What is the system unit and its devices. What is inside the computer What is inside the computer unit

The computer has the following main blocks:

• System unit.
• Monitor.
• Manipulators.

A person exists in the "ocean" of information, he constantly receives information from the surrounding world with the help of his senses, stores it in his memory, analyzes it with the help of thinking and exchanges information with other people. A computer, like a person, receives information, stores and processes it, and exchanges it with other computers. The computer is a tool that helps a person navigate this "ocean" of information.

personal computer(PC) is a relatively inexpensive universal microcomputer designed for one user. The exchange of information between individual devices of the computer is carried out along the highway connecting all the devices of the computer.

Personal computers are usually designed based on the principle of open architecture:

1. Only the description of the operating principle of a computer and its configuration (a certain set of hardware and connections between them) are regulated and standardized. Thus, the computer can be assembled from individual components and parts designed and manufactured by independent manufacturers.

2. The computer can be easily expanded and upgraded with internal expansion slots, where the user can insert a variety of devices that meet the specified standard, and thereby configure his machine according to his personal preferences.

System unit

The system unit contains the entire electronic filling of the computer:

• motherboard (or system) board, which contains the main components of a computer that define its architecture, namely:
  • microprocessor- to perform calculations and general computer management;
  • math coprocessor- to increase the speed of calculations with high precision numbers. The math coprocessor speeds up calculations that use floating-point operations by about 5-15 times. On the 486DX and PENTIUM processors, the coprocessor is already built into the main processor and no additional installation is required.
  • memory- for permanent and temporary storage of information. The following types of memory are allocated:
    • RAM- RAM, RAM (Random Access Memory) for storing executable programs, initial data for processing, for recording intermediate and final results. When you turn off the computer, reboot, random power failures, all the contents of RAM are erased. Therefore, when typing any data, texts, etc. it is necessary to periodically write intermediate results to the hard disk. The amount of memory is measured in megabytes (Mb) and gigabytes (Gb).
    • cache memory- to speed up access to RAM, "ultra-fast" static memory is used, which is a buffer between very fast processor and slower RAM.
    • ROM(read-only memory) - is used to store programs for internal testing of devices, the configuration program (SETUP). The combination of these firmware is called the BIOS (Basic Input/Output System), which is implemented as a microcircuit on the motherboard.
    • CMOS- part of the BIOS chip, which is powered by a special battery on the system board. It stores computer configuration parameters (RAM, hard drive type, floppy drives, etc.).
  • chipset- a set of super-large microcircuits on which the entire architecture of the board is implemented.
  • Expansion slots (buses) for installing controllers and adapters
• information accumulators- for input/output and storage of information; According to the method of writing and reading information to the media, disk drives can be divided into:
  • magnetic (hard disk, floppy drive);
  • optical (CD-ROM, CD-RW, DVD-ROM, DVD-RW drives);
  • magneto-optical.
• controllers and adapters- devices designed to transmit information from motherboard to the peripheral device and vice versa; There are a large number of different controllers and adapters. The most common of them are:
  • video card;
  • sound card;
  • Network Card;
  • modem.
• power unit- serves to convert the mains voltage 220 V (110 V) into the supply voltage of the structural elements of the computer: +12V, +5V and +3.3V.

The main hardware component of a computer is the motherboard. The system board has an information exchange highway, there are connectors for installing a processor and RAM, as well as slots for installing external device controllers.

The characteristics of the motherboard are:

• board size (Form factor);
• the type of processors supported and the corresponding type of processor socket;
• Chipset - a set of ultra-large chips that implement the entire architecture of the board;
• type and number of expansion bus slots (3xISA, 4xPCI, AGP);
• The type and amount of dynamic memory supported and the availability of appropriate slots for memory modules;
• Size and type of cache memory.

Over the past few years, one of the hottest topics has been the topic of MT integration - whether video, sound, and other features should be embedded in MT. Most power users strongly oppose the integration of MPs, as it limits their choice and believe that integration should be done on MPs that are supplied to the "mass market". On the other hand, manufacturers find MP integration quite attractive, as it allows them to present a more functional product to the user and at the same time reduce the price of the product due to the reduction in several expansion slots and smaller PCBs. Despite everything, the main task of manufacturers is to provide the user with as many options and functionality as possible along with their product. In the end, we will most likely witness that special slots will be invented where graphics chips will be inserted and thereby the video capabilities of a particular product will be improved, about the same we are doing today with a processor. The graphic memory will be built into the graphics chip in the MP or will be both there and there. Modems, sound and LAN controllers will also be included. This will allow manufacturers to eliminate the ISA slot as well as most PCI slots. USB and IEEE1394 devices will slowly replace the relatively slow serial, parallel, IDE, and SCSI devices that are now the most common.

CPU

The processor is implemented in hardware on a large integrated circuit (LSI). A large integrated circuit is not really "big" in size, but rather a small flat semiconductor wafer, approximately 20x20 mm in size, enclosed in a flat package with rows of metal pins (contacts).

The use of modern high technologies makes it possible to place a huge number (42 million in the Pentium 4 processor) of functional elements (switches) on the LSI of the processor, the dimensions of which are only about 0.18 microns (1 micron = 10 -6 meters).

These elements form a complex structure, which allows the processor to process information (for example, add numbers) at a very high speed. Modern processors are very fast, for example, the Pentium 4 processor can process information at a frequency of 1.5 GHz (perform 1.5 billion operations per second).

The central processing unit generally contains:

• arithmetic logic unit;
• data and address buses;
• registers;
• command counters;
• cache- very fast memory of small volume (from 8 to 512 KB);
• math coprocessor floating point numbers

A computer system may have several parallel processors; such systems are called multiprocessor. In the characteristics of a computer, the processor is put in the first place, since it determines the performance of the computer to the greatest extent. Therefore, when buying, they first choose it, and then they select other devices: chipset, RAM, motherboard, etc.

One of the main characteristics of the processor is clock frequency. The microprocessor performs certain operations (writing, reading, data processing) in precisely allotted time units (cycles), which is necessary to synchronize the process. Information processing is faster, the higher the clock frequency. It is measured in MHz (MHz, megahertz) and GHz (GHz, gigahertz). Distinguish cpu core frequency(internal) and system bus frequency(external).

The external clock frequency (processor bus frequency) is generated by the pulse generator on the motherboard and determines the performance of the CPU core. The processor bus is used to exchange data between the CPU, memory, and other devices.

The internal clock frequency determines to a large extent the speed of the processor. It indicates how many elementary operations (cycles) the microprocessor performs in one second. This frequency is indicated in the price lists of companies selling processors. This value is the product of the system bus frequency supplied from the crystal and the internal multiplier. This coefficient is determined by applying voltage to certain pins of the CPU. For example, 266*5=1330 MHz.

Memory

Name "operational" this memory is given because it is very fast, but the data contained in it is retained only while the computer is turned on. RAM is often referred to as RAM (random access memory, that is, random access memory). Since the elementary unit of information is a bit, RAM can be considered as a set of elementary cells, each of which is capable of storing one information bit.

Random access memory designed to store information is made in the form of memory modules. Memory modules are plates with rows of contacts on which memory LSIs are placed. Memory modules can differ in size and number of pins (SIMM or DIMM and DDR RA). The most important characteristic of RAM modules is speed, i.e. the frequency with which the operations of writing or reading information from memory cells occur. Modern memory modules provide a frequency of 133 MHz and higher.

In random access memory, an elementary memory cell is a capacitor capable of storing an electric charge for a short period of time, the presence of which can be associated with an information bit. Simply put, when a logical unit is written to a memory cell, the capacitor is charged, and when a zero is written, it is discharged. When data is read, the capacitor is discharged through the read circuit, and if the charge of the capacitor was not zero, then the output of the read circuit is set to one.

In addition, since the capacitor is discharged during reading, it must be charged to its previous value. Therefore, the reading process is combined with the recharging of capacitors (charge regeneration). If the cell is not accessed for a long time, then due to leakage currents, the capacitor is discharged over time and information is lost. As a result, memory based on an array of capacitors requires constant periodic recharging of capacitors (which is why it is called dynamic).

To compensate for charge leakage, regeneration is used, based on periodic cyclic access to memory cells, since each such access restores the previous charge of the capacitor. Regeneration in the microcircuit occurs simultaneously throughout the entire row of the matrix when accessing any of its cells, that is, it is enough to cycle through all the rows.

Each memory element is defined by its own address. Memory elements are combined in the body microchips, and the latter, in turn, are placed on special small printed circuit boards (modules). These boards are inserted into slots specially designed for them on the motherboard, the so-called banks (Banks). A bank is understood as one or more connectors combined into a logical unit.

The main characteristics of RAM are:

• throughput;
• type of structure (implementation technology) of memory;
• a kind of module (form factor, constructive) of memory.
• volume (size) of RAM of the memory module;

The main characteristic of memory is its throughput, that is, the maximum amount of data that can be read from memory or written to memory per unit of time. It is this characteristic that is directly or indirectly reflected in the name of the memory type.

Computer RAM consists of a large number of cells, each of which can store a certain amount of information. In modern personal computers the number of memory cells reaches tens of millions.

The most important characteristic of a computer as a whole is its performance, i. the ability of a computer to process large amounts of information quickly. Computer performance is largely determined by the speed of the processor, as well as the amount of RAM and the speed of access to it. M), by speed, by information capacity, etc.

Cache (cache)-memory

To speed up access to RAM in modern high-speed computers, a special "ultra-fast" ("super-rapid") memory is used, which is called cache memory and is like a buffer between a very fast processor and a fairly slow RAM. It began to be used starting from 486 computers and is now used in all modern PC models.

The cache memory is controlled by a special device - controller, which, by analyzing the executable program, tries to anticipate what data and commands are most likely to be needed in the near future by the processor, and pumps them into the cache. In this case, both "hits" and "misses" are possible. In the event of a hit, that is, if the necessary data is pumped into the cache, they are retrieved from memory without delay. If the required information is not in the cache, then the processor reads it directly from the RAM. The ratio of hits and misses determines the effectiveness of caching.

Modern microprocessors have a built-in cache memory, the so-called first-level cache (internal cache memory), which is designated L1 (Level 1) and has a size of about 64-128 KB. Its purpose is to match the speed of the processor and the external cache.

In addition, there is a second level cache (external cache memory), which is designated L2 (Level 2) and has a capacity of 128 KB to 256 KB and more. The main task of the external cache is to organize the exchange of data between the processor and memory with the least number of waiting cycles. There are currently three L2 cache layouts:

• The L2 cache is placed on the motherboard and connected to the memory bus in the same way as the main memory. This is the slowest option - the cache runs at the external frequency of the CPU.
• The L2 cache is connected to a separate bus called cache bus(Back Side Bus - BSB). The gain in comparison with the previous version is more than 2 times, because the cache bus is faster than the memory bus. The cache and memory buses operate independently of each other. This solution was first used by Intel Corporation in the Pentium II CPU and called by it Dual Independent Bus (DIB) - a double independent bus. This solution is implemented by a small processor board that houses the CPU, L2 cache, and BSB. The card is inserted into the system board slot in the same way as device cards. This solution is used in the Intel Pentium II/III CPU.
• The L2 cache is built into the CPU and runs at the full internal frequency of the CPU (the BSB is built into the CPU and the proximity of L2 and the CPU makes it possible to raise the cache frequency to the CPU's internal frequency). This solution was first implemented by Intel in the Celeron CPU.

Persistent memory

Persistent memory(ROM, English ROM, Read Only Memory - read-only memory) - non-volatile memory, used to store data that will never require changes. The contents of the memory are "sewn up" in the BIOS chip in a special way during its manufacture for permanent storage. ROM can only be read.

BIOS(Basic Input/Output System) is a basic input/output system. The BIOS is a complex system consisting of a large number of utilities designed to automatically recognize the hardware installed on the computer, configure it, and test its operation.

This system includes various input-output programs that provide interaction between the operating system, application programs on the one hand, and devices that make up the computer (internal and external) on the other.

Initially, the BIOS was intended to test the computer when it was turned on - the so-called POST (Power On Self Test) or BIST (Built In Self Test) procedures, and ensure the subsequent boot of the OS. This is true for the i8086, i8088 family PCs and for a large part of the 80286 family.

Currently, the BIOS is a complex system consisting of a large number of utilities designed to automatically recognize the equipment installed on a computer, configure it, and check its operation. BIOS programs are usually invoked via software or hardware interrupts. When the computer is powered on, the BIOS tests (POST - Power-On-Self-Test) system components - processor, memory, disk drives (both hard and floppy drives), keyboard, etc.

The BIOS is implemented as a microchip installed on the computer motherboard. Note that the name ROM BIOS is currently not entirely fair, because "ROM" implies the use of permanent storage devices (Read Only Memory), and flash memory devices are currently used to store BIOS codes. The most promising storage system BIOS is flash memory(replaceable memory cards). It allows you to modify functions to support new devices connected to your computer.

Flash memory media is the largest class of portable digital media and is used in the vast majority of modern digital devices. Various types of flash memory cards are increasingly being used in digital cameras, PDAs, audio players, mobile phones and other portable electronic systems.

The use of flash memory chips makes it possible to create miniature and very light, non-volatile, removable memory cards, which also have low power consumption. An important advantage of cards based on flash memory is also their highest reliability, due to the absence of moving parts, which is especially critical in the case of external mechanical influences: shocks, vibrations, etc.

The main disadvantages of such media are the rather high price of the flash memory cards themselves and the high unit cost of the data stored on them, although at present there is a trend towards a significant reduction in the prices of replaceable flash memory cards.

The most common types of flash cards today are CompactFlash (CF), SmartMedia (SM), Secure Digital (SD), MultiMediaCard (MMC) and Memory Stick (MS), which differ from each other in interfaces, dimensions, read / write speed and maximum possible capacity.

At the physical level, flash memory of various standards has much in common, and first of all, this is the architecture of the memory array and the device of the memory cell itself. The fundamental difference between flash memory and RAM memory is that it is a non-volatile memory capable of storing information for an unlimited time in the absence of external power.

In principle, there are several types of non-volatile memory, and in this sense, flash memory is just one of its varieties. The BIOS system is inextricably linked with CMOS RAM (CMOS - Complementary Metal Oxide Semiconductor).

CMOS (semi-permanent memory) is a small piece of memory for storing computer configuration settings that is adjusted using the CMOS Setup Utility. Has low power consumption. The contents of the CMOS memory do not change when the computer is powered off because it uses a special battery to power it.

video memory

video memory- a type of random access memory that stores encoded images. This memory is organized so that its contents are available to two devices at once - the processor and the display. Therefore, the screen image changes at the same time as the video data in the memory is updated.

The speed at which information enters the screen and the amount of information that exits the video adapter and is transmitted to the screen all depend on three factors:

• resolution of your monitor;
• the number of colors you can choose from when creating an image;
• the frequency with which the screen is updated;

Permission determined by the number of pixels on the line and the number of lines themselves. Therefore, on a display with a resolution of 1024x768, typical for systems using the Windows operating system, the image is formed every time the screen is updated from 786,432 pixels of information.

Usually screen refresh rate It is measured in hertz (Hz), or cycles per second. The result of screen flicker is eye strain and eye fatigue during prolonged viewing of the image. To reduce eye fatigue and improve image ergonomics, the screen refresh rate should be at least 75 Hz.

The number of reproducible colors, or color depth is the decimal equivalent of the binary value of the number of bits per pixel. Thus, 8 bits per pixel is equivalent to 28 or 256 colors, 16-bit color, often referred to simply as high-color, represents over 65,000 colors, and 24-bit color, also known as true or true color, can represent 16.7 million colors. . 32-bit color, to avoid confusion, usually means displaying true color with an extra 8 bits used to provide 256 degrees of transparency. So, in 32-bit representation, each of the 16.7 million true colors has an additional 256 degrees of transparency available. Such color rendering capabilities are available only in high-end systems and graphics workstations.

Previously, desktop computers were mainly equipped with 14-inch monitors. VGA resolution of 640x480 pixels covered this screen size quite well. As soon as the size of the average monitor increased to 15 inches, the resolution increased to a value of 800x600 pixels. As the computer becomes more of a visualization tool with ever-improving graphics, and as the graphical user interface (GUI) becomes the standard, users want to see more information on their monitors.

17-inch monitors are becoming standard equipment on Windows-based systems, and a resolution of 1024x768 pixels adequately fills a screen at that size. Some users use a resolution of 1280x1024 pixels on 17 inch monitors.

A modern graphics subsystem requires 1 megabyte of memory to provide a resolution of 1024x768. Although only three-quarters of this amount of memory is actually needed, the graphics subsystem typically stores cursor and shortcut information in an off-screen memory for quick access. Memory bandwidth is defined as how many megabytes of data are transferred in and out of memory per second. A typical resolution of 1024x768, at 8-bit color depth and a screen refresh rate of 75 Hz, requires a memory bandwidth of 1118 megabytes per second. Adding 3D graphics processing functions requires increasing the amount of available memory on board the video adapter to 4 megabytes. Additional memory beyond what is needed to create the image on the screen is used for z-buffer and texture storage.

Disk drives

Hard disk - hard drive

Hard magnetic disks are several tens of disks placed on the same axis, enclosed in a metal case and rotating at a high angular velocity. Due to the much larger number of tracks on each side of the disks and the large number of disks, the information capacity of hard drives can exceed the information capacity of floppy disks by tens of thousands of times.

Like a floppy disk, the working surfaces of platters are divided into circular concentric tracks, and the tracks are divided into sectors. The read/write heads, along with their supporting structure and disks, are enclosed in a hermetically sealed housing called data module. When a data module is installed on a drive, it automatically connects to a system that pumps purified cooled air.

The surface of the platter has a magnetic coating only 1.1 microns thick, as well as a layer of lubricant to protect the head from damage when lowering and raising on the go. When the platter rotates, an air layer is formed above it, which provides an air cushion for the head to hang at a height of 0.5 microns above the disk surface.

Each such head consists of two elements: a recording head and a magnetoresistive read head. The recording head is a miniature electromagnet consisting of a core and an inductor. In the section between the poles of the core, a magnetic field of the desired direction is created, which magnetizes the working surface of the disk, creating a magnetic domain with a given direction of magnetization.

The read head is a magnetoresistive (MR) element that changes its resistance in the presence of a magnetic field. In order to preserve information and performance, hard drives must be protected from shock and sudden changes in spatial orientation during operation.

Floppy disk drives

Floppy disk drives work with floppy disks (floppy disks) or simply floppy disks.

Floppy disk, floppy disk- a device for storing small amounts of information, which is a flexible plastic disk in a protective shell. Used to transfer data from one computer to another.

A floppy disk consists of a round polymer substrate coated on both sides with magnetic oxide and placed in a plastic package, the inner surface of which is coated with a cleaning coating. The package has radial slots on both sides through which the read / write heads of the drive gain access to the disk.

Information is recorded by concentric tracks (tracks), which are divided into sectors. The number of tracks and sectors depends on the type and format of the diskette. A sector stores the minimum piece of information that can be written to disk or read. The sector capacity is constant and is 512 bytes.

On a floppy disk, you can store from 360 kilobytes to 2.88 megabytes of information. Currently used floppy disks have the following specifications: 3.5" (89 mm) diameter, 1.44/2.88 MB capacity, 80 tracks, 18 sectors per track. Previously, 5.25" floppy disks were also used, capacity which was 360 KB or 1.2 MB.

The floppy disk is installed in a floppy-disk drive, automatically fixed in it, after which the drive mechanism spins up to a rotation speed of 360 min -1. The floppy disk itself rotates in the drive, the magnetic heads remain motionless. The floppy disk rotates only when it is accessed. The drive is connected to the processor through the floppy disk controller.

Today, despite the widespread use of 3.5-inch floppy disks, they are gradually becoming obsolete and floppy disk drives are no longer used in some modern PC models.

Optical drives

Laser disk drives (CD-ROM and DVD-ROM) use the optical principle of reading information. In appearance, both the drives themselves and the discs for CD-ROM and DVD-ROM practically do not differ.

Operating principle optical disc drive is as follows: A finely focused laser beam is reflected off the surface of a plastic disc. Information is recorded in the form of depressions on a spiral track. The reflected modulated light enters the photodetector and is then converted into a standard signal. On a disk, data is written on a very narrow (100 times thinner than a human hair) spiral track, the total length of which is 5 km. Any disc has a transparent polycarbonate substrate, which gives it rigidity, a reflective metal layer and a protective layer of acrylic plastic (label is printed on it). Laserdisc technology is evolving in several directions. These are CDs and DVDs.

Information on a laser disc is recorded on a single spiral track (like on a gramophone record) containing alternating sections with different reflectivity. The laser beam falls on the surface of a rotating disk, and the intensity of the reflected beam depends on the reflectivity of the track section and takes on the values ​​\u200b\u200bof 0 or 1. In order to preserve information, laser disks must be protected from mechanical damage(scratches), as well as from dirt.

Controllers

Controller (adapter)- a device that connects the internal and external devices of a computer with the central processor, releasing the processor from direct control of the operation of this equipment. Controllers exist for all devices that are not located on the motherboard. Consider the most important and commonly used controllers:

Video card (video adapter, video controller)- this is an electronic board that processes video data (text and graphics) and controls the operation of the display: it sends beam brightness control signals and image sweep signals to the display.

Video controller is responsible for displaying an image from the video memory, regenerating its contents, generating scan signals for the monitor, and processing requests from the central processor. To avoid conflicts when accessing memory from the side of the video controller and the central processor, the first one has a separate buffer, which is filled with data from the video memory during the time free from CPU access. If the conflict cannot be avoided, the video controller has to delay the CPU access to the video memory, which reduces the system performance; To avoid such conflicts in a number of cards, the so-called dual-port memory is used, which allows simultaneous access from two devices.

Many modern video controllers are streaming - their work is based on the creation and mixing together of several streams of graphic information. Usually this is the main image, on which the image of the hardware mouse cursor and a separate image in a rectangular window are superimposed. A video controller with streaming processing, as well as with hardware support for some typical functions, is called an accelerator or an accelerator, and serves to offload the CPU from routine image formation operations. The video card consists of three main devices: memory, DAC and ROM.

video memory serves to store the image. The maximum possible full resolution of the video card - A x B x C, where A - the number of dots horizontally, B - vertically, and C - the number of possible colors for each dot - depends on its volume. For example, for a resolution of 640x480x16, 256 kb is enough, for 800x600x256 - 512 kb, for 1024x768x65536 (another designation - 1024x768x64k) - 2 Mb, etc. Because colors are stored in an integer number of bits, the number of colors is always a power of two (16 colors is 4 bits, 256 is 8 bits, 64k is 16, etc.).

DAC(digital-to-analog converter, DAC) is used to convert the resulting data stream generated by the video controller into color intensity levels supplied to the monitor. Many modern monitors use an analog video signal, so the possible color range of the image is determined only by the DAC parameters. Most DACs have 8x3 bit depth - three channels of primary colors (red, blue, green, RGB) with 256 brightness levels for each color, which gives a total of 16.7 million colors. Usually the DAC is combined on the same chip with the video controller.

Video ROM- read-only memory containing video BIOS, screen fonts, service tables, etc. The ROM is not directly used by the video controller - only the central processor accesses it, and as a result of its execution of programs from the ROM, the video controller and video memory are accessed. ROM is needed only for the initial launch of the adapter and work in MS DOS mode; operating systems with a graphical interface do not use ROM to control the adapter.

Audio card

Audio adapter(Audio card or sound card) is a special electronic card that allows you to record sound, play it back and create software using a microphone, headphones, speakers, built-in synthesizer and other equipment.

The audio adapter contains two information converters:

• analog-digital, which converts continuous (that is, analog) audio signals (speech, music, noise) into a digital binary code and records it on a magnetic medium;
• digital-analog, which converts the digitally stored sound back into an analog signal, which is then played back using a speaker system, sound synthesizer, or headphones.

There are four more or less independent blocks in the audio adapter:

1. Digital Recording/Playback Block, also called the digital channel, or path, of the card. Performs analog->digital and digital->analog conversions in program transfer mode or via DMA. It consists of a node that directly performs analog-to-digital conversions - ADC / DAC (international designation - coder / decoder, codec), and a control node. The ADC/DAC is either integrated into one of the microcircuits of the card, or a separate microcircuit is used (AD1848, CS4231, CT1703, etc.). The quality of the used ADC / DAC largely depends on the quality of digitization and sound reproduction; it also depends on the input and output amplifiers.

2. Synth block. It is built either on the basis of OPL2 (YM3812) or OPL3 (YM262) FM synthesis chips, or on the basis of WT synthesis chips (GF1, WaveFront, EMU8000, etc.), or both. It works either under the control of a driver (FM, most WT) - a software implementation of MIDI, or under the control of its own processor - a hardware implementation. Almost all FM synthesizers are compatible with each other, various WT synthesizers are not. Most WT synthesizers contain a built-in ROM with a standard set of General MIDI instruments (128 melodic and 37 percussion instruments), as well as RAM for loading additional digitized sounds that will be used when performing music.

3. MPU unit. Receives/transmits data via an external MIDI interface connected to the MIDI/Joystick connector and the connector for daughter MIDI boards. Usually more or less compatible with the MPU-401 interface, but most often software support is required.

4. Mixer block. Performs level control, switching and mixing of analog signals used on the card. The mixer includes preliminary, intermediate and output amplifiers for audio signals.

Network card (network adapter)- This is an expansion card that is inserted into the computer motherboard connector, which is used to connect the computer to the network. Network boards are characterized by their:

• Bit depth: 8 bit (oldest), 16 bit and 32 bit.
• Data bus, through which information is exchanged between the motherboard and the network card: ISA, PCI, USB, PCMCIA, etc.
• Controller chip or chip, on which this board is manufactured, and which determines the type of compatible driver used, bit depth, bus type, etc. Examples of modern chips are Realtek, D-Link, Compex.
• Supported network media (network media), i.e. connectors installed on the card for connecting to a specific network cable. BNC for networks on coaxial cable, RJ45 for networks on twisted pair or connectors for connection to fiber optics.
• Operating speed (bandwidth). There are Ethernet 10 Mbit/s, Fast Ethernet 100 Mbit/s, Gigabit Ethernet 1000 Mbit/s.
• MAC address. Used to determine the destination of packets (frames) on an Ethernet network. This is a unique serial number assigned to each Ethernet network device to identify it on the network. The MAC address is assigned to the adapter by its manufacturer, but can be changed using the program.

Modem

Modem(derived from the words MODulator / DEModulator) is a device for receiving and transmitting information over telephone lines.

How it works: As we know, data in a computer is stored in digital form. And the telephone lines through which data is exchanged are mostly analog. Thus, in order to convert digital data into analog data, the modem uses special digital-to-analog and analog-to-digital converters (modulators / demodulators). The mode of operation, when data is transmitted in only one direction, is called half duplex (half duplex). Both computers can simultaneously exchange information in both directions. This mode of operation is called full duplex, or simply full duplex.

Analog signals are modulated, i.e. a change in their characteristic characteristics (frequency, phase, amplitude). Such a modulated signal is called a carrier. The modulation rate is measured in units of baud per second, and the amount of information transmitted (connection speed) is measured in bits per second (BPS - Bits Per Second). According to modern standards, up to 4 bits of information are transmitted in one modulation, and for digital communication channels, the number of bauds is equal to the number of bits per second. The unit of information transmitted in one modulation is called a character. To increase the amount of transmitted information, phase and amplitude modulation is used. From here, another unit of information measurement appeared - the number of transmitted characters per second (CPS), i.e. the amount of useful information transferred.

All modern modems are built according to one functionally similar scheme. They consist of a main processor, RAM, ROM, modulator/demodulator, telephone line matching circuit, and built-in speaker.

The main processor is responsible for executing instructions, buffering and data processing (encoding/decoding, compression/decompression, etc.), as well as signal processor control. A digital signal processor (DSP - Digital Signal Processor) together with a modulator / demodulator deals with signal operations, frequency division, etc. The ROM stores sets of microcommands for the main and signal processors (firmware).

Modern modems use a programmable ROM, which allows you to quickly change the firmware when new features appear. RAM is used as temporary memory during the operation of the main and signal processors. Line matching circuits use a transformer, a special device for identifying a ring signal, a line relay and a dialing relay (in recent times relays replace silent electronic keys). To protect the modem from line surges, each modem is equipped with an attenuator input device. The built-in speaker is used for audio status monitoring during dialing and connection.

Exist external and internal modems. Internal modem (soft modem)- this is a board inserted inside the system unit and located in the ISA, PCI, AMR, CNR slots. The internal modem is powered by the computer's motherboard and uses the computer's resources (processor, memory, etc.), so it costs less than an external modem. Internal modems are divided into WinModem, where the controller functions are performed by a special driver, and SoftModem, in which, in addition to the controller, there is no digital signal processor.

External modem- a peripheral device that connects to a COM or USB port. Such modems have their own power supply, as well as various controls and indicators. The vast majority of external modems connect to a computer via a serial interface called RS-232C or USB. To do this, connect the cable to the serial port (COM port) of the computer.

In addition to conventional modems are now quite common and fax modems, which, in addition to the main functions, also receive and send faxes, i.e. transmission or reception of graphic and text black-and-white images via telephone lines.

Power Supply

Power Supply converts the AC voltage of the mains into a DC voltage of various polarity and magnitude, necessary to power the system board and internal devices. The main characteristic of the PSU is power. The standard power supply of a modern computer is 300W or 400W.

The task of the power supply is to convert the mains voltage of 220 W (110 W) into the supply voltage of the structural elements of the computer: +12 V at a current of 3.5–10 A to power the motors of devices (floppy drive, hard drive, CD-ROM, etc.) and +5 V at a current of 10A to 20A to power all electronic circuits of the computer. The ATX power supply is significantly different from conventional AT units in terms of electrical interface. The ATX unit provides an additional +3.3V to power processors and RAM modules. There is also an additional "standby" low-power source with a load current of up to 10 mA with a voltage of +5V.

The power supply contains fan, which creates circulating air flows to cool the system unit. In light of the rapidly growing PC capacities, almost every motherboard or microcircuit began to have fans and heatsinks. For the processor, the fan and radiator (cooler) have long become the standard. Power from a single power supply is supplied to all circuits and devices of the system unit.

Port- this is a connector through which you can connect the computer's motherboard to an external device. Ports for connecting external devices. To connect peripheral equipment, as well as communicate with other computers on the system unit, there are connectors for various ports.

Serial ports transmit electrical impulses carrying information in machine code, sequentially one after the other. Serial ports are designated as COM1 and COM2, and are implemented in hardware using 25-pin and 9-pin connectors, which are displayed on the rear panel of the system unit. Serial ports typically connect a mouse and a modem.

Parallel port transmits simultaneously 8 electrical impulses carrying information in machine code. The parallel port is designated as LPT, and is implemented in hardware as a 25-pin connector on the back of the system unit. The parallel port provides a higher transfer rate than parallel ports and is used to connect a printer.

USB port. In recent years, widespread USB port(Universal Serial Bus - universal serial bus), which provides high-speed connection to the computer at once several peripheral devices (scanners, digital cameras, etc.).

SCSI adapters. You can also use the Small Computer System Interface to connect additional devices to your computer. SCSI adapters are installed in motherboard expansion slots and provide high-speed connection of up to 7 different devices (hard drives, scanners, CD-ROM drives, etc.). To connect joysticks designed to control games, a special Game-port (game port) is used, which is usually located on the sound card.

Monitor

Monitor is a universal output device and is connected to a video card, which is installed in the expansion slot of the system board in the system unit.

An image in a computer format (in the form of sequences of zeros and ones) is stored in the video memory located on the video card. The image on the monitor screen is formed by reading the contents of the video memory of the computer and displaying it on the screen.

The image reading frequency affects the stability of the image on the screen. In modern monitors, the image is usually updated at a frequency of 75 or more times per second, which ensures the comfort of the image perception by the computer user (a person does not notice the flickering of the image). For comparison, we can recall that the frame rate in the cinema is 24 frames per second.

Desktop computers usually use monitors on cathode ray tube (CRT). The quality of the image received on the monitor screen depends on the parameters of the cathode ray tube (CRT) and the electronic circuits that control it. The main parameters include: screen size and "grains" and the optical resolution associated with them, which determines the amount of information displayed and the possible degree of detail; Image refresh rate (Frequency), which determines the amount of flicker reduction. The perception of the image is also significantly affected by how black the screen is (contrast depends on this) and flat (higher naturalness, wider viewing angle, less glare).

The image on the CRT monitor screen is created by a beam of electrons emitted by an electron gun. This beam (electron beam) is accelerated by a high electrical voltage (tens of kilovolts) and falls on the inner surface of the screen, covered with a phosphor (a substance that glows under the influence of an electron beam). The beam control system makes it run through the entire screen line by line (creates a raster), and also regulates its intensity (respectively, the brightness of the glow of the phosphor point). The user sees the image on the monitor screen, because. phosphor emits light rays in the visible part of the spectrum.

In order for the electrons to freely reach the screen, air is pumped out of the tube, and between guns and screen a high electrical voltage is generated, accelerating electrons. In front of the screen in the path of electrons is placed mask- thin metal plate large quantity holes located opposite the dots of the phosphor. The mask ensures that electron beams hit only the dots of the phosphor of the corresponding color. Monitors may have different screen sizes. Screen size is measured in inches (1 inch = 2.54 cm) and is usually 14, 15, 17 or more inches.

However, the monitor is also a source of high static electrical potential, electromagnetic radiation and radiation, which may have adverse effects on human health. A necessary characteristic of monitors is their compliance with sanitary and hygienic requirements, which are fixed in the international safety standard (MPR II). When setting up a computer, it is useful to remember that electromagnetic and other radiation is most intense near the back of the monitor case.

In portable and pocket computers, flat-panel liquid crystal (LCD) monitors are used. Recently, such monitors have been used in desktop computers. Advantage LCD monitors consists in the absence of electromagnetic radiation harmful to humans and in compactness.

liquid crystals- this is a special state of some organic substances, in which they have fluidity and the ability to form spatial structures similar to crystalline ones. Liquid crystals can change their structure and light-optical properties under the influence of an electrical voltage. By changing the orientation of groups of crystals using an electric field and using substances introduced into a liquid crystal solution that can emit light under the influence of an electric field, high-quality images can be created that transmit more than 15 million color shades.

In LCD monitors, the image is formed using a matrix of pixels, consisting of liquid crystals. This is where the abbreviation LCD (Liquid Crystal Display) comes from, which stands for Liquid Crystal Display. The use of liquid crystals as the main image element is not accidental: they are able to change the direction of polarization of the light passing through them. And if an external voltage is applied to the crystal, then the direction of polarization will change. This allows you to control the intensity of the transmitted light. Polarizers are installed on both sides of the crystal, and so that their axes are located at right angles to each other. The beam of light, passing through the first of them, will become linearly polarized.

Then, in the liquid crystal cell, the plane of polarization of light will rotate through a certain angle, the value of which will depend on the applied voltage. Finally, the role of the second polarizer is to regulate the amount of transmitted radiation, if the angle between the direction of its axis and the plane of polarization of light gradually changes from 0 to 90 °, then the absorption of radiation will increase. In this way, the light intensity (pixel brightness) can be controlled. As you know, to form a color image, it is necessary to have pixels of three colors: red, green and blue. Since liquid crystals are absolutely transparent, they cannot affect the color characteristics of the radiation. For this purpose, filters are used that extract the necessary spectral components from the "white" radiation of backlight lamps.

Serves for entering information into the computer and supplying control signals. It contains a standard set of alphanumeric keys and some additional keys - control and function keys, cursor keys, as well as a small numeric keypad.

Cursor- a luminous symbol on the monitor screen, indicating the position at which the next character entered from the keyboard will be displayed. All characters typed on the keyboard are immediately displayed on the monitor at the cursor position.

Most common today 101-key keyboard with QWERTY key layout(read "kverti"), named after the keys located in the upper left row of the alphanumeric part of the keyboard:

This keyboard has 12 function keys along the top edge. Pressing a function key sends to the computer not a single character, but a whole set of characters.

Function keys can be programmed by the user. For example, in many programs for getting help (hints) the key is used F1, and to exit the program - the key F10.

The control keys have the following purpose:

• Enter- enter key;
• Esc(Escape - exit) key to cancel any action, exit the program, from the menu, etc.;
• ctrl and alt- these keys have no independent meaning, but when pressed together with other control keys, they change their action;
• Shift(case) - provides a change in the case of keys (upper to lower and vice versa);
• Insert(insert) - switches insertion modes (new characters are entered among already typed ones, pushing them apart) and replacements (old characters are replaced by new ones);
• Delete(delete) - deletes a character from the cursor position;
• back space deletes the character before the cursor;
• Home and End- move the cursor to the first and last position of the line, respectively;
• Page Up and Page Down- provide movement through the text one page (one screen) back and forth, respectively;
• Tab- the tabulation key, provides movement of the cursor to the right by several positions at once to the next tabulation position;
• cap lock- fixes the upper case, ensures the input of capital letters instead of lowercase;
• Print Screen- Provides printing of the information currently visible on the screen.
• scroll lock- turns on the mode of scrolling (scrolling) documents.
• pause break- turns on the pause mode when a process is running.
• WIN- designed to open and close the Windows Main Menu. Also used in combination with other keys.
• Menu- displaying the Windows context menu.
• Long bottom key untitled - intended for entering spaces.
• Keys - "arrows" are used to move the cursor up, down, left and right one position or line.

Small numeric keypad used in two modes - entering numbers and controlling the cursor. Switching between these modes is carried out with the key Num Lock. The keyboard contains a built-in microcontroller, which performs the following functions:

• sequentially interrogates the keys, reading the entered signal and generating a binary scan code of the key;
• controls the keyboard lights;
• conducts internal troubleshooting;
• interacts with the central processor through the keyboard input-output port.

The keyboard has built-in buffer- an intermediate memory of small size, where the entered characters are placed. In case of buffer overflow, pressing a key will be accompanied by a sound signal - this means that the character is not entered (rejected).

The operation of the keyboard is supported by special programs "hardwired" in the BIOS, as well as keyboard driver, which provides the ability to enter Russian letters, control the speed of the keyboard, etc.

It is now also widely used wireless keyboards. As the name implies, wireless keyboards transmit information to the computer not via a cable, but via radio waves or infrared radiation. In addition to the obvious advantages, wireless keyboards also have disadvantages, which include, for example, the need to use an independent power source.

Manipulators

Manipulators are special devices that are used for convenient cursor control. Manipulators include the following devices:

1. looks like a small box that fits completely in the palm of your hand. The mouse is connected to the computer with a cable through a special adapter block, and its movements are converted into corresponding cursor movements on the display screen. At the top of the device there are control buttons (usually there are three of them, and often the role of the third button is played by the scroll or scroll wheel), which allow you to set the beginning and end of the movement, select menus, etc.

Mouse classifications:

• By connection method
  • Cable connection
    • COM port. Outdated slow connection, no hot plug, with mandatory manual installation of drivers
    • PS/2 port. The main way to connect mice. There is no hot connection, you need to install drivers, but with the help of PS / 2 Rate you can change the mouse polling frequency.
    • USB port. The fastest port. Hot-pluggable, auto-install, standard high port polling rate. But often such features are not required for the mouse to work.
  • Wireless connection
    • Radio communication. A very reliable type of communication, does not require visual contact, is slightly sensitive to interference.
    • infrared port. It works only under the condition of direct visibility at a distance of no more than 2 meters, it is sensitive to interference in the form of light.
• By way of action
  • Mechanical. They have a ball at the bottom, when moving, it rotates the rollers, they have gear wheels, the position of the latter is determined by opto-pairs. Pros: relative simplicity and cheapness. Cons: sensitivity to dirt, play and wear inevitable for any mechanical device.
  • Optical. More developed. They have a microcamera below, it takes the position of the mouse (about 1000 times per second), its data is analyzed by the processor (not the CPU, but built into the mouse). Pros: insensitivity to dirt, performance on almost any surface (except mirror and reflective), the absence of any mechanics. Cons: difficult to manufacture, unexplored viability in extreme situations, more expensive.

2. - a small box with a ball built into the top of the case. The user rotates the ball by hand and moves the cursor accordingly. Unlike a mouse, a trackball does not require free space near the computer, it can be built into the car body. Most often it is used as a replacement for the mouse, especially for working with graphics.

In optical-mechanical manipulators, the main working body is a massive ball (metal, covered with rubber). In a mouse, it rotates when its body is moved along a horizontal surface, and in a trackball, it rotates directly by hand.

The rotation of the ball is transmitted to two plastic shafts, the position of which is read with great accuracy by infrared optocouplers (i.e., light emitter-photodetector pairs) and then converted into an electrical signal that controls the movement of the mouse pointer on the monitor screen. The main "enemy" of the mouse is pollution, and the way to deal with it is to use a special "mouse" pad.

Manipulators have one, two or three control buttons that are used when working with the graphical interface of programs. Currently there are mice with an additional button, which is located between the two large main buttons. It is designed to scroll up or down an image, text, or Web page that does not fit entirely on the screen. The manipulators can be connected to a computer in three different ways: using a serial COM port, a special small round five-pin PS / 2 connector, and a universal USB port.

3. . Another coordinate input device is the TouchPad (touchpad). In Russian, this name can be translated as "touch panel". The touchpad is a rectangular panel that is sensitive to finger pressure.

The touchpad plays the same role as a mouse, but is a more compact, non-drag input device and is ideal for portable computers. Sometimes a touchpad is built directly into a desktop keyboard. By placing a finger on the surface of the touchpad and moving it, the user can maneuver the cursor in the same way as when using a mouse. Pressing the touchpad surface is equivalent to pressing a mouse button.

4. - usually this is a pen-rod, the deviation of which from the vertical position leads to the movement of the cursor in the corresponding direction on the monitor screen. Often used in computer games. In some models, a pressure sensor is mounted in the joystick. In this case, the harder the user presses the knob, the faster the cursor moves across the display screen.

Joysticks are divided into two main classes - with or without proportional control.

The simplest joysticks(without a handle or with it) according to the principle of operation are completely similar to the keys. They have mechanical internal contacts that work on closing-opening. Compared to a simple keyboard, playing them is much worse, because. It takes longer to move the handle than it does to press the button. But this statement is true only for a relatively experienced player who is used to playing the keys. For a beginner, even such a joystick would be preferable, because. allows you to immediately, without a long addiction, more or less tolerably play.

Joysticks with proportional control are analog devices based on the change in resistance as the physical coordinates change. By design, modern joysticks are divided into five main categories:

• push-button(joypads) are similar to control panels. There are at least two buttons on the control pad, and left-handed players can flip it over for more natural use. These handy, compact and usually cheap joysticks are ideal for real-time offensive and defensive games;
• desktop(desktop);
• joysticks in the form aircraft handles controls (pistol-grip flightsticks) look like the levers of real military aircraft. They are usually equipped with a trigger switch and a thumb button, as well as a speed control. Without a doubt, such joysticks work great in "aircraft cockpits", but are rather inconvenient in sports, as well as games that require attack and defense, where you need the accuracy that desktop and push-button models have. Most joysticks of this type reflect the serious needs of actual computer flight simulators;
• joysticks in the form steering wheels(yokes) look very surreal and create a feeling similar to that experienced when flying small aircraft. Usually they are mounted on the table with special suction cups or clamps. At a fairly high price, these devices, however, greatly increase the attractiveness of flight simulation and car racing games;
• combined(hybrids) are the remaining loners that can only be used in some games.

Peripheral (external) devices

These are devices that are located outside the system unit, and are not mandatory when working with a computer, but rather complement and expand its capabilities.

1. Printer(from the English printer - printer) - a device designed to print on paper or film text or graphic information prepared on a PC. Main characteristics of printers:

• Print Technology.
• Permission(print quality) - the maximum number of dots per inch that the printer can print (for example, 1200 x 2400 dpi).
• Print speed- measured mainly by the number of printed pages per minute.
• Supported paper sizes. Most often, you have to print on A4 paper, so almost all printers have support for it.
.
• Connection type (interface)- LPT, USB, etc.
• Expendable materials- ink ribbons, ink cartridges, powder toners, etc.

The main printing technologies are:

matrix. Principle of operation: the dot matrix printer prints with the help of an ink ribbon; The ink from the ribbon is transferred to the media using retractable pins in the matrix. A vertical row (or two rows) of needles, or hammers, “pumps” the dye from the tape directly into the paper. Pins are usually 9, 18 or 24. Print speed 25-150 characters/s.

Inkjet. Inkjet printers are non-impact printers. In inkjet printers, the print head moves only in a horizontal plane, and the paper is fed vertically. The nozzles (channel holes) on the printhead through which the ink is sprayed correspond to the "impact" needles. Number of nozzles different models printers, as a rule, can vary from 12 to 64. The maximum resolution, as a rule, reaches a value of about 360 dpi.

Principle of operation: there is a nozzle that sprays ink along the contour of the symbol. With sudden heating, an ink vapor bubble is formed, which tries to push out the necessary portion (drop) of liquid ink through the nozzle outlet.

Text printing speed 5-150 characters / s (1-3 pages / min.). There are one-color, three-color and four-color. The print quality is high, comparable to laser, and the cost of printing is much lower, especially in color. The disadvantages include the fact that the quality depends on the paper, as well as quite expensive consumables.

laser. Principle of operation: the laser generates a thin light beam, which, reflected from a rotating mirror, forms an electronic image on a light-sensitive photodetector drum capable of changing the electric charge of a point under the action of a laser beam that hits it. The drum is preliminarily statically charged. The areas illuminated by the laser are discharged. When the image is built on the drum and covered with toner, the sheet being fed is charged so that the toner from the drum is attracted to the paper. After that, the image is fixed on it by heating the toner particles to the melting point. The final fixation of the image is carried out by special rubber rollers that press the molten toner to the paper.

2. . The scanner is used for optical input to a computer and digitization of images (photos, drawings, slides), as well as text documents. The scanned image is illuminated with white light (black and white scanners) or three colors (red, green and blue). The reflected light is projected onto a line of photocells, which moves, sequentially reads the image and converts it into a computer format.

Text recognition systems allow you to convert scanned text from graphic format to text. Such systems are able to recognize text documents in different languages, presented in different forms (for example, tables) and with different print quality (starting from typewritten documents).

Exist flatbed and handheld scanners. Flatbed scanners may come with a special slide module for scanning slides. The resolution of scanners is 600 dpi (dot per inch - dots per inch) and higher, i.e. On a 1-inch image strip, the scanner can recognize 600 or more dots. Scanners are connected to the computer in various ways: using SCSI adapters, to the parallel or USB ports of the computer.

3. multimedia devices. The term "multimedia" is formed from the words "multi" - a lot, and "media" - environment, carrier, means of communication, and in the first approximation it can be translated as "multi-media"

Multimedia- this is a collective term for various computer technologies that use several information media, such as graphics, text, video, photography, moving images (animation), sound effects, high-quality sound. Multimedia technology consists of two main components - hardware and software.

multimedia devices- these are PC devices that directly serve to work with sound, graphic and video information. multimedia computer- a computer equipped with hardware and software that implements multimedia technology.

In order for a computer to be called multimedia, it is necessary to have a high-performance processor with a clock frequency of at least 500 MHz, at least 64 MB of RAM, a hard drive with a capacity of 10-20 GB or more, manipulators, a multimedia monitor with built-in stereo speakers and an SVGA video adapter, as well as the presence of special devices, which are often referred to as multimedia devices. Media devices include:

• graphics accelerators(accelerators). Modern video cards are all graphics accelerators;
• CD-ROM/RW, DVD-ROM/RW drives and etc.;
• sound cards;
• columns- small loudspeakers through which the sound is played. Speakers are passive and active. Passive speakers work due to the power of the built-in amplifier of the sound card, while active ones contain an amplifier themselves. Active speakers usually sound better;
• microphone. Depending on the physical principles of action are divided into coal, dynamic, electromagnetic, piezoelectric, capacitor. The areas of application in a PC are very diverse: the implementation of the capabilities of a telephone, an answering machine, working with multimedia programs, network negotiations (video conferencing), etc .;
• acoustic systems- this is a set of emitters, each of which is assigned to reproduce its part of the sound frequency range.

Digital cameras and TV tuners. In recent years, digital cameras (camcorders and cameras) have become more widespread. Digital cameras allow you to capture video and still images directly in digital (computer) format. Digital video cameras can be permanently connected to a computer and provide video recording to a hard drive or its transmission over computer networks.

Digital cameras allow you to take high-quality photographs that are stored using special memory modules or very small hard drives. Images can be recorded to the computer's hard drive by connecting the camera to the computer's USB port.

If you install a special board (TV tuner) in your computer and connect a television antenna to its input, you will be able to watch TV programs directly on your computer.

In this lesson, we will look inside the system unit and get to know all the main internal components computer.

In the third lesson, we learned what a processor, RAM and hard drive are for. In the fourth lesson, we saw the computer from the outside and learned what the various buttons and connectors are for. Today we will open the cover of the system unit and get acquainted with all the internal components.

Computer internals

When talking about the internal structure of a computer, they usually mean those components that are inside its case. For a desktop computer, the case is a system unit, for laptops and netbooks it is the lower of the opened halves (I remind you that we were dedicated to varieties of computer equipment).

System block components

To begin with, let's take a not too new, but not too old system unit, in which all the main components are installed. And then we compare with a more inexpensive option with fewer additional components.

So, let's look at the photo of the system block of the IT-lessons website.

What will we see if we remove the cover of the computer system unit

The first thing that catches your eye is a lot of all sorts of printed circuit boards, "boxes" and wires. All boards and devices in a separate housing are components that perform different tasks. With the help of wires, components exchange information and receive electrical power.

Let's deal with all the components in turn.

1. Motherboard

All computer components are interconnected by one largest printed circuit board (which can be immediately recognized in the photo by its size), it is called system board or motherboard(in English version motherboard or mainboard).

System board (component of the system unit)

Some components are installed directly into the connectors located on the system board, other components are connected to it using special wires in the appropriate connectors, and are installed in special compartments of the case.

You can learn more about the motherboard from subsequent IT lessons, but at a higher level of knowledge.

2. Power supply

In order for all components to perform their task, they must be powered by electrical energy. This energy is supplied by computer power supply(in English power supply unit or PSU), from which wires stretch throughout the system unit.

Most devices have a special connector for connecting power, but some receive electrical energy through (which in this case will be an intermediary between the power supply and the device).

3. CPU

We already got acquainted with the processor in, let me remind you that the task of the processor is to process information.

CPU(English) central processing unit and CPU) is installed in a special connector on the system board (the English name of the connector is " Socket"). The processor socket is usually located at the top of the motherboard.

After installing the processor in the socket, a cooling system is installed on top - cooler(aluminum radiator with fan).

In the photo we see a cooler, under which the central processor is located.

4. RAM

We also met with RAM in the third lesson.

RAM(RAM, Random Access Memory, RAM), like the processor, is installed in special slots on the motherboard.

RAM (component of the system unit)

RAM is made in the form of a small printed circuit board with memory chips installed on it, this whole design is called " memory module". Due to the specific shape of the board, it is called a "bar".

The photo shows that there are four connectors, and two RAM modules, and they are installed in connectors of the same color to increase the speed of work (more on this mode in subsequent IT lessons at more "advanced" levels).

5. Video card

video card(video adapter, graphics adapter, graphics card, graphics card, video card, video adapter, display card, graphics card, etc.) is designed to process graphic objects that are displayed in the form / form of an image on the monitor screen.

The photo shows that in this case the video card is made in the form of a printed circuit board ( expansion cards) inserted into a special connector on the system board (expansion slot). Since this video card is very hot, at the bottom you can see large cooling system(Yes, yes, this is also a cooler).

For the first time in IT lessons, we encountered the concepts of "expansion card" and "expansion slot", so we will immediately set the definition, from which we will build on in the future.

Expansion card- a device in the form of a printed circuit board with a universal connector for installation on a system board (for example, a video card, network card, sound card).

Expansion cards are installed in addition to the main components to expand the capabilities of the computer, they can have different purposes (processing of graphics, sound or connection with computer network etc.).

Expansion card example (simpler video adapter)

Expansion slot- a special universal connector on the system board, designed to install additional computer devices made in the form of expansion cards.

With the new definitions figured out, moving on.

6. Network card

Network Card(network adapter, Ethernet adapter, network adapter, LAN adapter) is designed to connect a computer to a computer network.

Network card (component of the system unit)

In this case, the network card is also made in the form of an expansion card (printed circuit board), which is installed in a slot on the system board.

7. Sound card

Sound card(audio card, sound adapter, sound card) processes sound and outputs it to acoustic systems (speakers) or headphones.

Sound card (component of the system unit)

Like the two previous devices, the sound card is a printed circuit board inserted into a slot on the system board. True, this sound adapter is not ordinary, it consists of two printed circuit boards, but this is an exception to the rule.

8. Hard drive

On the hard drive all programs and computer data are stored (more on this in the IT lesson).

The hard drive, unlike previous components, is not installed on the system board, but is attached in a special compartment system unit (look at the photo).

Hard drive (aka hard drive)

You can install multiple hard drives in these bays and expand the internal memory of your computer.

Hard Drive is sometimes referred to by the acronym NMWR(hard disk drive) is often said " Winchester", and in English hard disk drive or HDD.

9. Optical drive

optical drive(DVD drive, optical disc drive or ODD) is needed to read and write DVD and CD discs. Like a hard drive, an optical drive is installed in a special compartment system block.

Optical drive (system unit component)

This bay is located at the top front of the case and is wider than for a hard drive, as the DVD drive is noticeably larger.

Components of the system unit (option 2)

So, we have considered all the main components of the system unit. Now let's see how the internal structure of a computer can differ using an example less expensive PC option.

The photo shows the same components, but no expansion cards (video card, network card, and sound card) are visible. How will this computer work without these components? In fact, these components are there, but they are not visible at first glance.

Embedded Components

The fact is that some components may not be made in the form of expansion cards, but may be built-in(integrated) to the motherboard or CPU.

In this case, additional microcircuits are installed on the system board, which act as a network and sound adapter. The video adapter is built-in (integrated) into the main chip of the system board.

In the photo, the number 1 indicates the video adapter, the number 2 is the network adapter, and the number 3 is the sound adapter.

At the same time, expansion slots (number 4) remained on the motherboard for installing more functional components (if the built-in ones, for some reason, do not suit you).

Notebook components

In principle, it would be possible to make a separate lesson on laptop internals and netbooks. But, in fact, there are the same components as in desktop computer, only these components are smaller and mounted differently.

Each of the components listed in this IT tutorial performs its own task, but it is probably interesting to know which components affect the speed of your computer the most?

Since most of the calculations are performed CPU, then it most of all affects the performance of the computer.

RAM needed by the processor in order to supply data and programs to perform calculations. Therefore, the amount of memory also significantly affects the performance of the entire computer.

If you need a computer for games or work with three-dimensional graphics, speed is of great importance video adapter.

But if the computer is used to surf the Internet, as well as text documents, photos, watching movies and listening to music, then you can get by with the slowest (but modern) video adapter, including those built into the motherboard or processor.

Video supplement

As a consolidation of new information, a very curious video, which describes in simple terms the purpose of computer components. Unfortunately, the comments are in English, but there is a translation with subtitles (use the pause to have time to read).

Conclusion

So, in the seventh IT lesson, we met with computer internals and reviewed briefly system block components. For the Beginner level, this knowledge is enough to consciously work in most programs that you may need.

In the next lesson, we will learn what devices can still be connected to the computer (external devices), it is called.

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Published: 14.01.2017

hello friends,
today we will consider in detail the device of the computer system unit. We will find out what it consists of, which components must be present in it, and which are optional. Let's define the purpose of each internal component of the system unit. Let's start.

Case of the system unit

The case is usually such an iron box, which is needed for the convenience of attaching the internal components of the system unit. It has special holes for mounting the motherboard, a basket for hard drives and cd / dvd drives, external holes on the front and back for the output of external connectors of the internal components of the system unit (motherboard, video card, etc.).

There are also a bunch of holes for coolers / fans to ensure the best cooling of the internal components of the system unit. In particularly cool cases, there is also the so-called "cable-management" system.

What is cable management?

Cable management is a system of special grooves inside the case for laying cables and wires between the internal components of the system unit. The whole thing is needed so that the wires stretched throughout the case do not interfere with the incoming and outgoing air flows to circulate freely inside the system unit case. In short, so that the wires do not interfere with cooling.

What are the sizes of the cases?

The cases themselves come in three main sizes: Mini Tower, Mid Tower and Full Tower. Simply put, small, medium and large. The size of the case is selected depending on what size motherboard you plan to fit into it and what size you plan to install internal components in it.

Do you need a body?

In general, the case is not a mandatory element of the system unit. The computer can easily work without a case. However, without a case, the computer will not work as efficiently. The internal components of the system unit will not be properly cooled and will be covered with a layer of dust more often. And it will be more difficult for you to mess around with a computer without a case.

The basis of each system unit, if not a computer. This is the most basic board, to which all the others are already connected. The motherboard is responsible for the interaction of all internal components with each other.

It regulates the frequency of the processor and RAM sticks. Regulates the speed of rotation of coolers, the speed of data transfer between hard drives. Distributes the current supply to internal components. Checks the functionality of all components connected to it when you turn on the computer using the BIOS.

Motherboard connectors

Among other things, the most connectors go from the motherboard to the outer panel of the case. All or almost all USB connectors, PS / 2 ports for connecting a mouse and keyboard. A network jack for the RJ45 connector can also be output if the network card is built into the motherboard.

Sometimes DVI or VGA video connectors also come from the motherboard. This happens if the video card is built into the motherboard or the processor has an integrated video chip.

CPU

You could say the brain of a computer. Responsible for the speed of performing various calculations. For example, for the speed of encoding video files, for the speed of interpretation and execution of program code, for calculating the movement of certain objects, and so on. The processor is mounted in a special one on the motherboard.

Each processor has its own characteristics. Such as the core frequency, the number of cores, the amount of cache memory, and so on. We will not delve into this in detail for now.

RAM sticks

As the name implies, these strips are responsible for the amount of computer RAM. The more slats and the larger they are, the more RAM the computer has.

The main characteristic of RAM sticks is the frequency range at which they can operate. The amount of each bar of RAM is also taken into account.

It is recommended that you always install RAM sticks of the same size and from the same manufacturer in your computer in order to avoid various system conflicts. The brackets are installed in special slots on the motherboard.

video card

An integral part of any computer. Responsible for displaying an image on the user's monitor. Responsible for the quality of computer graphics and the performance of 3D applications in general.

There are both external video cards and internal ones built into the motherboard or into the processor. However, on most home PCs, the graphics card is external.

A modern external video card differs from its ancestors by a large number of coolers and a massive radiator grille. All this is necessary to improve the cooling of the card and, as a result, increase its performance.

The main parameters of a video card are the amount of its video memory and the frequency range at which the video card operates.

Hard drives

There may be several of them or there may be one hard drive. At least one must be there so that you can install any operating system on it.

In the picture above, you can see an example of one of the modern hard drives connected to the motherboard using a SATA cable.

The main parameters of a hard disk are the speed of reading and writing data. I already wrote about how they are measured.

CD/DVD/Bluray drives

Needed to read and write files to disk. They are already gradually becoming obsolete, because small-sized CDs and DVDs are being replaced by fast and voluminous flash drives and external hard drives that are connected to the system unit via usb cables.

The drive is not a mandatory element of the system unit. The computer will be able to work quite quietly without it. But without a drive, it will not be possible to work with CD, DVD and Bluray discs.

The main parameters of any drive are the speed of reading a record from a disk and the speed of writing / burning data to a disk.

Power Supply

It is needed in order to properly distribute electricity from your home network between all components of the system unit.

The wires from the power supply go in order to power the motherboard, coolers, external video card and hard drives. The processor and RAM are powered by the motherboard. In addition, the motherboard regulates the voltage supply to the processor and RAM to increase or decrease performance.

Other boards

Quite often, in many system units there are additional boards. These can be external network cards, sound cards, TV tuners, GPS beacons, and so on. The whole thing is connected to the motherboard using PCI connectors.

In the picture above you can see an example of an external wi-fi network card. It is very popular in recent years due to the widespread use of home wi-fi networks. It is an ideal solution when you want to connect a stationary PC to the Internet, but there is no desire to throw a twisted pair cable from the system unit to the router.

Assembled system unit

When assembled, the system unit will look something like this.

In the upper right corner we see the power supply. We see how cables branch off from it to disk drives, to hard drives, to the motherboard and coolers. Exactly what I wrote to you about.

In the lower left corner we see three hard drives, and above them a basket with drives. In the center is the largest motherboard. It has an impressive cooler, located above the processor and under the whole thing some kind of video card.

That's actually all that I wanted to tell you today. I hope that the internal structure of the system unit is no longer a mystery to you. In any case, this information will still be useful to you when, in the following articles, we will learn how to choose components for the budget and assemble the computer system unit on our own.

It is known that personal computers consist of a system unit, monitor, keyboard and mouse. This set is called the basic package, to which you can additionally connect external devices such as a printer, scanner, speakers, external network cards. And how the computer works inside: this is available for children in this article.

What is inside the system unit?

If you carefully remove the side cover of the system side case, you can find metal and plastic parts of different sizes and shapes, connected by multi-colored wires, and in the center there is a large fan. What are these items and how do they work? Let's figure it out.

You can disassemble and assemble the computer only after disconnecting it from the mains, preferably in the presence of adults.

The internal devices that are located in the system unit include:

• motherboard;
• power unit;
• HDD;
• CD drive.

The most important part of a computer is the motherboard. It looks like a metal plate with many small details on it. In addition to the elements that are soldered to the board, there are removable devices. They are inserted into special connectors and can be replaced if necessary.

Rice. 1. Motherboard.

The device through which the computer is plugged into an outlet is called the power supply. It is designed to convert the voltage of a household electrical network into base voltages for powering computer devices. The power supply is screwed to the case of the system unit and connected to the motherboard and other devices.

For long-term storage of information, a hard disk (hard drive) is used. The hard disk has a non-volatile memory - when the power is turned off, the information recorded on it does not disappear. The hard drive is installed in special compartments of the system side and secured with screws. Multiple hard drives can be used at the same time.

You can install CD-ROM drives in the system unit, which are designed to read and write information to optical discs.

What is located on the motherboard?

The main device on the motherboard is the processor. It is a microcircuit in which all computational operations are performed. Since the processor heats up during operation, a radiator with a cooler is installed on it.

The cost of producing new types of microprocessors is very high, so they are produced only by large companies and in very large quantities. Processors for personal computers are manufactured by Intel and AMD.

The creation of microcircuits is based on photolithography technology, when microscopic electronic circuits consisting of a billion tiny transistors a few nanometers in size are applied to a thin, polished silicon wafer through photomasks.

The motherboard houses the RAM. It temporarily stores data used while the processor is running. RAM is volatile. When you turn off the computer, all information from the memory will be erased. Outwardly, the RAM resembles a green ruler, on which black rectangular microcircuits are installed. Along the long edge of the RAM line, you can see a small notch - a key. The location of the key for different types of memory is different. There are types of memory DDR, DDR2, DDR3 and DDR4.

Rice. 2. RAM.

As additional devices, expansion cards can be connected to the motherboard: video cards, sound cards, network cards, controllers for various ports (COM, LPT, SATA, USB).

Each device on the motherboard has its own connectors:

• CPU- installed in a special socket. It is a design with many holes or contacts, the number of which corresponds to the number of legs or pads of the processor. Sockets designed to install processors are called sockets. Each socket allows only a certain type of processor to be installed.
• - inserted into special connectors - slots. Slots have special grooves - keys that must match the notch on the RAM ruler. If the keys do not match, then the RAM will not be installed in the slot.
• External video card installed in a PCI Express slot, in earlier versions in AGP 8x.
• PCI expansion cards: sound adapters, video adapters, network cards, port expansion cards are installed in PCI slots.
• To connect external devices - hard drives, CD-ROM drives is used SATA connector.

Rice. 3. AGP and PCI slots.

It should be remembered that the type of socket on the motherboard must match the type of processor. The connectors for installing processors differ in the number and type of contacts, the distance of the cooler mounts. Therefore, connectors different types processors are incompatible. When replacing the processor, you need to know the marking of the socket. It is indicated on the metal or plastic part of the motherboard at the processor mount.

What have we learned?

So, a motherboard, a power supply, a hard drive, an optical drive are placed in the system unit of a personal computer. On the motherboard, a processor, RAM, and expansion cards are installed in special connectors.

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A personal computer is a universal technical system. His configuration(composition of equipment) can be flexibly changed as needed. However, there is a concept basic configuration, which is considered typical. In such a kit, the computer is usually supplied. The concept of a basic configuration may change. Currently, four devices are considered in the basic configuration:

• system unit;
• monitor;
• keyboard
• mouse.

System unit represents the main node, inside which the most important components are installed. The devices inside the system unit are called internal , and devices connected to it from the outside are called external . External auxiliary devices designed for input, output and long-term storage of data are also called peripheral .

The system block consists of:

1. corps;
2. motherboard;
3. processor;
4. random access memory;
5. hard disk;
6. floppy disk drive;
7. CD (or DVD) drive;
8. video cards;
9. sound card

Case of the system unit
In appearance, the system blocks differ in the shape of the case. Personal computer cases are produced in a horizontal (desktop) and vertical (tower) performance. Cases having a vertical design are distinguished by dimensions: full size (big tower), medium size (midi tower) and small size (mini tower). Among the buildings with a horizontal design, there are flat and especially flat (slim).

In addition to the shape, an important parameter for the body is called form factor. The requirements for hosted devices depend on it. Currently, two form factors are mainly used: AT and ATH. The form factor of the case must necessarily be consistent with the form factor of the main (system) board of the computer, the so-called motherboard.

Personal computer cases are supplied with a power supply, and thus the power of the power supply is also one of the parameters of the case. For mass models, the power supply of 200-250 W is sufficient.

Rice. 1. Examples of system blocks

All the main internal devices of a personal computer are concentrated in the system unit and are located mainly on a special device - the motherboard.

Motherboard- the main board of a personal computer, which is used to house its internal devices.

The internal circuit of a personal computer is shown in Fig.2.

Fig.2. Internal circuit of a personal computer

Motherboard (mainboard, matherboard, systemboard)

The motherboard is also often referred to as system board. This is the basis of the computer. It is this board that determines what type of processor can be used, what is the maximum size of RAM that can be installed, etc.

All expansion boards (video card, SCSI controller, modem, network card, etc.) are attached to the motherboard. In addition, there are microcircuits on the motherboard that control everything that is in the computer.

The main components of the motherboard, which are visible in the photo and are indicated by numbers:

1. Processor socket.
2. Connectors for RAM.
3. PCI bus interfaces.
4. Chip system logic(chipset).
5. Interfaces for connecting hard drives and CD or DVD drives.
6. Interfaces for connecting FDD.
7. I/O port block.

CPU

CPU is a device that processes and calculates data. Modern processors are very complex. The basis of any processor is the core, which consists of millions of transistors located on a silicon chip.

The processor can be divided into two parts:

• ALU (Arithmetic Logic Unit) - deals with data processing
• CU (Control Device) - is engaged in data transmission.

The processor is equipped internal memory. It's called cache memory and there are two levels.

The processor's internal memory is called cache memory

Modern processors have PGA (Pin Grid Array) packages. At this point in time, there are several manufacturers of processors, among them we can highlight Intel and AMD.

Structurally, the processor consists of cells similar to RAM cells, but in these cells data can not only be stored, but also changed. The internal cells of the processor are called registers. It is also important to note that data in some registers is considered not as data, but as commands that control the processing of data in other registers. Among the processor registers there are those that, depending on their content, are able to modify the execution of commands. Thus, by controlling the sending of data to different registers of the processor, it is possible to control the processing of data. This is what programs are based on.

Rice. 2. An example of processors (on the left - Athlon XP 3200+, on the right - Athlon XP 3000+)

Next element - microprocessor kit (chipset). This is a set of chips that control the operation of the internal devices of a computer and determine the main functionality of the motherboard.

Groups of microprocessors

The wider the set of system commands of the processor, the more complex its architecture, the longer the formal record of the command (in bytes), the higher the average duration of the execution of one command, measured in processor cycles. So, for example, the command system of Intel Pentium processors currently has more than a thousand different commands. Such processors are called processors with an extended instruction set - CISC-processors (CISC - Complex Instruction Set Computing).

In contrast to CISC processors, in the mid-80s, processors of the architecture appeared ^ RISC c abbreviated command system (RISC - Reduced Instruction Set Computing). With this architecture, the number of instructions in the system is much smaller, and each of them is executed much faster. Thus, programs consisting of the simplest instructions are executed by these processors much faster. The downside of the abbreviated instruction set is that complex operations have to be emulated by a far from efficient sequence of the simplest abbreviated instructions.

As a result of the competition between the two approaches to processor architecture, the following distribution of their areas of application has developed:

• CISC processors are used in universal computing systems;
• RISC processors are used in specialized computing systems or devices focused on performing uniform operations;
• Neuroprocessors - in one cycle of counting, he performs not 4 addition operations, but 288.

In addition, there are two more types of microprocessors:

• VLIW (Very Length Instruction Word) - with an extra large command word;
• MISC (Minimum Instruction Set Command) - with a minimum instruction set and very high performance

TIRES

If the processor is the heart of a personal computer, then the tires are the arteries and veins through which electrical signals flow.

Tires- These are communication channels used to organize interaction between computer devices.

Those connectors where expansion cards are inserted are not buses. it interfaces (slots, connectors), with their help, connections are made to buses, which, often, are not visible at all on motherboards.

There are three main indicators of tire performance. These are the clock frequency, bit depth and data transfer rate.

ISA (Industrial Standard Architecture)

Historic achievement of platform computers IBM PC has become the introduction almost twenty years ago of an architecture that received the status industry standard ISA (Industry Standard Architecture). It not only allowed to connect all the devices of the system unit with each other, but also provided a simple connection of new devices through standard connectors (slots). The bandwidth of a bus made according to this architecture is up to 5.5 MB / s, but, despite the low bandwidth, this bus continues to be used in computers to connect relatively "slow" external devices, such as sound cards and modems.

Rice. 3. ISA connector - 16bit

The 8-bit ISA interface had 8 data channels and 20 address channels. All this made it possible to address up to 1 MB of memory. With the advent of the 80286 processor, which could already process 16 bits of data, a need arose for a 16-bit ISA, which was implemented in 1984. The connector was supplemented with 36 more channels, 8 of which were brought out for data, and 7 for the address. It should be noted that some expansion boards designed for an 8-bit bus can also work with a 16-bit one. By the way, the concept of a key - a protrusion in the connector and a cutout in the plug-in board, appeared along with 16-bit ISA. Since until 1987 IBM refused to publish a full description and timing diagrams of ISA, many hardware manufacturers decided to develop their own buses. This is how 32-bit ISA appeared, which did not find application, but actually predetermined the appearance of MCA and EISA buses. In 1985, Intel developed the 32-bit 80386 processor, which saw the light of day in late 1986. There was an urgent need for a 32-bit I / O bus. Instead of continuing further development of ISA, IBM created a new MCA bus (Micro Channel Architecture - microchannel architecture) that was superior to its predecessor in every respect:

1. The bus arbiter CACP (Central Arbitration Control Point) was used, which allowed any device connected to the bus to transmit data to any other device also connected to this bus. In addition, CACP prevented conflicts and monopolization of the bus by any one device.
2. The MCA bus is not synchronized with the processor, which reduces the possibility of unnecessary conflicts and interference between boards.
3. The absence of switches and jumpers has reduced the installation of expansion cards to a simple action that does not require additional qualifications.

But this standard has not found application, because:

1. IBM required all manufacturers wishing to use MCA to pay money for using ISA in all previously released computers.
2. the computer world was simply not ready to accept the Plug and Play approach in 1987
3. the price of the first MCAs was very high.

All these factors led to the emergence of the EISA bus, everyone forgot about MCA.

EISA (Extended Industry Standard Architecture)

Standard extension ISA became the standard EISA (Extended ISA), characterized by an increased connector and increased performance (up to 32 MB / s). Like isa, this standard is now considered obsolete. After 2000, the release of motherboards with connectors ISA/EISA and devices connected to them is terminated.

With several partner firms, Compaq formed an EISA committee to develop the new standard. Already in 1989, the first personal computers appeared, the motherboards of which were equipped with the EISA bus. Its main difference was in 32-bit technology, although it was created on the basis of the same ISA architecture (the clock frequency remained the same - 8.33 MHz). The advantages of the new technology are obvious: as in MCA, ISP (Integrated System Peripheral) request arbitration is used, the data exchange speed has increased, the power consumed by each of the adapters can reach 45 watts. At the same time, compatibility with boards designed to work with ISA was preserved. The data transfer rate was 33 MB/sec. In addition, computers with the EISA bus had the ability to automatically configure interrupts and adapter addresses. But, unfortunately, this project turned out to be not viable after a short time.

With the increase in clock frequencies and processor capacity, an urgent problem arose in increasing the data transfer rate in buses (what's the point of using a stone with a clock frequency of, say, 66 MHz, if the bus operates at a frequency of only 8.33 MHz). In some cases, such as a keyboard or mouse, high speed is useless. But the engineers at expansion board firms were ready to produce devices at a speed that tires could not provide.

What decision was made? Part of the data exchange operations is carried out not through standard I/O bus connectors, but through additional high-speed interfaces. The fact is that these same high-speed interfaces are connected to the processor bus. It follows from this that plug-in boards will have access directly to the processor through its bus. All this was called LB (Local Bus - local bus). The first ISA buses were just local, but when their clock frequency exceeded 8 MHz, a separation occurred. And in 1992, another extended version of ISA appeared - VLB (VESA Local Bus).

VLB (VESA Local Bus)

The name of the interface translates as local bus of the VESA standard (VESA Local Bus). The concept of "local bus" first appeared in the late 80s. It is due to the fact that when the processors of the third and fourth generations (Intel 80386 and Intel 80486) were introduced, the frequencies of the main bus (the main bus was used ISA/EISA) was not enough for the exchange between the processor and RAM. The local bus, which has an increased frequency, interconnected the processor and memory, bypassing the main bus. Subsequently, an interface for connecting a video adapter, which also requires increased bandwidth, was "embedded" into this bus - this is how the standard appeared vlb, which made it possible to raise the local bus clock speed to 50 MHz and provide a peak throughput of up to 130 MB / s.

The main disadvantage of the interface VLB became that the limiting frequency of the local bus and, accordingly, its bandwidth depend on the number of devices connected to the bus. So, for example, at a frequency of 50 MHz, only one device (video card) can be connected to the bus. For comparison, let's say that at a frequency of 40 MHz, it is possible to connect two, and at a frequency of 33 MHz - three devices.

VLB was a local bus that did not change, but supplemented existing standards. Just a few new high-speed local slots were added to the main buses. The popularity of the VLB tire lasted until 1994. VESA (Video Electronic Standard Association) is an association that proposed a new, already really local, bus (not without the participation of NEC). The VLB data transfer rate was 128 - 132 MB / s, and the bit depth was -32. The clock frequency reached 50 MHz, but actually did not exceed 33 MHz due to the frequency limitations of the slots themselves. Additional VLB connectors have 116 pins. The main function for which the new bus was intended was data exchange with the video adapter. But the new bus had a number of shortcomings that did not allow it to exist for a long time on the information technology market. Well, okay: the farther into the forest, the thicker the partisans. Already in 1992, the development of a new local PCI bus began.

PCI (Peripheral Component Interconnect bus)

Interface PCI (Peripheral Component Interconnect) - external component connection standard) was introduced in personal computers based on Intel Pentium processors. At its core, this is also a local bus interface that connects the processor with RAM, into which connectors for connecting external devices are embedded. To communicate with the main computer bus (ISA/ EISA) special interface converters are used - PCI bridges (PCI Bridge). Bridge functions in modern computers PCI perform chips of a microprocessor set (chipset).

This interface supports a bus frequency of 33 MHz and provides a throughput of 132 MB/s. Latest Versions The interfaces support frequencies up to 66 MHz and provide a throughput of 264 MB/s for 32-bit data and 528 MB/s for 64-bit data.

An important innovation implemented by this standard was the support for the so-called mode plug and play later developed into an industry standard for self-installing devices. Its essence lies in the fact that after the physical connection of an external device to the PC / bus connector, data is exchanged between the device and the motherboard, as a result of which the device automatically receives the number of the interrupt used, the address of the connection port and the number of the direct memory access channel.

Conflicts between devices for possession of the same resources (interrupt numbers, port addresses and direct memory access channels) cause a lot of problems for users when installing devices connected to the bus ISA. With the advent of the interface PC1i with the design of the standard plug and play it became possible to install new devices using automatic software tools - these functions were largely assigned to the operating system.

In June 1992, a new standard appeared on the scene - PCI, whose parent was Intel, or rather the Special Interest Group organized by it. By the beginning of 1993, a modernized version of PCI appeared. In fact, this bus is not a local bus (a local bus is one that is directly connected to the system bus). PCI, on the other hand, uses Host Bridge (main bridge) to connect to it, as well as Peer-to-Peer Bridge (peer-to-peer bridge) which is designed to connect two PCI buses. Among other things, PCI itself is a bridge between ISA and the processor bus. The appearance of the PCI bus in the market of manufacturers of all kinds of devices was a kind of small revolution. The variety of expansion boards using the PCI bus is so great that it is difficult to even list them. The PCI clock speed can be either 33 MHz or 66 MHz. Bit depth - 32 or 64. Data transfer rate - 132 MB / s or 264 MB / s. The PCI standard provides for three types of boards depending on the power supply:

1. 5 Volts - for desktop computers
2. 3.3 Volts - for laptops
3. Universal boards that can work in both types of computers.

The big advantage of the PCI bus is that it satisfies the Plug and Play specification. In addition, in the PCI bus, any signaling occurs in a packet manner, where each packet is divided into phases. A packet begins with an address phase, which is usually followed by one or more data phases. The number of data phases in a packet can be indefinite, but is limited by a timer that determines the maximum time a device can be used by the bus. Each connected device has such a timer, and its value can be set during configuration. An arbitrator is used to organize the work of data transfer. The fact is that there can be two types of devices on the bus - the master (initiator, master, master) of the bus and the slave. The master takes control of the bus and initiates the transfer of data to the destination, i.e. the slave. Any device connected to the bus can be a master or a slave, and this hierarchy is constantly changing depending on which device has requested permission to transfer data from the bus arbiter and to whom. The chipset, or rather North Bridge, is responsible for the conflict-free operation of the PCI bus.

The constant improvement of video cards led to the fact that the physical parameters of the PCI bus were not enough, which led to the emergence of AGP.

AGP (Accelerated Graphics Port - accelerated graphics port)

Video card (video adapter)
During the existence of personal computers, several video adapter standards have changed: (monochrome); CGA (4 colors); EGA (16 colors); VGA(256 colors). Currently used video adapters SVGA, providing optional reproduction of up to 16.7 million colors with the possibility of arbitrary selection of screen resolution from a standard range of values ​​(640x480, 800x600, 1024x768, 1152x864; 1280x1024 pixels and more).

Screen resolution is one of the most important parameters of the video subsystem. The higher it is, the more information can be displayed on the screen, but the smaller the size of each individual dot and, thus, the smaller the visible size of the image elements. Using too high a resolution on a small monitor results in illegible image elements and eye strain when working with documents and programs. Using a lower resolution results in image elements becoming large, but there are very few of them on the screen.

video acceleration- one of the properties of a video adapter, which lies in the fact that part of the imaging operations can occur without performing mathematical calculations in the main computer processor, but purely by hardware - by converting data in microcircuits video accelerator. Video accelerators may be part of the video adapter (in such cases, they say that the video card has hardware acceleration functions), but they can be supplied as a separate board installed on the motherboard and connected to the video adapter.

Video adapter- a device requiring a particularly high data rate. As with local bus implementation vlb, and when implementing a local bus PCI the video adapter has always been the first device to be "cut" into the new bus. Tire parameters today PCI no longer meet the requirements of video adapters, so a separate bus has been developed for them, called AGP (Advanced Graphic Port - advanced graphics port). The frequency of this bus corresponds to the frequency of the bus PCI(33 MHz or 66 MHz), but it has a much higher bandwidth - up to 1066 MB / s (in quadruple mode).

Fig.4. How system memory works (including AGP)

On the motherboard, this port exists in a single form (and there is nothing else). It is neither physically nor logically dependent on PCI. The first AGP 1.0 standard appeared in 1996 thanks to Intel engineers.

This specification met the clock frequency of 66.66 MHz, signaling mode 1x and 2x, and a voltage of 3.3 V. The next version, AGP 2.0, was released in 1998 and had a 4x signaling mode and an operating voltage of 1.5 V Data transfer rate - 533 MB / s (2x) and 1066 MB / s (4x). And what is it - 2x, 4x? The main (basic) mode of AGP is called 1x. In this mode, there is a single data transfer per cycle. In 2x mode, transmission occurs twice per cycle. In 4x mode, data is transmitted four times per cycle. And so on. The width of AGP 1.0 is 32 bits. A great achievement of AGP is that this specification allows you to get fast access to RAM, as it is local.

PCMCIA

(Personal Computer Metolu Card International Association - the standard of the international association of manufacturers of memory cards for personal computers)

This standard defines the interface for connecting small flat memory cards and is used in portable personal computers.

FSB - (front side bus)

Tire PCI, which appeared in computers based on Intel Pentium processors as a local bus designed to connect the processor with RAM, did not remain in this capacity for long. Today it is used only as a bus for connecting external devices, and for connecting the processor and memory, starting from Intel processor Pentium Pro uses a special bus that has received the name of the front side bus (FSB). This bus operates at a very high frequency of 100-125 MHz. Currently, motherboards with a bus frequency of FSB 133 MHz and boards with frequencies up to 200 MHz are being developed. Bus frequency FSB is one of the main consumer parameters - it is he who is indicated in the specification of the motherboard. Bus bandwidth FSB at a frequency of 100 MHz is about 800 MB / s.

USB - (Universal Serial Bus - universal serial bus)

This standard defines the way a computer interacts with peripheral equipment. It allows you to connect up to 256 different devices with a serial interface. Devices can be switched on in chains (each next device is connected to the previous one). Tire performance USB relatively small and up to 1.5 Mbps, but for devices such as keyboard, mouse, modem, joystick, etc., this is enough. The convenience of the bus is that it virtually eliminates conflicts between different equipment, allows you to connect and disconnect devices in "hot mode" (without turning off the computer) and allows you to combine several computers into a simple local network without the use of special equipment and software.

Sound card

The sound card was one of the most recent improvements in the personal computer. It connects to one of the motherboard slots in the form of a daughter card and performs computational operations related to the processing of sound, speech, and music. The sound is played through external speakers connected to the output of the sound card. A special connector allows you to send an audio signal to an external amplifier. There is also a microphone jack that allows you to record speech or music and store it on your hard drive for later processing and use.

Ports

Ports- these are connectors on the back panel of the computer system unit, which are used to connect peripheral devices such as a monitor, keyboard, mouse, printer, scanner, etc. to the computer.

Parallel port

Parallel port - this is a high-speed port through which the signal is transmitted in two directions along 8 parallel lines.

The parallel port was developed in 1981 and was used in the first personal computers. Then he was called normal.

The data transfer rate through the parallel port is from 800 Kbps to 16 Mbps.

In the diagrams, parallel ports are labeled LP1, LP2, and so on. (LP - Line Printer).

Parallel ports connect printers, streamers, and other devices that require high data transfer rates to your computer. Parallel ports are also used to connect two computers to each other.

Serial port

Serial port (Serial port or COM-port: Communications port) - it is a port through which data is transferred in only one direction at a time.

Data is transmitted sequentially in series, first in one direction, then in the other direction.

Devices that do not require high data transfer rates are connected through serial ports - mice, keyboards, modems.

Transfer rate via serial port- 115 Kbps

In the diagrams, parallel ports are labeled COM1, COM2, and so on.

USB port

USB (Universal Serial Bus) - universal serial port. This is a port that allows you to connect almost any peripheral device.

Currently, manufacturers of peripheral devices produce them in two versions - with the usual ports for these devices (different for different devices) and USB. There are mice and keyboards for the USB port.

An important feature of USB ports is that they support technology plug and play, i.e. when you connect a device, you do not need to install a driver for it, in addition, USB ports support the ability to "hot plug"- connections while the computer is running.

The USB port was developed in 1998. Back then it was just called USB. After a faster port was developed, the existing one was called USB 1.1, and the new one was called USB 2.

The development of high-speed technology and, accordingly, the USB 2 port began at the initiative of by Intel. In addition to Intel, other companies, including Microsoft, participated in the development. The USB 2 specification was adopted in April 2000.

Data transfer rate via USB 1.1 port - 12 Mbps. For mice and keyboard - 1.5 Mbps.

Data transfer rate via USB 2 port - 480 Mbps.

PS/2 port

PS/2 ports - These are parallel ports for the mouse and keyboard.

The PS / 2 port was developed by IBM in 1987 and originally these ports appeared on IBM computers. These ports and port connectors were significantly smaller than existing AT/MIDI ports and connectors, so other manufacturers began to use PS/2 ports in their computers.

PS / 2 ports are 5-pin and 6-pin, but for the user they are identical.

AT/MIDI port

AT/MIDI port (Musical Instrument Digital Interface - connection with digital musical instruments) - these are the ports through which keyboards were originally (pre-PS / 2) connected, and at present, musical keyboards and synthesizers are mainly connected.

Firewire port

firewire- literally - fire wire (pronounced "fire wire") is a serial port that supports a data transfer rate of 400 Mbps.

This port is used to connect video devices to the computer, such as a VCR, as well as other devices that require fast transfer of large amounts of information, such as external hard drives.

The FireWire ports are Plug and Play and hot pluggable.

FireWire ports come in two types. Most desktop computers use 6-pin ports, while laptops use 4-pin ports.

6-pin FireWire port	4-pin FireWire port

Controllers

Electronic circuits that control various devices in a computer are called controllers. All IBM PCs have controllers to control the keyboard, monitor, floppy disk drives, hard drive, and so on.

Power Supply

The computer power supply is a metal box that is located inside the system unit close to its rear panel.

The rear panel has a connector for the power cable, a switch, holes for the power supply fan.

Some power supplies have an additional connector for connecting the monitor's power cable. This connector is used when there are no free electrical outlets. Using a special cable, you can connect the monitor's power through the computer's power supply. In this case, the power of the computer's power supply is not consumed, because. this auxiliary connector is simply connected in parallel with the main connector, and when the main connector is connected to the power cable and plugged into an electrical outlet, the auxiliary connector itself becomes a socket.
The power supply contains a transformer, a rectifier and a cooling fan. Inside the computer, several sets of wires come out of the power supply to connect the system board, hard drive, and disk drives to the electrical power supply. To connect additional devices, such as an additional optical drive, streamer, free sets of wires are provided in the power supply.

an example from the "life" of computers

Seiko Epson announced the expansion of its mobile graphics engine lineup with the S1D13732, an LCD controller for mobile phones, PDAs and mobile information terminals equipped with a one-megapixel camera. Samples of the chip in a 161-pin FCBGA package (8x8x1 mm) will be offered to customers in the near future.

The S1D13732 differs from previous models, in particular the S1D13715 currently commercially available, in a higher graphics processing speed. The LCD controller provides hardware support for MPEG-4 as well as H.263 (a video compression standard for Europe). Among other things, the LCD screen controller allows you to reduce power consumption cell phones, and the block responsible for graphics provides the ability to record and play video without specialized software, and, therefore, equip devices with a low-power CPU.

S1D13732 is equipped with 448 KB of built-in memory, camera interface (supported cameras are up to 1.3 million pixels), dual LCD screen interface with a maximum resolution of 240x320 pixels.