The first mass personal computer. Personal Computer: Definition and Classification, Open Architecture Principle, Computer Compatibility Concept, Basic PC Configuration, Basic and Additional Devices Most Modern PCs are

Introduction

Human society As it was developed, not only the substance and energy, but also information. With the appearance and mass distribution of computers, a person received a powerful tool for efficient use. information resources, To strengthen its intellectual activity. From this point on (the middle of the 20th century), the transition from an industrial society to the society of information, in which information is becoming the main resource.

The possibility of using members of society full, timely and reliable information to a large extent depends on the degree of development and development of new information technologies, the basis of which are computers. Consider the main milestones in the history of their development.

The beginning of the era of the EUM.

The first computer * ENIAC was created at the end of 1945 in the United States.

The main ideas in which many years have developed computing, were formulated in 1946 by American mathematician John von Neumanan. They got the name of architecture von Neuman.

In 1949, the first computer was built with the architecture of Nymanan - English EDSAC machine. A year later, an American computer EDVAC appeared.

In our country, the first computer was established in 1951. It was called MESM - Small Electronic counting machine. Designer MESM was Sergey Alekseevich Lebedev.

Serial production of computer began in the 50s of the 20th century.

Electronics and computing equipment is customary to divide for generations related to the change of element base. In addition, cars of different generations differ in logical architecture and software, speed, operational memory, method of entering and output information, etc.

The first generation of EUM.

The first generation of computers - lamp machines of the 50s. The speed of the account of the fastest first-generation machines reached 20 thousand operations per second. Perflectors and perfocards were used to enter programs and data. Since the internal memory of these machines was small (could accommodate several thousand numbers and program teams), then they were mainly used for engineering and scientific calculations that are not related to the processing of large amounts of data. These were pretty bulky structures that contain thousands of lamps, sometimes occupied hundreds of square meters that consumed electricity to hundreds of Kilowatt. Programs for such machines were compiled in the languages \u200b\u200bof machine commands, so programming in those times was available to a little.

Second generation of EUM.

In 1949, the first semiconductor device replacing the electronic lamp was created in the United States. He got the name of the transistor. In the 60stransistors have become an element base for the second generation. The transition to semiconductor elements has improved the quality of the computer in all respects: they have become more compact, more reliable, less energy-intensive. The speed of most machines has reached tens and hundreds of thousands of operations per second. Volume internal memory Erected hundreds of times compared with the first generation computer. Large development received devices of external (magnetic) memory: magnetic drums, drives on magnetic ribbons. Due to this, it became possible to create information and reference on the computer, search engines (This is due to the need to continue to store large amounts of information on magnetic media). In the second generation, programming languages \u200b\u200bactively began to develop high level. The first of them were Fortran, Algol, Cobol. Programming as a literacy element has become widely distributed, mainly among people with higher education.

First mass personal computer

30 years ago, on August 12, 1981, the world's first personal computer called IBM PC 5150, released by the well-known and understudy of the American International Business Machines, was born. One of the key figures participated in the creation of the first PC was the scientist and lead engineer IBM Mark Dean. Now the "computer dad" is 54 years old, and he still works in his native company.

It was the development of IBM PC 5150 that opened a new era of modern personal computers. This computer had a progenitor with an index 5100 - released in 1975, he, however, was intended to solve scientific tasks and therefore did not suit the mass user. Yes, and the price of the "scientist" of the computer was not a lot of 20 thousand dollars, while IBM PC 5150 at the most expensive configuration cost only 3 thousand dollars. In those days it was an impressive amount, but it did not prevent the mass spread of the PC.

IBM PC 5150 even looked like a familiar home computer - it consisted of a system unit in which drives, keyboards and a color display were placed. IBM itself, which was mostly engaged in the development of "large" computing machines, did not attach great importance to his new brain. However, it was in him that many computer standards that have lived more than a decade and only then changed to more advanced and progressive.

The third generation of EUM.

The third generation of computers was created on a new element base - integrated circuits: on a small plate made of semiconductor material, with an area of \u200b\u200bless than 1 cm2, complex electronic circuits were mounted. They were called integrated circuits (IP). The first IP contained dozens, then - hundreds of elements (transistors, resistance, etc.). When the degree of integration (the number of elements) approached a thousand, they began to call large integrated circuits - bis; Then there appeared super-high integrated circuits - SBI. The third generation computer began to be made in the second half of the 60s, when the American company IBM began to release the IBM-360 system. In the Soviet Union in the 70s, the release of cars began

EU Series EUM (Unified ECM System). The transition to the third generation is associated with significant changes in the computer architecture. There was an opportunity to perform several programs at the same time on one machine. Such a mode of operation is called multiprogram (multi-program) mode. The speed of operation of the most powerful models of EMM reached several million operations per second. On the third generation machines, a new type of external storage devices appeared - magnetic discs. New types of I / O devices are widely used: displays, grapheatteners. During this period, the areas of application of the computer were significantly expanded. Databases began to be created, the first artificial intelligence systems, automated design systems (CAD) and control (ACS) began. In the 70s received a powerful development of a small line (mini) computer.

Fourth generation EUM.

Another revolutionary event in electronics occurred in 1971, when an American company Intel announced the creation of a microprocessor. The microprocessor is a super-high integrated circuit capable of performing the functions of the main block of the computer - processor. Originally microprocessors began to embed in various technical devices: Machine tools, cars, airplanes. By connecting the microprocessor with I / O devices, external memory, received a new type of computer: microevm. Microevm belongs to the fourth generation machines. The essential difference between the microevm from its predecessors is their small dimensions (size of a household TV) and a comparative cheapness. This is the first type of computers that appeared in retail.

The most popular type of computers today are personal computers (PCs). The first PC appeared in 1976 in the United States. Since 1980, the American company IBM is becoming a "legislator mod" in the PC market. Its constructors managed to create such an architecture that became actually an international standard for professional PC. Machines of this series were named IBM PC (Personal Computer). The emergence and distribution of PCs in its value for social development is comparable to the advent of typography. It is PC that made computer literacy by mass phenomenon. With the development of this type of machines, the concept appeared information Technology", Without which it becomes impossible to do in most areas of human activity.

A computer (Computer - "Computer"), computer (Electronic computing) - a computing machine for transmitting, storing and processing information.

The term "computer" and abbreviation "EUM" (electronic computing) adopted in the USSR are synonymous. However, after the appearance of personal computers, the term computers was practically disassembled. Currently, the abbreviation "EUM" is mainly used in the historical sense - for the designation of computer equipment of the 1940-1970s, especially Soviet production, as well as, as a legal term, in legal documents.

With the help of calculations, the computer is able to process information on a predetermined algorithm. Computers received their name by the main function - carry out calculations. Currently, most computers are used to process and manage information, as well as games, but also these tasks for the computer are also a sequence of computing.

Physically, a computer can function due to the movement of any mechanical parts, movement of electrons, photons, quantum particles, or by using the effects of any other physical phenomena.

Computer architecture can directly simulate the solved problem, as close as possible (in the sense of the mathematical description) reflecting the studied physical phenomena. Thus, electronic streams can be used as water stream models when modeling dams or dams. Similarly, constructed analog computers were common in the 1960s, but today they became quite rare.

In most modern computers, the problem is first described in them in mind (at the same time, all the necessary information is usually represented in binary form - in the form of units and zeros, although there were computers on the Tropic Number System), after which the actions for its processing are applied to the use of simple Logic algebra. Since almost all mathematics can be reduced to the execution of boolean operations, fast enough electronic computer It can be applicable to solving most mathematical problems, as well as most of the tasks for processing information that can be reduced to mathematical.

It was found that computers may not solve any mathematical task. For the first time, the tasks that cannot be solved with the help of computers were described by the English mathematician Alan Turing.

The result of the task performed can be submitted to the user using various I / O devices, such as lamp indicators,

4. Tencies of the development of computing

According to experts, in the first decade of the XXI century. The importance of software will increase, increase the problems of its compatibility and security.

Among operating systems, further development will receive linux systems and Windows. From the point of view of the end user, in the coming years there must be serious changes in the style of its communication with the computer. First, the graphic data entry will be wider, including in the automatic manuscript recognition mode. Secondly, voice input will be used - first to control commands, and then automatic speech digitization will be mastered. To solve the above tasks, appropriate external devices will be developed.

A great importance in the future will have work in the field of intelligent processing of unstructured data, first of all texts, and then graphics, sound, video.

One of the most promising areas for the development of computing equipment is to implement the network computing concept using the idea of \u200b\u200battracting for computing free computers. This concept received the name GRID and includes five key items:

Application of open standards;

Combining heterogeneous systems;

Data sharing;

Dynamic allocation of resources;

Combining computing networks of multiple enterprises and organizations.

The development of the computer will go along the way to create optoelectronic computers with mass parallelism and neural structure, which are a distributed network of a large number (tens of thousands) simple microprocessors that simulate the architecture of neural biological systems.

Further development will receive portable personal computers with wireless connections to the global Internet.

It should be noted that the development of computing technology is entirely depends on the development trends of the global economic system.

Lecture number 6 History of development of computing

Lecture No. 3 generation and computers

1. Computing technology

Select five email generations.

First generation (1945-1954) is characterized by the appearance of equipment on electronic lamps. This is the era of the formation of computing equipment. Most of the first-generation machines were experimental devices and were created to verify those or other theoretical provisions. The weight and size of these computers were such that they often demanded separate buildings.

The founders of computer science are considered to be Claude Shannon - the creator of the theory of information, Alan Turing - mathematician, who has developed the theory of programs and algorithms, and John von Neumann - the author of the design of computing devices, which up to the present is based on most computers. In the same years, another new science associated with computer science appeared - cybernetics - science of management as one of the main information processes. The founder of cybernetics is American mathematician Norbert Wiener.

In the second generation (1955-1964) Instead of electronic lamps, transistors were used, and magnetic cores and drums were used as memory devices - prototypes of modern hard drives. All this allowed to reduce the dimensions and the cost of computers, which then began to be made for the first time.

But the main achievements of this era relate to the fields of programs. In the second generation, for the first time, it appeared that today is called the operating system. At the same time, the first high-level languages \u200b\u200bwere developed - Fortran, Algol, Cobol. Two of these important improvements made it possible to significantly simplify and speed up writing programs for computers.

This expanded the scope of application of computers. Now, not only scientists could count on access to computing, since computers have found application in planning and management, and some large firms even began to computerize their accounting, anticipating this process for twenty years.

IN third generation (1965-1974) Integrated circuits were used for the first time - integrated devices and knots of dozens and hundreds of transistors, made on one semiconductor crystal (chip). At the same time, a semiconductor memory appeared, which is still used in personal computers as an operational.

In those years, the manufacture of computers has accepted industrial scope. IBM first implemented a series of fully compatible with each other computers from the smallest, size with a small wardrobe (less then did not yet), up to the most powerful and expensive models. The most common System / 360 family of the company IBM was the most common in those years, on the basis of which the EU AUM series was developed in the USSR. Even in the early 1960s. The first minicomputers appeared - little powerful computersAvailable at small firms or laboratories. Mini computers were the first step towards personal computers, the trial samples of which were released only in the mid-1970s.

Meanwhile, the number of elements and compounds that fit in one microcircuit constantly growed, and in the 1970s. Integrated schemes have already contained thousands of transistors.

In 1971, Intel released the first microprocessor, which was intended for only the desktop calculators. This invention has produced the real revolution next decade. The microprocessor is the main component of the modern personal computer.

At the turn of the 1960 -70s. (1969) appeared the first global computer network ARPA, prototype of the modern Internet. In the same 1969, at the same time the UNIX operating system and the programming language with ("SI") appeared, which had a huge impact on the program world and still retaining their dominant position.

Fourth generation (1975 -1985) is characterized by a small number of fundamental innovations in computer science. Progress was mainly in the way of developing the fact that already invented and invented, first of all, by increasing the capacity and miniaturization of the element base and the computers themselves.

The main innovation of the fourth generation is the appearance in the early 1980s. Personal computers. Thanks to them, computing equipment becomes truly massive and publicly available. Despite the fact that personal and mini computers are still in computing power behind solid cars, most of the innovations, such as a graphical user interface, new peripheral devices, global networks are related to the emergence and development of this technique.

Large computers and supercomputers, of course, continue to develop. But now they no longer dominate the computer world, as it was before.

Some characteristics of the computing equipment of the four generations are given in

Characteristic	Position
	first	second	third	fourth
Main element	Electric lamp	Transistor	Integrated circuit	Large integrated circuit
The number of computers in the world, pcs.			Tens of thousands	Millions
EU size		Significantly less	Tens of thousands	Micro EUM.
Speed \u200b\u200b(conditional) operations /from	Several units	Several dozen units	Several thousand units	Several tens of thousands of units
Media information	Perfocart, pungent	Magnetic tape		Flexible disk

Fifth generation (1986 so far) is largely determined by the results of the Japanese Committee of Scientific Research in the EMM, published in 1981. According to this project, the computer and computational systems of the fifth generation besides high performance and reliability at a lower cost using the latest technologies should meet the following qualitatively new functional requirements:

ensure the simplicity of computer use by implementing information I / O systems to voice, as well as dialogue information processing using natural languages;

ensure the possibility of trainee, associative constructions and logical conclusions;

simplify the process of creating software by automating the synthesis of programs on the specifications of source requirements in natural languages;

improve the main characteristics and performance of computing equipment to meet various social tasks, improve cost ratios and results, speed, ease, compactness of computer;

provide a variety of computing equipment, high adaptability to applications and reliability in operation.

Currently, intensive work is underway to create optoelectronic computers with mass parallelism and neural structure, which are a distributed network of a large number (tens of thousands of thousands) simple microprocessors that simulate the architecture of neural biological systems.

2. Classification of electronic computing machines

EUM can be classified for a number of signs:

According to the principle of action.

For appointment of computer.

In size and functionality.

According to the principle of operation of the computer :

AVM - Analog Computing Machines of Continuous Action, work with information presented in a continuous (analog) form, i.e. in the form of a continuous range of any physical values \u200b\u200b(most often electrical voltage);

TsMM - digital computing machines of discrete action, work with the information presented in the discrete (digital) form;

GMM - hybrid computing machines of combined action, work with information presented in digital and analog form. GWM combine the advantages of AVM and TsM. It is advisable to use them to solve the tasks of management of complex high-speed technical complexes.

By appointment of EUM. :

universal EUM. Designed to solve various engineering and technical tasks: economic, mathematical, information and other, characterized complexity of algorithms and a large amount of data being processed;

problem-oriented computers serve to solve a narrower circle of tasks associated, as a rule, with the control of technological processes;

specialized EUM. Used to solve a narrow circle of tasks or implementing a strictly defined group of functions.

In size and functional :

ultra-low (micro computer) are obliged by their appearance of the microprocessor, the presence of which originally served as a determining sign of a micro computer, although now microprocessors are used in everyone without exception;

small (mini-computer) used most often to control technological processes;

large EUM. Most often called mainframes (Mainframe). The main directions of the effective use of mainframes are the solution of scientific and technical tasks, work in computing systems with batch processing information, work with large databases, management of computing networks and their resources;

super-heavy (superevm)- Powerful multiprocessor computing machines to the speed of tens of billions of operations per second and the amount of RAM of dozens GB.

3. Principles of the structure and functioning of the computer John von Neumana

Most modern computers operate on the basis of the principles formulated in 1945 by American scientists of Hungarian origin John von Neumanan.

1. The principle of binary coding. According to this, all information coming into the computer is encoded using binary characters (signals).

2. Program management principle. The computer program consists of a set of commands that are performed by the processor automatically after each other in a specific sequence.

3. The principle of uniformity of memory. Programs and data are stored in the same memory, so 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.

4. Principle of targeted. Structurally, the main memory consists of numbered cells, any of which is available to the processor at any time.

According to Nimanan, the computer consists of the following main blocks:

1) information input / output device;

2) Memory computers;

3) A processor, including control device (UU) and an arithmetic logic device (ALU).

During the work of the computer, information via input devices is in memory. The processor retrieves the processed information from memory, it works with it and puts the results of processing. The results obtained through the output devices are communicated to a person.

EMM memory consists of two types of memory: internal ( operative) and external ( long term).

RAM - this is electronic devicewhich stores information while powered by electricity. External memory is various magnetic media (ribbons, discs), optical discs.

Over the past decades, the process of improving computer was walking within the framework of the above-generalized structure.

4. Classification of personal computers

As mentioned above, the personal computer (PC) is a universal single-user micro computer.

Personal computer primarily is a public computer and has a certain versatility.

To meet the needs of the PC user must have the following properties:

have a relatively small cost, be accessible to an individual buyer;

ensure the autonomy of operation without special requirements for environmental conditions;

ensure the flexibility of architecture that makes it possible to restructure for various applications in the field of management, science, education, in everyday life;

the operating system and software should be simple enough to work with the PC to work without professional special training;

have a high reliability of work (more than 5,000 hours of failure).

In accordance with the International Standard-specification of the PC99, the PC for intended purpose is divided into the following categories:

mass PC (Consumer);

business PC (Office PC);

portable PC (Mobile PC);

workstation (Workstation PC);

entertainment PC (Entertainment PC).

Most PCs currently available on the market are massive. For business PCs, the requirements for the reproduction of graphics are minimized, and the requirements are not presented to the tools with sound data. For portable PC, the presence of means for creating remote access connections, i.e. Computer communication means. The workstation categories have increased requirements for storage devices, and in the category of entertainment PCs - to the means of playing sound and video.

According to PC generations are divided:

on the 1st generation PC, 8-bit microprocessors use;

PC 2nd generation, 16-bit microprocessors are used;

3rd generation PCs, 32-bit microprocessors are used;

4th generation PCs, use 64-bit microprocessors.

PC can also be divided into two large groups: stationary and portable. Portable computers include laptops, electronic notebooks, secretaries and notebooks.

Classification of computers.

Computer definition.

In the left and right parts of the EV equation in the vertical sections of the calculation scheme.

The equation is solved relative to H 1. Substituting EV expressions (see Formulas 5, 7, 8) We get:

Personal computers (PCs) and their classification.

(Slide 1)

1. Definition of a computer.

2. Classification of computers on the principle of action

3. Classification of computers in the creation stages and element database.

4. Classification on the principles of operation and use.

4.1. Large computers or mainframe.

4.2. Small computers or Mini -computer.

4.3. Microcomputerii Micro -computer .

5. Network classification of computer.

6. Personal computers (PCs) and their classification.

6.1. Classification according to the PC99 specification.

6.2. Classification in terms of specialization.

6.3. Classification for appointment and sizes.

6.4. Compatibility classification

6.5. Classification of the type of processor used.

7. The main conclusions.
1. Definition of a computer.

Preliminary definitions .

· Computer Engineering - a combination of devices intended for automatic or automated data processing .

· Computing system - a specific set of interacting devices and programs intended for servicing one workplace.

· computer (electronic computing) or A computer - ­ central device of most computing systems.

· A computer - this is a universal electronic device designed to automate processes and work on creating, storing, processing, transporting, playing and issuing data.

Basic definition.

Electronic computeror a computer - this is a complex of hardware and software, designed to automate the preparation and solving user tasks. Under user. Understand the person, in the interests of which data processing is carried out. To reduce the complexity of the preparation of tasks to solve, efficiently use individual technical, software and computer In general, as well as facilitating their operation, each computer has a special software package.

Part of the software provides user interaction with computer And is a kind of mediator between them. She got a name operating system and is software core computer.

Under software meals complex software regular use, the purpose of creating the necessary service to work users.

2. Classification of computers projections.

Computers can be classified for a number of signs, in particular:

· operating principle;

· Stages of creation and element base;

· Appointment;

· Method for organizing computing process;

· Size, computing power;

· Functionality;

· The ability to parallel execution of programs, etc.

By principle of action computer They are divided into three large classes:

· analog;

· digital;

· hybrid.

TSM- digital computing machines or discrete-action computing machines - work with information presented in discrete, or rather digitally form.

AVM- analog computing machines or computational machines of continuous action - work with the information presented in a continuous (analog) form, that is, in the form of a continuous range of any physical values \u200b\u200b(most often electrical voltage).

GMM. - hybrid computing machines or computing machines of combined action - work with information presented in digital and in analog form; they combine dignity AVM and TSM. GMM. It is advisable to use for solving problems of management of complex high-speed technical complexes.

In economics , in science and technology gained overwhelming use Tsm S.electric reporting of discrete information - electronic Digital Computing Machines, commonly referred to electronic computational machines (COMPUTER).

3. Classification of computers to the creation and elemental database.

The main stages and trends of the development of computers, their hardware and software - (Slide 2)

By stages of creation and element base computers are conventionally divided into generations:

1st generation, 50s: computer on electronic vacuum lamps.

The main active element of computers first generation was electric lampThe remaining components of electronic equipment are conventional resistors, condensers, transformers. For the construction of RAM already from the middle 50-H. The elements specially designed for this purpose were used - ferrite cores. As an I / O devices, standard telegraph equipment (teletypes, ribbon perforators, transmitters, the equipment of countable perforation machines) were first used, and then electromechanical storage devices were developed on magnetic tapes, drums, disks and high-speed printing devices.

Computers of this generation had significant sizes, consumed greater power, had a relatively small speed, a small capacity of RAM, low reliability of operation. The speed of these machines was from several hundred to several thousand operations per second, the memory capacity is several thousand machine words, reliability was calculated by several hours of work.

In them, automation was subject to only the sixth stage, since there was practically no software. All five previous users had to be prepared manually independently, until receiving engine codes. The time-consuming and routine nature of these works was a source of a large number of errors in tasks. Therefore B. computer The following generations appeared first elements, and then entire systems that facilitate the process of preparing tasks to the solution.

2nd generation, 60s: computer on discrete semiconductor devices (transistors).

To change the lamps in the machines second generation (Start 60s XX century) Transistors came. Computers have become greater speed, rapid memory capacity, reliability. All major characteristics have increased by 1-2 order. Sizes, weight and power consumed were significantly reduced. The use of printed installation was a great achievement. Reliability increased electromechanical I / O devices whose share has increased. The second generation machines began to possess large computational and logical capabilities.

The feature of the second generation machines is their differentiation for use. Computers appeared for solving scientific and technical and economic tasks, to manage production processes and various objects (control machines).

Along with technical improvement computer Methods and techniques of programming of calculations are developed, the highest level of which is the emergence of programming automation systems that significantly facilitate the difficult labor of programmer mathematicians. Great development and application received algorithmic languages \u200b\u200b( Algol, Fortran et al.), significantly simplifying the process of preparing tasks to solve. With the advent of algorithmic languages, the states of pure programmers sharply decreased, since the preparation of programs in these languages \u200b\u200bwas valid by the users themselves.

3rd generation, 70s: Computers on semiconductor integrated circuits with small and medium degree of integration (hundreds - thousands of transistors in one case).

Third generationEvm (in the end 1960s - early 1970s years) is characterized by wide use of integrated circuits.

Integrated circuit - Electronic special purpose circuit, made in the form of a single semiconductor crystal, combining a large number of active elements (diodes and transistors) - is a complete logical and functional block, corresponding to a rather complex transistor scheme.

Through the use of integrated circuits, it was possible to improve the technical and operational characteristics of the machines. Computing equipment has become a wide range of devices that allow building a variety of data processing systems oriented to various applications. This was also facilitated by the use of the so-called. multilayer printed mounting .

The third-generation computers significantly expanded a set of various electromechanical input and output devices. A distinctive feature of the development of software tools of this generation is the appearance of pronounced software (BY) and the development of his kernel - operating systems responsible for organizing and managing the computing process. It is here that the word " computer"More often began to be replaced by the concept of" computing system ", With a greater extent reflected the complication of both the equipment and software parts. computer.

Operating system (OS.) Plans to the sequence of distribution and use resources computing system, and also ensures their consistent work.

Under resources Usually understand the means that are used for computing:

· Machine time of individual processors or computerin the system;

· Volumes of operational and external memory;

· Separate devices,

· Information arrays;

· Program libraries;

· Separate programs, both in common and special applications, etc.

In the third generation machines, opportunities are significantly expanded to ensure direct access to them from subscribers who are on various, including significant (dozens and hundreds of kilometers) distances. The convenience of communicating the subscriber with the machine is achieved due to the developed network of subscriber points associated with computer Information communication channels, and appropriate software.

4th generation, 80-90s: Computers on large and super-high integrated circuits, the main of which is a microprocessor (hundreds of thousands of tens of millions of active elements in one crystal).

BIS - large integrated circuits Contain tightly packaged active elements. All computer electronic equipment 1st generation engaged in the hall 100-150 sq. M. M. posted in one microprocessor area 1.5-2 square meters. cm. The distances between the active elements in the ultra-large integrated circuit are the tenths of the micron. For comparison, the thickness of the human hair is several dozen microns.

For machines fourth generation (80s xx century) Characterized by application big-in-law schemes (BIS). The high degree of integration contributed to an increase in the layout density of electronic equipment, complicating its functions, increase reliability and speed, reduce cost. A closer becomes the connection of the structure of the machine and its software, especially the operating system.

In the bowels of the fourth generation with the appearance in USA microprocessors ( 1971.) A new class of computing machines appeared - microcomputerto shift which in 1980s Came personal computer t. eTS ( PC). In this class computer as well as BIS began to be used ultra-high integralness (SBI) 32-, and then 64- bit.

The 5th generation is the present time: computers with many dozen parallel microprocessors that allow you to build effective knowledge processing systems; Computers on ultrasound microprocessors with a parallel-vector structure that simultaneously perform hundreds of consistent program commands.

6th and subsequent generations: Optoelectronic computers with mass parallelism and neuronatic structure, with distributed Network Of tens of thousands of simple microprocessors that simulate the architecture of neural biological systems.

The performance of each next generation of computers and the container of all storage devices increases, as a rule, more than an order of magnitude. Complyingly evolved and computer technologies (slide 3).

4. Classification on the principles of operation and use.

Distinguish (Slide 4):

· large computers (computer ) or mainframe

· small computers or mini -computer ,

· microcomputers or micro -computer ,

· PC - Personal Computers (Classification PC will be discussed below).

4.1. Large computers or mainframe (Mainframe).

The most powerful computers used to serve very large organizations and entire sectors of the national economy. Service staff largecomputer Maintains many dozens of people. On the basis of such supercomputers are created VTS - computational centers, Including several departments or groups.

Despite widespread PC, Value big computer Not declining. Due to the high cost of their maintenance when working bigcomputer It is customary to plan and take into account every minute. To save time big computer Low-performance input, output and primary data preparation operations are performed using PCworking in the complex. Prepared data transfer to greasycomputer.

Central processor (CPU) - Main block EUM -data processing unit and calculating results. CPU and drives are several hand struts, and are placed in a separate room - the so-called. hermone which complies with increased requirements for temperature, humidity, protectedness from electromagnetic interference and dust.

Large EUM. serviced by the following structural units VTS:

· Group of system programming Provides software and hardware interface computing system. Personnel - system programmers .

· Applied programming group Provides user interface computing system . Staff - application programmers.

· Data preparation group .

· Technical support group.

· Group information support - creates and stores the archives of previously developed programs and accumulated data - libraries programs or bank banks .

· Data Department. Information is printed on print devices - printers or displayed on displays.

Large EUM. They are distinguished by the high cost of equipment and maintenance, so the work of such supercomputers is organized by the continuous cycle. At the same time, to improve the efficiency, the computer works simultaneously with several tasks and, accordingly, with several users. The distribution of the resource of the computing system is called the principle of division of time .

Large computers are often called mainframes; These include, as a rule, computers having as minimum :

· Performance, not less 100 mips.;

· Basic memory capacity from 512 before 10,000 MBAt;

· Non-less memory 100 GB;

· Multiplayer mode of operation (served simultaneously from 16 before 1000 users).

The main directions of effective use mainfreumov - Solution of scientific and technical tasks, work in computing systems with batch processing of information, work with large databases, management of computing networks and their resources. Last Destination - Use mainfreumov As large servers of computing networks - is often marked by specialists as the most relevant.

The primestrine of modern large computers, according to the standards of which in the past few decades the machines of this class have developed in most countries of the world, are the companies of the company IBM.

1st generation mainfreumov - Models IBM 360. and IBM 370. with their architecture and software are taken as a basis and when creating a domestic system of large cars EU computer.

2nd generation mainfreumov (1979 year) - IBM 3090, IBM 4300;

3rd generation mainfreumov (1990) - IBM ES / 9000;

4th generation mainfreumov :

· 1997 - small-sized mainfrey S / 390. with the scope of RAM 16 GB represented a family mainfreumov from single-processor model with speed 50 MIPS. before 10- processor model with speed 500 mips.. To improve performance, you can combine to 32 machines S / 390. in the so-called clusters .

· 1999 - mainfrey average productivity AS / 400.including in its composition 12 Models. Maximum capacity RAM of the new family is 16 GBand disk memory 2.1 TBA..

· Reliability,

· Performance;

· Capacity of the main and external memory;

· Time to appeal to the main memory;

· Access time and transfer of external storage devices;

· Cache memory characteristics;

· Number of channels and efficiency of the I / O system;

· Hardware I. software compatibility with others computer; Network support, etc.

Quite detailed consideration mainfreumov due to the fact that modern user The computer who is accustomed to the widespread spread of the PC is difficult to explain what other computing techniques also happen. According to experts, mainframes Now there are about 70% of computer information; Only in the US installed hundreds of thousands mainfreumov.

4.2. Small computers or Mini - EUM.

Small computers (mini-computer ) - Reliable, and convenient computers with a slightly lower compared to mainframes. They differ in reduced dimensions and, accordingly, less productivity and cost and are used. large enterprises, scientific institutions, banks and some higher educational institutions that combine learning activities with scientific activities.

At industrial enterprises mini - Evm. Manage production processes, but can combine production management with other tasks. documents for organizing work with mini - Evm. also requires a special computing center, although not so numerous as for large EUM. .

Mini computers(and the most powerful of them supermini computers ) possess the following characteristics:

· Performance - up to 1000 mips.;

· Capacity of the main memory - to 8000 MB;

· Disk capacity - up to 1000 GB;

· Number of supported users - 16-1024.

All models mini-computers are developed on the basis of microprocessor sets of integrated circuits, 32-, 64- and 128-discharge microprocessors.

Their main features:

· Wide performance range in specific conditions of use;

· Simple implementation of multiprocessor and multi-milk systems;

· High recurring speed of interrupts;

· Ability to work with data formats of different lengths.

TO advantages Mini-computers can be attributed:

· Specific architecture with great modularity;

· Best than that mainfreumov productivity / price ratio;

The degree of modern mini-computers Computers can be considered PDP-11. Firms DEC (USA), they were a prototype and domestic mini -computer - Small systems computer (Cm evm.): CM 1,2,3,4,1400,1700 etc.

Modern supermini - computers are actually catching up in their mainframe parameters.

4.3. Microcomputerii Micro -computer .

Computers of this class are available to many enterprises. Organizations using micro - EUM. Usually do not create computing centers. To maintain such a computer, they have a sufficiently small state of several people.

The necessary system programs are usually buying together with a computer, and the development of the necessary application programs are ordered by a larger VTS or specialized organizations, or buy ready-made software.

Microcomputers are very numerous and varied:

· Multiplayer microcomputers - These are powerful microcomputers equipped with several video terminals and operating in time separation mode, which makes it possible to effectively work on them at once to several users.

· Servers (Server) - Powerful multiplayer microcomputers In computing networks allocated to process requests from all workstations network.

· Network Computers (Network Computer) - Simplified microcomputers providing networking and access to network resources, often specialized in performing a certain type of work (network protection from unauthorized access, and an organization of viewing network resources, email, etc.).

Separately subsequently subsequently subclasses - personal computers (PC ) - single user microcomputers satisfying the requirements of the publicly available and versatility of application. Workstation Stations (Workstation) represent single user microcomputers , often specialized to perform a certain type of work (graphic, engineering, publishing, etc.).

Home\u003e Lecture

Lecture 4.

PC device

Classification of computers.

The entire spectrum of modern computing systems can be divided into three large classes: mini-computer (including personal computers), mainframes, supercomputers. Currently, these classes differ not so much in appearance as the functionality. Sovage of various types of computers is determined by the difference in tasks, to solve which they are intended. Over time, new types of tasks appear, which leads to the emergence of new types of computers. Therefore, the division below is very conditionally. PC. Modern personal computers have almost the same characteristics as the mini-computer of the eighties of the eighties: 32- and 64-bit architecture and tire organization of the system. Currently, the mini-computer class is extremely diverse: from laptops and palmtopes to powerful servers for enterprise scale systems. The genetic signs of this class of machines are the bus organization of the system, in which all devices are "rolled out" to the overall highway and standardization of hardware and software. Mainframe - Universal electronic computing machines general purpose. Mainframes are actively used in the financial sphere, defense complex and occupy from 10 to 15% of the computer market. Supercomputers - Special type of computers created to solve extremely complex computing tasks (predicting forecasts, modeling complex phenomena, processing super-large amounts of information). The principle of operation of the supercomputer is that it is able to perform several operations in parallel. Modified from leading companies in the world in the production of supercomputers is Cray Research. Her founder, the legend of Seymour Cree, already in the mid-70s built a computer Cray-1.who struck the world with its speed: dozens and even hundreds of millions of arithmetic operations per second. As well known, the speed of propagation of any signal does not exceed the speed of light in vacuo - 300 thousand kilometers per second, or 300 million meters per second. If the computer performs 300 million operations per second, then during the execution of one operation, the signal has time to go through no more than one meter. It follows that the distance between the parts of the supercomputer performing one operation cannot exceed several tens of centimeters. Indeed, Cray supercomputers were very compact and looked like a "bagel" with a diameter of less than two meters. This "bagel" was engaged only by calculations. To communicate with a person and delivery of data for computing to "Bublik", several sufficiently productive ordinary computers were connected. It should be allocated for two more types of computers: specialized computers servers; Built-in invisible computers (microprocessors). In addition to familiar computers with keyboards, monitors, drives, today's world of things is filled with invisible computers. Microprocessor It is a computer in miniature. In addition to the processing unit, it contains a control unit and even memory (internal memory cells). This means that the microprocessor is capable of autonomously performing all the necessary actions with information. Many components of a modern personal computer contain a miniature computer inside. The mass spread of microprocessors received both in production, where control can be reduced to the return of a limited sequence of commands. Microprocessors are indispensable in modern technique. For example, the management of a modern engine is to ensure the savings of fuel consumption, limiting the maximum speed speed, health control, etc. - is unthinkable without using microprocessors. Another promising area of \u200b\u200btheir use is appliances - The use of microprocessors gives it new consumer qualities. Desktop PCs Supporting one workplace, make up the most numerous group of personal computers, or micro-computer. Before the appearance of portable PC, the words "table" and "personal" were synonymous. Desktop PCs are also called computers for the workplace or office computers (although at present office PCs are more often called workstations). The overwhelming majority of home computers are also desktops. Both those and others have almost the same characteristics: 32- and 64-bit architecture and tire organization system, apply standardized hardware and software. Most desktop PCs relate to two large groups: IBM-compatible PCs and Apple Macintosh PCs. Computers from these groups are not compatible with each other, i.e., fully or partially not able to use hardware and software products each other.



Desktop PCs have a system unit containing the power supply, motherboard with a processor, hard disk, drives, monitor, keyboard, mouse. Fax, modem and other external devices can be connected to them, such as audio colors. In some models of the home PC, the system unit with the monitor is collected in a single case (Apple IMAC, Acer Aspire., COMPAQ PRESARIO). In 1981, the American company IBM launched the production of IBM PC personal computers operating under the DOS operating system developed by Microsoft's specialists. IBM PC computers enjoyed commercial success, and many manufacturers of electronic technology set up IBM PC clones. So the class of IBM compatible computers appeared that most external devices and programs intended for IBM PC. The principle of compatibility provided a significant savings and time in the modernization of old and creating new computers. All IBM-compatible computers can use the Microsoft DOS operating system (PS-DOS at IBM, MS-DOS in other manufacturers) or Windows and Intel processors (or compatible with them). Alternative to IBM-compatible personal computers are Apple Macintosh computers. TO

ommomps are taken, recycling, stored and issue information. Computer actions manages the operator. Long sequences of instructions are fixed in advance in programs. Computing operations make a central processor. According to the principles of operation of the computer formulated in 1945 by American Mathematics John von Neumanan, the central processor consists of two parts. The control device perceives the program commands and organizes their execution. The arithmetic and logical device performs calculations. Data is stored in different storage devices. For long-term storage of information, constant media are used, which serve to enter data and output the results of the work. For storing currently executed programs and intermediate data, RAM is used, which works much faster than permanent media. Hardware is all internal components and external computer devices - integrated chips (including microprocessors), drives, system and interface cards, monitors, printers, manipulators, modems, etc. The software is the sets of instructions for the computer necessary to control the operation of the computer and performing the useful tasks. The main feature of the computer design is program principle Works. Principle of the program stored in the computer's memory is considered the most important idea of \u200b\u200bmodern computer architecture. The essence of the idea is that 1) the computing program is introduced into the memory of the computer and is stored along with the initial numbers; 2) Commands that make up the program are presented in the numerical code in the form of anything different from the numbers.

Internal and external devices.

Under the architecture of the computer means its logic organization, structure, resources, i.e. the means of computing system that can be allocated to the processing process. The architecture of modern PC is based on mascinal modular principle. The modular principle allows the consumer to choose the computer's configuration you want and produce its upgrade if necessary. The modular organization of the system relies on the trunk (tire) principle of information sharing. Mainer or system tire - This is a set of electronic lines connecting the transmission of data and service signals to the processor, memory and peripheral devices. The exchange of information between individual devices of the computer is made in three multi-digit tires connecting all modules - data bus, address bus and tire control. The bit of the data bus is set to the processor bit, i.e. the number of binary discharges that the processor processes in one clock. Data bus data can be transmitted from both the processor to any device and in reverse side, i.e. the data bus is bidirectional. The main modes of the processor operation using the data bus can be attributed to the following: Recording / reading data from RAM and from external storage devices, reading data from input devices, sending data to output devices. The selection of the data exchange of the data generates a processor that generates code Addresses of this device, and for RAM - the code of the memory cell address. Address code is transmitted by address bus, moreover, signals are transmitted in one direction, from the processor to devices, i.e., this tire is unidirectional. tire control Signals are transmitted that determine the nature of the exchange of information, and signals, synchronizing the interaction of devices involved in the exchange of information. The following devices are connected to the tires by means interface. Under the interface understand the totality various characteristics A peripheral device of the PC, which determine the organization of information exchange between it and the central processor. In case of incompatibility of interfaces (for example, the system bus and hard drive interface) use controllers.

To make the devices included in the computer, can interact with the central processor, in IBM compatible computers provided interrupt system (Interrupts) . The interrupt system allows the computer to pause the current action and switch to others in response to the received request, for example, by pressing the key on the keyboard. After all, on the one hand, it is desirable that the computer be busy with the work entrusted to him, and on the other hand, its instant reaction is needed to any request. Interrupts provide immediate response of the system.

The computer includes the following components:

central processor (CPU); RAM (Memory); Information storage devices (Storage Devices); input devices (INPUT DEVICES); Output devices (Output Devices); Communication Devices (Communication Devices).

The system of the personal computer contains the housing and the power supply in it, the motherboard (system, or the main) board with the processor and the RAM, the extension board (video card, sound card), various drives (hard disk, drives, CD-ROM drives), Additional devices. The system unit usually has several parallel and serial ports that are used to connect the input and output devices, such as keyboard, mouse, monitor, printer.


The main node that determines the capabilities of the computer is a systemic, or motherboard. It is usually placed: the basic microprocessor; RAM; Superoperative memory, also called cache memory; ROM with a system BIOS (Basic I / O System), a set of control chips, or chipset (chipset), auxiliary chip and I / O controllers; CMOS memory with hardware settings and battery for its power; Expansion connectors, or slots (SLOT);


connectors for connecting hard disk interface cables, drives, serial and parallel ports, infrared port, as well as a universal USB serial bus; power connectors; 5V voltage converter to lower processor power (for example, I486DX4 processors, Intel Pentium, Intel Pentium Pro consumes 3.3 V, and modern Intel Pentium III and 4, as well as AMD Athlon and Duron consume less than 2V); Connector for connecting the keyboard and a number of other components. To connect indicators, buttons and dynamics located on the system unit housing, there are special miniature plug connectors on the motherboard. Similar connectors serve as contacts for jumpers when specifying hardware system configuration. If the system board focuses all the elements necessary for its operation, then it is called all-in-one. Most personal computers have only basic functional components, and the remaining elements are located on separate printed circuit boards (expansion cards) that are installed in the expansion connectors. For example, an image forming device on the monitor screen - a video adapter is still most often located on a separate extension board - a video card. All components of the motherboard are connected with each other system of conductors (lines), for which information is exchanged. This set of lines is called a tire. Unlike other connection systems, the tire lines are divided into three groups depending on the type of information transmitted: data lines, address lines and control lines. Tires in PC differ in their functional purpose. The most important component of any personal computer, its "brain" is a microprocessor (CPU, Central Processor Unit - CPU, or a central processor device), which manages the operation of the computer and performs most of the processing of information. The microprocessor is ultra-handed integrated circuitThe degree of integration of which is determined by the crystal size and the number of transistors implemented in it. Sometimes integrated chips are called chips (eng. Chip). The base elements of the microprocessor are transistor switches, based on which registers are constructed, for example, registers, which are a set of devices with two stable states and are intended for storing information and quick access to it. The number and charge of the registers are largely determined by the microprocessor architecture. The microprocessor commands are provided, as a rule, arithmetic actions, logical operations, control (conditional and unconditional) and data transfer (between registers, RAM and I / O ports). With external devices, the microprocessor may communicate due to its address tires, data and controls derived from the microcircuit's special contacts. The process of communication processor with an external world through I / O devices compared to information processes Inside it proceeds hundreds and thousands of times slower. This is due to the fact that information input and output devices often have a mechanical principle of operation (printers, keyboard, mouse) and work slowly. To free up the processor from idle while waiting for the end of such devices, specialized microprocessors of controllers are inserted into the computer (from English. controller -- manager). Having received a command to output from the central computer processor, the controller independently controls the operation of the external device. After graduating output information, the controller reports the processor on completing the execution of the command and availability to get the following. The number of such controllers corresponds to the number of input and output devices connected to the processor. So, to control the work of the keyboard and mouse, uses its own separate controller. It is known that even a good typist is not capable of typing more than 300 characters per minute on the keyboard, or 5 characters per second. To determine which one of the hundred keys is pressed, the processor that is not supported by the controller would have to interview the keys at a speed of 500 times per second. Of course, according to his standards, this is not a god of news what speed. But this means that part of its time the processor will not spend not to process already available information, but to wait for the keypad keys. In the way, the use of special controllers to manage I / O devices, complicating a computer device, at the same time unloads its central processor from unproductive spending time and improves the overall performance of the computer. The microprocessor as a universal information processing unit was developed in 1962. Intel's American corporation in 1971 began the release of 4004 microprocessors who worked with four-digit binary numbers. Intel's firstborn consisted of 2300 transistors. The improvement of microprocessors was accelerated. In 1978, an eight-bit microprocessor of 8080 was created, and in 1981 - the sixteen-digit microprocessor 8086 and 8088. It was based on its basis that personal computers were launched. In 1982, on the basis of the sixteen-digit microprocessor 80286, IBM has established the production of IBM PC personal computers, whose clones have received the widest distribution worldwide. In 1985, a 32-bit I386 microprocessor was created, which contained 275 thousand transistors and providing 5 million operations per second. In 1989, the I486 microprocessor appeared, which contained 1.2 million transistors and had the speed of 20 million operations per second. In 1993, a 32-bit Pentium microprocessor was created, which contained 3.1 million transistors and had the speed of 90 million operations per second. Pentium III microprocessors provide 800 million operations per second at clock frequency 800 MHz. All these successes were achieved at the expense of miniaturization of microcircuits. In 1999, the distance between the transistors was reduced to 0.18 microns. But soon the developers will suit the frontier for which fundamental physical restrictions begin. Further predicts the appearance of molecular computing devices. In them for storing and transformation of information suggest to use instead electrical charges and impulses - chemical states of molecules.

Memory

All computers use three types of memory: operational, permanent and external. RAM (RAM - operational storage device) is intended for storing information to which it is often necessary to access and provides modes of its recording, reading and storage. This type of memory is also called random access memory (Random Access Memory, RAM). According to the information storage method, the RAM is static and dynamic. Permanent memory (ROM - A constant storage device) usually contains such information that should not change during the microprocessor performing various programs. The permanent memory also has the name ROM (Read Only Memory), which indicates that only the read and storage modes are provided. The constant memory is non-volatile, i.e. can save information and dial-up. All permanent memory chips in the method of enhancing information are divided into mask, programmable by the manufacturer (ROM), once programmable by the user (Programmable ROM) and repeatedly programmable by the user (Erasable Prom). The latter, in turn, are divided into erasable electrically and using ultraviolet irradiation. EPROM elements with electrical erasing information include, for example, flash memory chips (Flash). From ordinary eprom, they are characterized by a high speed of access and quick erasing recorded information. This type of memory today is widely used for BIOS storage and other permanent information. Different types of operational and permanent memory can be built in the form of a specific hierarchy by data access. RAM - The combination of special electronic cells, each of which can store a specific 8-digit combination of zeros and units - 1 byte (8 bits). Each such cell has an address (byte address) and contents (byte value). The address is needed to appeal to the contents of the cell, to record and read the information. Operational storage device (RAM) stores information only during computer operation. The capacity of the RAM of the modern computer is 32-128 MB. When performing a microprocessor computing operations must at any time, access to any cell of RAM is provided. Therefore, it is called memory with an arbitrary sample - RAM (Random Access Memory). RAM is usually performed on dynamic type chips with an arbitrary sample (Dynamic Random Access Memory, Dram). Each bit of such memory is presented in the form of (or lack) charge on the condenser formed in the structure of the semiconductor crystal.

Static memory

Static Memory (SRAM)modern PCs are usually used as a second-level cache for caching the main volume of RAM. The static memory is usually performed on the basis of TTL, a CMOS or bikmop chip and according to a method of access to data can be both asynchronous and synchronous. Asynchronous is access to data that can be carried out during an arbitrary moment. Asynchronous SRAM was used on motherboards for the third - fifth generation of processors. Access time to the cells of such a memory ranged from 15 ns (33 MHz) to 8 ns (66 MHz). Synchronous memory provides access to data not in arbitrary moments of time, but synchronously with clock pulses. In the intervals between them, the memory can be prepared to access the following data portion.

Dynamic memory.

Dynamic memory (DRAM) in modern PCs is usually used as a general-purpose RAM, as well as memory for a video adapter. Of the dynamic memory types used in modern and promising PCs, DRAM and FPM DRAM, EDO DRAM and BEDO DRAM, EDRAM, and CDRAM, SYNCHRONOUS DRAM, DDR SDRAM and SLDRAM, MDRAM, VRAM, WRAM, and SGRAM, RDRAM video memory, RDRAM. In the memory of a dynamic type of bit, the bits are presented in the absence and availability of charge on the condenser in the structure of the semiconductor crystal. Structurally, it is performed as a SIMM module (Single in Line Memory Module). Each bit of information is recorded in a separate memory cell consisting of a condenser and transistor. The presence of charge on the condenser corresponds to 1 in binary code, no - 0. The transistor when switching makes it possible to read the information bits or write a new bit into an empty memory cell. The search for cells is carried out by special decrypting schemes that form the matrix, that is, they cross the memory crystal with two stripes - horizontally and vertical. When the central processor reports the cell's address, horizontal decoders indicate the desired column, and the vertical - string. At the intersection there is a desired cell. After finding the cell there is a sample of their data byte. Cache memory (Cache Memory) - a memory device with a small access time (several times less than the access to the main RAM) used for temporary storage of intermediate results and the content of frequently used cells. In general, the data caching is called the placement of data in memory with more rapid access. As a living analogy, you can give a student library whose textbooks you need every day lie on the desktop, occasionally readable classics stand on the bookshelf, and old unnecessary notebooks are folded in boxes. If necessary, access time to these sources will be different, however, the likelihood that a textbook or an old notebook will be required, too different. IN

This principle is applied to the world of computer memory because the faster memory is usually much more expensive than slower, but the use of a small amount of fast (but expensive) cache, in a complex with a large volume of slow (but cheap) memory allows you to create an acceptable price and speed decision. The application of caching is particularly effective when data access is carried out mainly in a consistent manner. Then, after the first request for reading data located in slow (cached) memory, you can read the following data blocks in advance in order for the next time you send the data reading almost instantly to give them from the cache. This technique is called proactive reading. Proactive reading applied in all modern hard diskshaving from 64 to 1024 KB cache made based on dynamic RAM. The data read from the disk with some reserve is placed in the disk cache and a certain time there is stored. When re-accessing the same information, they are already read from the cache, which is 10-1000 times faster. Data caching is also applied in processors. Inside the processor crystal there is a small volume (from 1 to 1024 KB) very fast static memory operating at the processor frequency. This memory is used to caching significantly slower RAM made on the basis of dynamic RAM. Thus, in different situations, one and the same memory can be both cache and cached memory. Chipset (chipset) The motherboard is called a set of microcircuits that controls the processor, RAM and ROM, Cash memory, system tires and data transmission interfaces, and nearby peripheral devices. The chipsets are constructively tied to the type of processor used, and during the processor's life cycle, several generations of chipsets have time to change, and the first chipsets make it possible to use the advantages of a new processor only in part, and the latter allow you to squeeze the maximum performance and use a wide range of processors. Bios.(Basic Input Output System is a basic I / O system) - part of microcomputer software that supports control of external adapter adapters, testing and starting a computer. BIOS can be considered as composite part hardware, and as one of the software modules of the operating system. BIOS is built into the PC and contains keyboard control programs, video cards, discs, ports and other devices before downloading any operating system.
The BIOS also contains a test program when you turn on the POST, POWER ON SELF TEST) and the initial boot program. Most modern video adapters, as well as many SCSI controllers have their own BIOS, which usually complements the system. In general, BIOS can be considered as a binder between the specific features of the implementation of equipment in the PC and the standard requirements of the operating system. The BIOS system in modern computers is implemented as a ROM microcircuit (ROM) installed on the computer's system board. Electrically reprogrammable storage devices (EEPROM or Flash EEPROM) are used in motherboards for fifth and later generations of processors (EEPROM or Flash EEPROM), in older boards or in video cards - ultraviolet erasing devices (EPROM). Such elements BIOS are called Flash-BIOS. Now the user can update the BIOS promptly by downloading the latest version from the Internet or from a floppy disk. Many modern motherboards are equipped with two BIOS chips, which allows you to store various settings in them and increases the reliability of the system. Under a not quite accurate term CMOS RAM (Compledenary Metal-Oxide Semiconductor, CMOS or CMOS) is understood as non-volatile memory, which stores information about the current date, clock readings, computer configuration (number of RAM, storage facilities). The inaccuracy of the term is that the CMOS is not the name of the device, but only the technology of manufacturing a chip (it reminds a common error: ... FM radio station ... ", while FM is a signal modulation method, no way Not related to the range). Therefore, the documentation also uses the terms EEPROM or NON-VOLATILE RAM. The BIOS system has a SETUP program that can change the contents of the CMOS memory, that is, set the system configuration parameters. This program is called by a specific key combination: DEL - for Award BIOS and INS or F2 - for some versions of AMI BIOS. In general, when booting on the screen, as a rule, the name of the key is written, which should be pressed to start the SETUP program. When loading and performing control of BIOS equipment, sounds the sounds for which the problem can be diagnosed. If everything is in order, a long beep is fed; If the video card is faulty - then 1 long and 2 short beeps; If the memory is faulty - then repetitive short beeps. These codes are written in more detail in the motherboard manual. If the processor is faulty, there will be no beeps, since the POSTYLE \u003d "program is performed by the processor. System bus. It is simplified to be simplified as a set of signaling lines combined by their purpose (data, addresses, management), which also have well-defined electrical characteristics and information transfer protocols. The main responsibility of the system tire is to transfer information between the processor (or processors) and the other electronic components of the computer. On this bus, not only the transfer of information is carried out, but also addressing devices, and the exchange of special service signals is exchanged. The bus used currently differ in charge, a method for transmitting a signal (serial or parallel), bandwidth, quantity and type of supported devices, as well as a protocol of work. As a rule, the PC tires can be represented in the form of a certain hierarchical structure - tire architecture. A feature of modern PC is the presence of an ISA tire, inherited from the very first IBM PC models. In addition to her, the PCs are used EISA, MCA, VLB, PCI, PCMCIA (Cardbus) and AGP tires. Tires can be synchronous (data transmission only on clock pulses) and asynchronous (data transmission into arbitrary times), as well as use various arbitration schemes (that is, the method of sharing a tire by multiple devices). E.

if the exchange of information is carried out between the peripheral device and the controller, the data connecting the data line is called the data transfer interface, or simply an interface. Among the interfaces used in modern and promising PCs, you can mark EIDE, SCSI, SSA and FIBRE CHANNEL, USB, FireWire (IEEE 1394) and DeviceBay. Among the data transmission interfaces, the I / O ports are used to connect low-speed peripheral devices: serial port (COM), parallel port (LPT), game port / MIDI port and infrared port (IRDA).

Parallel Port (LPT) The IBM PC compatible computer is most often used to connect the printer, so it is also called the printer port. Personal computer works with three parallel ports that have logical names LPT1, LPT2 and LPT3. Connecting the cable to the adapter of the parallel interface is performed via a 25-pin connector of the DB-Shell type connector (DB-25), and from the printer side, a special 36-pin connector of the Centronics type is used. Since the frequency of transmitted signals can reach tens of kHz, the length of such cables usually does not exceed three meters. There are several modifications of parallel high-speed interfaces, such as EPP (ENHANCED PARALLEL PORT) and ECP (Extended Capabilities Port). These interfaces provide speeds up to 2-5 MB / s and support bilateral data transmission. Currently, both modifications are combined in one IEEE 1284 standard. The serial interface is used for most peripheral devices, such as a plotter, a remote printer, a mouse, an external modem. To date, for serial communication, IBM PC-compatible computers uses adapters with an RS-232C interface (new EIA-232D name). In a modern IBM PC-compatible computer, up to four consecutive ports that have logical names, respectively, COM1, COM2, COM3 and COM4 can be used. The basis of the serial adapter is the UART microcircuit (Universal Asynchronous Receiver / Transmitter) - a universal asynchronous transceiver. Usually used UART 16550A chip. It has a 16-character buffer for receiving and transmitting and, in addition, can use multiple channels of direct access to DMA memory. When transferring the UART chip converts a parallel code into a sequential and transmits it to a line into a line, framing the initial sequence of start, stop and control bits. When receiving data, the UART converts a sequential code into parallel (of course, dropping service characters). An indispensable condition for proper transmission (reception) is the same speed of operation of the receiving and transmitting the UART, which is ensured by the stable frequency of the quartz resonator. The main advantage of serial transmission is the ability to send data over long distances, as a rule, not less than 30 meters. In IBM PC-compatible personal computers from 25 signals provided for by the RS-232 standard are used in accordance with EIA only 9; Thus, this interface uses both 25- and 9-pin connectors of the DB-Shell type. In the PC99 specification (see desktop PC), it is emphasized that only a printer can be in the new PC in the new PC. The remaining devices must use FireWire or USB tires. Universal Serial USB Bus Universal Serial Bus) according to the PC97 specification is a mandatory element of the modern PC. It should gradually replace all the previously existing interfaces for connecting reimaged devices (parallel and sequential

ots, PS / 2 connectors for mouse and keyboard, SCSI interface). The USB standard was developed in 1995 by the COMPAQ, DEC, IBM, Microsoft, NEC, Northern Telecom consortia, and in the summer of 1996, the first computers appeared on the market. uSB ports. The USB bus is a serial data interface for medium and low-speed peripheral devices (for devices requiring a higher exchange speed, the FireWire bus) is offered. USB bus is designed to connect up to 127 devices, while maintaining their auto definition plug-n-play, as well as the so-called "hot" connection, that is, connecting to a working computer without rebooting it. USB data transfer rate is 12 Mbps (i.e. not more than 1.5 MB / s), and for slow devices, it was selected for 1.5 Mbps. The cable uses twisted steam. The length of the USB segment can reach 5 meters. USB devices There are two types: Hub (HUB) to connect other devices and a regular device. Hubs can be separate devices or (which is more common) part of other autonomous dialing devices, such as monitors. The USB interface is released modems, keyboards, mice, CD-ROMs, joysticks, ribbon and disk drives, scanners and printers, digital cameras, monitors (not for signal transmission, but to manage the monitor settings) and other devices. In the Apple IMAC computer, for example, the USB bus serves as the only interface for connecting slow peripheral devices. USB support at the motherboard level is implemented in all modern PCs based on the fifth and sixth generation of X86 processors, but support from the BIOS and the operating system is fully implemented only in Windows 98 and Windows NT 5.0. In October 1999, a preliminary version of the USB 2.0 standard was agreed, which provides for the rate of data exchange of 360-480 Mbps. To communicate portable computers with desktop, as well as to connect to them laser printers used wireless interfaceInfrared Range. The principle of operation of the infrared port is quite simple: the LED (LED), operating in the infrared range, emits the pulse sequence that the corresponding photodiode receives and then converts back to electrical signals. Such a connection has a number of advantages: a low price, low power consumption and lack of harmful high-frequency emissions. SCSI interface It was developed in the late 1970s by the organization Shugart Associates. Initially known called SASI (Shugart Associates System Interface), he after standardization in 1986 by SCSI (SCSI reads) has become one of the industrial standards for connecting peripheral devices - Winchesters, streamers, replaceable hard and magneto optical disks, scanners, CD-ROM and CD-R, DVD-ROM, etc. The SCSI interface is parallel. To the bus simultaneously can be connected to eight devices, including the main SCSI controller (or host adapter). The SCSI controller is essentially an independent processor And has its own BIOS (which can sometimes be placed in the BIOS motherboard). It performs all SCSI maintenance and management operations, freeing the central processor from this. Physically, the SCSI interface is a flat cable with 25- or 50-pin connectors for connecting peripheral devices. SCSI bus contains eight data lines accompanied by parity control line, and nine control lines. The SCSI standard defines two ways to transmit signals - unipolar, or asymmetric (Single Ended) and differential (differential). In the first case, there is one wire with zero potential ("Earth") relative to which signals are transmitted over data lines with signals levels corresponding to TTL logic. With differential signal transmission, two wires are selected for each data line, and the signal on this line is obtained by subtracting the potentials at their outputs. At the same time, much better noise is achieved, which makes it possible to increase the length of the cable. For the SCSI interface, it is necessary for terminators - matching resistances that absorb signals at the ends of the cable and prevent echo formation. The SCSI interface is generally characterized by high sensitivity to the quality of cable manufacturing and to their length, which can be different depending on the interface version. The software for the SCSI interface does not operate with the physical characteristics of the drive (i.e., the number of cylinders, heads, etc.), and it only deals with logical data blocks, so in one SCSI chain, it is easy to get along, for example, a scanner, hard disk and CD-R drive. The device survey is performed by the SCSI controller immediately after the power is turned on. At the same time, for SCSI devices, autoconfiguration of devices (Plug-N-Play) is implemented using SCAM (SCSI Configured Automagally), in which SCSI ID values \u200b\u200bare automatically highlighted. For standardized SCSI devices, the ASPI program interface (Advanced SCSI Programming Interface) is most widely applied. There are more than a dozen different versions of the SCSI interface. The most essential of them are SCSI-1, FAST SCSI, Fast Wide SCSI, Ultra SCSI, Ultra 2 SCSI. PCI Tire Specification (Revision 1.0) was introduced by Intel in June 1992 as a processor-independent bus. Given the experience of operating the VL-BUS tires (see Tire VESA), the PCI developers abandoned the use of the processor tire and introduced another "mesanin" (mezzanine) bus. Thanks to this, the tire can work in parallel with the processor bus (for example, the processor runs the RAM, and at this time the PCI bus is exchanged data with a video adapter or hard disk). An important factor contributing to the widespread PCI to be the fact that Intel announced the PCI tire standard open and transferred it to the Non-Profit Organization PCI SIG (PCI Special Interest Group), which began to lead all the work on supporting it and further development.

The PCI bus is a synchronous 32- or 64-bit bus operating at a frequency of 33 or 66 MHz. In modern PCs, the 32-bit 33 MHz PCI bus is used, although there are exceptions: MICRON SAMURAI PC chips and Intel 450NX AGPSET supports support 64-bit bus, 64-bit PCI bus is also used in the Digital and Sun workstations. To reduce the number of contacts in the PCI, multiplexing is applied (address and data transmission over the same lines at different points in time). PCI allows you to use supply boards 5 and 3.3 V. Tire supports multiple bus arbitrators (Multiply Bus Master). During data transmission, caching and block transmission are supported. The PCI bus supports automatic definition and configuration of the extension boards (Plug-N-Play). The PCI specification allows you to create multifunctional devices on one board with the number of functions up to eight (for example, modem, sound, network interface, etc.). The PCI bus in the desktop construct has 4 124/188-pin connector (32/64-bit versions) or 8 connectors in the CompactPCI construct, used in industrial and military computers. If a larger number of connectors are needed, the PCI-PCI bridge chips are used (while bandwidth Tires decrease). The maximum possible data transfer rate over the PCI bus ranges from 132 MB / s for a 32-bit / 33 MHz to 528 MB / s for a 64-bit / 66 MHz bus implemented. Video adapter (synonym - video card) Designed to store video information and its display on the monitor screen. It directly controls the monitor, as well as the process of outputting information on the screen by changing the signals of the lowercase and frame sweep Elt Monitor, Brightness of image elements and color mix parameters. The main nodes of the modern video adapter are the actual video controller, BIOS video, video memory, a special digital radio transmitter RAMDAC (Random Access Memory Digital To Analog Converter), a quartz generator (one or more) and interface chips with a system bus (ISA, VLB, PCI, AGP or other ). An important element of the video subsystem is its own memory. For this purpose, the video adapter is used for this purpose, which is often also called video memory, or frame buffer, or part of the PC RAM (in the UMA shared memory architecture). All modern video subsystems can work in one of the two main video modes: text or graphic. In text mode, the monitor screen is divided into separate symbolic positions, in each of which only one character can be displayed at the same time. To convert the characters stored in the adapter video memory, the so-called signogenerator is used on the screen, which is usually the ROM, where the images of the characters "decomposed" are stored. Upon receipt of the symbol code, the sign generator generates the corresponding binary code at its output, which is then converted into the video signal. Text mode in modern operating systems is used only at the initial load stage.


In graphical mode, for each point of the image, called a pixel, is assigned to one (monochrome mode) to 32-bit (color). The graphic mode is often referred to as all points addressing all points (All Points AddResable), since only in this case it has access to each image point. The maximum resolution and the number of reproducible colors of a particular video content primarily depend on the total volume of video memory and the number of bits occurring on one image element. There are several standards of video cards. During the existence of IBM PC-compatible personal computers, several generations of video adapters and related image representation standards have changed. The main parameter in these standards is the resolution (number of characters, or pixels horizontally and vertical), the number of colors simultaneously displayed on the screen and the frame rate of the frame scan (which is the image of the image perverts on the monitor screen performed by the scanning device).

Drives.

For storing programs and data in personal computers, various kinds of drives are used, the total capacity of which, as a rule, is hundreds of times greater than the battery capacity. In relation to the computer, drives can be external and embedded (internal). External drives They have their own body and power supply, which saves the space inside the computer housing and reduces the load on its power supply. Built-in drives are attached in special mounting compartments (Drive Bays), which allows you to create compact systems that are combined in the system unit all the necessary devices. The drive itself can be considered as a totality of the carrier and the corresponding drive. There are storage drives with replaceable and non-carriers. The most common information storage devices are listed. Winchesters (Hard Discs)Hard drives are the fastest of external storage devices. In addition, the information stored on the Winchester can be read from it in an arbitrary order (disk - a device with arbitrary access). The capacity of the disk of the modern personal computer is tens of gigabytes. In one computer, several hard drives can be installed. Optical disks (CDROMS)Laser discs, as they are also called, have a capacity of up to 750 megabytes and provide only reading the information recorded on them once in arbitrary access mode. The read speed of the information is determined by the device in which the CD (CDROM DRIVE) is inserted. Magneto-optical disksUnlike optical discs, magnetic optical discs allow not only to read, but also write information. Floppy Discs (Floppy Discs)The basis of these storage devices is a flexible magnetic disc, placed in a solid shell. In order to read the information stored on a diskette, it must be inserted into the drive (FLOPPY DISC DISC). Capacity of modern diskets is only 1.44 megabytes. By way of accessing a floppy diskette is similar to Winchester. Zip. and. Jaz. Iomega. discs.These are relatively new media, which are designed to replace flexible magnetic discs. They can be considered as quick and large on the tank (100 megabytes - ZIP, 1 gigabyte - jaz) floppy disks. Magnetic Tapes (Magnetic Tapes) Modern magnetic tapes that store large amounts of information (up to several gigabytes), externally resemble ordinary tape recorder cassettes and are characterized by strictly serial access to the information contained on them.

HDD.

Hard disk (Winchester), a device for constant storage of information used when working with a computer. Its name "hard" received in contrast to carriers of information on flexible magnetic tapes and disks. The principles of modern technology for making a hard disk were developed in 1973 by an American Ai-Bi-Em (IBM). A new device that could store up to 16 kilobytes of information had 30 cylinders (tracks) for recording, each of which was divided into 30 sectors. Therefore, it was named 30/30. Famous rifles Winchester have a 30/30 caliber, so hard drives Also became known as "Winchesters". In addition, a hard disk was developed in the American city of Winchester. As a rule, a hard disk is fixed, but there are models of removable (Removable) hard drives. The hard disk is mounted on the spindle axis, which is driven by a special engine. It contains from one to ten drives (platters). The speed of rotation of the engine for conventional models can be 3600, 4500, 5400, 7200, 10,000, 12000 rpm. The wheels themselves are treated with high accuracy ceramic or aluminum plates with a magnetic coating - a thin layer of iron oxide (in earlier models) or chromium oxide (in later models). Each disk (platter) is divided into sequentially located tracks sectors corresponding to the zones of residual magnetization created by the heads. The amount of sector memory is 512 bytes.

The read-write heads along with their supporting design and discs were originally enclosed in a hermetically closed case, called the data module. When installing this module on the drive, it automatically connected to the system feeding the purified air. In modern hard drives, the disk package is already constantly attached on the drive, the system is not sealed, and there is no forced ventilation. The thickness of the airbag, created by the aerodynamics of the rotating disk and the shape of the head, much thinner of the human hair. The most important part of the hard drive is the reading and writing heads (Read-Write Head). As a rule, they are on a special positioner (Head Actuator). To move the positioner, mainly linear motors are used (such as Voice Coil - "sound coil"). In the hard drives there are several types of heads: monolithic, composite, thin-film, magnetic (MR, MAGNETO-resistive), as well as heads with a strong magnetorezistive effect (GMR, Giant Magneto-Resistive). The magnetorezistive head developed by IBM in the early 1990s is a combination of two heads: thin-film for recording and magnetorevical reading. Such heads allow almost one and a half times to increase the record density. Even more allows you to increase the density of the GMR head record. The heads do not touch the surfaces of the disks, but move over them at the distance of the fraction of the micron. Inside any hard drive necessarily electronic boardwhich decrypts the hard disk controller commands, stabilizes the motor rotation speed, generates signals for recording heads and enhances them from reading heads. Under the package of discs with spindle placed engine. In earlier models of hard drives for the positioner drive, a stepper motor was used, so the distance between the tracks was determined by its step. In modern models, a linear engine is used, which has no discreteness characteristic of a stepper motor. Therefore, the guidance of magnetic heads on the track is made more accurately, which provides a greater density of recording on disks. In the course of the procedure of the so-called low-level formatting (low-level formatting), information is recorded on the hard disk, which determines the marking of the hard drive to the cylinders and sectors. The format structure includes various service information: synchronization bytes, identification headers, parity control bytes. In modern hard drives, such information is recorded once in the manufacture of hard drive. Damage to this information with independent low-level formatting is fraught with the complete disobability of the disk and the need to restore this information in the factory conditions. The hard drive tank is measured in megabytes. By the end of the 1990s, the average capacity of hard drives for desktop systems reached 15 gigabytes, and in servers and workstations with sCSI interface Applied hard drives with a capacity of over 50 gigabytes. Most modern personal computers use hard disks with a capacity from 10 to 100 gigabytes. IBM has mastered the release of the smallest hard disk in the world intended for manual computers and digital cameras. Its diameter is 25 mm, and the amount of memory is 340 MB.

Flexible disk.

In the floppy disk (flexible disc, or simply diskette) there are two engines: one provides a stable speed of rotation inserted into the diskette drive, and the second moves the write-reading head. The speed of rotation of the first engine depends on the type of floppy disk and ranges from 300 to 360 rpm. The engine for moving the heads in these drives is always a stepper. With its help, the head is moved along the radius from the edge of the disk to its center discrete intervals. Unlike the drive drive, the head in this device will not "hide" above the surface of the floppy disk, and relate to it. The operation of all drives controls the corresponding controller.

FROM
the bandage interface for all drives in IBM compatible computers is SA-400 (Shugart Associates), the controller of which is connected to the drives by means of a 34-pin cable. On the drive of the disks with a 5.25 inches form factor, a "knife" (printed) connector is used, and a 3.5-inch disk drive is a regular pin plug. For connecting different types Discovers are intended usually combined cables with four connectors included in pairs. On the usual interface cable for the extreme connector, the conductors on contacts from the 10th to the 16th are twisted. When using a "direct" cable, you must definitely change the jumper setting on the drive defining its number (DS1-DS4). Some BIOS computers allow you to programmatically change the purpose of the physical address: "first" (a :) and "second" (B :) drive. Unlike hard drives, for floppy drives, the order of the drive (A: or B :) is determined by the position of the device on the cable. For each of the sizes, diskettes (5.25 or 3.5 inches) there are their special drives of the corresponding form factor. The first sample of the diskette was created by IBM in 1967. It was a diameter of 8 inches, had a capacity of 100 KB and received the name Flexible Disk, that is, a flexible disk. The name of the floppy disk it received later from the English word FLOP, which means "clap wings". The first sample of the diskette was a round plate with a central, reinforced along the edges of the hole. The envelope diskette had holes for the spindle, which rotated the media, slot for heads and optocouplers to read the index. In 1976, the size of the flexible disk was reduced to 5.25 inches and then the name of the dimpette name of the diskette appeared. At first, its volume was 180 KB, then it rose to 360 KB and 1.2 MB. The disadvantage of the flexible disk was weak protection from mechanical damage. In 1980, Sony developed a floppy disk and a drive by 3.5 inches. The carrier in it was placed in a solid body of solid plastic. The only hole for accessing heads to the carrier was covered with a metal curtain with a return spring. From this time the floppy disk has ceased to be flexible. Currently, floppy disks are used as the cheapest reserve tool (no more than 10 MB of information), as well as for transferring data from one PC to others, including portable to stationary PCs. The disks of each size (5.25 and 3.5 inches) are usually bilateral (Double Sided, DS), one-sided has long become an anachronism. Record density can be different: single (Single density, SD), dual density, dd) and high (high density, HD). Since few people already remember about a single density, such a classification is usually simplified, speaking only about double-density two-way diskettes (DS / DD, capacity 360 or 720 KB) and high density two-sided diskettes (DS / HD, capacity 1.2, 1.44 or 2.88 MB). Opeakers are formatted and unformatted. Although the diskettes formatted in the factory defense conditions are a bit more expensive to unformatted, the user does not have to spend time on their formatting, and in addition, they passed additional testing. The most common 3.5-inch floppy disks. Their magnetic disk is placed in a durable plastic case. The contact zone of magnetic heads with the surface of the disk is closed with a special curtain (valve), moved only inside the drive. The read / write speed for the 3.5-inch drive is about 63 KB / s, the average search time is about 80 ms. The disk contains 80 tracks (although some formatting programs allow you to use technological paths 80, 81 and 82 to increase the capacity of the disk). In the late 1980s, Toshiba, due to improving the production technology and methods, managed to increase the capacity of floppy disk to 2.88 MB. However, this format did not take place, and up to the end of the 20th century, the overwhelming majority of the diskettes had a 1,44 MB. Like any other magnetic disk carrier, a flexible diskette disk is divided into concentrated tracks, which, in turn, spawns on the sectors. Move the head to access various paths is carried out using a special head positioning drive, which moves the magnetic heads from one path to the other in the radial direction. Numbering tracks begins with 0, and sectors with 1. This system subsequently switched to hard drives. The principle of recording information on a floppy disk is the same as in the tape recorder, with a direct mechanical contact of the head with a magnetic layer applied to an artificial film. However, in contrast to the tape recorder, the recording is carried out here without high-frequency additions, and by magnifying the material of the carrier to saturation. General principles The principles of the structure of the block of heads for reading and writing information over time almost did not change. Their peculiarity is the presence of two erasing heads located on the sides from behind from the recording / playback head (the so-called tunnel erasing).

CD.

CD is a carrier of information in a numerical form recorded on an optical (laser) disk. The greatest distribution received CDs for recording audio (audio) and computer CDs (CD-ROM, Compact Disk Read Only Memory - memory on a CD only for reading). The technology of the optical disk was developed and demonstrated by Philips in 1979. The optical CD consists of a durable, transparent base (polycarbonate or polychloroquinyl), reflective and protective layers. A layer of sprayed aluminum is usually used as a reflective surface. Digital information is represented on the reflective surface with the alternation of the depression (non-reflecting spots) and reflecting the light of the plots. The CD has only one physical path in the form of a continuous helix, which comes from the outer diameter of the disk to the internal. The reading of information from the CD is happening with the help of a laser beam, which, falling on the reflective light, is deflected onto a photodetector, an interpreting signal as a binary unit. The laser beam falling into the cavity is not reflected and the photodetector fixes binary zero. Live CDs contain up to 640 megabytes of information, which is enough to write large software complexes, games, multimedia programs. Most computer CDs, like all audio discs are for reading information only. Data recording on CDs is carried out in their manufacturer in the factory. But there are special CDs on which you can write (CD-R) and overwrite information (CD-RW). Information from computer CDs reads a CD disc. Modern personal computers certainly have a CD-ROM drive and in the presence of sound card May lose audio. New generation motherboards support computer boot with CD-ROM, which is convenient when installing a new operating system or when checking a computer for viruses. In the late 1990s, new generation CDs appeared - DVD (Digital Versatile Disc - digital multi-purpose disk) with a large capacity, which are used to record full-length films, ultra-high quality and multimedia sound computer programs. There are several DVD variants that differ in capacity: one-sided, double-sided, single-layer and two-layer. One-sided single-layer DVD discs have a capacity of 4.7 GB of information, two-layer - 8.5 GB, double-sided single-layer contains 9.4 GB, double-sided two-layer - 17 GB. The laser beam in the usual CD-ROM drive has a wavelength of 780 nm, and in DVD devices - from 635 to 650 nm, making the recording density significantly increased.

CD-RW.

Currently, the CD-ROM drives with the ability to recording (CD-R) and Rewashing (CD-RW) are available. Thanks to a low rate of drive and clean media for a single recording, these devices began to be widely used to archive data, backup, storing large amounts of information, etc. CD-R drive (previously used the name WRITE ONCE - READ MANY) Allows you to Create (or copy) audio parts that can be reproduced on any household audio equipment. This allows, for example, to independently create discs with collections of compositions of favorite performers without loss of quality when a census, since the recording is carried out in digital video. Media on a CD with a single record have very high reliability. The shelf life of a clean disc to the record is from 5 to 10 years, and the recorded disk can be stored by different estimates from 70 to 200 years. Standard disk volume is 74 minutes (when recording audio data), or 650 MB. There are disks with a diameter of 120 mm and a capacity of 63 and 74 minutes, and with a diameter of 80 mm and a capacity of 18 and 21 minutes. An important advantage of CD-R disks is the possibility of reading them on any CD-ROM drive.

Lecture 1 History of development of computing equipment. purpose

Lecture

Logic diagrams were created on discrete radio components and electronic vacuum lamps with a filament. In operational storage devices, magnetic drums, acoustic ultrasound mercury and electromagnetic

Lectures on Informatics Lecture Introduction to Informatics The term "Informatics" (Franz Informatique)

Lectures

The term "informatics" (Franz. Informatique) comes from French information words (information) and Automatique (automation) and literally means "information automation".