Peripheral equipment, etc. Functions of the main and peripheral devices of a computer

Hello dear readers of the site. In one of the lessons, we figured out that a computer can be divided into a system unit with all its contents and peripheral devices. It is peripheral devices that will be discussed in today’s article. If you have not read the article about computer devices, then follow the link « » .

Personal computer peripherals are devices that connect to the computer using special connectors. Below are examples of the main devices that can often be found on home computers.

Monitor, display, screen. This is a device that users often call a “TV.” It displays images on the screen, which means it is a very important component in a computer.

Based on operating technology, monitors are divided into CRT (Cathode Ray Tube) and LCD (Liquid Crystal). The first type is a device containing a kinescope, the same as in old televisions. Using such a monitor is quite harmful to the user’s health; fortunately, they are rarely used today. The second type - liquid crystal monitor - is a modern solution, its use is much less harmful to health.

The second important characteristic is the screen size of the monitor. It is usually measured diagonally and indicated in inches. LCD monitors are widescreen, which means that the screen will be slightly elongated in width; the aspect ratio of such a screen is usually 16:9 (a regular square one is 4:3).

Monitors can be connected via the following interfaces: VGA, DVI, HDMI and DisplayPort. Currently, VGA and DVI interfaces are widely used on personal computers, and there are also various adapters if the monitor or motherboard does not provide these interfaces.

This is a device for entering information. All keys are divided into several groups:

Alphanumeric;
Control keys (Enter, Backspace, Shift, Ctrl, Alt, Win, Caps Lock, Tab, Print Screen, Scroll Lock, Pause Break, Num Lock keys);
Functional (keys F1 – F12);
Cursor keys (Arrows, Insert, Delete, Home, End, Page Up, Page Down);
Small numeric keypad.

In addition to those listed above, the keyboard may contain a set of multimedia keys for various purposes. There are also usually Num Lock, Caps Lock, and Scroll Lock mode indicators.

The device can be connected via Ps/2,USB interface. There are also adapters that allow you to connect a USB keyboard to a PS/2 port and vice versa.

On laptops and netbooks, in order to save space, some groups of keys may be missing. They may also be missing from regular keyboards.

The advantage of a USB keyboard is that it can be connected with the computer turned on and after a while the operating system will automatically recognize the keyboard, so you do not need to restart the computer to start working with it. If you connect a PS/2 keyboard while the computer is turned on, the system will not be able to detect the device and you will have to restart the computer to start using the keyboard.

This is a manipulator device that converts the user's hand movements into cursor movements on the screen. The minimum set is two keys and a scroll wheel; some models may have an expanded set: more than one wheel and additional keys on the left and right sides of the mouse, which are very popular among “gamers”.

Mouse buttons are usually called “left mouse button” (LMB, Mouse 1) and “right mouse button” (RMB, Mouse 2); there is usually also a third additional button under the wheel.

Based on the principle of operation, mice can be mechanical, optical and laser. Mechanical ones contain a rubberized ball inside, which, when moving, rotates small shafts, from which information about the direction and speed of movement of the manipulator is read (outdated model). Optical mice have a downward-facing LED. The light reflected from the surface makes it possible to find out the direction and speed of movement. Laser mice are a type of optical mouse.

The difference is that the LED is replaced by a miniature laser. This made it possible to get rid of the mouse glow and increased positioning accuracy. Mechanical mice are outdated and almost never used; types of optical manipulators are usually used.

The connection methods for the mouse are the same as for the keyboard: USB and PS/2. As with USB keyboards, mice are detected when the computer is turned on.

This is a device for outputting (printing) information onto paper.

First of all, they differ in printing technology. There are laser (LED printer), inkjet, matrix and other printers (solid ink, sublimation).

Laser printers are the most practical devices for operation. They have the highest printing speed, cartridge life and the lowest cost of maintenance and refilling. They are usually black and white, although they also exist in color. A special powder called toner is used for printing. It is applied to a sheet of paper in the desired places, and then fixed to it by heating and melting. There is also an LED printer, which is a parallel branch of development of laser printing technology.

An inkjet printer is the most suitable option for printing color images, including photographs. Liquid ink of 4 or 6 colors is used as a printing medium. Mixing these colors in different combinations gives the entire palette when printing. The disadvantage is the danger of the ink drying out in the cartridge in case of prolonged inactivity and the low printing speed. However, such printers provide the highest quality color printing, as well as a low cost of refilling, provided that they use CISS - a continuous ink supply system. This is a system in which ink containers are located next to the printer and the cartridges are supplied through special tubes.

Dot matrix printer. This is the oldest and least convenient option. It uses a ribbon impregnated with a dye for printing. The tape is pressed against the paper with special corners in the right places and forms an image from the dots. The main disadvantages of such printers are: low print speed, quality and increased noise when printing. However, they are still used in many organizations because some older software products can only print on such printers.

Printers are connected to a computer via a USB or LPT interface (older models).

. A device for transferring information from paper to a computer. By scanning the image, we get a picture. If text is scanned and needs to be edited, special text recognition programs are used. One of the popular programs that recognizes text from a scanned document is ABBYY FineReader, which is distributed as a paid software product.

The scanners are connected via USB.

. The abbreviation stands for multifunctional device. This is a very practical solution, which is a complete set of printer and scanner. Modern MFPs also make it possible to make copies without turning on the computer (copier), and can also perform fax functions.

Connect via USB and Ethernet (over the network).

. These are devices for playing sound.

The speakers differ primarily in power. They must be connected in two places: to the signal source - a green round connector on the motherboard or discrete sound card; as well as to a power source, usually a regular outlet, but there are versions powered by USB. Peripheral devices include many other devices: uninterruptible power supplies, web cameras, external modems and many other useful devices. It is not possible to consider them all in one lesson, so we will focus on the most popular representatives of this group of peripherals described above. Currently, wireless peripherals are being developed: mice, keyboards, printers, etc.

The main purpose of the PU is to ensure that programs and data are supplied to the PC from the environment for processing, as well as the output of the results of the PC in a form suitable for human perception or for transfer to another computer, or in another necessary form. PUs to a large extent determine the possibilities of using PCs.

Peripheral devices can be divided into several groups according to their functionality:

1. I/O devices- are intended for entering information into a PC, outputting it in the format required by the operator, or exchanging information with other PCs. This type of control unit includes external drives and modems.

2. Output devices- designed to display information in the format required by the operator. This type of peripheral devices includes: printer, monitor, audio system.

3. Input devices- Input devices are devices through which information can be entered into a computer. Their main purpose is to implement an impact on the machine. This type of peripheral devices includes: keyboard, scanner, graphics tablet, etc.

4. Additional PU- such as a “mouse” manipulator, which only provides convenient control of the graphical interface of PC operating systems and does not have pronounced functions for input or output of information; WEB-cameras that facilitate the transmission of video and audio information on the Internet, or between other PCs. The latter, however, can also be classified as input devices, thanks to the ability to save photos, video and audio information on magnetic or magneto-optical media.

Each of the listed groups of devices perform certain functions limited by their capabilities and purpose.

Peripheral information input/output devices.

I/O peripherals come in several types depending on their purpose.

Winchester

Winchesters or hard drives is a large-capacity external memory designed for long-term storage of information, combining the storage medium itself and the writing/reading device in one package. Compared to disk drives, hard drives have a number of very valuable advantages: the volume of stored data is immeasurably larger, and the access time of a hard drive is an order of magnitude shorter. The only drawback: they are not designed for information exchange.

The physical dimensions of hard drives are standardized by a parameter called form factor.

The hard drive consists of several hard drives, with a magnetic layer applied to the surface and located one below the other. Each disk has a pair of write/read heads. When the computer is turned on, the hard drive disks are constantly spinning, even when there is no access to the hard drive, thus saving time on overclocking it.

To date, the following types of hard drives have been developed: MFM, RLL, ESDI, IDE, SCSI.

External drives:

· Tape (magnetic) drives- streamers. Due to their fairly large volume and fairly high reliability, they are most often used as part of data backup devices in enterprises and large companies.

· Magneto-optical storage- CD-ROM, CD-R, CD-RW, DVD-R, DVD-RW drives. They can also be used as backup devices, but, unlike streamers, they have much less data capacity.

Flash cards.

Fifteen years ago, Toshiba came up with a non-volatile semiconductor memory technology it called flash memory. Flash memory allows you to write and erase data without such difficulties, due to which it has good performance and, moreover, is quite reliable.

Soon, flash memory chips began to be built into various devices, and on their basis, flash cards were created, with which various data could be transported.

Modems.

Currently, there are two types of modems: analog and digital.

Analogue modems are more popular because they are cheap and are used mainly for accessing the Internet, and only sometimes for communicating with other PCs. Digital modems are quite expensive and are used for high-speed connections to the Internet, or for organizing a local network over long distances. Modems have several types of connections to a PC: COM, USB or via a network card. A modem connected via a COM port requires an additional power source, but when connected via a USB port, there is no need for a power supply. xDSL modems also require an additional power source.

Peripheral information output devices.

Peripheral output devices are designed to display information in the format required by the operator. Among them there are mandatory and optional devices.

Monitors

The monitor is a necessary information output device. The monitor allows you to display alphanumeric or graphic information in a form that is easy for the user to read and control. In accordance with this, there are two operating modes: text and graphic. In text mode, the screen is presented in rows and columns. In a graphic format, screen parameters are specified by the number of dots horizontally and the number of dot lines vertically. The number of horizontal and vertical lines on the screen is called resolution. The higher it is, the more information can be displayed per unit of screen area.

· Digital monitors. The simplest - a monochrome monitor allows you to display only black and white images. Digital RGB monitors support both monochrome and color modes.

· Analog monitors. Analog signal transmission occurs in the form of different voltage levels. This allows you to create a palette with shades of varying degrees of depth.

· Multi-frequency monitors. The video card generates synchronization signals that relate to the horizontal line frequency and vertical frame repetition rate. The monitor must recognize these values and switch to the appropriate mode.

CRT monitor

If possible, settings can be distinguished: single-frequency monitors, which perceive signals of only one fixed frequency; multi-frequency, which perceive several fixed frequencies; multi-frequency, tuning to arbitrary frequencies of synchronous signals in a certain range.

· Liquid crystal displays (LCD). The main disadvantage is the inability to quickly change pictures or quickly move the mouse cursor, etc. Such screens require additional backlighting or external lighting. The advantages of these screens are a significant reduction in the range of harmful effects.

Liquid crystal display

· Gas plasma monitors. They do not have the limitations of LCD screens. Their disadvantage is their high energy consumption.

A special group needs to be highlighted touch screens, since they allow not only to display data on the screen, but also to enter it, that is, they fall into the class of input/output devices. Such screens provide the easiest and shortest way to communicate with a computer: you just need to point to what interests you. The input device is completely integrated into the monitor.

Gas plasma monitor

PC users spend many hours in a row in close proximity to working monitors. In this regard, display manufacturers have increased their attention to equipping them with special means of protection against all types of influences that negatively affect the user’s health. Low-emission monitors are now becoming common. Other methods are also used to improve the comfort of working with displays.

Printers

A printer is a widespread device for outputting information onto paper; its name is derived from the English verb to print - to print. The printer is not included in the basic PC configuration. There are different types of printers:

· Typical printer works similarly to an electric typewriter. Advantages: clear image of characters, ability to change fonts when replacing a standard disk. Disadvantages: printing noise, low printing speed, graphic images cannot be printed.

· Matrix (needle) printers- these are the cheapest devices that provide satisfactory print quality for a wide range of routine operations. Advantages: acceptable print quality, provided there is a good ink ribbon, and the ability to print as a carbon copy. Disadvantages: rather low printing speed, especially graphic images, significant noise level.

Dot Matrix Printer

· Inkjet printers provide higher print quality. They are especially useful for displaying color graphics. The use of inks of different colors produces a relatively inexpensive image of acceptable quality.

Inkjet printers are much less noisy. Print speed depends on quality. This type of printer occupies an intermediate position between dot matrix and laser printers.

Inkjet printer

· Laser printers - have even higher print quality, close to photographic. They are much more expensive, but the printing speed is 4-5 times higher than that of dot matrix and inkjet printers. The disadvantage of laser printers is that they have rather strict requirements for the quality of the paper - it must be thick enough and should not be loose, printing on plastic-coated paper, etc. is unacceptable.

Laser printers are divided into two types: local and network. You can connect to network printers using an IP address.

Laser printer

· LED printers - alternative to laser.

Thermal printers are used to produce photographic quality color images. They require special paper. These printers are suitable for business graphics.

Much cheaper than laser and inkjet printers. Prints on any paper and cardboard. The printer operates at low noise levels.

Plotters ).

This device is only used in certain areas: drawings, diagrams, graphs, diagrams, etc. Plotters are also indispensable when developing architectural projects.

The plotter's drawing field corresponds to A0-A4 formats, although there are devices that work with a roll and do not limit the length of the output drawing. That is, there are flatbed and drum plotters.

· Flatbed plotters, mainly for A2-A3 formats, they fix the sheet and draw a drawing using a writing unit moving in two coordinates. They provide higher accuracy of printing of drawings and graphs compared to drum printing.

· Roll (drum) plotter - remains in fact the only developing type of plotter with a roller sheet feed and a writing unit moving along one coordinate.

Distributed cutting plotters to print the drawing on film, instead of a writing unit, they have a cutter.

Plotters usually communicate with a computer via a serial, parallel or SCSI interface. Some plotter models are equipped with a built-in buffer.

Plotters can use both special technologies and technologies that are familiar from printers. Currently, inkjet devices are becoming increasingly widespread.

Projection technology.

A multimedia projector allows you to reproduce on a large screen information received from a wide variety of signal sources: computer, VCR, video camera, photo camera, game console. A modern projector is the most advanced link in the chain of evolution of projection equipment.

Multimedia projector

A multimedia projector is a modern and high-tech device. The reliability of most manufactured models is high, and the user is unlikely to have to contact a service center to request repairs. The only replaceable part of the projector is its lamp. Most projectors use arc lamps, which have high brightness and a flatter spectrum than incandescent lamps. Their average service life is 2000 hours of operation. Sometimes it is useful to use the lamp's economical mode function, which doubles its life.

Audio system

Personal computers use a wide variety of sound signal generation schemes, from simple to complex.

These days there are a lot of speaker systems on the market that consist of two active speakers and are made using a 2.1 system. Such systems are popularly called “tweeters” because they are not capable of providing high quality sound even at low volume levels.

More recently, the ideal in the world of computer speaker systems was the 5.1 system, but recently speaker manufacturers have been expanding the capabilities of their systems, which led first to the emergence of the 6.1 system, and later 8.1

Peripheral input devices.

Input devices are those devices through which information can be entered into a computer. Their main purpose is to implement an impact on the PC. The variety of input devices produced has given rise to entire technologies: from touch to voice.

Keyboard

The main input device of most computer systems is keyboard. Until recently, a standard keyboard was used, 101/102 keys, but with the development of personal computers, manufacturers tried to develop the main information input device. This led to the creation of multimedia keyboards, which are becoming more and more popular these days.

Additional keys include groups of keys for controlling multimedia applications, keys for controlling system volume, a group of keys for quickly launching office applications, a calculator, Internet Explorer, etc.

Keyboards differ in two ways: connection method and design. The keyboard can be connected to the computer via the PS/2 port, USB and via the IR port for wireless models. In the latter connection method, the keyboard requires an additional power source, such as a battery.

Scanner

To directly read graphic information from paper or other media in a PC, optical scanners. The scanned image is read and converted into digital form by elements of a special device: CCD chips. There are many types and models of scanners.

Handheld scanners- the simplest and cheapest. The main disadvantage is that the person himself moves the scanner around the object, and the quality of the resulting image depends on the skill and steadiness of the hand. Another important disadvantage is the small bandwidth

laser handheld scanner

· Drum scanners used in professional printing activities.

"home" drum scanner industrial drum scanner

· Sheet scanners. Their main difference from the previous two is that during scanning, a ruler with CCD elements is fixedly fixed, and the sheet with the scanned image moves relative to it using special rollers.

· Flatbed scanners. This is the most common type for professional work today. The object to be scanned is placed on a glass sheet, the image is read line by line at a uniform speed by a reading head with CCD sensors located at the bottom.

Flatbed scanner

· Projection scanners. A color projection scanner is a powerful multifunctional tool for inputting any color images, including three-dimensional ones, into a computer.

Handheld projection scanner

The interface may be different:

· Own interface - The scanner comes with its own unique card and only works with it.

· SCSI- If you use the scanner not with the card supplied, then easy compatibility is not always achieved.

· LPT- the scanner may need the port to support one of the high-speed protocols. While EPP is usually always available, the 8-bit Bi-Directional option required for Epson scanners is not implemented everywhere.

· USB - the most common connection option today.

· Graphics tablet.

Peripherals refer to those external computer devices that are connected to it using a USB connector. They are considered optional, although without many of them, modern users simply would not be able to work or would face great difficulties. All existing ones are usually divided into two large categories: those adapted for input and output of information. Let's take a closer look at each of these groups.

Basic data input devices

Keyboard

Gadgets can carry a variety of functions, but the general purpose remains the same - to control the operation of the machine by entering information and sending special signals. Therefore, perhaps the most important and irreplaceable devices of a personal computer are various keyboards, which are necessarily included with the latter when sold. They are often external in stationary models, since laptops, netbooks and other compact models usually have a built-in keyboard.

The main parameters for such devices are the following: convenience, design and the maximum number of key presses before it fails. Currently, there are a large number of models for every taste, even futuristic ones. One of the most interesting new products is This model looks like a luminous projection on a plane, which is why the appearance strongly resembles a device from a science fiction film.

Other computer peripheral devices (similar in function to the previous ones) are mice. They are laser, optical and mechanical. Mice, as well as keyboards, can be wireless. As a rule, they have a wheel or a middle button that replaces it. There are even special gaming mice for gamers. They are equipped with a large number of additional buttons and also have improved response parameters. A little aside there is a separate subspecies - trackball.

The latter is often used in military computers, as it allows you to maintain controllability during strong vibrations and external interference. Mice have the same basic parameters as keyboards. In addition, the speed of response to the user's hand movement and resolution are important. These gadgets are another indispensable computer control device. In fact, a mouse and keyboard are a standard set for most operations performed on a PC.

These external computer devices are mainly intended for laptops. They operate by moving your finger over the active area. There are also two buttons similar in meaning to those found on the mouse. By their standard dimensions, touchpads are small, which allows you to significantly save space.

In addition, you should list computer peripherals such as joysticks and Both have a narrower focus. Tablets are actively used by artists and designers, while joysticks are most popular among computer game enthusiasts.

There is also another subtype of technology. These are peripheral devices of a personal computer designed to input entire graphic images. Unlike a tablet, you don’t need to draw anything here; you just need to place the necessary information in the working area of the device. Next, he will analyze it himself and, having converted it into digital form, display a copy on the monitor. Scanners come in color and black and white. Based on type and size, these devices are divided into portable, hand-held, network, office (tablet) and large-format.

Basic computer peripherals for outputting information

What you definitely cannot do without when working at a computer is a means of graphically displaying information. Monitors are the same indispensable element in work as mice and keyboards. They are graphic and alphanumeric. In addition, there are monochrome and color: active-matrix and passive-matrix liquid crystal devices.

Such devices are designed for conversion and printing. Most often, the data is displayed on paper, but it can also be, for example, a laser disk. There are matrix printers - the very first ones to appear - and more modern ones - laser and inkjet printer models.

In addition to the above devices, peripherals include speakers, modems, web cameras, various streamers and plotters.

The main purpose of the PU is to ensure that programs and data are supplied to the PC from the environment for processing, as well as the output of the results of the PC in a form suitable for human perception or for transfer to another computer, or in another necessary form. Peripheral devices can be divided into several groups according to their functionality:

I/O devices - designed to input information into a PC, output it in the format required by the operator, or exchange information with other PCs. This type of control unit includes external drives (tape, magneto-optical) and modems.

Output devices – designed to display information in the format required by the operator. This type of peripheral devices includes: printer, monitor (display), audio system.

Input Devices – Input devices are devices through which information can be entered into a computer. Their main purpose is to implement an impact on the machine. This type of peripheral devices includes: keyboard (included in the basic PC configuration), scanner, graphics tablet, etc.

Additional controls - such as a mouse manipulator, which only provides convenient control of the graphical interface of PC operating systems and does not have clear functions for input or output of information; WEB-cameras that facilitate the transmission of video and audio information on the Internet, or between other PCs.

Chapter 2. Peripheral input devices

2.1 External drives

Tape (magnetic) drives – streamers. Due to their fairly large volume and fairly high reliability, they are most often used as part of data backup devices in enterprises and large companies (they store backup copies of databases and other important information). The tape drive not only stores a backup copy of the data, but also creates an image of the data drive. This allows the user to restore a specific state or use this image as a reference data bank, for example when data has been changed. The principle of recording on magnetic media is based on changing the magnetization of individual sections of the magnetic layer of the media. Recording is carried out using a magnetic head, which creates a magnetic field. When reading information, magnetized areas create weak currents in the magnetic head, which turn into a binary code corresponding to what was written.

Magneto-optical drives – CD-ROM, CD-R, CD-RW, DVD-R, DVD-RW drives. They can also be used as backup devices, but, unlike streamers, they have a much smaller data capacity (CD-R, CD-RW up to 700 MB of data, DVD-R, DVD-RW up to 4.7 GB of data). Information on magneto-optical CD-R drives is represented by alternating depressions and peaks. This relief is created mechanically during production. Information is applied along thin tracks. Reading occurs by scanning the tracks with a laser beam, which is reflected differently from the depressions and peaks. On disks that allow multiple rewrites, the magneto-optical principle is used, which is based on a physical property: the reflection coefficient of a laser beam from differently magnetized areas of a disk with a specially applied magnetic coating is different.

2.2 Flash cards

As soon as computers learned to process data arrays, the problem arose of where and how to store and transfer this data. There were many solutions - from paper punched cards to magnetic tapes and disks. Each of the technologies had many advantages and, as usual, even more disadvantages. We are all prone to laziness, looking for the most pleasant and comfortable conditions, and are not ready to make sacrifices if fashion does not require it. And therefore, as soon as the personal computer lost its status as a prestigious and expensive toy, users, in an increasingly demanding manner, began to hint to manufacturers about the inconvenience of handling them. Today the subject of our conversation is removable memory. Users have several modest requirements for this type of memory:

Energy independence – i.e. do not need batteries, the unexpected discharge of which will lead to loss of information.

Reliability - do not lose data under the influence of a thunderstorm, fall or fall into a puddle.

Compact - so as not to think about whether it’s worth carrying all this with you.

Durable - so as not to run to the store every month for a new one, because the old one has served its purpose.

Universal – compatible with many devices that may require data.

2.3 Modems

Currently, there are two types of modems: analog and digital (xDSL technology).

Analog modems are more popular because they are cheap and are used mainly for accessing the Internet, and only sometimes (due to the low (up to 56 Kbps) data transfer speed) for communication with other PCs. Digital modems are quite expensive and are used for high-speed connections to the Internet, or for organizing a local network over long distances (xDSL modems allow you to transmit and receive information at speeds of up to 5 Mbit/s at a distance of 5-7 km).

Modems have several types of connections to a PC: COM, USB or (for digital modems) via a network card. A modem connected via a COM port requires an additional power source (unit), but when connected via a USB port, there is no need for a power supply. xDSL modems also require an additional power source.

Chapter 3. Peripheral information output devices.

Peripheral output devices are designed to display information in the format required by the operator. Among them there are mandatory (included in the basic PC configuration) and optional devices.

3.1 Monitors

The monitor is a necessary information output device. A monitor (or display) allows you to display alphanumeric or graphic information on the screen in a form that is easy for the user to read and control. In accordance with this, there are two operating modes: text and graphic. In text mode, the screen is presented in rows and columns. In a graphic format, screen parameters are specified by the number of dots horizontally and the number of dot lines vertically. The number of horizontal and vertical lines on the screen is called resolution. The higher it is, the more information can be displayed per unit of screen area.

Digital monitors. The simplest - a monochrome monitor allows you to display only black and white images. Digital RGB monitors (Red-Green-Blue) support both monochrome and color modes (with 16 shades of color).

Analog monitors. Analog signal transmission occurs in the form of different voltage levels. This allows you to create a palette with shades of varying degrees of depth.

Multi-frequency monitors. The video card generates synchronization signals that relate to the horizontal line frequency and vertical frame repetition rate. The monitor must recognize these values and switch to the appropriate mode.

CRT monitor According to the possibility of customization, we can distinguish: single-frequency monitors, which perceive signals of only one fixed frequency; multi-frequency, which perceive several fixed frequencies; multi-frequency, tuning to arbitrary frequencies of synchronous signals in a certain range.

Liquid crystal displays (LCD). Their appearance is associated with the struggle to reduce the size and weight of portable computers.

The main disadvantage is the inability to quickly change pictures or quickly move the mouse cursor, etc. Such screens require additional backlighting or external lighting. The advantages of these screens are a significant reduction in the range of harmful effects.

Gas plasma monitors. They do not have the limitations of LCD screens. Their disadvantage is their high energy consumption.

It is especially necessary to highlight the group of touch screens, since they allow not only to display data on the screen, but also to enter it, that is, they fall into the class of input/output devices. This relatively new technology is not yet widely used. Such screens provide the easiest and shortest way to communicate with a computer: you just need to point to what interests you. The input device is completely integrated into the monitor. Used in information and reference systems.

3.2 Printers

A typical printer operates similarly to an electric typewriter. Advantages: clear image of characters, ability to change fonts when replacing a standard disk. Disadvantages: noise during printing, low printing speed (30-40 characters/sec.), printing of graphic images is impossible.

Matrix (needle) printers are the cheapest devices that provide satisfactory print quality for a wide range of routine operations (mainly for preparing text documents). They are used in savings banks, in industrial environments where roll printing, printing on books and thick cards and other media made of thick material is necessary. Advantages: acceptable print quality, provided there is a good ink ribbon, and the ability to print as a carbon copy. Disadvantages: rather low printing speed, especially graphic images, significant noise level. Among the motherboard printers, there are also quite fast devices (the so-called Shuttle printers).

Inkjet printers provide higher quality printing. They are especially useful for displaying color graphics. The use of inks of different colors produces a relatively inexpensive image of acceptable quality. The color model is called CMYB (Cyan-Magenta-Yellow-Black) after the names of the primary colors that form the palette.

Inkjet printers are much less noisy. Print speed depends on quality. They are quite effective when creating advertising brochures, calendars, and greeting cards. This type of printer occupies an intermediate position between dot matrix and laser printers.

Laser printers have even higher print quality, close to photographic. They are much more expensive, but the printing speed is 4-5 times higher than that of dot matrix and inkjet printers. The disadvantage of laser printers is that they have rather strict requirements for the quality of the paper - it must be thick enough and should not be loose, printing on plastic-coated paper, etc. is unacceptable.

Laser printers are especially effective in producing original layouts of books and brochures, business letters and materials that require high quality. They allow you to print graphics and drawings at high speed.

LED printers are an alternative to laser ones. The developer is OKI.

Thermal printers. Used to obtain photographic quality color images. They require special paper. These printers are suitable for business graphics. Printer based on Micro Dry technology. These printers produce full photo-natural colors and have the highest resolution. This is a new competitive direction. Much cheaper than laser and inkjet printers. Developed by Citizen. Prints on any paper and cardboard. The printer operates at low noise levels.

3.3 Plotters (graph plotters).

This device is only used in certain areas: drawings, diagrams, graphs, diagrams, etc. Plotters are widely used in conjunction with programs of automatic design systems, where design or technological documentation becomes part of the results of the program. Plotters are also indispensable when developing architectural projects. The plotter's drawing field corresponds to A0-A4 formats, although there are devices that work with a roll that do not limit the length of the output drawing (it can be several meters long). That is, there are flatbed and drum plotters.

Flatbed plotters, mainly for A2-A3 formats, fix the sheet and draw a drawing using a writing unit that moves in two coordinates. They provide higher accuracy of printing of drawings and graphs compared to drum printing.

The roll (drum) plotter remains in fact the only developing type of plotter with a roller sheet feed and a writing unit moving along one coordinate (the paper moves along another coordinate).

Cutting plotters for printing drawings on film are common; instead of a writing unit, they have a cutter. Plotters usually communicate with a computer via a serial (COM), parallel (LPT) or SCSI interface. Some plotter models are equipped with a built-in buffer (1 MB or more).

3.4 Projection technology

A multimedia projector allows you to reproduce on a large screen information received from a wide variety of signal sources: computer, VCR, video camera, photo camera, DVD player, game console. The image in a multimedia projector is formed in several main ways: using liquid crystal panels (LCD technology) and using DMD micromirror chips (DLP technology). In LCD projectors, the light from the lamp passes through a liquid crystal panel, on which a picture is created, like a regular film, but using a digital electronic circuit. Light passes through the panel and lens, and as a result, an image magnified many times is projected onto the screen. In DLP projectors, the light from the lamp is reflected from many electronically controlled micromirrors and also hits the screen through the lens.

3.5 Audio system

Personal computers use a wide variety of sound signal generation schemes, from simple to complex. It seems that the problem with sound for personal computers has been finally solved. It's rare to see motherboards not equipped with an audio controller. However, even if we consider the issue with audio cards closed, the topic of speaker systems remains a burning issue. This question remains pressing, because many users do not limit themselves to watching videos and playing games with surround sound. True audiophiles prefer high-quality stereo sound with surround sound and deep bass, not to mention enthusiasts who create music using their personal computers. For them, a generally obligatory element of a home studio is high-quality stereo acoustics, even if the rest of the role is assigned to a computer with a sound card. These days there are a lot of speaker systems on the market that consist of two active speakers and are made using a 2.1 system. Such systems are popularly called “tweeters” because they are not capable of providing high quality sound even at low volume levels. More recently, the ideal in the world of computer (and not only) speaker systems was the 5.1 system (five satellites and one subwoofer), but recently acoustic manufacturers have been expanding the capabilities of their systems, which led first to the emergence of the 6.1 system, and later 8.1

Chapter 4. Peripheral input devices.

Input devices are those devices through which information can be entered into a computer. Their main purpose is to implement an impact on the PC.

4.1 Keyboard

The main input device for most computer systems is the keyboard. Until recently, a standard keyboard was used, 101/102 keys (the first keyboard model contained only 83 keys), but with the development of personal computers, manufacturers tried to develop the main information input device. This led to the creation of multimedia keyboards, with many more buttons, which are becoming more and more popular these days.

Additional keys include groups of keys for controlling multimedia applications (for example, calling and controlling video viewing programs), keys for controlling system volume, a group of keys for quickly launching office applications (Word, Excel), calculator, Internet Explorer, etc. Keyboards differ in two ways: connection method and design. The keyboard can be connected to a computer via a PS/2 port, USB, and via an IR (infrared) port for wireless models. In the latter connection method, the keyboard requires an additional power source, such as a battery.

4.2 Scanner

Optical scanners are used to directly read graphic information from paper or other media into a PC. The scanned image is read and converted into digital form by elements of a special device: CCD chips. There are many types and models of scanners. Which one to choose depends on the tasks for which the scanner is intended. The simplest scanners recognize only two colors: black and white. These scanners are used to read bar codes.

Hand-held scanners are the simplest and cheapest. The main disadvantage is that the person himself moves the scanner around the object, and the quality of the resulting image depends on the skill and steadiness of the hand. Another important drawback is the small scanning bandwidth (up to 10 cm), which makes reading wide originals difficult.

Drum scanners are used in professional printing activities. The principle is that the original on the drum is illuminated by a light source, and photosensors convert the reflected radiation into a digital value.

Sheet scanners. Their main difference from the previous two is that during scanning, a ruler with CCD elements is fixedly fixed, and the sheet with the scanned image moves relative to it using special rollers.

Flatbed scanners. This is the most common type for professional work today. The object to be scanned is placed on a glass sheet, the image is read line by line at a uniform speed by a reading head with CCD sensors located at the bottom. The flatbed scanner can be equipped with a special slide attachment device for scanning transparencies and negatives. Slide scanners were previously used to scan slides and microimages.

Projection scanners. A relatively new direction. A color projection scanner is a powerful multifunctional tool for inputting any color images, including three-dimensional ones, into a computer. It can easily replace a camera.

Nowadays, scanners have another application - reading handwritten texts, which are then converted into ASC II codes by special character recognition programs and can subsequently be processed by text editors.

The interface may be different:

Own interface - the scanner comes with its own unique card and works only with it. This card may not work in your computer or may fail.

SCSI – if you use the scanner not with the card supplied, then easy compatibility is not always obtained.

LPT (and its variants, with support or requirement for EPP, ECP or Bi-Directional) - the scanner may need to support one of the high-speed protocols by the port. While EPP is usually always available, the 8-bit Bi-Directional option required for Epson scanners is not implemented everywhere.

USB is the most common connection option today. It’s easy to connect and, if you have all the drivers and programs, it always works.

4.3 Graphics tablet

Desktop computers for engineering and design work have been equipped with graphics tablets for more than ten years. This device greatly simplifies the entry of drawings, diagrams and drawings into a PC. At first, tablets were expensive devices and therefore were designed for purely professional use. But cheap home models have been produced for about five years now. Even despite good hand-drawing skills, you are unlikely to be able to draw anything useful in a graphics editor by moving your mouse. The pen and tablet fundamentally change the situation. If we add to this the emergence of new opportunities for graphic editors. We are talking about pressure sensitivity. Depending on the force with which you draw the line, its thickness and transparency change in the program window. The transparent film covering the tablet allows you to trace the originals - i.e. You can put a picture under it and, tracing its lines with the tip of the pen, repeat the drawing in the editor window.

Chapter 5. Additional peripheral devices.

5.1 Manipulators

A mouse is one of the pointing input devices that provides a user interface with a computer. There are two types of mice: ball mice and optical mice.

Ball manipulators use a mechanical method of transmitting the direction of movement (the ball located at the bottom of the manipulator, when moving, rotates two rollers located inside).

Optical mice use an LED instead of a ball.

The mouse has several connection types: COM, PS/2, USB, IR (infrared port). “Mice” with a connection type using a COM port are one of the first manipulators. Basically they were equipped with two buttons. It stayed on the market for quite a long time. PS/

Modern personal computers usually have many peripheral devices at their disposal.

Peripherals– these are any additional and auxiliary devices that are connected to a PC to expand its functionality.

Let's take a look at some of the peripherals.

Printer(print - print) – a device for printing text and graphic information. Printers usually work with A4 or A3 paper. The most common today are laser and inkjet printers; dot matrix printers are already out of use.

IN dot matrix printers The print head consisted of a series of thin metal needles, which, when moving along a line, hit the ink ribbon at the right moment, and thereby ensured the formation of characters and images. Dot matrix printers had low print speed and quality.

IN inkjet printers Ink is pressurized out of holes (nozzles) in the print head and then adheres to the paper. In this case, the formation of the image occurs as if from individual points - “blots”. Inkjet printers are characterized by a high cost of consumables.

IN laser printers The laser beam, running across the drum, electrifies it, and the electrified drum attracts particles of dry paint, after which the image is transferred from the drum to the paper. Next, a sheet of paper passes through a heat drum and, under the influence of heat, the paint is fixed on the paper. Laser printers have high speed and print quality.

Plotter(plotter) – a device for printing large drawings, drawings and other graphic information on paper. The plotter can display graphic information on A2 or larger paper. Structurally, it can use either a roll paper drum or a horizontal tablet.

Scanner(scanner) – a device that allows you to enter graphic information into a computer. When moving across a picture (a sheet of text, a photograph, a drawing), the scanner converts the image into a numerical format and displays it on the screen. This information can then be processed using a computer.

Mouse manipulator(mouse) – a device that makes it easier to enter information into a computer.

CD-ROM drive– a device for reading information recorded on laser compact discs (CD ROM – Compact Disk Read Only Memory, which means a CD with read-only memory). CDs can store a large amount of information (up to 650 MB). Such disks are used to store reference information, large encyclopedias, databases, music, video information, etc.

The main indicator for a CD-ROM drive is the speed of reading information from a CD.

DVD drive is a further development of laser technology. It uses advanced laser beam technology to write and read information from CDs. The abbreviation DVD means Digital Video Disk (digital video disc) or in another interpretation - Digital Versatile Disk (digital multi-purpose disc).