The main devices of a computer, their functions and relationships during the operation of the machine. Computer as a universal information processing device

Transaction Interaction The interesting process of determining whether Current version garbage or, perhaps, some transaction still needs it. To describe this process, you will have to introduce several important concepts. First of all, it should be noted that all definitions are based

3.9. Calibrating computer devices Device profiles What to do if the same file is on different monitors looks different? And where do the differences in the picture come from if the same picture is printed on different printers? In such cases, devices are most often

Communication Notify your team and superiors of trouble. Outline your plan to overcome the crisis. Contact them for information and advice. Avoid surprises. Nothing makes people angry or less rational than surprises. Surprises increase

Purpose and device of a computer

What do computers and humans have in common?

For computer science, a computer is not only a tool for working with information, but also an object of study. You will learn how a computer works, what work can be done with it, and what software tools exist for this.

Since ancient times, people have sought to make their work easier. For this purpose, various machines and mechanisms were created that enhance human physical capabilities. The computer was invented in the middle of the 20th century to enhance the capabilities of human mental work, i.e., working with information.

From the history of science and technology it is known that man “spotted” the ideas for many of his inventions in nature.

For example, back in the 15th century, the great Italian scientist and artist Leonardo da Vinci studied the structure of the bodies of birds and used this knowledge to design aircraft.

Russian scientist N. E. Zhukovsky, the founder of aerodynamics, also studied the mechanism of bird flight. The results of these studies are used in aircraft design calculations.

We can say that Leonardo da Vinci and Zhukovsky “based” their flying cars on birds.

Is there a prototype of a computer in nature? Yes! Such a prototype is man himself. Only inventors sought to transfer to the computer not the physical, but the intellectual capabilities of a person.

According to its purpose, the computer is a universal technical means for a person to work with information.

According to the principles of its design, a computer is a model of a person working with information.

What devices are included in the computer? There are four main components information function person:

receiving (entering) information;

remembering information (storing in memory);

thinking process (information processing);

transmission (output) of information.

A computer includes devices that perform these functions of a thinking person:

Input Devices;

storage devices - memory;

processing device - processor;

output devices.

During computer operation, information enters memory through input devices; the processor retrieves the processed information from memory, works with it and places the processing results into it; The results obtained are communicated to humans through output devices. Most often, a keyboard is used as an input device, and a display screen or a printer (printing device) is used as an output device (Fig. 2.2).

What is data and program. Still, one cannot equate the “mind of a computer” with the mind of a person. The most important difference is that the work of a computer is strictly subordinate to the program embedded in it, while a person controls his own actions.

Computer memory stores data and programs.

Data- this is processed information presented in computer memory in special form. A little later, you'll learn about ways to represent data in computer memory.

Program is a description of the sequence of actions that a computer must perform to solve a given data processing task.

If information for a person is the knowledge that he possesses, then information for a computer is data and programs stored in memory. Data is “declarative knowledge”; programs are “procedural knowledge of a computer”.

Von Neumann's principles. In 1946, the American scientist John von Neumann formulated the basic principles of the design and operation of computers. The first of these principles determines the composition of computer devices and methods for their information interaction. This was discussed above. You have yet to become familiar with other von Neumann principles.

Questions and tasks

1. What human capabilities are reproduced by a computer?

2. List the main devices included in the computer. What is the purpose of each of them?

3. Describe the process of exchanging information between computer devices.

4. What is a computer program?

6. How is data different from a program?

Computer memory

Internal and external memory. When working with information, a person uses not only his own knowledge, but also books, reference books and other external sources. In Chapter 1, “Man and Information,” it was noted that information is stored in human memory and on external media. A person can forget information that has been memorized, but records are stored more reliably.

A computer also has two types of memory: internal (RAM) and external (long-term) memory.

Inner memory is an electronic device that stores information while it is powered by electricity. When the computer is disconnected from the network, information from RAM disappears. The program is stored in the internal memory computer. The formulated rule refers to the Neumann principles. It is called the stored program principle.

External memory - these are various magnetic media (tapes, disks), optical discs. Storing information on them does not require constant power supply.

In Fig. Figure 2.3 shows a diagram of a computer structure taking into account two types of memory. The arrows indicate the directions of information exchange.

The smallest element of computer memory is called a memory bit. In Fig. 2.4 each cell represents a bit. You see that the word "bit" has two meanings: a unit of measurement of the amount of information and a particle of computer memory. Let us show how these concepts are related to each other.

Each bit of memory can currently store one of two values: zero or one. The use of two characters to represent information is called binary encoding .

Data and programs in computer memory are stored in the form of binary code.

One character of a two-character alphabet carries 1 bit of information.

One bit of memory contains one bit of information.

The bit structure determines the first property of the computer’s internal memory - discreteness . Discrete objects are made up of individual particles. For example, sand is discrete because it consists of grains of sand. The “grains of sand” of computer memory are bits.

The second property of the computer's internal memory is addressability . Eight consecutive bits of memory form a byte. You know that this word also denotes a unit of information, equal to eight bits. Therefore, one byte of memory stores one byte of information.

In the internal memory of a computer, all bytes are numbered. Numbering starts from zero.

The sequence number of a byte is called its address.

The principle of addressability means that:

Recording information into memory, as well as reading it from memory, is carried out at addresses.

Memory can be thought of as apartment house, in which each apartment is a byte, and the apartment number is an address. In order for the mail to reach its destination, you must provide the correct address. This is exactly how the processor accesses the internal memory of the computer, by addresses.

Modern computers have another type of internal memory called read only memory (ROM). This is non-volatile memory, information from which can only be read.

External memory media and devices. External memory devices are devices for reading and writing information to external media. Information on external media is stored in the form of files. You will find out more about what this is later.

The most important external memory devices on modern computers are magnetic disk drives(NMD), or floppy drives.

Who doesn't know what a tape recorder is? We are used to recording speech and music on a tape recorder, and then listening to the recordings. Sound is recorded on magnetic tape tracks using a magnetic head. With the help of the same device, the magnetic recording is again converted into sound.

The NMD operates similarly to a tape recorder. The same binary code is written to the disc tracks: the magnetized section is one, the non-magnetized section is zero. When read from disk, this record turns into zeros and ones in the internal memory bits.

A recording head is connected to the magnetic surface of the disk (Fig. 2.5), which can move along the radius. During operation of the NMD, the disk rotates. At each fixed position, the head interacts with the circular track. Binary information is recorded on these concentric tracks.

Rice. 2.5. Drive and magnetic disk

Another view external media are optical discs (another name is laser discs). They use not a magnetic, but an optical-mechanical method of recording and reading information.

First came laser discs, on which information is recorded only once. It cannot be erased or overwritten. Such disks are called CD-ROM - Compact Disk-Read Only Memory, which means “read-only compact disk”. Later, rewritable laser discs were invented - CD-RW. On them, as on magnetic media, stored information can be erased and recorded again.

Media that the user can remove from the drive is called removable media.

The greatest information capacity of removable media Laser discs of the DVD-ROM type are video discs. The amount of information stored on them can reach tens of gigabytes. Video discs contain full-length video films that can be viewed on a computer, just like on TV.

Questions and tasks

1. Try to explain why a computer needs two types of memory: internal and external.
2. What is the "stored program principle"?
3. What is the discrete property of the internal memory of a computer?
4. What two meanings does the word “bit” have? How are they related?
5. What is the addressability property of the internal memory of a computer?
6. Name the external computer memory devices.
7. What types optical disks You know?

How does a personal computer (PC) work?

What is a PC? Modern computers are very different: from large ones that occupy an entire room, to small ones that fit on a table, in a briefcase, and even in a pocket. Various computers are used for different purposes. Today, the most popular type of computer is personal computers. Personal computers (PCs) are intended for personal (personal) use.

Despite the variety of PC models, there are many similarities in their design. These general properties will now be discussed.

Basic PC devices. The main “part” of a personal computer is the microprocessor (MP). It is a miniature electronic circuit created by very complex technology, performing the function of a computer processor.

A personal computer is a collection of interconnected devices. The main thing in this set is system unit. The system unit contains the “brain” of the machine: a microprocessor and internal memory. The following are also located there: the power supply unit, disk drives, and external device controllers. The system unit is equipped with an internal fan for cooling.

The system unit is usually placed in metal case, on the outside of which there are: a power button, slots for installing replaceable disks and disk devices, connectors for connecting external devices.

Connected to the system unit keyboard device(keyboard), monitor(another name is display) and mouse(manipulator). Sometimes other types of manipulators are used: joystick, trackball, etc. Additionally, the following can be connected to the PC: Printer(printing device), modem(to access telephone line communications) and other devices (Fig. 2.6).

In Fig. Figure 2.6 shows a desktop PC model. In addition, there are portable models (laptops) and pocket computers.

All PC devices, except the processor and internal memory, are called external devices. Each external device interacts with the PC processor through a special unit called a controller (from the English "controller" - "controller", "manager"). There are a disk drive controller, a monitor controller, a printer controller, etc. (Fig. 2.7).

The main principle of interaction between PC devices. The principle on which it is organized information communication between the processor, RAM and external devices, similar to the principle of telephone communication. The processor through a multi-wire line called highway(other name - tire), communicates with other devices (Fig. 2.8).

Just like every subscriber telephone network has its own number, each external device connected to the PC also receives a number that serves as the address of this device. Information transmitted to an external device is accompanied by its address and sent to the controller. In this analogy, the controller is like a telephone set that converts the electrical signal traveling through the wires into sound when you listen to the phone, and converts the sound into an electrical signal when you speak.

A trunk is a cable consisting of many wires. The typical organization of the highway is as follows: one group of wires ( data bus) the processed information is transmitted, through another ( address bus) - addresses of memory or external devices accessed by the processor. There is also a third part of the highway - control bus; control signals are transmitted through it (for example, checking the device’s readiness for operation, a signal to start the device’s operation, etc.).

Questions and tasks

1. Name the minimum set of devices that make up a personal computer.

2. What devices are included? system unit?

3. What is a controller? What function does it perform?

4. How are the various PC devices physically connected to each other?

5. How does information transmitted over the bus get to the desired device?

Basic characteristics of a personal computer

Increasingly, personal computers are used not only in production and in educational institutions, but also at home. They can be bought in a store in the same way as they buy televisions, VCRs and other household appliances. When purchasing any product, it is advisable to know its main characteristics in order to purchase exactly what you need. PCs also have these basic characteristics.

Microprocessor characteristics. There are different models of microprocessors produced by different companies. The main characteristics of the MP are the clock speed and processor bit capacity.

The operating mode of the microprocessor is set by a microcircuit called generator clock frequency . This is a kind of metronome inside the computer. The processor is allocated a certain number of clock cycles to perform each operation. It is clear that if the metronome “knocks” faster, then the processor works faster. Clock frequency is measured in megahertz - MHz. A frequency of 1 MHz corresponds to a million clock cycles per second. Here are some typical microprocessor clock frequencies: 600 MHz, 800 MHz, 1000 MHz. The last value is called gigahertz - GHz. Modern microprocessor models operate at clock speeds of several gigahertz.

The next characteristic is the processor bit capacity. Bit depth is the maximum length of binary code that can be processed or transmitted by the processor as a whole. The processor capacity on the first PC models was 8 bits. Then 16-bit processors appeared. Modern PCs most often use 32-bit processors. The most high-performance machines have 64-bit processors.

The amount of internal (RAM) memory. We have already talked about computer memory. It is divided into operational (internal) memory and long-term (external) memory. The performance of a machine greatly depends on the amount of internal memory. If there is not enough internal memory to run some programs, the computer begins to transfer some of the data to external memory, which sharply reduces its performance. The speed of reading/writing data into RAM is several orders of magnitude higher than into external memory.

The amount of RAM affects the performance of your computer. Modern programs require tens and hundreds of megabytes of RAM.

For modern programs to work well, they require RAM hundreds of megabytes: 128 MB, 256 MB and more.

Characteristics of external memory devices. External memory devices are magnetic and optical disk drives. The magnetic disks built into the system unit are called hard drives, or hard drives. This is very an important part computer, since this is where all the programs necessary for the computer to operate are stored. Reading/writing to a hard drive is faster than to all other types of external media, but still slower than to RAM. The larger the volume hard drive, all the better. Modern PCs are equipped with hard drives, the volume of which is measured in gigabytes: tens and hundreds of gigabytes. When you buy a computer, you also buy required set programs on the hard drive. Typically, the buyer himself orders the computer software.

All other external memory media are removable, i.e. they can be inserted into and removed from the drive. These include flexible magnetic disks - floppy disks and optical disks - CD-ROM, CD-RW, DVD-ROM. A standard floppy disk holds 1.4 MB of information. Floppy disks are convenient for long-term storage of programs and data, as well as for transferring information from one computer to another.

IN Lately Flash memory is replacing floppy disks as the main means of transferring information from one computer to another. Flash memory is an electronic external memory device used to read and write information to file format. Flash memory, like disks, is a non-volatile device. However, compared to disks, flash memory has a much larger information volume (hundreds and thousands of megabytes). And the speed of reading and writing data on flash media approaches the speed of RAM.

CD-ROM drives have become an almost mandatory component of a PC set. Modern software is distributed precisely on these media. The capacity of a CD-ROM is hundreds of megabytes (standard volume is 700 MB).

You can purchase DVD drives at at will. The amount of data on disks of this type is calculated in gigabytes (4.7 GB, 8.5 GB, 17 GB). Videos are often recorded on DVDs. Their playback time reaches 8 hours. These are 4-5 full-length films. Writers optical drives allow you to record and rewrite information on CD-RW and DVD-RW. The constant reduction in prices for the listed types of devices transfers them from the category of “luxury items” to generally available ones.

All other device types are classified as input/output devices. Mandatory ones are a keyboard, a monitor and a pointing device (usually a mouse). Additional devices: printer, modem, scanner, sound system and some others. The choice of these devices depends on the needs and financial opportunities buyer. You can always find sources reference information about the models of such devices and their operational properties.

Questions and tasks

1. What characteristics of a computer determine its performance?

2. What order of information volume do they have: floppy disks, hard drives, CD-ROM, DVD-ROM?

3. Which memory devices are built-in and which are removable?

4. Which input/output devices are required for a PC, and which are optional?

Computer as a universal information processing device

Purpose and device of a computer

What do computers and humans have in common?

For computer science, a computer is not only a tool for working with information, but also an object of study. You will learn how a computer works, what work can be done with it, and what software tools exist for this.

Since ancient times, people have sought to make their work easier. For this purpose, various machines and mechanisms were created that enhance human physical capabilities. The computer was invented in the middle of the 20th century to enhance the capabilities of human mental work, i.e., working with information.

From the history of science and technology it is known that man “spotted” the ideas for many of his inventions in nature.

For example, back in the 15th century, the great Italian scientist and artist Leonardo da Vinci studied the structure of the bodies of birds and used this knowledge to design aircraft.

Russian scientist N. E. Zhukovsky, the founder of aerodynamics, also studied the mechanism of bird flight. The results of these studies are used in aircraft design calculations.

We can say that Leonardo da Vinci and Zhukovsky “based” their flying cars on birds.

Is there a prototype of a computer in nature? Yes! Such a prototype is man himself. Only inventors sought to transfer to the computer not the physical, but the intellectual capabilities of a person.

According to its purpose, a computer is a universal technical tool for a person to work with information.

According to the principles of its design, a computer is a model of a person working with information.

What devices are included in the computer? There are four main components of the human information function:

receiving (entering) information;
remembering information (storing in memory);
thinking process (information processing);
transmission (output) of information.

A computer includes devices that perform these functions of a thinking person:

Input Devices;
storage devices - memory;
processing device - processor;
output devices.

During computer operation, information enters memory through input devices; the processor retrieves the processed information from memory, works with it and places the processing results into it; The results obtained are communicated to humans through output devices. Most often, a keyboard is used as an input device, and a display screen or a printer (printing device) is used as an output device (Fig. 2.2).

Rice. 2.2. Information exchange in a computer

What is data and program. Still, one cannot equate the “mind of a computer” with the mind of a person. The most important difference is that the work of a computer is strictly subordinate to the program embedded in it, while a person controls his own actions.

Computer memory stores data and programs.

Data- This is processed information presented in the computer memory in a special form. A little later, you'll learn about ways to represent data in computer memory.

Program is a description of the sequence of actions that a computer must perform to solve a given data processing task.

If information for a person is the knowledge that he possesses, then information for a computer is data and programs stored in memory. Data is “declarative knowledge”; programs are “procedural knowledge of a computer”.

Von Neumann's principles. In 1946, the American scientist John von Neumann formulated the basic principles of the design and operation of computers. The first of these principles determines the composition of computer devices and the methods of their information interaction. This was discussed above. You have yet to become familiar with other von Neumann principles.

Questions and tasks

1. What human capabilities are reproduced by a computer?
2. List the main devices included in the computer. What is the purpose of each of them?
3. Describe the process of exchanging information between computer devices.
4. What is a computer program?
6. How is data different from a program?

Computer memory

Internal and external memory. When working with information, a person uses not only his own knowledge, but also books, reference books and other external sources. In Chapter 1, “Man and Information,” it was noted that information is stored in human memory and on external media. A person can forget information that has been memorized, but records are stored more reliably.

A computer also has two types of memory: internal (RAM) and external (long-term) memory.

Inner memory is an electronic device that stores information while it is powered by electricity. When the computer is disconnected from the network, information from RAM disappears. The program is stored in the internal memory of the computer during its execution. The formulated rule refers to the Neumann principles. It is called the stored program principle.

External memory - these are various magnetic media (tapes, disks), optical disks. Storing information on them does not require constant power supply.

In Fig. Figure 2.3 shows a diagram of a computer structure taking into account two types of memory. The arrows indicate the directions of information exchange.

The smallest element of computer memory is called a memory bit. In Fig. 2.4 each cell represents a bit. You see that the word "bit" has two meanings: a unit of measurement of the amount of information and a particle of computer memory. Let us show how these concepts are related to each other.

Each bit of memory can currently store one of two values: zero or one. The use of two characters to represent information is called binary encoding .

Data and programs in computer memory are stored in the form of binary code.

One character of a two-character alphabet carries 1 bit of information.

One bit of memory contains one bit of information.

The bit structure determines the first property of the computer’s internal memory - discreteness . Discrete objects are made up of individual particles. For example, sand is discrete because it consists of grains of sand. The “grains of sand” of computer memory are bits.

The second property of the computer's internal memory is addressability . Eight consecutive bits of memory form a byte. You know that this word also denotes a unit of information, equal to eight bits. Therefore, one byte of memory stores one byte of information.

In the internal memory of a computer, all bytes are numbered. Numbering starts from zero.

The sequence number of a byte is called its address.

The principle of addressability means that:

Recording information into memory, as well as reading it from memory, is carried out at addresses.

Memory can be thought of as an apartment building, in which each apartment is a byte, and the apartment number is an address. In order for the mail to reach its destination, you must provide the correct address. This is exactly how the processor accesses the internal memory of the computer, by addresses.

Modern computers have another type of internal memory called read only memory (ROM). This is non-volatile memory, information from which can only be read.

External memory media and devices. External memory devices are devices for reading and writing information to external media. Information on external media is stored in the form of files. You will find out more about what this is later.

The most important external memory devices on modern computers are magnetic disk drives(NMD), or floppy drives.

Who doesn't know what a tape recorder is? We are used to recording speech and music on a tape recorder, and then listening to the recordings. Sound is recorded on magnetic tape tracks using a magnetic head. With the help of the same device, the magnetic recording is again converted into sound.

The NMD operates similarly to a tape recorder. The same binary code is written to the disc tracks: the magnetized section is one, the non-magnetized section is zero. When read from disk, this record turns into zeros and ones in the internal memory bits.

A recording head is connected to the magnetic surface of the disk (Fig. 2.5), which can move along the radius. During operation of the NMD, the disk rotates. At each fixed position, the head interacts with the circular track. Binary information is recorded on these concentric tracks.

Rice. 2.5. Floppy drive and magnetic disk

Another type of external media is optical discs (another name for them is laser discs). They use not a magnetic, but an optical-mechanical method of recording and reading information.

First came laser discs, on which information is recorded only once. It cannot be erased or overwritten. Such disks are called CD-ROM - Compact Disk-Read Only Memory, which means “read-only compact disk”. Later, rewritable laser discs were invented - CD-RW. On them, as on magnetic media, stored information can be erased and recorded again.

Media that the user can remove from the drive is called removable media.

Laser discs such as DVD-ROM - video discs - have the greatest information capacity among removable media. The amount of information stored on them can reach tens of gigabytes. Video discs contain full-length video films that can be viewed on a computer, just like on TV.

Questions and tasks

1. Try to explain why a computer needs two types of memory: internal and external.
2. What is the "stored program principle"?
3. What is the discrete property of the internal memory of a computer?
4. What two meanings does the word “bit” have? How are they related?
5. What is the addressability property of the internal memory of a computer?
6. Name the external computer memory devices.
7. What types of optical disks do you know?

How does a personal computer (PC) work?

What is a PC? Modern computers are very different: from large ones that occupy an entire room, to small ones that fit on a table, in a briefcase, and even in a pocket. Different computers are used for different purposes. Today, the most popular type of computer is personal computers. Personal computers (PCs) are intended for personal (personal) use.

Despite the variety of PC models, there are many similarities in their design. These general properties will now be discussed.

Basic PC devices. The main “part” of a personal computer is the microprocessor (MP). This is a miniature electronic circuit, created using a very complex technology, that performs the function of a computer processor.

A personal computer is a collection of interconnected devices. The main thing in this set is system unit. The system unit contains the “brain” of the machine: a microprocessor and internal memory. The following are also located there: the power supply unit, disk drives, and external device controllers. The system unit is equipped with an internal fan for cooling.

The system unit is usually placed in a metal case, on the outside of which there are: a power button, slots for installing removable disks and disk devices, connectors for connecting external devices.

Connected to the system unit keyboard device(keyboard), monitor(another name is display) and mouse(manipulator). Sometimes other types of manipulators are used: joystick, trackball, etc. Additionally, the following can be connected to the PC: Printer(printing device), modem(for access to a telephone line) and other devices (Fig. 2.6).

In Fig. Figure 2.6 shows a desktop PC model. In addition, there are portable models (laptops) and pocket computers.

All PC devices, except the processor and internal memory, are called external devices. Each external device interacts with the PC processor through a special unit called a controller (from the English "controller" - "controller", "manager"). There are a disk drive controller, a monitor controller, a printer controller, etc. (Fig. 2.7).

The main principle of interaction between PC devices. The principle by which information communication between the processor, RAM and external devices is organized is similar to the principle of telephone communication. The processor through a multi-wire line called highway(other name - tire), communicates with other devices (Fig. 2.8).

Just as each telephone network subscriber has its own number, each external device connected to a PC also receives a number that serves as the address of this device. Information transmitted to an external device is accompanied by its address and sent to the controller. In this analogy, the controller is like a telephone set that converts the electrical signal traveling through the wires into sound when you listen to the phone, and converts the sound into an electrical signal when you speak.

A trunk is a cable consisting of many wires. The typical organization of the highway is as follows: one group of wires ( data bus) the processed information is transmitted, through another ( address bus) - addresses of memory or external devices accessed by the processor. There is also a third part of the highway - control bus; control signals are transmitted through it (for example, checking the device’s readiness for operation, a signal to start the device’s operation, etc.).

Questions and tasks

1. Name the minimum set of devices that make up a personal computer.
2. What devices are included in the system unit?
3. What is a controller? What function does it perform?
4. How are the various PC devices physically connected to each other?
5. How does information transmitted over the bus get to the desired device?

Basic characteristics of a personal computer

Increasingly, personal computers are used not only in production and in educational institutions, but also at home. You can buy them in a store in the same way you buy televisions, VCRs and other household appliances. When purchasing any product, it is advisable to know its main characteristics in order to purchase exactly what you need. PCs also have these basic characteristics.

Microprocessor characteristics. There are different models of microprocessors produced by different companies. The main characteristics of the MP are the clock speed and processor bit capacity.

The operating mode of the microprocessor is set by a microcircuit called clock generator. This is a kind of metronome inside the computer. The processor is allocated a certain number of clock cycles to perform each operation. It is clear that if the metronome “knocks” faster, then the processor works faster. Clock frequency is measured in megahertz - MHz. A frequency of 1 MHz corresponds to a million clock cycles per second. Here are some typical microprocessor clock frequencies: 600 MHz, 800 MHz, 1000 MHz. The last value is called gigahertz - GHz. Modern microprocessor models operate at clock speeds of several gigahertz.

The next characteristic is the processor bit capacity. Bit depth is the maximum length of binary code that can be processed or transmitted by the processor as a whole. The processor capacity on the first PC models was 8 bits. Then 16-bit processors appeared. Modern PCs most often use 32-bit processors. The most high-performance machines have 64-bit processors.

The amount of internal (RAM) memory. We have already talked about computer memory. It is divided into operational (internal) memory and long-term (external) memory. The performance of a machine greatly depends on the amount of internal memory. If there is not enough internal memory to run some programs, the computer begins to transfer some of the data to external memory, which sharply reduces its performance. The speed of reading/writing data into RAM is several orders of magnitude higher than into external memory.

The amount of RAM affects the performance of your computer. Modern programs require tens and hundreds of megabytes of RAM.

For modern programs to work well, RAM of hundreds of megabytes is required: 128 MB, 256 MB or more.

Characteristics of external memory devices. External memory devices are magnetic and optical disk drives. The magnetic disks built into the system unit are called hard drives, or hard drives. This is a very important part of the computer because it is where all the programs necessary for the computer to operate are stored. Reading/writing to a hard drive is faster than to all other types of external media, but still slower than to RAM. The larger the hard drive capacity, the better. Modern PCs are equipped with hard drives, the volume of which is measured in gigabytes: tens and hundreds of gigabytes. When you buy a computer, you also purchase the necessary set of programs on the hard drive. Typically, the buyer himself orders the computer software.

All other external memory media are removable, i.e. they can be inserted into and removed from the drive. These include flexible magnetic disks - floppy disks and optical disks - CD-ROM, CD-RW, DVD-ROM. A standard floppy disk holds 1.4 MB of information. Floppy disks are convenient for long-term storage of programs and data, as well as for transferring information from one computer to another.

Recently, flash memory has replaced floppy disks as the main means of transferring information from one computer to another. Flash memory is an electronic external memory device used to read and write information in file format. Flash memory, like disks, is a non-volatile device. However, compared to disks, flash memory has a much larger information volume (hundreds and thousands of megabytes). And the speed of reading and writing data on flash media approaches the speed of RAM.

CD-ROM drives have become an almost mandatory component of a PC set. Modern software is distributed precisely on these media. The capacity of a CD-ROM is hundreds of megabytes (standard volume is 700 MB).

You can purchase DVD drives at your own discretion. The amount of data on disks of this type is calculated in gigabytes (4.7 GB, 8.5 GB, 17 GB). Videos are often recorded on DVDs. Their playback time reaches 8 hours. These are 4-5 full-length films. Writeable optical drives allow you to write and rewrite information on CD-RW and DVD-RW. The constant reduction in prices for the listed types of devices transfers them from the category of “luxury items” to generally available ones.

All other device types are classified as input/output devices. Mandatory ones are a keyboard, a monitor and a pointing device (usually a mouse). Additional devices: printer, modem, scanner, sound system and some others. The choice of these devices depends on the needs and financial capabilities of the buyer. You can always find sources of reference information about the models of such devices and their operational properties.

Questions and tasks

1. What characteristics of a computer determine its performance?
2. What order of information volume do they have: floppy disks, hard drives, CD-ROM, DVD-ROM?
3. Which memory devices are built-in and which are removable?
4. Which input/output devices are required for a PC, and which are optional?

From a technical point of view, a personal computer can be defined as a single system, which is a set of replaceable components interconnected by standard interfaces. A component here is a separate unit (device) that performs a specific function as part of the system.

An interface is a standard for connecting components to a system. These are connectors, sets of chips that generate standard signals, and standard program code.

In the computer industry, there is a set of similar components with different functionality (and, accordingly, different costs) that are included in the system via a single interface. Full description The set and characteristics of the devices that make up a given computer is called the PC configuration. The devices located inside the system unit are called internal, and devices connected to it externally are called external. External additional devices designed for input, output and long-term storage of data are also called peripheral.

There is a “minimal” PC configuration, i.e. minimum set devices without which working with a PC becomes meaningless. These are: system unit, monitor, keyboard, mouse. Typically, a set of components united by the concept of a “standard personal computer” is understood as the following composition:

Personal computer – universal technical system. His configuration(equipment composition) can be flexibly changed as needed.

System unit

The system unit is the main unit within which the most important components are installed.

A monitor is a device for visually presenting data. This is not the only possible, but the main output device. Its main consumer parameters are: the size and pitch of the screen mask, maximum frequency image regeneration, protection class.

Monitor size measured between opposite corners of the kinescope tube diagonally. The unit of measurement is inches. Standard sizes: 14";15";17"; 19"; 20"; 21" etc. Currently, 15- and 17-inch monitors are the most versatile, while 19-21-inch monitors are desirable for graphics operations.

Keyboard

Keyboard is a keyboard control device for a personal computer. Used to enter alphanumeric (sign) data as well as control commands. The combination of a monitor and keyboard provides the simplest user interface. The keyboard is used to control the computer system, and the monitor is used to receive feedback from it.

Keyboard composition. A standard keyboard has more than 100 keys, functionally distributed into several groups:

Key groups standard keyboard

A group of alphanumeric keys is intended for entering character information and commands typed by letter. Each key can operate in several modes (registers) and, accordingly, can be used to enter multiple characters. Switch between lower case(for entering lowercase characters) and uppercase(to enter capital characters) is performed by holding the Shift key (non-fixed switching). If necessary, hard register switching is used Caps key Lock (fixed switching). If the keyboard is used to enter data, the paragraph is closed by pressing the Enter key. This automatically starts text entry with new line. If the keyboard is used to enter commands, the Enter key ends the command entry and begins its execution.

For different languages exist various schemes assigning symbols of national alphabets to specific alphanumeric keys. Such schemes are called keyboard layouts. Switching between different layouts is done programmatically - this is one of the functions of the operating system. Accordingly, the switching method depends on what operating system the computer is running on. For example, in Windows 98 the following combinations can be used for this purpose: left key Alt+Shift or Ctrl+Shift. When working with another operating system, the switching method can be set using the help system of the program that performs the switch.

Common keyboard layouts have their roots in typewriter keyboard layouts. For personal computers IBM PC Typical layouts are QWERTY (English) and YZUKENG (Russian). Layouts are usually named after the symbols assigned to the first keys of the top line of the alphabetical group.

Group function keys includes twelve keys (F1 to F12) located at the top of the keyboard. The functions assigned to these keys depend on the properties of the specific program currently running, and in some cases, on the properties of the operating system. It is a common convention for most programs that the F1 key calls up the help system, where you can find help about the actions of other keys.

Service keys located next to the alphanumeric group keys. Due to the fact that they have to be used especially often, they have an increased size. These include the Shift and Enter keys discussed above, the Alt and Ctrl register keys (they are used in combination with other keys to form commands), Tab key(to enter tab stops when typing), the Esc key (from the English word escape) to refuse to execute the last entered command and the Backspace key to delete the characters just entered (it is located above Enter key and is often marked with an arrow pointing to the left).

Service Print keys Screen, Scroll Lock and Pause/Break are located to the right of the group of function keys and perform specific functions depending on the operating system. The following actions are generally accepted:

Print Screen – prints the current screen state on the printer (for MS DOS) or storing it in a special area of ​​RAM called clipboard(for Windows).

Scroll Lock – switching the operating mode in some (usually outdated) programs.

Pause/Break – pause/interrupt the current process.

Two groups cursor keys located to the right of the alphanumeric bar. Cursor called a screen element indicating the location for entering character information. The cursor is used when working with programs that enter data and commands from the keyboard. The cursor keys allow you to control the input position.

The four arrow keys move the cursor in the direction indicated by the arrow. The actions of other keys are described below.

Page Up/Page Down – moves the cursor one page up or down. The term “page” usually refers to the portion of a document that is visible on the screen. In graphical operating systems (for example, Windows), these keys “scroll” the contents in the current window. The action of these keys in many programs can be modified using service register keys, primarily Shift and Ctrl. The exact result of the modification depends on the specific program and/or operating system.

The Home and End keys move the cursor to the beginning or end current line, respectively. Their action is also modified by register keys.

The traditional purpose of the Insert key is to switch the data input mode (switching between modes inserts And replacements). If the text cursor is located inside existing text, then in insert mode new characters are entered without replacing existing characters (the text is, as it were, moved apart). In replace mode, new characters replace the text that was previously in the input position.

In modern programs, the effect of the Insert key may be different. Specific information should be obtained from the program help system. It is possible that the action of this key is customizable - this also depends on the properties of the specific program.

The Delete key is designed to delete characters located to the right of the current cursor position. The position of the input position remains unchanged.

Compare the action of the Delete key with the action service key Backspace. The latter is used to delete characters, but when used, the input position is shifted to the left, and, accordingly, characters located not to the right, but to the left of the cursor are deleted.

Additional panel key group duplicates the action of the numeric and some symbolic keys of the main panel. In many cases, to use this group of keys, you must first enable the Num Lock switch key (the state of the Num Lock, Caps Lock and Scroll Lock switches can be judged by LED indicators, usually located in the upper right corner of the keyboard).

A mouse is a manipulator-type control device. It is a flat box with two or three buttons. Mouse movement on a flat surface is synchronized with movement graphic object (mouse pointer) on the monitor screen.

Operating principle. Unlike the keyboard discussed earlier, the mouse is not a standard control, and the personal computer does not have a dedicated port for it. There is no permanent dedicated interrupt for the mouse, and the basic input and output facilities (BIOS) computers located in read-only memory (ROM) do not contain software to handle mouse interrupts.

Due to this, the mouse does not work the first moment after turning on the computer. It requires the support of a special system program - mouse drivers. The driver is installed either when you connect the mouse for the first time, or when installing the computer's operating system. Although the mouse does not have a dedicated port on the motherboard, to work with it, use one of the standard ports, tools for working with which are included in the BIOS. The mouse driver is designed to interpret the signals coming through the port. In addition, it provides a mechanism for communicating information about the position and state of the mouse to the operating system and running programs.

The computer is controlled by moving the mouse along the plane and briefly pressing the right and left buttons. (These presses are called clicks.) Unlike a keyboard, a mouse cannot be used directly to enter character information - its control principle is eventful. Moving the mouse and clicking its buttons are events from the point of view of its driver program. By analyzing these events, the driver determines when the event occurred and where the pointer was located on the screen at that moment. This data is transmitted to application program, with which the user is currently working. Based on them, the program can determine the command that the user had in mind and begin executing it.

Internal devices of the system unit

Motherboard

Motherboard is the main board of a personal computer. It contains:

· processor - the main chip that performs most mathematical and logical operations;

· microprocessor kit (chipset) – a set of microcircuits that control the operation of the internal devices of a computer and determine the main functionality motherboard;

· tires– sets of conductors through which signals are exchanged between the internal devices of the computer;

· random access memory (random access memory, RAM) – a set of chips designed to temporarily store data when the computer is turned on;

· ROM (Read Only Memory) – a chip designed for long-term data storage, including when the computer is turned off;

· connectors for connection additional devices(slots).

HDD

HDD - the main device for long-term storage of large amounts of data and programs. In fact, this is not one disk, but a group of coaxial disks that have a magnetic coating and rotate at high speed. Thus, this “disk” does not have two surfaces, as an ordinary flat disk should have, but 2n surfaces, where n – number of individual disks in the group.

Above each surface is a head designed for reading and writing data. At high disk rotation speeds (90 rps), an aerodynamic cushion is formed in the gap between the head and the surface, and the head hovers above the magnetic surface at a height of several thousandths of a millimeter. When the current flowing through the head changes, the dynamic voltage changes magnetic field in the gap, which causes changes in the stationary magnetic field of the ferromagnetic particles that form the coating of the disk. This is how data is written to a magnetic disk.

The reading operation occurs in reverse order. Magnetized coating particles sweeping across high speed near the head, a self-induction emf is induced in it. The electromagnetic signals generated in this case are amplified and transmitted for processing.

The operation of the hard disk is controlled by a special hardware-logical device - hard drive controller.

The main parameters of hard drives include capacity And performance.

Floppy drive

Information on a hard drive can be stored for years, but sometimes it needs to be transferred from one computer to another. Despite its name, a hard drive is a very fragile device, sensitive to overloads, shocks and shocks. Theoretically, it is possible to transfer information from one workplace to another by moving a hard drive, and in some cases this is done, but still this technique is considered low-tech, since it requires special care and certain qualifications.

To quickly transfer small amounts of information, so-called floppy disks(floppy disks), which are inserted into a special drive - drive. The drive's receiving hole is located on the front panel of the system unit. The correct direction for feeding the floppy disk is indicated by an arrow on the plastic casing.

The main parameters of floppy disks are: technological size (measured in inches), recording density (measured in multiples of units) and total capacity.

Floppy disks are considered unreliable storage media. Dust, dirt, moisture, temperature changes and external electromagnetic fields very often cause partial or complete loss of data stored on a floppy disk. Therefore, using floppy disks as the main means of storing information is unacceptable. They are used only for transporting information or as an additional (backup) storage device.

CD-ROM drive

Abbreviation CD-ROM (Compact Disc Read-Only Memory) translated into Russian as CD-ROM based read-only storage device. Principle The operation of this device is to read numerical data using a laser beam reflected from the surface of the disk. Digital recording on a CD is very different from recording on magnetic disks. high density, and a standard CD can store approximately 650 MB of data.

Personal computer peripherals

Peripheral devices of a personal computer are connected to its interfaces and are designed to perform auxiliary operations. Thanks to them, the computer system gains flexibility and versatility.

According to their purpose, peripheral devices can be divided into:

· data input devices (scanners, digitizers, etc.);

· data output devices (printers, plotters, etc.);

· data storage devices (streamers, magneto-optical drives, etc.);

· data exchange devices (modems).

The system unit case contains all the main devices of the computer:

· microprocessor – the brain of the computer, which executes the commands received at its input: carries out calculations and controls the operation of other PC devices;

· RAM, designed for temporary storage of programs and data;

· controllers designed for processor-independent control of individual processes in PC operation;

· floppy disk drives used for reading and writing to floppy disks;

· a hard magnetic disk drive designed for reading and writing to a hard magnetic disk (hard drive);

· CD drives, which provide the ability to read data from computer CDs and play audio CDs, as well as write information to a CD;

· a power supply that converts the network power supply into direct current supplied to the electronic circuits of the computer;

· a time counter that functions regardless of whether the computer is turned on or not;

· Other devices.

All PC components, according to their functional relationship to working with information, can be divided into:

· information processing devices (central processor, specialized processors);

· information storage devices (hard drive, CD-ROM, RAM, etc.);

· information input devices (keyboard, mouse, microphone, scanner, etc.);

information output devices (monitor, printer, acoustic system etc.);

· information transmission devices (telefax modem).

4. Processing devices - microprocessor

4.2. Internal organization of the microprocessor

We list the main functions of the microprocessor:

Fetching commands from RAM;

Decoding commands (i.e. determining the purpose of the command, the method of its execution and the addresses of the operands);

Performing operations coded in commands;

Managing the transfer of information between its internal registers, RAM and external (peripheral) devices;

Processing of intraprocessor and software interrupts;

Processing signals from external devices and implementing corresponding interrupts;

Control of various devices included in the computer.

The internal structure of microprocessors is very complex (remember the three million transistors in the Pentium). Even if you try to consider the most general diagram of the main functional units, you will get a rather complex picture. Besides internal organization The MP is highly dependent on its brand, and therefore studying the structure of one processor does not necessarily help to understand the operation of another. It should be considered inappropriate for the user (and even, perhaps, for the programmer) to study the engineering details of the processor modern computer, and limit ourselves, as is customary, to only those functional units that are available programmatically. With this approach, it turns out that MPs have a lot in common, and some patterns of their internal structure become clearly visible. In addition, the intimidating complexity disappears and a pleasant and useful feeling arises that the computer is not some kind of “thing in itself” and its behavior can be understood.

Microprocessor (central microprocessor, CPU) is a software-controlled device designed to process information under the control of a program currently located in RAM. Structurally, it is a small microcircuit located inside the system unit and installed on the motherboard, connected to the motherboard via a processor socket interface (Socket).

4.3. Processor operating principles and characteristics

Small microprocessors (about the size of a sugar cube or a cell phone) are the powerhouse of a computer and often its most expensive internal component. The processor basically reads data from memory, manipulates it, and returns it back to memory or transmits it to external devices such as a monitor or printer.

A microprocessor can process data of any nature: text, numbers, graphics, sound, etc. This is possible because the data is converted to its simplest form, represented in binary code, and “digitized” before being used on a computer. Physically, this may look like an alternation of magnetized and demagnetized areas of the hard drive, reflective and non-reflective areas of the CD, transmitted high and low voltage signals, etc.

For job description digital devices The binary number system, Boolean logic, and the laws of algebra of logic are used.

The main characteristics of the processor are:

· performance – the number of operations performed in 1 second, measured in bits/sec. Each subsequent model has more high performance compared to the previous one. Modern processors have the MMX extension (MultiMediaeXtention - multimedia extension);

· Clock frequency – the number of clock cycles produced by the processor in 1 second. The operations performed by the processor are not continuous; they are divided into clock cycles. This characteristic determines the speed of operations and directly affects the performance of the processor. The Pentium processor and its modifications have clock speeds from 60 MHz to 1.5 GHz (perform 1.5 billion operations per second);

· bit depth – the number of binary bits that the processor processes in one clock cycle. When indicating the processor bit size is 64, they mean that the processor has a 64-bit data bus, i.e. it processes 64 bits in one clock cycle.

Approved
Director of the State Educational Institution NPO "Kachkanarskoye PU"
________________________ (S.M. Borodulina)

SAFETY REGULATIONS
AND BEHAVIORS IN THE COMPUTER CLASS

Students who have studied the operating instructions and these technical rules are allowed to work on a PC safe work on a PC, as well as having undergone safety training in the workplace.

It is strictly prohibited:

1. be in the computer class during a break without the permission of a senior (teacher);

2. turn on equipment without permission;

3. touch the connectors of connecting cables and wires (possible damage electric shock);

4. touch power wires and grounding devices;

5. touch the screen and the back of the monitor, keyboard;

6. turn on and off the equipment without instructions from the teacher;

7. work in outerwear and with wet hands;

8. jump, run (dust);

9. place disks, books, notebooks and other objects on the monitor and keyboard;

10. install or copy programs from floppy disks, disks and flash drives to a computer without first checking them with an antivirus;

11. If a burning smell appears, immediately stop working, turn off the equipment and notify the teacher.

During operation:

1. strictly follow all the above rules, as well as the current instructions of the teacher;

2. Monitor the serviceability of the equipment and stop working immediately if an unusual sound or spontaneous shutdown equipment;

3. Press the keys easily and quickly, avoiding sudden impacts;

4. Do not use the keyboard and mouse unless the computer is turned on;

5. operate the keyboard with clean hands;

6. Never try to troubleshoot equipment malfunctions on your own;

7. do not get up from your workstations when visitors enter the office.

Basic computer devices, their purpose and relationship

According to its purpose, the computer is a universal device for working with information. According to the principles of its design, a computer is a model of a person working with information.

Personal Computer(PC) is a computer designed to serve one workstation. Its characteristics may differ from mainframe computers, but is functionally capable of performing similar operations. According to the method of operation, desktop (desktop), portable (laptop and notebook) and pocket (palmtop) PC models are distinguished.

Hardware. Since the computer provides all three classes of information methods for working with data (hardware, software and natural), it is customary to speak of a computer system as consisting of hardware and software working together. The components that make up the hardware of a computer are called hardware. They perform all physical work with data: registration, storage, transportation and transformation, both in form and content, and also present them in a form convenient for interaction with natural information methods person.

The totality of a computer's hardware is called its hardware configuration.

YouTube Video

Software. Programs can be in two states: active and passive. In a passive state, the program does not work and looks like data, the content of which is information. In this state, the contents of the program can be “read” by other programs, like books are read, and changed. From it you can find out the purpose of the program and how it works. In the passive state, programs are created, edited, stored and transported. The process of creating and editing programs is called programming.

When a program is in an active state, the content of its data is considered as commands according to which the computer hardware operates. To change the order of their operation, it is enough to interrupt the execution of one program and start the execution of another, containing a different set of commands.

The set of programs stored on a computer forms its software. The set of programs prepared for operation is called installed software. The set of programs running at one time or another is called a software configuration.

Computer device. Any computer (even the largest one) consists of four parts:

input devices

information processing devices

storage devices

information output devices.

Structurally, these parts can be combined in one case the size of a book, or each part can consist of several rather bulky devices

Basic PC hardware configuration. The basic hardware configuration of a personal computer is the minimum set of hardware sufficient to start working with a computer. Over time, the concept of a basic configuration gradually changes.

Most often, a personal computer consists of the following devices:

System unit

Keyboard

Additionally, other input and output devices can be connected, for example, sound speakers, a printer, a scanner.

System unit- the main unit of a computer system. It contains devices that are considered internal. Devices connected to the system unit externally are considered external. The term peripheral equipment is also used for external devices.

Monitor- a device for visual reproduction of symbolic and graphic information. Serves as an output device. For desktop PCs, the most common monitors today are those based on cathode ray tubes. They vaguely resemble household TVs.

Keyboard- a keyboard device designed to control the operation of a computer and enter information into it. Information is entered in the form of alphanumeric character data.

Mouse— graphical control device.

Internal devices of a personal computer. Devices located in the system unit are considered internal. Some of them are accessible on the front panel, which is convenient for quick changes information media, such as floppy magnetic disks. The connectors of some devices are located on the rear wall - they are used to connect peripheral equipment. Access to some system unit devices is not provided - it is not required for normal operation. CPU. Microprocessor- the main microcircuit of a personal computer. All calculations are performed in it. The main characteristic of the processor is the clock frequency (measured in megahertz, MHz). The higher the clock speed, the higher the processor performance. For example, at a clock frequency of 500 MHz, a processor can change its state 500 million times in one second. For most operations, one clock cycle is not enough, so the number of operations a processor can perform per second depends not only on the clock speed, but also on the complexity of the operations.

The only device the processor “knows from birth” about its existence is RAM—it works together with it. This is where data and commands come from. Data is copied into processor cells (called registers) and then converted according to the contents of the instructions. You'll get a more complete picture of how the processor interacts with RAM in the chapters on programming fundamentals.

RAM. RAM can be thought of as a vast array of cells that store numeric data and commands while the computer is turned on. The amount of RAM is measured in millions of bytes - megabytes (MB).

The processor can access any RAM cell (byte) because it has a unique numeric address. The processor cannot access an individual bit of RAM, since the bit does not have an address. At the same time, the processor can change the state of any bit, but this requires several actions.

Motherboard. The motherboard is the largest circuit board of a personal computer. It contains highways that connect the processor with RAM - the so-called buses. There is a data bus through which the processor copies data from memory cells, an address bus through which it connects to specific memory cells, and a command bus through which the processor receives commands from programs. All other internal devices of the computer are also connected to the motherboard buses. The operation of the motherboard is controlled by a microprocessor chipset - the so-called chipset.

Video adapter. A video adapter is an internal device installed in one of the connectors on the motherboard. The first personal computers did not have video adapters. Instead, a small area was allocated in RAM for storing video data. A special chip (video controller) read data from video memory cells and controlled the monitor in accordance with them.

As the graphic capabilities of computers improved, the video memory area was separated from the main RAM and, together with the video controller, was separated into a separate device, which was called a video adapter. Modern video adapters have their own computing processor (video processor), which has reduced the load on the main processor when constructing complex images. The video processor plays a particularly important role when constructing three-dimensional images on a flat screen. During such operations, he has to perform a particularly large number of mathematical calculations.

In some models of motherboards, the functions of the video adapter are performed by chipset chips - in this case they say that the video adapter is integrated with the motherboard. If the video adapter is made in the form separate device, it is called a video card. The video card connector is located on the rear wall. A monitor is connected to it.

Sound adapter. For IBM computers PC work with sound was not initially provided. For the first ten years of its existence, computers of this platform were considered office equipment and did without sound devices. Currently, audio tools are considered standard. To do this, a sound adapter is installed on the motherboard. It can be integrated into the motherboard chipset or implemented as a separate plug-in card called a sound card. The sound card connectors are located on the back wall of the computer. To play sound, speakers or headphones are connected to them. A separate connector is intended for connecting a microphone. In the presence of special program this allows you to record sound. There is also a connector ( line output) for connection to external sound recording or sound reproducing equipment (tape recorders, amplifiers, etc.). HDD. Since the computer's RAM is cleared when the power is turned off, a device is needed to store data and programs for a long time. Currently, so-called hard drives are widely used for these purposes. The operating principle of a hard drive is based on recording changes in the magnetic field near the recording head.

The main parameter of a hard drive is capacity, measured in gigabytes (billions of bytes), GB. The average size The size of a modern hard drive is 80 - 160 GB, and this parameter is steadily growing.

Floppy drive. To transport data between remote computers They use so-called floppy disks. A standard floppy disk (floppy disk) has a relatively small capacity of 1.44 MB. By modern standards, this is completely insufficient for most data storage and transportation tasks, but the low cost of media and high availability have made floppy disks the most common storage media.

To write and read data located on floppy disks, is a special device - a disk drive. The drive receiving hole is located on the front panel of the system unit.

CD-ROM drive. To transport large amounts of data, it is convenient to use CD-ROMs. These discs can only read previously written data; they cannot be written to. The capacity of one disk is about 650-700 MB.

CD-ROM drives are used to read CDs. The main parameter of a CD-ROM drive is read speed. It is measured in multiple units. The reading speed approved in the mid-80s is taken as one. for music CDs (audio CDs). Modern CD-ROM drives provide reading speeds of 40x - 52x. The main disadvantage of CD-ROM drives - the inability to burn discs - has been overcome in modern devices write-once - CD-R. There are also CD-RW devices that allow multiple recordings.

The principle of data storage on CDs is not magnetic, like floppy disks, but optical.

Communication ports. To communicate with other devices, such as a printer, scanner, keyboard, mouse, etc., the computer is equipped with so-called ports. A port is not just a connector for connecting external equipment, although a port ends in a connector. A port is a more complex device than just a connector, having its own chips and controlled by software.

Network adapter. Network adapters are necessary for computers to be able to communicate with each other. This device ensures that the processor does not send a new portion of data to the external port until the network adapter of a neighboring computer has copied the previous portion to itself. After this, the processor is given a signal that the data has been collected and new ones can be submitted. This is how the transfer takes place.

When a network adapter “learns” from a neighboring adapter that it has a piece of data, it copies it to itself, and then checks whether it is addressed to it. If yes, it passes them to the processor. If not, it puts them on the output port, from where the network adapter of the next neighboring computer will pick them up. This is how data moves between computers until it reaches the recipient.

— Webcam needed to input dynamic images into a computer and sound (for communication and the ability to create teleconferences).

— Uninterruptable power source needed in case emergency shutdown electricity. hardware.

Printer Designed for printing text and graphic images. Printers are dot matrix, inkjet and laser. IN dot matrix printers the image is formed from dots by impact. Inkjet printers Instead of needles, the print head has thin tubes - nozzles, through which tiny droplets of ink are thrown onto the paper. Inkjet printers also perform color mixing printing basic colors. The advantage is high print quality, the disadvantage is the danger of ink drying out and the high cost of consumables.

Laser printers use the electrographic method of image formation. The laser is used to create an ultra-thin beam of light that traces the contours of an invisible dotted electronic image on the surface of a pre-charged light-sensitive drum. After developing the electronic image with dye (toner) powder adhering to the discharged areas, printing is performed - transferring the toner from the drum to paper and fixing the image on the paper by heating the toner until it melts. Laser printers provide the highest quality printing with high speed. Color laser printers are widely used. — Speakers output sound. The sound quality depends - again - on the power of the speakers and the material from which the cabinets are made (preferably wood) and its volume. An important role is played by the presence of a bass reflex (hole on the front panel) and the number of reproduced frequency bands (high, mid and low speakers on each speaker). — USB drives on flash memory, in my opinion, have become the most universal remedy transfer of information. This miniature device is smaller in size and weight than a lighter. It has high mechanical strength and is not afraid of electromagnetic radiation, heat and cold, dust and dirt.

The most sensitive part of the drive is the connector, covered with a cap. The capacity of these devices ranges from 256 MB to 32 GB, which allows you to select a drive of the required capacity, in accordance with your needs. Thanks to the interface, the USB drive can be connected to any modern computer. It works with Windows 98SE/Me/2000/XP/Vista/7, Mac OS 8.6 ~ 10.1, Linux 2.4 operating systems. In Windows you don’t even need to install any drivers: just plug it into a USB port and go.