer is learning to work with different monitors, keyboards, printers, mice, use Russian. These programs are not launched as executable files;

tTF, FON, FNT, SFP, STL, XFR - fonts for different programs;

bAS, C, PAS, ASM - contain text of programs in Basic, Si, Pascal, Assembler.

There may be files and with other extensions.

The most important feature of the file is its the size. It is measured in bytes, Kabletes, MB.

3.4.3. Folders

File names are registered on disks in directories (or directories). In Windows, catalogs are called folders.

Folders - This is a special place on a disk in which file names, file size information, their time is stored. last update, attributes (properties) of files, etc. If the file is stored in the folder, it is said that this file is in this folder. Each disk can have several folders.

Each folder has a name. Requirements for folder names are the same as file names. As a rule, the name extension for folders is not used, although it is not prohibited.

Full file nameit has the following form (brackets [and] denote optional elements):

[Drive:] [path \\] File name

Way - This is a sequence of folder names (directories) or ".." characters, separated by the "\\" symbol. The path sets the route from the current or root disk folder to the folder in which the file is located. If the path starts with the "\\" symbol, the route is calculated from the root disk root folder, otherwise - from the current folder. Each name of the folder on the path corresponds to the input to the folder with the same name, the ".." symbol corresponds to the input to the folder level above. For example:

A: \\ TEXT1.TXT - the text1.txt file is located in the root folder of the disk A :;

C: \\ Works \\ Pascal \\ Prog1.pas - the prog1.pas file is located in the Pascal folder, which, in turn, is located in the Works folder located in the root folder of the C drive folder.

3.4.4. File disk file

In order for a new magnetic disk you can record information, it must be pre-formatted. Formatting - This is the preparation of the disk to record information.

During formatting on disk, service information is recorded (markup is made), which is then used to record and read information. The markup is performed using the electromagnetic field created by the recording drive head.

Information record is carried out by roads, and each track is divided into sectors, for example, 1024 bytes (Fig. 3.5). A 10.5-inch floppy disk with a volume of 1.44 MB contains 80 tracks and 18 sectors.

Fig. 3.6. Cylinder Winchester

The figure shows two cylinders (first and second) formed by equidistant tracks on three Winchester discs. When the hard drive is operation, several heads simultaneously read information from the tracks of one cylinder.

To refer to the file in the file, you need to know the address of the first sector from those in which the file data is stored. The sector address is determined by three coordinates: path number (cylinder), surface number and sector number.

The operating system (OS) takes the storage of this information for each file. To implement access to the OS file, use the root directory, the FAT file location table and the boot sector of the disk. These elements form system Disc Area(or diskettes) and are created during the initialization process (formatting) of the disk.

Boot sector, file placement table, root directory and the remaining free disk memory space, called the data area, are elements disc File Structure.

The hard disk can be broken into several sections. Therefore, in the initial sectors hard Disc placed information on the number of sections, their location and size. The hard disk sections are further considered as autonomous discs, each of which is separately initialized, has its own letter designation (C :, D: E: F:, etc.) and their elements of the file structure.

Boot sector(Boot Record) - This is a dial business card in which the data required to work with the disk are recorded. It is located on each disk in the logical sector with the number 0. The following characteristics are recorded in the boot sector:

system identifier if the operating system is recorded on the disk;

size of the disc sectors in bytes;

the number of sectors in the cluster;

the number of elements in the catalog;

number of sectors on disk, etc.

If the disk is prepared as a system (bootable), the boot sector contains the operating system loading program. Otherwise, it contains a program that when attempting to boot from this disk operating system displays a message that this disc is not systemic.

Behind the boot sector on the disk follows the file placement table.

File Placement Table(File Allocation Table - Abbreviated FAT) It contains a description of the order of all files in the sectors of this disk, as well as information on defective disk sections. The FAT table follows its exact copy, which increases the reliability of preserving this very important table.

During the work of users on a computer, the disk content changes: new files are added, unnecessary, some files are expanded or decreased, etc.

Performing these operations requires a special mechanism for the distribution of the disk storage space between files and access access to them. This mechanism is implemented by using the file placement table.

When performing read-write operations data, the exchange of information between the disk drive and memory of the computer is carried out by blocks. The minimum block volume is equal to the sector. To reduce the number of references to the disk for one handling, information from several sequentially located sectors forming a kind of superblock may be referred to cluster. In this way, cluster - Several sequentially located sectors that are read or recorded in a file for one appeal to it. The size of the cluster can be different.

The file written to the disk is allocated a whole number of clusters, and the highlighted clusters can be in various places of the disk. Unlike continuous fileslocated in one memory area, files that occupy several areas called disk fragmented. Assign FAT - Store location data on the file fragment disk.

The mechanism of access to files using FAT is implemented as follows. The disk data area is considered as a sequence of numbered clusters. Each cluster is put in accordance with the FAT element with the same number. For example, the element 2Fat corresponds to the cluster 2 of the disk data area, element 3Fat cluster 3, etc. The directory containing information about the disk files is specified for each file the number of the first cluster occupied by the file. This number is called the entrance point in FAT. The system, reading in the directory number of the first file cluster, refers to this cluster, for example, writes data to it. In the FAT, the first file cluster contains the number of the second file cluster or a sign of the end of the file, etc. An example of file access mechanism using FAT is presented in Table. 3.1.

Table 3.1

Mechanism of access to files using Fat

Entrance to Fat.

Fat elements number

Values \u200b\u200bof Fat elements

To present information in the memory of the computer (both numerical and not numeric) uses a binary method of coding.

Elementary email memory cell has a length of 8 bits (1 byte). Each byte has its own number (it is called the address). The greatest sequence of the bit, which computer can process as a whole, called machine word. The length of the machine word depends on the discharge of the processor and may be equal to 16, 32 bits, etc.

For encoding characters is enough single byte. In this case, you can present 256 characters (with decimal codes from 0 to 255). Set of characters personal computers Most often is the ASCII Code extension (American Standart Code of Information Interchange - Standard American Code for Exchange Information).

In some cases, when viewed in the memory of the computer, a mixed binary-decimal number system is used, where it is necessary to store each decimal sign. designed to store integers with 18 significant figures and occupies 10 bytes in memory (senior of which is a sign), uses this particular option.

Another way to represent integers - additional code. The range of values \u200b\u200bof values \u200b\u200bdepends on the number of the memory bits of the memory for storage. For example, the types of type Integer lie in the range from
-32768 (-2 15) to 32677 (2 15 -1) and 2 bytes are given to storage: Longint type - in the range from -2 31 to 2 31 -1 and placed in 4 bytes: type Word - in the range from 0 Up to 65535 (2 16 -1) uses 2 bytes, etc.

As can be seen from examples, data can be interpreted as numbers with a sign and without signs. In the case of representing the value with the sign, the leftmost (senior) discharge indicates a positive number if it contains zero, and on a negative, if the unit.

In general, the discharges are numbered on the right, starting from scratch.

Additional code a positive number coincides with his direct code. The direct code of an integer may be represented as follows: the number is translated into the binary number system, and then its binary recording from the left is complemented by such a number of insignificant zeros, how much does the data type require that the number belongs to. For example, if the number 37 (10) \u003d 100101 (2) is declared the value of the Integer type, then its direct code will be 0000000000100101, and if the value of type Longint, then its direct code will be. For a more compact record, hexadecimal code is used more often. The obtained codes can be rewritten according to 0025 (16) and 00000025 (16).

Additional code of a whole negative number can be obtained according to the following algorithm:

1. record the direct code of the module number;
2. invert it (replace units with zeros, zeros - units);
3. add a unit to the inversion code.

For example, we write an additional number code -37, interpreting it as a value of type Longint:

1. the direct number of the number 37 is1
2. invert code
3. additional code or ffffffdb (16)

When receiving an additional code of the number, first of all, it is necessary to define its sign. If the number turns out to be positive, then simply translate its code into a decimal calculus system. In the case of a negative number, the following algorithm must be performed:

1. subtract from code 1;
2. invert code;
3. translate to a decimal number system. The resulting number is written with a minus sign.

Examples. We write numbers corresponding to additional codes:

1. 0000000000010111.

   Since zero is recorded in the older discharge, the result will be positive. This is the number 23 code.

2. 1111111111000000.

   The negative number code is recorded here, by performing the algorithm:

   1. 1111111111000000 (2) - 1 (2) = 1111111110111111 (2) ;
   2. 0000000001000000;
   3. 1000000 (2) = 64 (10)

A slightly different method is used to represent real numbers in the memory of the personal computer. Consider the representation of values \u200b\u200bwith floating point.

Any valid number can be written in the standard form M * 10 P, where 1 ≤ m< 10, р- целое число. Например, 120100000 = 1,201*10 8 . Поскольку каждая позиция десятичного числа отличается от соседней на степень числа 10, умножение на 10 эквивалентно сдвигу десятичной запятой на 1 позицию вправо. Аналогично деление на 10 сдвигает десятичную запятую на позицию влево. Поэтому приведенный выше пример можно продолжить: 120100000 = 1,201*10 8 = 0,1201*10 9 = 12,01*10 7 ... Десятичная запятая плавает в числе и больше не помечает абсолютное место между целой и дробной частями.

In the above recording M called mantissa numbers and r - it procedure. In order to preserve the maximum accuracy, the computing machines are almost always stored by the Mantissa in a normalized form, which means that the Mantissa in this case is the number lying between 1 (10) and 2 (10) (1 ≤ m< 2). Основные системы счисления здесь, как уже отмечалось выше,- 2. Способ хранения мантиссы с плавающей точкой подразумевает, что двоичная запятая находится на фиксированном месте. Фактически подразумевается, что двоичная запятая следует после первой двоичной цифры, т.е. нормализация мантиссы делает единичным первый бит, помещая тем самым значение между единицей и двойкой. Место, отводимое для числа с плавающей точкой, делится на два поля. Одно поле содержит знак и значение мантиссы, а другое содержит знак и значение порядка.

The IBM PC personal computer with a mathematical coprocessor 8087 allows you to work with the following valid types (the range of values \u200b\u200bis indicated by absolute value):

63

52

0

It can be noted that the older bit, allotted under the mantissa, has number 51, i.e. Mantissa takes the younger 52 bits. The trait indicates a binary point here. Before the comma should be a bit of the whole part of the mantissa, but since it is always equal to one, this bit is not required and there is no corresponding discharge in memory (but it is meant). The value of the order is stored here not as an integer presented in the additional code. To simplify the calculations and compare the actual numbers, the value of the order in the computer is stored as displaced number. To the present value of order, the displacement is added before recording it. The offset is selected so that the minimum value of the order corresponds to zero. For example, for the type Double, the order takes 11 bits and has a range from 2 -1023 to 2 1023, so the offset is 1023 (10) \u003d 1111111111 (2). Finally, the bit with number 63 indicates the number of numbers.

Thus, the following algorithm follows from the above for obtaining a valid number in memory of the computer:

1. translate the module of this number to the binary number system;
2. normalize binary number, i.e. Write in the form of m * 2 p, where M - Mantissa (its integer part is 1 (2)) and r - order recorded in a decimal number system;
3. add to the order offset and translate the displaced order into the binary number system;
4. considering the sign of a given number (0 - positive; 1 - negative), write it down in memory of the computer.

Example. Write the number code -312,3125.

1. The binary entry of the module of this number has a view of 100111000,0101.
2. We have 100111000,010101 \u003d 1.001110000101 * 2 8.
3. We obtain a displaced order of 8 + 1023 \u003d 1031. Next, we have 1031 (10) \u003d 10000000111 (2).
4. Finally
   

   63

   52

   0

   1. First of all, we notice that this is the code of a positive number, because in the discharge of the number 63, zero is recorded, we get the order of this number. 011111111110 (2) \u003d 1022 (10). 1022 - 1023 \u003d -1.
   2. The number is 1.1100011 * 2 -1 or 0.11100011.
   3. Translation into a decimal number system we get 0.88671875.

   We reviewed the types of information in memory of the computer, now you can proceed to check knowledge.

   If you need options on paper

Computer Engineering - This is a set of devices intended for automatic or automated data processing to information.

Computing system - This is a specific set of related devices. The central device of most computing systems is an electronic computing machine (computer) or a computer.

Computer- This is a device consisting of electronic and electromechanical components, which performs input, storage and data processing operations according to a specific program in order to obtain information, the output of which is carried out in the form suitable for human perception.

Computer architecture. Under the computer architecture, it is necessary to understand the combination of the characteristics that is necessary for the user. These are, first of all, the main devices and computer blocks, as well as the structure of links between them and software management.

General principles for building a computer, which relate to architecture:

• eCM memory structure;
• methods for access to memory and external devices ";
• the ability to change the configuration;
• command system;
• data formats;
• interface organization.

Based on this, it is possible to define that Architecture- This is the most general principles Building a computer that implements software management work and interaction of its main functional nodes.

The classic principles of building an architecture of the computer were offered in the work of J. Background Neymanan. Goldstayig and A. Berse in 1946 and are known as "principles of Nimanana". These principles declare the following architecture provisions:

• Using binary system Data presentation. The advantages of the binary system for technical implementation made the convenience and ease of performing arithmetic and logical operations. EUM has become processing and non-numeric information - textual, graphic, sound and others. Binary data coding is still the informational basis of any modern computer.
• Principle of stored program. Neumann was the first to guess that the program could also be stored in the form of zeros and units, and in the same memory as the number processed by it. The lack of a fundamental difference between the program and data gave the opportunity to form a program for itself in accordance with the results of calculations. Background Neumann not only put forward the fundamental principles of the logical device of the computer, but also proposed its structure that was reproduced during the first two generations of the computer.
• Principle of sequential operations. Structural memory consists of numbered cells. A processor in an arbitrary moment of time is available any cell. From here it is necessary to give names in memory areas like this. In order for the values \u200b\u200bstored in them, it would be possible to file or change them during the program execution using the assigned names.
• The principle of arbitrary access to cells random access memory . Programs and data are stored in the same memory. Therefore, the computer does not distinguish that it is stored in this memory cell - the number, text or command. Over the commands you can perform the same actions as above the data.

Figure 3. Control device (UU). Arithmetic logical device (Allu). Memory (memory) stores information (data) and programs, includes an operational storage device (RAM) and external storage devices.

Modern computer architecture. The real structure of the computer is much more complicated than the scheme discussed above (Fig. 3). In modern computers, in particular microcomputers (personal), there is increasingly a departure from the traditional architecture von Neuman, due to the desire of developers and users to improve the quality and performance of computers (Fig. 4).

EUM quality is characterized by many indicators. This is the set of commands that the computer can understand and perform, the speed of work (speed) of the central processor, the number of peripheral devices attached to the computer simultaneously and much more. At the same time, the main indicator characterizing the computer (computer) is its speed.

Speed - This is the number of operations that the processor is capable of performing per unit of time. In practice, the user more interested computer performance - An indicator of its effective speed, that is, the abilities are not just functioning quickly, but to quickly solve specifically set tasks.

As a result, all these and other factors contribute to the principled and constructive improvement of the elementary base of computers, that is, the creation of new, faster, reliable and convenient processors, memorizing devices, I / O devices, etc. However, it should be borne in mind that the speed of the elements cannot be increased irrelevant (there are modern technological limitations and restrictions due to physical laws). Therefore, the developers of computer equipment are looking for solving this problem by improving the computer architecture.

This appeared computers with multiprocessor (or multiprocessor) architecture in which several processors work simultaneously, and this means that the performance of such a computer is equal to the amount of processor performance.

In powerful computers designed for complex engineering calculations and automated design systems (CAD), two or four processors are often installed. In heavy duty computers (such machines may, for example, simulate real-time nuclear reactions, predict the weather on a global scale, simulate full-scale scenes for cinema and animation) The number of processors reaches several tens.

Fig. 4. General structure of the modern microcomputer

All major architectural blocks consist of separate smaller devices that perform strictly defined functions.

In particular, in cPU an arithmetic logical device ( Al.). Internal storage device in the form of processor registers and internal cache memory, managing device (Uu).

The input device is usually not a single structural unit. Since the types of input information are diverse, data input sources can be several. The same applies to the output devices.

CPU - This is a central computing unit in an AUM of any type. It calculates the program stored in RAM and provides general computer management.

The processor, at least contains:

• Arithmetic and logical device (Allu)intended for performing arithmetic and logical operations;

• Control device (UU)intended to complete the overall management of the computing process on the program and coordinate all the devices of the computer. UU in a specific sequence selects the command command from RAM. Then: Each, the command is decoded, the need for the data elements from the RAM cells specified in the command are transmitted to Allu. Alu is configured to perform the action specified by the current command (the I / O devices can also participate in this action); A command is given to perform this action. This process will continue until then. So far, one of the following situations will arise: the input data has been exhausted, a command to stop the computer is turned off from one of the devices.

Storage device (memory) - This is an architectural computer unit intended for temporary (RAM) and long-term (permanent memory) of software storage, input and result data, as well as intermediate results on an external storage device devices.

RAM (RAM) - Serves for receiving, storing and issuing information. It contains programs and data available for use by the microprocessor, as well as intermediate and final results of calculations. The process of executing the program is reduced to transformation of the initial state of memory in the final (final). RAM is an energy-dependent device, which means loss of information when the power is turned off. The speed of the computer significantly depends on the speed of RAM. Therefore, it is constantly looking for elements for RAM, spending less time on read-write operations. The problem is solved by building multi-level memory.

RAM consists of two or three parts: the main part of the larger capacity is built on relatively slow (cheaper) elements, and the additional (so-called cache memory) consists of high-speed elements. The data that the processor is most often drawn is in cache, and more operational information is stored in basic memory.

Permanent storage device (ROM). Non-volatile device intended for long-term storage of service and primary information. Presented in the form of microcircuits located on the maternal (system) board.

Outdoorstorage device (Pump). Non-volatile devices that ensure reliable storage and issuance of information. They are stored frequently used programs and data (see Devices, Storage). However, the exchange rate between constant memory and the central processor, in the overwhelming majority of cases, is significantly less than that of RAM.

Input devices (UVV) and output (HC)Categories the category of peripheral devices. Before work I / O devices led the central processor, which occupied a lot of time. The architecture of modern computer provides for the presence of direct access channels to exchange data with I / O devices without the participation of the central processor, as well as the transmission of most peripheral control functions with specialized processors unloading the central processor and increases its performance.

Interrupt system. Interruptthe situation is called the situation that requires any actions of the microprocessor when a certain event occurs. Under the interrupt system, a software and hardware complex that ensures the execution and processing of interrupts is understood.

The processor must respond quickly to various events occurring in a computer as a result of operator actions or without its knowledge. As examples of this kind, you can press the keypad keys, an attempt to divide to zero (during the program), power failure (other malfunctions in the equipment), planned access to the core of the operating system and the other. The necessary interrupt response provides interrupt system.

Processing interrupt It comes down to the suspension of the current command sequence, instead of which the other sequence corresponds to the interrupt type and called the interrupt handler begins to be interpreted. After its implementation, the execution of the program can be continued if this is possible or appropriate, which depends on the type of interrupt.

I / O port system Provides direct connection of the peripheral device adapter to the system bus, that is, in fact, it is a point of such a connection of the peripheral device to the computer system. Each I / O port has its own address, with a peripheral device several I / O ports can be assigned. The set of I / O ports form a system of I / O ports. A simplified I / O port can be considered a register in which the information for transmitting its e l peripheral device or from which the information obtained from the peripheral device is read.

From the user's point of view, port - This is an interface (connector) for connecting the device (keyboard, mouse, display, printer, headphones, etc.) to the computer. Typically, the input ports are located on the rear panel of the system module case, some of them can be carried out on the front panel.

Adapter, controller. The concept of "peripheral adapter" can be considered synonymous with the term "controller", but the latter is more often used for the device implementing more complex functions for controlling peripheral devices (Fig. 5).

Fig. 5.Videocontroller. Manages image output to display

Developed controllers of peripheral devices include specialized microprocessors and memory. The same applies to peripheral devices with complex work algorithms that require the presence of perfect control units. From the user's point of view, the (adapter or controller) is a board with a set of chips and I / O ports, its task is controlled by the device connected to it. It can be display, printer, audio devices, etc.

Interface adapter - This is a means of interfacing a central part of a computer with peripheral devices, in which all physical and logical parameters meet predetermined parameters (specific protocol) and are widely used in other devices.

Fig. 6. Interface adapter

Modern computer system architecture. Saving the principles of building a computer architecture on Neymanan, modern architecture has been enriched with additional principles and today the architecture of the EUM is determined by the following principles:

• Program management principle. Provides automation of the process of computing on a computer, according to this principle, a program is drawn up to solve each task that determines the sequence of computer actions. The efficiency of the software control will be higher when solving the task of the same program many times (albeit with different initial data).
• The principle of the program stored in memory. According to this principle, the program commands are submitted, as data, in the form of numbers and processed in the same way as the numbers, and the program itself is loaded into RAM itself, which speeds up the process of its execution.
• The principle of arbitrary access to memory. In accordance with this principle, the elements of the programs can be recorded in an arbitrary RAM location, which allows you to contact any specified address (to a specific section of memory) without viewing the previous ones.
• The principle of separation of functions. The processor manages all the highest level operations, while the specific interpretation of its general commands for individual devices implements special control devices - controllers. The processor can process information only if it has already undergone primary processing. This feature takes on the controllers of the input device. They lead the input to the Unified Standard. Then the data is sent to the RAM, where they are distributed over the cells and are provided with references (addresses) necessary to use them. The output of information is also occurring through the mediation of the control devices of the output, which again produce reformatted data to the desired standard. In principle, all computer devices have their own controllers (drives, monitor, printer, plotter, streamer, etc.) based on this, one of the important principles of the computer work can be formulated.

Functional subsystems. In the process of its work, the computer carries out:

• Entering information from outside;
• Temporary storage;
• Transformation;
• Conclusion in the form, accessible to perception, her man.

The process of obtaining data by computer is called briefly " input", And issuing it to the user - "output". These processes are so important that a large number of diverse devices have been proposed to implement them. In addition, we must not forget that "input" and "output" are two sides of one process of information sharing, and without one of them there is no other. Therefore, when NE is talking about data transformation, and the term "Introduction" is used to transmit them to the computer for computing and obtaining the outcome result.

During the input process, the data is given to the format that can be perceived by the computer, and when the output is to the form, familiar to humans.

In each of the listed stages of the process, a separate functional subsystem is being implemented:

• data entry subsystem;
• data storage subsystem;
• data conversion subsystem;
• information conclusion subsystem.

All subsystems are interconnected by exchange channels, grouped into streams. In addition to the data and commands, they carry timer signals and the supply voltage to all computer blocks. These streams have a constructive expression in the form of wires and connectors that have a tire name (see below).

Subsystem of input devices. Entering information to the computer is carried out by specialized devices as standard, (see below) and non-standard (optional).

Entering information into a personal computer is carried out in three stages:

• perception of information from outside;
• bringing data to a specific format, understandable computer;
• transmission of data on a computer tire;

Subsystem of output devices. The information conclusion subsystem allows the computer to get the results of work in the usual form. Information output devices as well. Like information entry devices, may be standard (see below) and non-standard (optional).

The output of information is also carried out in three stages, and their order is reverse in the process of input:

• perception of information transmitted by tire channels;
• bringing information to the format characteristic of the output device;
• issuing results of work on. Information output devices.

Conversion subsystem. The data conversion to information in the computer is carried out by the processor. The processor, at least contains a control device ( Uu) and arithmetic logical device ( Al.). The control device is essentially a "master" of the computer and performs the following functions:

• sets the order for the tasks performed by the system;
• generates control signals to distribute operations and data streams both inside an arithmetic and logical device and outside;
• manages the transfer of information on the address bus and the data bus;
• perceives and processes the service signals following the system control bus.

Storage subsystem. In order to work effectively with data, the processor must have quick and free access to them. Intermediate storage functions performs information storage subsystem. Enrolled in the computer from the entry subsystem, the information provided to a specific internal standard is located in the RAM cells, after which, as needed. processed by a processor.

The memory of the personal computer is implemented on electronic elements and, as mentioned above, is energy-dependent. This method of storing information is very vulnerable. Upon completion of the session, the contents of the RAM is recorded on the disk. Now there is no sugudious power off for the data, because the information recorded on the disk will restore everything in memory. What was before.

For long-term and reliable data storage, many more reliable devices have been created; Magnetic and magneto optical drives, magnetic tape drives and others.

In external storage devices ( Piping) There are two main advantages over RAM:

• storage of information does not require energy;
• information volumes can be extremely large.

Based on these principles, it can be argued that modern computer - This is a technical device that after entering the initial data in the form of digital codes and their processing programs, expressed by digital codes, is able to automatically implement a computing process as specified by the program, and to issue the finished results of solving the problem in the form suitable for human perception.

Methods computer classifications. Nomenclature of computers today is huge: the cars differ in purpose, power, size, element base, etc. Therefore, classified computers on different features. It should be noted that any classification is to some extent conditional, since the development of computer science and technology is so stormy that. For example, today's MI to computer is not inferior in power with a miniva of five years ago and even supercomputers of the recent past. In addition, enrollment of computers to a specific class is quite conditionally through the fuzziness of the separation of groups and due to the implementation of the customer assembly of computers, where the native nomenclature and specific models adapt to the requirements of the customer. Consider the common criteria for classifying computers.

Classification by appointment

• large electronic computing machines (BESM);
• miniva;
• microcomputer:
• personal computers.

Large EUM.(Main.Frame.) . Apply for servicing large areas of the national economy. They are characterized by powerful parallel working processors (the number of which reaches up to 100), integral speed up to tens of billions of operations per second, multiplayer work regime.

On the basis of large computers, a computing center is created, which contains several departments or groups (Table 1). The structure of the computing center based on a large computer may be as follows:

• CPU - The main BEVM unit. in which data processing and the calculation of the results occurs. It is several system units in a separate room, where constant temperature and air humidity are supported.
• Group of system programming - Engaged in developing, debugging and implementing the software necessary for the functioning of the computing system. System Programs Provide interaction of programs with equipment, that is, the software and hardware interface of the computing system.
• Applied programming group - Creation of programs for performing specific actions with data, that is, providing the user interface of the computing system.
• Data preparation group - Data preparations that will be processed on applied programs created by application programmers. In particular, this is a set of text, scanning images, filling in databases.
• Technical Support Group - Engaged maintenance All computing system, repair and debugging of equipment, connecting new devices.
• Information support group - Provides technical information All units of the computing center creates and saves the archives of the developed programs (program library) and accumulated data (data banks).
• Division Division - Gets data from the central processor and turns them into a form, convenient for the customer (printout).

The high cost of equipment and maintenance is inherent in the high computer, so the work is organized by a continuous cycle.

Minicomputer. This category is similar to large computer, but smaller sizes. Used at large enterprises, scientific institutions and organizations. Often used to manage production, processes. Characterized by multiprocessor architecture, connecting up to 200 terminals, disk storage devices that are increasing to hundreds of gigabytes, branched periphery. To organize work with miniva, we need a computing center, but less than for large computers.

Microcomputer. Microcomputer (Microcomputer) is a computing system in which a microprocessor is used as a control and arithmetic device. In more advanced micro-computers, several microprocessors can be used. The performance of this system is determined not only by the characteristics of the processor used, but also the capacity of the available RAM, types of peripheral devices, the quality of structural solutions, extensibility, etc. Now they have become in tools To solve complex tasks. Microprocessors have become more powerful, and the peripheral devices are more efficient, so micro-computer is currently displaced by mini-computer and the difference between them gradually decreases. On computers of this particular category, this course is calculated.

Microcomputers can be divided into professional and domestic ones. Due to the reduction of hardware, the line between them is gradually blurred. Since 1999, an international certification standard has been introduced - the PC99 specification:

• mass personal computer (Consumer PC) - relatively non-expensive systems that meet the requirements of the user;
• business Personal Computer (Office PC) - have a minimum of playback of graphics and sound;
• portable Personal Computer (Mobile PC) - differ in the presence of means of communication of remote access (Computer Communication);
• workstation (workstation) - differ in increased requirements for storage and processing devices;
• entertainment Personal Computer (Entertainment PC) - make the focus on multimedia using developed graphics and sound playback.

Classification of microcomputers for the intended purpose or level of specialization.

• multiplayer microcomputers (Servers) are microcomputers working in time separation mode ensuring the operation of several users at the same time. They are performed in one small-sized rack or in the desktop version and in most cases are a subset of the computer network.
• specialized or workstations (ARMS) - are a microcomputer equipped with all the means necessary to perform a specific type of work. There are AWP Engineering, graphic, automated design, publishing (desktop publishing systems) and others.
• built-in microcomputers - are computing systems created to solve specific tasks. Used to control (for example, a machine or machine complex, scientific equipment, combat unit, etc.) and measurement processing. Structurally, they are performed in the form of one or several boards and do not ensure the implementation of a wide range of computing functions, as well as standard interaction with the user.

Classification by size. In addition to the target, depending on constructive use, microcomputers are divided into stationary and portable.

• Stationary microcomputers. Installed on the table, a tamba or in the form of a small-sized rack on the floor.
• Portable microcomputers. Have a relatively small mass and dimensions, transported by one person, as a rule, do not have an autonomous nutrition;
• Portable microcomputers C. autonomous nutrition . They are divided into a number of categories:
• Challenged(Laptop), made in the form of a diplomat;
• Pocket(Pocket) placed in your pocket.

The most common are desktop microcomputers that allow you to easily change the configuration. Portable are convenient for use, have computer communication. Pocket models can be called "intelligent" notebooks, allow you to store operational data and get quick access to them.

Compatibility classification. There are a great many types of computers that are collected from parts made by different manufacturers. It is important to ensure the compatibility of the computer, which has several levels:

• hardware compatibility (IBM PC and Apple Macintosh Platform);
• compatibility at the level of the operating system;
• software compatibility;
• data Compatibility.

Questions for self-control

1. What is called computing technology?
   1. What is called computing system?
   2. What is a computer?
   3. What is an AMM architecture?
   4. List the principles of building an architecture of the Neumanu computer?
   5. What is speed?
   6. What is computer performance?
   7. What is a processor?
   8. What is an arithmetic logical device?
   9. What is the control device?
   10. What is a storage device?
   11. What is RAM?
   12. What is an external storage device?
   13. What is interruption?
   14. What is the interrupt system?
   15. What is the processing of interrupts and interrupt handler?
   16. What is an I / O port?
   17. What is an adapter and controller?
   18. What is the interface adapter?
   19. What functions performs computer in the process of its work?
   20. List the functional support subsystems.
   21. What functions does the data entry subsystem?
   22. What functions is the data output subsystem?
   23. What functions is carried out by the data conversion subsystem?
   24. What is a microcomputer?
   25. What is the server?
   26. What is AWP?
   27. List the types of compatibility of computer systems?

EUM memory consists of binary storage elements - bits (Binary Digit - binary digit). In conventional computers, cells consisting of four sequentially located bytes are used (from words), but in early computers, single or double-byte cells (half-use) are used, and in some super-computer - eight-bike cells.

Only one number or one command can be recorded in each memory cell. The binary code is stored in the cell until the new binary code is recorded in it or the machine will not be de-energized. Selling memory for words for four-proof computer is represented in Fig. 2.16.

64-bit processor

32-bit processor

16-bit cPU

Half-word

Half-word

Half-word

Half-word

Double Word

Fig. 2.16. Breakage of memory for words in PEVM

Modern computers adopted 32-bit addressing, which means that independent addresses can be 2 32. Thus, it is possible to directly add to the memory field in size 2 32 \u003d 4 294 967 296 bytes (4.3 GB).

There are information storage devices implemented in the form of electronic circuits, and information drives with which data is written to any carrier (Fig. 2.17), for example, magnetic or optical (previously used paper carriers - cards and punched).

External memory is located on magnetic or optical disks. Recording and reading information when working with external memory occurs more slowly than when working with Jam, but the external memory has a large volume and its contents does not change when the computer is turned off.

Non-volatile memory is represented by the memory microcircuit, which records information about the type of computer equipment

Electronic circuits information drives

Operational magnetic magnetic

storage device (RAM, RAM) or RAM

Permanent storage device (ROM, ROM)

tape disks

Flexible hard

magnetic Magnetic Disks Disks

(Disa) (Winchesters)

Optical magneto optical disks

Simple with the ability (CD) entries

Fig. 2.17. Classification of drives and devices

information storage

thera and its configuration. The PC setting may vary at the request of the user, so non-volatile memory allows not only to read data from it, but also record. Essentially, the usual RAM chip, but made according to special CMOS technology, which provides small energy consumption during the operation of this device, so non-volatile memory is often called CMOS memory. On CMOS technology, all microcircuits for portable PCs are manufactured to provide long-term operation of their batteries. The non-volatile memory microcircuit is connected to the battery, which saves the data recorded in the chip when the PC is turned off from the network.

Devices electronic circuitsDifferent with a small data access time, but do not allow to store large amounts of information. Information storage devices, on the contrary, make it possible to store large amounts of information, but the time of its recording and reading is large, therefore effective work On a computer is possible only when sharing the drives of information and storage devices implemented in the form of electronic circuits.

BIOS CHIP (BASIC INPUT / OUTPUT SYSTEM - Basic I / O system). This is a built-in computer softwarewhich is available without accessing the disk; A set of programs designed to automatically test devices after turning on the computer and download the operating system into RAM.

The role of BIOS double: on the one hand, this is an integral element of equipment (hardware), and on the other hand, an important module of any operating system (Software). BIOS contains the code required to control the keyboard, video card, discs, ports and other devices.

Usually, the BIOS is located in the ROM microcircuit (ROM) located on the computer's motherboard (therefore this chip is often called ROM BIOS). This technology allows BIOS to always be accessible, despite damage, for example, a disk system and allows the computer to load yourself independently. Because access to RAM (RAM) is carried out much faster than ROM, computer manufacturers create systems in such a way that when the computer is turned on, the BIOS is copied from the ROM into RAM.

The permanent memory is designed to store the constant information that is recorded in the constant memory chipboard by the manufacturer of the computer. The BIOS includes the computer's self-testing program when it is turned on, drivers of some devices (monitor, disk drives of information, etc.), as well as the operating system boot program from disk devices. Currently, almost all motherboards are equipped with a microcircuit for constant storage of the initial executable code for downloading a Flash BIOS Comer, which at any time can be overwritten in the ROM chip using a special program.

External storage device (s). This device is divided into an operational storage device, a constant storage device and cache memory.

The external memory is designed for long-term storage of programs and data, and the integrity of its content does not depend on whether the computer is turned on or off. Additional devices external memory are:

• FDD (FLOPPY DISK Drive) - Drive on flexible magnetic discs, Capacity - 1.44 MB;
• CD-ROM and R / W - drive on laser CDs, capacity - 800 MB;
• DVD-ROM and R / W - drive on laser DVDs, capacity - up to 16 GB;
• HDD (Hard Disk Drive) - storage device on rigid magnetic disks, capacity - more than 100 GB;
• Flash is a storage device on memory chips, capacity - up to 8 GB.

The computer's memory should consist of a certain number of numbered cells, each of which may be either processed data, or instructions of programs. All memory cells must be equally available for other computer devices.

Operational storage device (RAM, English Random Access Memory, RAM) - Designed for recording, reading and temporary storage of programs (system and applied), source data, intermediate and final results.

When you turn off the computer, information in RAM is erased. In modern computers, the amount of memory is usually from 128 MB to 2 GB. The amount of memory is an important feature of the computer, it affects the speed of the computer and on the performance of programs. Modern application programs Often require more than 4 MB of memory, otherwise the program simply will not be able to work. Part of the RAM, called "video memory", contains data corresponding to the current image on the screen.

Constructively elements of RAM are performed as a DIP type chip (Dual In-Line Package - a two-row output position) or in the form of a SIP memory modules (Single In-Line Package - a single-row conclusion location).

Personal computer contains four types of RAM: SIMM modules used in outdated computers on processors 386, 486 and PENTIUM; More advanced DIMM modules used in computers from Pentium II and Celeron to Pentium III and Athlon; More modern DDR DIMM and MMM modules, which are used with new processors and motherboards. The operational storage device is built on memory chips with arbitrary access to any cell. RAM is either static (on triggers) and is called SRAM (Static RAM) or dynamic (based on condenser cells) - DRAM (Dynamic RAM).

In static RAM, a static trigger is used as EP, which is capable of maintaining a state of 0 or 1 indefinitely for a long time (with a PC included). Dynamic RAMs are built on capacitors implemented inside silicon crystal. Dynamic EP (capacitors) over time Ca-moralized and recorded information is lost, so the dynamic EP requires periodic charge recovery - regeneration. During regeneration, recording new information should be prohibited.

Compared with static dynamic RAMs have a higher specific capacity and less cost, but more power consumption and less speed. Operational storage devices have modular structure. An increase in the RAM capacitance is made by installing additional modules. Access time to DRAM modules is 60-70 ns.

Modern computers have RAM, which makes up 512-1024 MB. The computer processor can only work with data that are in RAM. Data from disk for processing is read into RAM. Main firms - Memory Manufacturers - IBM, Seagate, Maxtor, Western, Digital, Fujitsi and Kingston. The share of DIMM memory sales is significantly reduced, giving way to the DDR DIMM memory modules (256 and 512 MB) or RIMM (128 and 256 MB).

Permanent memory (ROM, English Real Only Memory - ROM - read-only memory) - non-volatile memory, used to store data that never require change.

ROM modules and cassettes have a container, as a rule, not exceeding several hundred kilobytes. Structurally, the main memory consists of millions of individual memory cells with a capacity of 1 bytes each. The total capacity of the main memory of modern PCs usually lies in the range from 1 to 32 MB.

Reprogramped permanent memory (Flash Memory) - non-volatile memory that allows multiple rewriting of its contents from a floppy disk.

Register Cash Memory - High-speed memory, which is a buffer between the RAM and a microprocessor, allowing to increase the speed of operations. It is advisable to create it in a personal computer with a clock frequency of a solid generator 40 MHz and more. Cash memory registers are not available for the user, from here and the name of the cache (English, Cache is a cache). According to the principle of recording results, two types of cache memory distinguish:

With a return record - the results of operations before writing them with RAM, fixed in the cache, and then

the cache-memory troller independently overwrites this data in RAM;

With through recording - the results of operations are simultaneously written in parallel and in the cache, and in RAM.

To speed up operations with the basic memory, register cache memory inside the microprocessor (first-level cache) is used or outside the microprocessor on the motherboard (second-level cache memory). To speed up operations with disk memory, cache memory is organized on electronic memory cells.

Pentium and Pentium Pro microprocessors have cache memory separately for data and separately for teams, and if the Pentium contains a small capacity of this memory - 8 KB, then the Pentium Pro it reaches 256-512 KB. It should be borne in mind that for all MPs an additional cache memory, placed on the motherboard outside the MP, which can be achieved by several megabytes.

The main purpose of the application of cache - compensation of the difference in the rate of information processing processor (its registers are the fastest) and somewhat less high-speed RAM. Cache memory is not available for the user, used by the computer automatically. It should be borne in mind that the presence of a cache with a capacity of 256 KB increases the PC performance by about 20%.

Main memory The computer is divided into two logical areas: directly addressed memory, which occupies the first 1024 kb of cells with addresses from 0 to 1024 KB - 1, and advanced memory, access to cells of which is possible when using special drivers.

Standard memory Conventional Memory Area - SMA) is called directly addressable memory in the range from 0 to 640 KB. Directly addressed memory in the address range from 640 to 1024 KB is called upper memory(Uma - Upper Memory Area). The top memory is reserved for monitor memory (video memory) and a permanent storage device. However, it usually remains free areas - "windows", which can be used using a memory manager as a general-purpose RAM.

Extended memory - Memory with addresses 1024 KB and higher. Immediate access to this memory is possible only in the protected mode of the microprocessor. In real mode there are two ways to access this memory, but only when using drivers: by XMS specifications and EMS (Expended Memory Specification).

Access to advanced memory according to the XMS specification is organized when using Hmm Drivers (Extended Memory Manager). This memory is often referred to as additional, given that in the first models of personal computers, this memory was posted on separate additional fees. The EMS specification is earlier, it is implemented by displaying Expanded Memory fields to a specific top memory area. At the same time, not processed information is stored, but only addresses that provide access to this information. Memory, organized by the EMS specification, is called displayed.

Extended memory can be used mainly to store data and some OS programs. Advanced memory is often used to organize virtual (electronic) disks.

Video memory (VRAM) is a kind of operational RAM, which stores encoded images. This memory is organized so that its contents are available directly to two devices - processor and monitor, so the image on the screen changes simultaneously with the update of video data in memory.

Controllers and adapters There are sets of electronic circuits that are supplied with a computer device in order to compatibility of their interfaces. Controllers, in addition, are directly controlled by peripheral devices at the request of the microprocessor.

Ports of devices There are electronic circuits containing one or more I / O registers and allow you to connect the peripherals of the computer to the outer tires of the microprocessor.

System (maternal) computer board. The motherboard is the main board of PC (Fig. 2.18), on which:

• processor (microcircuit that performs most computing operations);
• microprocessor kit (chipset) - a set of microcircuits controlling the operation of the internal devices of the computer;
• three tires (sets of conductors for which signal exchange between the internal devices of the computer);
• RAM (RAM) - a set of microcircuits intended for temporary storage of data;
• ROM is a microcircuit designed for long-term storage of data;
• connectors (slots) to connect additional devices;
• System board monitoring tools.

Zones of external connectors slots board

built-in periphery expansion

Fig. 2.18. Computer motherboard

Synchronization and acceleration of motherboard. The main clock generator of the motherboard produces highly stable pulses of the reference frequency used to synchronize the processor, memory and I / O bus. Since the speed of these subsystems differs significantly, each of them can be synchronized with its frequency. In the chipsets of asynchronous type of frequency relatively independent, which opens up the possibility to optimize productivity and acceleration. The most frequent object for overclocking is the central processor. It is quite obvious that the performance of a specific processor depends on the clock frequency of the kernel and the frequency of the system tire. The first component determines the processing rate, and the second is the speed of delivery of instructions and data. The maximum allowable clock frequency is determined by the delays between various signals and the dispersed power of the processor.

Cache memory - Memory of a small capacity, but extremely high speed (treatment time to the MPP, i.e. the time required for the search, recording or reading information from this memory is measured by nanoseconds). It is intended for short-term storage, recording and issuing information in the nearest clocks of the machine, directly participating in the calculations.

CPU. This is the central part of any modern computer controlling the other devices. It contains an arithmetic logical device, a control device and registers for temporary storage of information. The processor reads data from RAM (RAM) of the computer, it sends the result of the action above these data. The processor can perform the following operations over binary numbers: arithmetic, logical, comparison operations, memory operations and control transmission operations.

The processor performs all actions only on the program, i.e. a certain sequence of commands. Most computer errors while working due to the programmer errors, which failed to provide all possible situations.

The processor performs the following functions:

• data processing for a given program by performing arithmetic and logical operations;
• Software management of computer devices.

The speed of the processor is determined by its clock frequency. What it is more, the more high-speed processor. Modern processors operate at frequencies of more than 3 GHz (Table 2.3).

Each specific processor can only work with a certain number of RAM. The maximum number of memory that the processor can serve,

Table 2.3. Processor manufacturers firms

is on targeted processor space and is an important characteristic of the computer. The address bus is determined by the address tire bit.