This book is devoted to the consideration of hardware - as people call the material component of computers (or Hardware - hardware), in contrast to the software part of the functioning of computers (or Software - software). The standard configuration of a home personal computer is shown in the figure below.
What does the hardware of a personal computer consist of? First of all, from the system unit, inside of which there are internal devices And external devices, connected to the system unit using information cables or establishing communication with it via wireless information channels (using infrared radiation, radio waves, etc.).
TO external devices These include those located outside the system unit. These include: keyboard, mouse, display, and there may be other devices: printer, external modem, scanner and other devices.
TO internal devices include the system board (popularly called the motherboard or simply “mother”), central processor, RAM, power supply, hard drive, previously installed floppy drive, CD-ROM drive and (or) DVD drive, sound board, video card, speaker, as well as some other additional devices inserted into the so-called expansion slots - network cards, television cards, etc. The figure below shows the standard arrangement of internal devices in the system unit.
The motherboard, processor, RAM, video card, sound card, expansion cards, hard drive and speaker are located inside the system unit, not visible to the user, or rather, do not have access to the front panel of the system unit.
Internal devices.
Computer case used to install basic devices in it, protect them from dust and other external influences, and also to some extent protect the user from electromagnetic radiation from the components that are located in it. The front panel contains indicators and buttons; some internal devices (floppy drives, DVD-RW drives) also face it.
power unit designed to convert alternating electric current of 220 volts into direct current of lower voltage and power it to devices located inside the system unit. As a rule, this unit is supplied with the system unit, but it can also be purchased separately. The system unit has connectors on the rear side for connecting to a power source (electrical outlet or surge protector), in some models - a connector for connecting power to a 220 volt monitor (if the monitor has a cathode ray tube) and a switch for different input voltages - 110 or 220 volt. Inside the system case there are wires that come out of the power supply and connect to internal devices.
Motherboard serves to interconnect information flows between various computer components. It contains a central processor, RAM, a Bios chip, in some cases, its own fan for cooling the central processor, as well as various connectors (for connecting fans external to the board, connecting serial and parallel ports, expansion cards, and so on). In addition, recently they began to install built-in network, sound and video subsystems on the motherboard, as well as their own speaker - a tweeter.
CPU. The processor, which can be called the brain of the computer, performs basic operations. Processors can be: 86, 286, 386, 486 (x86 series), Pentium, Pentium MMX, Pentium Pro, Pentium II, Pentium III, Pentium IV, Atom, Pentium Dual 2 Core, Pentium i 3, Pentium i 5, Pentium i 7 - manufactured by Intel, as well as other companies, for example, AMD - Athlon XP, Athlon 64, etc. The difference between them is performance. The higher the processor clock frequency, the higher the performance of your computer (although not always, for example, performance is affected by the size of the cache memory of the first and second levels, as well as the information processing structure, for example, Hyper-Threading second processor emulation technology). Performance is also affected by the presence of cores; A dual or triple core processor is much faster than a single core processor.
The clock speed determines how many operations per second the processor can perform. For earlier types of processors (for example, 286), one instruction was executed in several clock cycles. In modern ones, several operations are performed in one clock cycle.
RAM. After turning on the computer, data from the hard drive is transferred to RAM, and the processor works with it. If this type of memory did not exist, the processor would work only with the hard drive and each data would have to be written to and read from it. In this case, the speed of operation would decrease sharply, since the system would be waiting for I/O operations. Having RAM that operates at a speed close to the processing speed of the processor improves computer performance. The larger the memory size, the fewer disk accesses, the faster the computer will run.
The main characteristic of memory is its size, which is measured in gigabytes. Can be set to 0.5, 1, 2, 3, 4, etc. gigabytes in the system. It is often cheaper to increase the size of RAM to improve performance than to upgrade the processor to a higher frequency.
In order to speed up calculations and not wait until data comes from RAM or data needs to be written to it, the processor has a more powerful cache memory, which differs in volume. Having a cache memory can significantly increase your computer's performance.
The system unit also contains speaker, which is usually supplied with the case. The main function of the speaker is to produce sound signals after turning on the computer and in case of malfunction. As a rule, it is used quite rarely in other cases. A sound card is designed to work with sound.
Sound card. This board processes audio data that comes from RAM. Data can also come from a DVD-ROM drive when playing music. After processing, the data is sent to speakers, a tape recorder or other devices.
Video card processes data for the display (monitor). For programs that work with two-dimensional or three-dimensional images, processing video data for the display can be taken over by a special processor located on the video card, which will relieve the load on the main processor. This usually improves image quality dramatically.
One of the main characteristics is the size of the board's video memory. It can have 1, 2, 4, 8…. 64, 128, 256,512,1024 or more megabytes (usually 0.5 - 1 Gigabyte). The more memory, the faster the data processing.
HDD. Data in a computer is stored on the hard drive. When the power is turned off, the information on the hard disk is retained. One of the main parameters is the disk capacity, which is measured in gigabytes (One gigabyte is equal to approximately one billion bytes. A byte stores one character). The disk can have a capacity from 8 gigabytes to 4 terabytes (1 terabyte is equal to 1024 gigabytes). Older drives have capacities measured in megabytes (one megabyte is equal to approximately one million bytes).
Now let's look at the devices facing the front surface of the system unit (see figure below).
Floppy disk drives. On the front panel of the computer case, as a rule on outdated computers, the front side faces a device for working with 3.5-inch floppy disks (picture on the right). 5 1/4-inch floppy disks have long been out of use and will not be considered by us practically, although many of the principles of their operation are the same as for 3.5-inch ones. Note that modern computers have long abandoned the use of 3.5-inch drives due to the insignificant amount of recorded information.
A 3.5-inch floppy disk (hereinafter simply floppy disk, floppy disk) has the appearance shown in the figure above. Data written by the user on a floppy disk can be moved from one computer to another, since almost any computer previously had the same device for reading floppy disks.
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A schematic view of the drive is shown in the figure above. Taking the floppy disk, insert it into the floppy disk hole as far as it will go so that the metal plate is in front and the arrow on the floppy disk body is on top and its point is directed into the device. After this, the protective cover of the reader will return to its original place. To remove the floppy disk, you need to press the button located on the front panel of the drive. In this case, the floppy disk will come out of the device approximately 1/3 of its length, after which it can be removed by hand.
In the picture, the left corner of the floppy disk is beveled. This is done so that the system can determine which side the floppy disk is inserted into. If you try to insert the floppy disk backwards, the floppy disk will not be inserted into the device. In this case, you do not need to use force, but turn the floppy disk over.
There are two windows on the floppy disk. There is a switch on the right window on the back side. If the switch closes the window, then information can be written to and read from the floppy disk. If the latch is open, then the data can only be read. Typically, the switch is used so that when storing important data, other information is not accidentally written to it, which will lead to its destruction, or as protection against viruses.
The figure above shows the front panel of the floppy drive. The button is used, as already indicated, to remove the floppy disk. The indicator lights when the diskette is undergoing I/O operations, that is, data is being written to or read from the diskette.
Storage forCD (DVD) - disks Works with CDs, DVDs of various types. The appearance of these discs, also called CDs, is the same and is shown in the figure to the right. CD-ROM (DVD-ROM) discs are manufactured industrially and additional information cannot be recorded on them. CD-R (DVD-R, DVD +R) discs allow you to write information on them, but only once, although you can add additional information if there is free space on the disk. CD-RW (DVD-RW, DVD +RW) discs allow you not only to write information on them, but also to erase the previous one, which allows you to use them repeatedly.
Once the disc has been placed in the tray, press the tray eject button again and the tray will slide into the unit. CD (DVD) - discs are usually found in a box or paper bag. Open the box. To remove a disc, move your index finger to the center of the disc and remove it with your thumb and middle finger, then place it on the tray with the work surface facing down, respectively, the name will be at the top. In order to insert a CD (DVD) disc, you need to press the button on the front panel of the drive while the computer is running (see figure above). This will automatically extend the tray onto which you can place the disc. The tray has two recesses because there are two disc formats. One of them, a smaller one, is rarely used, although it is sometimes shown in science fiction films. Discs of this format are inserted into a smaller recess. The second type of disk, the most common, is placed in a large recess, with the working surface down, and the drawn image on top. Once the disc has been placed in the tray, press the tray eject button again and the tray will slide into the unit.
Sometimes when you press the button, the tray stays in place. In order to pull out the tray, you can use the hole to force the tray to open. To do this, straighten the paper clip, insert its end into this hole and press slightly. The tray will come out of the stacker.
On the back of the disc is its name or other information. The opposite side is the working side and should not be touched with hands. When cleaning CD (DVD) discs from dust, gently rub a cloth perpendicular to the recording tracks from the inner hole to the outer edge.
CD (DVD) discs come in two types. The first is discs with recording of text, graphic and other information, usually with programs or text. The second type is music discs used in laser audio players and they can also be used for playback on a CD (DVD) disc reader (hereinafter referred to as CD devices) on a computer. The sound can be listened to through headphones or speakers. The headphone plug is inserted into a special hole on the front surface of the drive. To increase/decrease the volume of the headphones, use the regulator, which is located near the hole for the plug. The indicator light works when reading information from the disk. Since the reading occurs intermittently, the indicator may flash.
The appearance of DVD drives is similar to a drive for reading CD-ROM discs. The front panel of the CD-RW drive is shown in the figure above.
Buttons on the system unit. In addition to the above devices, on the front panel of the system unit, as a rule, there are Reset and Power keys, as shown in the figure above; on outdated units there may be a Turbo key, a key lock and an indicator. Recently, there has been a transition to the ATX standard, which lacks a key lock, a Turbo button and a system frequency indicator. Thus, on a modern system (and all-in-one), as a rule, there is only a power button and, often, an indicator of the operation of the hard drives.
Power button designed to turn on the computer. When it is pressed, electric current is supplied to the main components inside the system unit, they are tested and then the operating system programs are loaded, depending on which one is installed on the computer: UNIX or Windows 9x. In older computers, this button was located on the back wall of the system case, then on the side, but for ten years now it has been installed on the front panel. Near the switch there is usually an inscription like Power or On and Off. In order to turn off the computer, usually when exiting the operating system, by clicking on the button Shutdown from the Start panel, the computer automatically turns off. However, in some cases, for example, when the system freezes, you need to force the computer to shut down. To do this, press the Power button and hold it down for a few seconds.
Reset button(in older computers) serves to restart the computer. When you press it, the operating system restarts, just like when you turn on the computer at the very beginning.
In what cases is this button used? System crashes occur from time to time. The more complex and undebugged the program, the more errors it contains. Over time, with the release of more modern and, accordingly, more debugged versions, the number of errors decreases, but it is impossible to completely get rid of them due to the complexity of the programs. There are even standards that define the number of errors in large systems.
They say that the computer is “frozen” when the system does not respond to pressing keys on the keyboard, or the program begins to display strange symbols on the screen, or when pressing one key, an action occurs similar to pressing another. In this case, it is advisable to restart the computer. However, if you turn off the computer's power and then press the Power key, thus turning on the computer, then all systems experience a kind of shock. With a large number of switches on and off, the probability of microcircuit failure increases (the same principle as when turning on a light bulb). For these cases, a Reset key is provided, which allows you to restart the computer without turning off the electrical current.
If you nevertheless decide to turn off and turn on the computer using the Power key, then wait 40-50 seconds between turning off and turning on. This way you will extend the life of your system. In addition to errors in software, computer freezes can occur due to the actions of virus programs. In this case, it is advisable to reboot from the system floppy disk.
Not all system units have a Reset button. In some blocks, the Reset button may be located inside the Power button (its fixed part) or near it.
Turbo key currently practically used. If you have it, then it is best to turn it on (that is, a larger number or the word High will appear on the indicator) and not touch it again. This key appeared in computers when, with the advent of faster processors, there was a need to reduce power so that older programs could run. Nowadays, programs themselves determine the performance of the computer and can slow down the computer (this is mainly used in game programs), so the Turbo key is not used.
Indicators. As a rule, there are four types of them on a computer.
Frequency indicator(in old computers) the operation of the processor is shown on the display by the numerical value of the frequency. These values can be numeric or text. There are usually two numerical values, the first is the clock frequency of your processor, the second is the reduced frequency of its operation. There are also two text values: High (increased) and Low (low), which means the processor operates at normal (High) or low (Low) frequency. If your computer has been modified or was purchased from a company where the computer was assembled there, then the indicator may show a different value than what the processor actually operates. In order to determine the processor operating frequency, it is better to use test programs. When working with a computer, the indicator is now practically not used. On modern computers this indicator is not used.
Hard disk access indicator lights up when I/O operations are performed on the hard drive. There may be an icon next to it 
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Power-on indicator lights up when the computer is turned on. Next to the indicator is the name Power or the icon.
Turbo indicator(in older computers) lights up in Turbo mode, that is, increased power or that for which the central processor is designed. Next to it is the Turbo inscription or icon 
. It is practically not used when working in modern computers.
Additionally, on the front panel or on the side of it there may be USB connectors and audio input and output.
External devices .
In addition to the system unit, the personal computer includes display(also called monitor), which displays text and graphic information. Outwardly, it resembles a TV, as can be seen from the picture earlier. There are two types of monitors: color and monochrome (black and white, almost no longer used). The main characteristics are frequency displaying lines on the screen (the larger it is, the better for the eyes), permission, which can be 480x640, 600x800, 768x1024, etc. (the larger this value, the better), screen diagonal size in inches(maybe 14, 15, 17, 19 and others).
The next component is keyboard(figure below), with which you enter text information and control the computer using function keys. In fact, it is very similar to a typewriter, but it has additional keys and, in addition, allows you to work with different character sets, for example, with the Cyrillic (Russian) and Latin (English) characters.
Next to the keyboard there is a device like mouse, which allows you to control the cursor (picture on the right). It has become a standard pointing device, is used in almost all computers and actually looks like a mouse - small, with a long tail, that is, a cable that connects to the system unit. Hereinafter, for convenience, we will simply call this device a mouse or mouse.
At the bottom of the device there is a ball (or LED device) that allows you to move the cursor on the display screen when you move the mouse across the mousepad. You can try to work without a mat, but since the adhesion between the mat and the mouse ball is higher than on the table surface, it is better to have a mat, especially since it is inexpensive. The mouse has two or three buttons, but in practical work two of them are used: left and right. In the latest mouse models, instead of the third button, there is a wheel that allows you to “scroll” the text displayed on the screen.
Computers often have a device for outputting information onto paper, called printer. The main characteristics of the printer are its type (needle, inkjet, laser), the size of the paper it works with (A4, A3, etc.), the ability to output images in color, the output speed of printed sheets, etc.
A computer that can handle sound has speakers to reproduce audio information. As a rule, there are two of them to provide stereo sound. Speakers can be built into the display.
In addition, other external devices can be additionally included in the personal computer package - scanner (picture below) , plotter, joystick, external hard disk etc. However, the specified equipment is basic, sufficient to run standard sets of programs called in packages such as Microsoft Office and solving some applied problems, in particular, Multimedia– work with sound and image.
A computer has means for input, output, information processing and a device that controls the operation of computer components. To standard devices input information include keyboard, with which characters are entered and commands are given for the operation of the computer, mouse, scanner, microphone, digital camcorder And camera and others. To standard devices output information include display, on the screen of which visual information is displayed, Printer, sound speakers etc.
There are also I/O devices that not only introduce information, but And take her out: floppy drives , drives on CD And DVD - disks , hard disks , tape recorders (or more correctly - streamers ), modems etc.
A personal computer is a universal technical system.
Its configuration (equipment composition) can be flexibly changed as needed.
However, there is a concept of a basic configuration that is considered typical. The computer usually comes with this kit.
The concept of a basic configuration may vary.
Currently, four devices are considered in the basic configuration:
- system unit;
- monitor;
- keyboard;
- mouse.
In addition to computers with a basic configuration, multimedia computers equipped with a CD reader, speakers and a microphone are becoming increasingly common.
Reference: "Yulmart", by far the best and most convenient online store where for free You will be advised when purchasing a computer of any configuration.
The system unit is the main unit within which the most important components are installed.
Devices located inside the system unit are called internal, and devices connected to it from the outside are called external.
External additional devices designed for input, output and long-term storage of data are also called peripherals.
How the system unit works
In appearance, system units differ in the shape of the case.
Personal computer cases are produced in horizontal (desktop) and vertical (tower) versions.
Vertical housings are distinguished by dimensions:
- full-size (big tower);
- mid-size (midi tower);
- small-sized (mini tower).
Among the cases that have a horizontal design, there are flat and especially flat (slim).
The choice of one or another type of case is determined by the taste and needs of upgrading the computer.
The most optimal type of case for most users is a mini tower case.
It has small dimensions and can be conveniently placed both on your desktop, on a bedside table near your desktop, or on a special holder.
It has enough space to accommodate five to seven expansion cards.
In addition to the shape, a parameter called form factor is important for the case. The requirements for the devices to be placed depend on it.
Currently, cases of two form factors are mainly used: AT and ATX.
The form factor of the case must 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 case parameters.
For mass models, a power supply of 200-250 W is sufficient.
The system unit includes (can accommodate):
- Motherboard
- ROM chip and BIOS system
- Non-volatile CMOS memory
- HDD
Motherboard
Motherboard (mother board) - the main board of a personal computer, which is a sheet of fiberglass covered with copper foil.
By etching the foil, thin copper conductors connecting electronic components are obtained.
The motherboard contains:
- processor - the main chip that performs most mathematical and logical operations;
- buses - sets of conductors through which signals are exchanged between the internal devices of the computer;
- random access memory (random access memory, RAM) - a set of chips designed to temporarily store data when the computer is turned on;
- ROM (read only memory) is a chip designed for long-term storage of data, including when the computer is turned off;
- microprocessor kit (chipset) - a set of chips that control the operation of the internal devices of the computer and determine the basic functionality of the motherboard;
- connectors for connecting additional devices (slots).
(microprocessor, central processing unit, CPU) - the main computer chip in which all calculations are performed.
It is a large chip that can be easily found on the motherboard.
The processor has a large copper finned heatsink cooled by a fan.
Structurally, the processor consists of cells in which 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 placed in some registers is not considered as data, but as instructions that control the processing of data in other registers.
Among the processor registers there are those that, depending on their content, are capable of modifying the execution of commands. Thus, by controlling the sending of data to different registers of the processor, you can control the processing of data.
This is what program execution is based on.
The processor is connected to the rest of the computer devices, and primarily to the RAM, by several groups of conductors called buses.
There are three main buses: data bus, address bus and command bus.
Address bus
Intel Pentium processors (namely, they are the most common in personal computers) have a 32-bit address bus, that is, it consists of 32 parallel lines. Depending on whether there is voltage on any of the lines or not, they say that this line is set to one or zero. The combination of 32 zeros and ones forms a 32-bit address pointing to one of the RAM cells. The processor is connected to it to copy data from the cell into one of its registers.
Data bus
This bus copies data from RAM to processor registers and back. In computers built on Intel Pentium processors, the data bus is 64-bit, that is, it consists of 64 lines, along which 8 bytes are received at a time for processing.
Command bus
In order for the processor to process data, it needs instructions. It must know what to do with the bytes stored in its registers. These commands also come to the processor from RAM, but not from those areas where data arrays are stored, but from where programs are stored. Commands are also represented in bytes. The simplest commands fit into one byte, but there are also those that require two, three or more bytes. Most modern processors have a 32-bit instruction bus (for example, the Intel Pentium processor), although there are 64-bit processors and even 128-bit processors.
During operation, the processor services data located in its registers, in the RAM field, as well as data located in the external ports of the processor.
It interprets some of the data directly as data, some of the data as address data, and some as commands.
The set of all possible instructions that a processor can execute on data forms the so-called processor instruction system.
The main parameters of processors are:
- operating voltage
- bit depth
- operating clock frequency
- internal clock multiplier
- cache size
The operating voltage of the processor is provided by the motherboard, so different brands of processors correspond to different motherboards (they must be selected together). As processor technology develops, the operating voltage gradually decreases.
The processor capacity shows how many bits of data it can receive and process in its registers at a time (in one clock cycle).
The processor is based on the same clock principle as in a regular watch. The execution of each command takes a certain number of clock cycles.
In a wall clock, the oscillation cycles are set by a pendulum; in manual mechanical watches they are set by a spring pendulum; For this purpose, electronic watches have an oscillatory circuit that sets the clock cycles at a strictly defined frequency.
In a personal computer, clock pulses are set by one of the microcircuits included in the microprocessor kit (chipset) located on the motherboard.
The higher the clock frequency arriving at the processor, the more commands it can execute per unit time, the higher its performance.
Data exchange within the processor occurs several times faster than exchange with other devices, such as RAM.
In order to reduce the number of accesses to RAM, a buffer area is created inside the processor - the so-called cache memory. This is like “super-RAM”.
When the processor needs data, it first accesses cache memory, and only if the necessary data is not there does it access RAM.
Receiving a block of data from RAM, the processor simultaneously enters it into cache memory.
Successful accesses to cache memory are called cache hits.
The larger the cache size, the higher the hit rate, which is why high-performance processors come with a larger cache size.
Cache memory is often distributed across several levels.
The first level cache runs on the same chip as the processor itself and has a volume of the order of tens of kilobytes.
The L2 cache is either on the processor die or on the same node as the processor, although executed on a separate die.
The first and second level caches operate at a frequency consistent with the frequency of the processor core.
Third-level cache memory is performed on high-speed SRAM-type chips and is placed on the motherboard near the processor. Its volume can reach several MB, but it operates at the frequency of the motherboard.
Motherboard bus interfaces
The connection between all native and connected devices of the motherboard is performed by its buses and logical devices located in the microprocessor chipset (chipset).
The performance of a computer largely depends on the architecture of these elements.
Bus interfaces
ISA(Industry Standard Architecture) is an outdated system bus of IBM PC-compatible computers.
EISA(Extended Industry Standard Architecture) - Extension of the ISA standard. It features a larger connector and increased performance (up to 32 MB/s). Like ISA, this standard is now considered obsolete.
PCI(Peripheral Component Interconnect - literally: interconnection of peripheral components) - an input/output bus for connecting peripheral devices to the computer motherboard.
AGP(Accelerated Graphics Port - accelerated graphics port) - developed in 1997 by Intel, a specialized 32-bit system bus for a video card. The main goal of the developers was to increase performance and reduce the cost of the video card by reducing the amount of built-in video memory.
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 connected in chains (each subsequent device is connected to the previous one). The performance of the USB bus is relatively low and amounts to up to 1.5 Mbit/s, but for devices such as a keyboard, mouse, modem, joystick, and the like, this is enough. The convenience of the bus is that it practically eliminates conflicts between different equipment, allows you to connect and disconnect devices in “hot mode” (without turning off the computer) and allows you to connect several computers into a simple local network without the use of special equipment and software.
The parameters of the microprocessor kit (chipset) to the greatest extent determine the properties and functions of the motherboard.
Currently, most motherboard chipsets are produced on the basis of two chips, called “north bridge” and “south bridge”.
The North Bridge controls the interconnection of four devices: processor, RAM, AGP port and PCI bus. Therefore, it is also called a four-port controller.
"South Bridge" is also called a functional controller. It performs the functions of a hard and floppy disk controller, ISA - PCI bridge functions, keyboard controller, mouse controller, USB bus, etc.
(RAM - Random Access Memory) is an array of crystalline cells capable of storing data.
There are many different types of RAM, but from the point of view of the physical principle of operation, they distinguish between dynamic memory (DRAM) and static memory (SRAM).
Dynamic memory (DRAM) cells can be thought of as microcapacitors capable of storing charge on their plates.
This is the most common and economically available type of memory.
The disadvantages of this type are associated, firstly, with the fact that both when charging and discharging capacitors, transient processes are inevitable, that is, data recording occurs relatively slowly.
The second important drawback is related to the fact that cell charges tend to dissipate in space, and very quickly.
If the RAM is not constantly “recharged,” data loss occurs within a few hundredths of a second.
To combat this phenomenon, the computer undergoes constant regeneration (refreshing, recharging) of RAM cells.
Regeneration occurs several tens of times per second and causes wasteful consumption of computing system resources.
Static memory cells (SRAM) can be thought of as electronic microelements - flip-flops consisting of several transistors.
The trigger stores not the charge, but the state (on/off), so this type of memory provides higher performance, although it is technologically more complex and, accordingly, more expensive.
Dynamic memory chips are used as the main RAM of a computer.
Static memory chips are used as auxiliary memory (the so-called cache memory), designed to optimize the operation of the processor.
Each memory cell has its own address, which is expressed as a number.
One addressable cell contains eight binary cells in which 8 bits, that is, one byte of data, can be stored.
Thus, the address of any memory cell can be expressed in four bytes.
RAM in a computer is located on standard panels called modules.
RAM modules are inserted into the corresponding slots on the motherboard.
Structurally, memory modules have two designs - single-row (SIMM modules) and double-row (DIMM modules).
The main characteristics of RAM modules are memory capacity and access time.
Access time shows how much time is needed to access memory cells - the shorter it is, the better. Access time is measured in billionths of a second (nanoseconds, ns).
ROM chip and BIOS system
When the computer is turned on, there is nothing in its RAM - neither data nor programs, since RAM cannot store anything without recharging the cells for more than hundredths of a second, but the processor needs commands, including at the first moment after turning it on.
Therefore, immediately after switching on, the start address is set on the processor address bus.
This happens in hardware, without the participation of programs (always the same).
The processor addresses the set address for its first command and then begins to work according to the programs.
This source address cannot point to RAM, which does not yet have anything in it.
It refers to another type of memory, read-only memory (ROM).
The ROM chip is capable of storing information for a long time, even when the computer is turned off.
Programs located in ROM are called “hardwired” - they are written there at the stage of manufacturing the microcircuit.
A set of programs located in ROM forms the basic input/output system (BIOS - Basic Input Output System).
The main purpose of the programs in this package is to check the composition and functionality of the computer system and ensure interaction with the keyboard, monitor, hard drive and floppy drive.
The programs included in the BIOS allow us to observe diagnostic messages on the screen that accompany the startup of the computer, as well as interfere with the startup process using the keyboard.
Non-volatile CMOS memory
The operation of standard devices such as a keyboard can be supported by programs included in the BIOS, but such tools cannot provide operation with all possible devices.
For example, BIOS manufacturers know absolutely nothing about the parameters of our hard and floppy disks; they know neither the composition nor the properties of any computer system.
To get started with other hardware, the programs included with the BIOS must know where to find the settings they need.
For obvious reasons, they cannot be stored in either RAM or ROM.
Especially for this purpose, the motherboard has a “non-volatile memory” chip, called CMOS according to its manufacturing technology.
It differs from RAM in that its contents are not erased when the computer is turned off, and it differs from ROM in that data can be entered and changed into it independently, in accordance with what equipment is included in the system.
This chip is constantly powered by a small battery located on the motherboard.
The charge of this battery is enough to ensure that the microcircuit does not lose data, even if the computer is not turned on for several years.
The CMOS chip stores data about floppy and hard drives, the processor, and some other devices on the motherboard.
The fact that the computer clearly tracks time and calendar (even when turned off) is also due to the fact that the system clock is constantly stored (and changed) in CMOS.
Thus, programs written in the BIOS read data about the composition of the computer's hardware from the CMOS chip, after which they can access the hard disk, and, if necessary, the flexible disk, and transfer control to the programs that are recorded there.
HDD
HDD- the main device for long-term storage of large amounts of data and programs.
In fact, this is not one disk, but a group of coaxial disks that have a magnetic coating and rotate at high speed.
Thus, this “disk” does not have two surfaces, as a regular flat disk would have, but 2n surfaces, where n is the number of individual disks in the group.
Above each surface is a head designed for reading and writing data.
At high disk rotation speeds (90 rps), an aerodynamic cushion is formed in the gap between the head and the surface, and the head floats above the magnetic surface at a height of several thousandths of a millimeter.
When the current flowing through the head changes, the intensity of the dynamic magnetic field in the gap changes, which causes changes in the stationary magnetic field of the ferromagnetic particles that form the coating of the disk. This is how data is written to the magnetic disk.
The reading operation occurs in reverse order.
Magnetized coating particles flying at high speed near the head induce a self-induction emf in it.
The electromagnetic signals generated in this case are amplified and transmitted for processing.
The operation of the hard drive is controlled by a special hardware-logical device - the hard drive controller.
Currently, the functions of disk controllers are performed by microcircuits included in the microprocessor kit (chipset), although some types of high-performance hard disk controllers are still supplied on a separate board.
The main parameters of hard drives include capacity and performance.
It can be stored on your hard drive for years, but sometimes you need to transfer it from one computer to another.
Despite its name, a hard drive is a very fragile device, sensitive to overloads, shocks and shocks.
Theoretically, it is possible to transfer information from one workplace to another by moving a hard drive, and in some cases this is done, but still this technique is considered low-tech, since it requires special care and certain qualifications.
To quickly transfer small amounts of information, so-called flexible magnetic disks (floppy disks) are used, which are inserted into a special storage device - a floppy drive.
The drive's receiving hole is located on the front panel of the system unit.
Since 1984, 5.25-inch high-density (1.2 MB) floppy disks have been produced.
Today, 5.25-inch drives are not used, and 5.25-inch drives are not included in the basic configuration of personal computers after 1994.
3.5-inch floppy disks have been produced since 1980.
Nowadays, 3.5-inch high-density disks are considered standard. They have a capacity of 1440 KB (1.4 MB) and are marked with the letters HD (high density).
On the bottom side, the floppy disk has a central sleeve, which is captured by the drive spindle and rotated.
The magnetic surface is covered with a sliding curtain to protect it from moisture, dirt and dust.
If a floppy disk contains valuable data, you can protect it from being erased or overwritten by sliding the security flap to create an open hole.
Floppy disks are considered unreliable storage media.
Dust, dirt, moisture, temperature changes and external electromagnetic fields very often cause partial or complete loss of data stored on a floppy disk.
Therefore, using floppy disks as the main means of storing information is unacceptable.
They are used only for transporting information or as an additional (backup) storage device.
CD-ROM drive
The abbreviation CD-ROM (Compact Disc Read-Only Memory) is translated into Russian as a permanent storage device based on a compact disc.
The operating principle of this device is to read numerical data using a laser beam reflected from the surface of the disk.
Digital recording on a CD differs from recording on magnetic disks in its very high density, and a standard CD can store approximately 650 MB of data.
Large amounts of data are typical for multimedia information (graphics, music, video), so CD-ROM drives are classified as multimedia hardware.
Software products distributed on laser discs are called multimedia publications.
Today, multimedia publications are gaining an increasingly stronger place among other traditional types of publications.
For example, there are books, albums, encyclopedias and even periodicals (electronic magazines) published on CD-ROM.
The main disadvantage of standard CD-ROM drives is the inability to write data, but in parallel with them there are both CD-R (Compact Disk Recorder) write-once devices and CD-RW write-once devices.
The main parameter of CD-ROM drives is the data reading speed.
Currently, the most common devices are CD-ROM readers with a performance of 32x-50x. Modern examples of write-once devices have a performance of 4x-8x, and write-multiple devices - up to 4x.
A personal computer is a universal technical system. His configuration(equipment composition) can be flexibly changed as needed. However, there is a concept basic configuration, which is considered typical. The computer usually comes with this kit. The concept of a basic configuration may vary. Currently, four devices are considered in the basic configuration:
- system unit;
- monitor;
- keyboard;
- mouse.
System unit represents the main assembly within which the most important components are installed. The devices located inside the system unit are called internal , and devices connected to it externally are called external . External additional devices designed for input, output and long-term storage of data are also called peripheral .
The system unit consists of:
- housings;
- motherboard;
- processor;
- random access memory;
- hard drive;
- floppy disk drive;
- CD (or DVD) drive;
- video cards;
- sound card
In appearance, system units differ in the shape of the case. Personal computer cases are produced in horizontal (desktop) and vertical (tower) performance. Vertical housings are distinguished by dimensions: full-size (big tower), mid-size (midi tower) And small-sized (mini tower). Among the buildings having a horizontal design, there are flat And especially flat (slim).
In addition to the shape, a parameter called form factor. The requirements for the devices being placed depend on it. Currently, cases of two form factors are mainly used: AT and ATX. The form factor of the case must 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 case parameters. For mass models, a power supply of 200-250 W is sufficient.
Rice. 1. Examples of system units
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 diagram 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 called system board. This is the basis of a computer. It is this board that determines what type of processor can be used, what maximum size of RAM can be installed, etc.All expansion cards (video card, SCSI controller, modem, network card, etc.) are attached to the motherboard. In addition, the motherboard contains chips that control everything in the computer.
The main components of the motherboard, which are visible in the photo and indicated by numbers:
- Processor socket.
- Connectors for RAM.
- PCI bus interfaces.
- System logic chip (chipset).
- Interfaces for connecting hard drives and CD or DVD drives.
- Interfaces for connecting FDD.
- Block of input/output ports.
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) – deals with data transfer.
The internal memory of the processor is called cache memory
Modern processors have PGA (Pin Grid Array) packages. At this point in time, there are several processor manufacturers, among them Intel and AMD can be particularly highlighted.
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 placed in some registers is not considered as data, but as instructions that control the processing of data in other registers. Among the processor registers there are those that, depending on their content, are capable of modifying the execution of commands. Thus, by controlling the sending of data to different registers of the processor, you can control the processing of data. This is what program execution is based on.
Rice. 2. Example of processors (left – Athlon XP 3200+, right – Athlon XP 3000+)
Next element - microprocessor set (chipset). This is a set of chips that control the operation of the internal devices of the computer and determine the basic functionality of the motherboard.
Microprocessor groups
The wider the set of system commands of a processor, the more complex its architecture, the longer the formal command record (in bytes), the higher the average execution time of one command, measured in processor cycles. For example, the instruction set of Intel Pentium processors currently contains more than a thousand different commands. Such processors are called processors with an extended instruction system - CISC processors (CISC - Complex Instruction Set Computing).In contrast to CISC processors, architecture processors appeared in the mid-80s ^ RISC with abbreviated command system (RISC - Reduced Instruction Set Computing). With this architecture, the number of commands in the system is much smaller, and each of them executes much faster. Thus, programs consisting of simple commands are executed by these processors much faster. The downside of the reduced set of commands is that complex operations have to be emulated with a far from efficient sequence of the simplest commands of the reduced set.
As a result of competition between two approaches to processor architecture, the following distribution of their application areas has developed:
- CISC processors are used in general-purpose computing systems;
- RISC processors are used in specialized computing systems or devices aimed at performing uniform operations;
- Neuroprocessors - in one counting cycle it performs not 4 addition operations, but 288.
- VLIW (Very Length Instruction Word) – with an extra large command word;
- MISC (Minimum Instruction Set Command) - with a minimal set of commands and very high performance
TIRES
If the processor is the heart of a personal computer, then the buses 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. This interfaces (slots, connectors), with their help, connections are made to buses, which are often not visible at all on motherboards.
There are three main indicators of tire performance. These are clock frequency, bit depth and data transfer rate.
ISA (Industrial Standard Architecture)
Historical achievement of platform computers IBM PC became the introduction of architecture almost twenty years ago, which received the status industrial standard ISA (Industry Standard Architecture). It not only made it possible to connect all the devices of the system unit with each other, but also provided easy connection of new devices through standard connectors (slots). The bus bandwidth of 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
8 data channels and 20 address channels were output to the 8-bit ISA interface. 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, there was a need for a 16-bit ISA, which was implemented in 1984. The connector was supplemented with another 36 channels, 8 of which were output for data, and 7 for address. It should be noted that some expansion cards designed for an 8-bit bus can also work with a 16-bit bus. By the way, the concept of a key - a protrusion in the connector and a cutout in the connected board - appeared along with the 16-bit ISA. Since IBM refused to publish a complete description and timing diagrams of the ISA until 1987, many hardware manufacturers decided to develop their own buses. This is how the 32-bit ISA appeared, which was not used, but actually predetermined the emergence of MCA and EISA buses. In 1985, Intel developed a 32-bit 80386 processor, which was released at the end of 1986. There is an urgent need for a 32-bit I/O bus. Instead of continuing further development of the ISA, IBM created a new MCA (Micro Channel Architecture) bus, which was superior to its predecessor in every way:
- A CACP (Central Arbitration Control Point) bus arbiter 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.
- The MCA bus is not synchronized with the processor, which reduces the possibility of unnecessary conflicts and interference between boards.
- The absence of switches and jumpers reduced the installation of expansion cards to a simple action that did not require additional qualifications.
- IBM required all manufacturers wishing to use MCA to pay money for the use of ISA in all previously released computers.
- The computer world was simply not ready to accept the Plug and Play approach in 1987
- the price of the first MCAs was very high.
EISA (Extended Industry Standard Architecture)
Extension of the standard ISA became standard EISA (Extended ISA), featuring a larger 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 are terminated.With several partner firms, Compaq created the EISA committee, which was involved in developing a new standard. Already in 1989, the first personal computers appeared, the motherboards of which were equipped with an EISA bus. Its main difference was the 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 adapter can reach 45 W. At the same time, compatibility with boards designed to work with ISA was maintained. The data transfer speed was 33 MB/sec. In addition, computers with an EISA bus provided the ability to automatically configure interrupts and adapter addresses. But, unfortunately, this project also turned out to be unviable after a short time.
With the increase in clock frequencies and bit depth of processors, an urgent problem arose in increasing the data transfer speed on the buses (what is 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 engineers from companies that manufactured expansion cards were ready to produce devices at a speed that the buses could not provide.
What decision was made? Some data exchange operations are carried out not through standard I/O bus connectors, but through additional high-speed interfaces. The fact is that these very high-speed interfaces are connected to the processor bus. It follows from this that the connected boards will have access directly to the processor through its bus. All this was called LB (Local Bus). The first ISA buses were local, but when their clock speed exceeded 8 MHz, separation occurred. And in 1992, another extended version of ISA appeared - VLB (VESA Local Bus).
VLB (VESA Local Bus)
The name of the interface is translated as local bus standard VESA (VESA Local Bus). The concept of a "local bus" first appeared in the late 80s. It is due to the fact that when introducing processors of the third and fourth generations (Intel 80386 and Intel 80486), the frequencies of the main bus (the bus was used as the main one) ISA/EISA) became insufficient for exchange between the processor and RAM. The local bus, which has an increased frequency, connected the processor and memory, bypassing the main bus. Subsequently, an interface was built into this bus for connecting a video adapter, which also required increased bandwidth - this is how the standard appeared VLB, which made it possible to raise the local bus clock frequency to 50 MHz and provided peak throughput of up to 130 MB/s.The main disadvantage of the interface VLB This means that the maximum frequency of the local bus and, accordingly, its throughput depend on the number of devices connected to the bus. So, for example, at a frequency of 50 Hz, 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. Simply, several 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 the association that proposed a new, truly local, bus (with the participation of NEC). The VLB data transfer speed was 128 – 132 MB/sec, 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 long in the information technology market. Well, oh well: the further into the forest, the thicker the partisans. Already in 1992, development of a new local PCI bus began.
PCI (Peripheral Component Interconnect bus - peripheral component connection bus)
Interface PCI (Peripheral Component Interconnect) - standard for connecting external components) 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 are embedded for connecting external devices. To communicate with the computer's main bus (ISA/EISA) special interface converters are used - PCI bridges (PCI Bridge). In modern computers, bridge functions PCI carry out microcircuits of a microprocessor kit (chipset).This interface supports a bus frequency of 33 MHz and provides a throughput of 132 MB/s. The latest versions of the interface support frequencies up to 66 MHz and provide performance of 264 MB/s for 32-bit data and 528 MB/s for 64-bit data.
An important innovation implemented by this standard was support for the so-called mode plug-and-play subsequently formed into an industrial standard for self-installing devices. Its essence is that after physically connecting 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 RS1i with the design of the standard plug-and-play it became possible to install new devices using automatic software - these functions were largely assigned to the operating system.
In June 1992, a new standard appeared on the scene - PCI, the parent of which 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 local (a local bus is one that is directly connected to the system bus). PCI uses the Host Bridge (main bridge) to connect to it, as well as the Peer-to-Peer Bridge (peer-to-peer bridge), which is designed to connect two PCI buses. Among other things, PCI is itself a bridge between the ISA and the processor bus. The appearance of the PCI bus on the market for manufacturers of all kinds of devices was a kind of small revolution. The variety of expansion cards 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 speed – 132 MB/sec or 264 MB/sec. The PCI standard provides three types of cards depending on the power supply:
- 5 Volts – for desktop computers
- 3.3 Volts – for laptop computers
- Universal boards that can work in both types of computers.
The constant improvement of video cards led to the fact that the physical parameters of the PCI bus became insufficient, which led to the emergence of AGP.
AGP (Accelerated Graphics Port)
Video card (video adapter)During the existence of personal computers, several video adapter standards have changed: MOL (monochrome); C.G.A. (4 colors); E.G.A. (16 colors); VGA(256 colors). Currently used video adapters SVGA providing optional reproduction of up to 16.7 million colors with the ability to arbitrarily select 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 apparent size of the image elements. Using an inflated resolution on a small monitor results in image elements becoming illegible and working with documents and programs causes visual fatigue. Using a low resolution results in large image elements, but there are very few of them on the screen.
Video acceleration- one of the properties of a video adapter, which is that part of the operations for constructing images can occur without performing mathematical calculations in the main computer processor, but purely in hardware - by converting data in microcircuits video accelerator. Video accelerators can be included in the video adapter (in such cases the video card is said to have hardware acceleration functions), but can be supplied as a separate board installed on the motherboard and connected to the video adapter.
Video adapter- a device that requires particularly high data transfer rates. How to implement a local bus VLB, and when implementing a local bus PCI The video adapter has always been the first device to be plugged into the new bus. Today tire parameters 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 bus frequency PCI(33 MHz or 66 MHz), but it has much higher throughput - up to 1066 MB/s (in quadruple multiply mode).
Fig.4. How system memory works (including AGP)
On the motherboard, this port exists in only one form (and there is nothing else needed). Neither physically nor logically it depends on PCI. The first AGP 1.0 standard appeared in 1996 thanks to Intel engineers.
This specification had a clock frequency of 66.66 MHz, 1x and 2x signaling modes, 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 speed – 533 MB/sec (2x) and 1066 MB/sec (4x). What is this - 2x, 4x? The main (basic) AGP mode is called 1x. In this mode, a single data transfer occurs per cycle. In 2x mode, transmission occurs twice per cycle. In 4x mode, data transmission occurs four times per cycle. And so on. AGP 1.0 width is 32 bits. A big achievement of AGP is that this specification allows for fast access to RAM because it is local.
PCMCIA
(Personal Computer Method Card International Association - 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 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 to connect the processor and memory, starting with the Intel Pentium Pro processor, a special bus is used, which has received name front side bus (FSB). This bus operates at a very high frequency of 100-125 MHz. Motherboards with bus speeds are currently being introduced 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 what is indicated in the motherboard specification. Bus capacity FSB at a frequency of 100 MHz it 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 connected in chains (each subsequent device is connected to the previous one). Bus performance USB is relatively small and amounts to 1.5 Mbit/s, but for devices such as a keyboard, mouse, modem, joystick, etc., this is enough. The convenience of the bus is that it practically eliminates conflicts between different equipment, allows you to connect and disconnect devices in “hot mode” (without turning off the computer) and allows you to connect 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 slots on the motherboard as a daughter card and performs computing operations related to processing sound, speech, and music. The sound is played through external sound speakers connected to the sound card output. A special connector allows you to send an audio signal to an external amplifier. There is also a microphone connector, which allows you to record speech or music and save it on your hard drive for later processing and use.Ports
Ports- these are connectors on the rear 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.
Data transfer speed through the parallel port is from 800 Kbps to 16 Mbps.
In the diagrams, parallel ports are designated LP1, LP2, etc. (LP - Line Printer).
Printers, streamers and other devices that require high data transfer speeds are connected to the computer through parallel ports. Parallel ports are also used to connect two computers to each other.
Serial port
Serial port or COM-port: Communications port - This is a port through which data is transmitted in only one direction at a time.
Data is transmitted sequentially in series, first in one direction, then in the other.
Devices that do not require high data transfer speeds - mice, keyboards, modems - are connected through serial ports.
The data transfer rate through the serial port is 115 Kbps.
In the diagrams, parallel ports are designated COM1, COM2, etc.
USB port
USB (Universal Serial Bus) - universal serial port. This is a port that allows you to connect almost any peripheral devices.
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 both mice and keyboards for the USB port.
An important feature of USB ports is that they support Plug and Play, i.e. When connecting a device, you do not need to install a driver for it; in addition, the USB ports support the ability "hot plug"- connections while the computer is running.
The USB port was developed in 1998. Back then it was simply 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 Intel. In addition to Intel, other companies, including Microsoft, also participated in the development. The USB 2 specification was adopted in April 2000.
Data transfer speed via USB 1.1 port is 12 Mbit/s. For mice and keyboards - 1.5 Mbit/sec.
Data transfer speed via USB 2 port is 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 these ports originally appeared on IBM computers. These ports and port connectors were significantly smaller than existing AT/MIDI ports and connectors, so other manufacturers began using PS/2 ports in their computers.
PS/2 ports come in 5-pin and 6-pin types, but they are identical to the user.
AT/MIDI port
AT/MIDI port (Musical Instrument Digital Interface - connection to digital musical instruments) are the ports through which keyboards were originally connected (before PS/2), and currently, 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 Mbit/s.
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.
FireWire ports support Plug and Play and hot pluggability.
FireWire ports come in two types. Most desktop computers use 6-pin ports, while laptops use 4-pin ports.
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| 6-pin FireWire port |
4-pin FireWire port |
Controllers
Electronic circuits that control various computer devices are called controllers. All IBM PC computers have controllers to control the keyboard, monitor, floppy disk drives, hard drive, etc.power unit
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, and 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 available electrical outlets. A special cable can be used to connect the monitor's power supply through the computer's power supply. In this case, the power of the computer's power supply is not consumed, because this auxiliary jack is simply connected in parallel to the main jack, and when the main jack is connected to a power cord and plugged into an electrical outlet, the auxiliary jack itself becomes an outlet.
The power supply contains a transformer, rectifier and cooling fan. Several sets of wires come out of the power supply inside the computer to connect to the electrical power supply of the system board, hard drive, and floppy drives. To connect additional devices, such as an additional optical drive or streamer, the power supply contains free sets of wires.
An example from the “life” of computers
Seiko Epson announced the expansion of its line of graphics processors for mobile devices (mobile graphics engine) with the S1D13732 model, which is an LCD screen 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, which is currently in mass production, in its 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 the power consumption of cell phones, and the unit responsible for graphics provides the ability to record and play video without specialized software, and therefore equip devices with low-power CPUs.
The S1D13732 is equipped with 448 KB of internal memory, a camera interface (supported cameras with a resolution of up to 1.3 million pixels), and an interface of two LCD screens with a maximum resolution of 240x320 pixels.
In this lesson we will look inside the system unit and Let's get acquainted with all the main internal components computer.
In the third lesson we learned what a processor, RAM and hard drive are needed for. In the fourth lesson, we saw the outside of a computer 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 people talk about the internal structure of a computer, they usually mean those components that are located inside its housing. For a desktop computer, the case is the system unit; for laptops and netbooks, it is the lower of the opening halves (let me remind you that we were dedicated to types of computer equipment).
System unit components
To begin with, let's take a system unit that is not too new, but also not too old, in which all the main components are installed. And then we compare it with a more inexpensive option with fewer additional components.
So, let's look at the photo of the system unit of the IT lessons website.
What 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 case are components that perform different tasks. Using wires, components exchange information and receive electrical power.
Let's look at all the components one by one.
1. Motherboard
All computer components are interconnected by one of the largest printed circuit boards (which can be immediately recognized in the photograph by their size), it is called system board or motherboard(in English version motherboard or mainboard).
System board (system unit component)
Some components are installed directly into the connectors located on the motherboard, while other components are connected to it using special wires into the corresponding 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 with electrical energy. To supply this energy it is used 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. Central processor
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 the cooler, under which the central processor is located.
4. RAM
We also got acquainted with RAM in the third lesson.
RAM(RAM, Random Access Memory, RAM), like the processor, is installed in special sockets on the motherboard.
RAM (system unit component)
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 operating speed (more about 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 for processing graphic objects that are displayed in the 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 gets very hot, you can see large cooling system(yes, this is also a cooler).
For the first time in IT lessons, we came across the concepts of “expansion card” and “expansion slot”, so we will immediately set a definition from which we will build in the future.
Expansion card– a device in the form of a printed circuit board with a universal connector for installation on the system board (for example, a video card, network card, sound card).
Expansion cards are installed in addition to the main components in order to expand your computer's capabilities, they can have different purposes (graphics processing, sound processing or connection to a computer network, etc.).
Example of an expansion card (a simpler video adapter)
Expansion slot- a special universal connector on the system board, designed for installing additional computer devices in the form of expansion cards.
We've sorted out the new definitions, let's move on.
6. Network card
LAN card(network adapter, Ethernet adapter, network adapter, LAN adapter) is designed to connect a computer to a computer network.
Network card (system unit component)
In this case, the network card is also made in the form of an expansion card (printed circuit board), which is installed in a connector on the system board.
7. Sound card
Sound card(sound card, sound adapter, sound card) processes sound and outputs it to speaker systems or headphones.
Sound card (system unit component)
Like the previous two devices, a sound card is a printed circuit board inserted into a connector on the system board. True, this sound adapter is not an ordinary one, it consists of two printed circuit boards, but this is an exception to the rule.
8. Hard drive
On hard drive All computer programs and data are stored (more about this in the IT lesson).
The hard drive, unlike previous components, is not installed on the motherboard, but is attached in a special compartment of the case system unit (look at the photo).
Hard drive (aka hard drive)
You can install multiple hard drives in such bays and increase the amount of internal memory on your computer.
Hard drive is sometimes referred to by the acronym NMJD(Hard Magnetic Disk Drive), 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 unit.
Optical drive (system unit component)
This compartment is located at the top front of the case, it is wider than for the hard drive, since the DVD drive is noticeably larger.
System unit components (option 2)
So, we have looked at 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 same components are visible in the photo, but expansion cards (video card, network card and sound card) are not visible. How will this computer work without these components? In fact, these components exist, but they are not visible at first glance.
Built-in Components
The fact is that some components may not be made in the form of expansion cards, but may be built-in(integrated) into the motherboard or central processor.
In this case, additional chips are installed on the motherboard that perform the functions of a network and sound adapter. The video adapter is built (integrated) into the main chip of the motherboard.
In the photo, number 1 is the video adapter, number 2 is the network adapter, and number 3 is the sound adapter.
At the same time, expansion slots (number 4) remain on the motherboard for installing more functional components (if the built-in ones, for some reason, do not suit you).
Laptop components
In principle, it would be possible to make a separate lesson on internal structure of laptops and netbooks. But, essentially, it contains the same components as in a desktop computer, only these components are smaller and are mounted differently.
Each of the components listed in this IT lesson performs its task, but perhaps it is interesting to know which components most affect the speed of your computer?
Since most of the calculations are performed CPU, then it most affects the performance of the computer.
RAM The processor needs it 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 gaming or working with 3D graphics, then the speed of operation is of great importance video adapter.
But if the computer is used to surf the Internet, as well as with text documents, photographs, watch movies and listen to music, then you can get by with the slowest (but modern) video adapter, including one built into the motherboard or processor.
Video supplement
To reinforce the new information, there is a very interesting video that describes in simple language 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 got acquainted with internal device of the computer and briefly reviewed everything system unit components. For the Beginner level, this knowledge is quite enough to consciously work in most programs that you may need.
In the next lesson we will learn what other devices can be connected to the computer (external devices), it is called.
Copying is prohibited, but links can be shared:
A computer consists of a system unit and peripheral devices (monitor, mouse, keyboard). In this post, I would like to disassemble the computer in detail down to every bolt, consider the structure of the computer as a whole, what it contains and what each part is needed for.
System unit
The system unit is the computer itself. The system unit contains: PSU (power supply), HDD (hard drive), motherboard, RAM, processor, sound card, video card, network card, disk drive and other components that are necessary to expand capabilities. Let's now take a closer look at each device and find out what function it performs.
System unit case
Cases come in different types: compact, transparent, backlit, but its main task is to fit all the computer devices. Of course, you could do without it, hang the motherboard on the wall, and put everything else on the table next to it, but this is stupid, inconvenient and dangerous.
While the system unit is turned on, under no circumstances should you touch its components. High voltage passes inside, which can even kill. This is why the case is always used, it is convenient and safe.
PSU – Power supply
Almost all the wires in the computer come from the power supply. It provides each device in the system unit with electricity, without which nothing will work. The power supply weighs about a kilogram, and is approximately the size of .
The power supply produces: 3.3v, 5v and 12v. Each device has a separate voltage. Also, to prevent the power supply from overheating, it is equipped with a radiator and a cooling fan. This is where the sound of a working computer comes from.
Motherboard
The main task of the motherboard is to connect ALL devices of the computer. It literally combines everything: mouse, keyboard, monitor, USB drives, HDD, processor, video card and everything else. For more information on the holes/connectors and ports of the motherboard, see the picture above.
CPU - computer's central processing unit
The processor powers and calculates all operations on the computer. When compared to human organs, a computer processor can be compared to the brain. The more powerful the chip (CPU), the more calculations it can do, in other words: the computer will run faster. But this is only one of the main devices responsible for the speed of your computer.
RAM - random access memory
RAM is a random access memory device. Also called RAM, random access memory and random access memory. This small board is needed to store temporary data. When you copy something, this information is temporarily stored in RAM, and it also stores information from system files, programs and games. The more tasks you assign to your computer, the more RAM it will need. For example, at the same time the PC will download something, play an audio file and the game will be launched, then there will be a large load on the RAM.
The more RAM, the better and faster the computer works (as is the case with the processor).
Video card (video adapter)
A video card, also called a video adapter, is necessary to transfer images from a computer to a screen/monitor. As mentioned above, it is inserted into the mat. board into its connector.
In general, the computer is designed in such a way that each device has its own hole, and even with brute force it is impossible to insert something into the wrong place.
The more complex the image (HD video, game, graphical shell and editor), the more memory the graphics card should have. For example, 4k. The video will not play properly on a weak video card. The video will slow down, and you may think that the Internet is weak.
A modern video card also contains a small cooler (cooling fan), both for power supply and CPU cooling. Under the cooler is a small graphics processor that works like a central processor.
HDD (hard disk) Hard Disk Drive
HDD – aka: hard disk, hard drive, hard drive, screw, drive. No matter what people call him, he has one task. It stores all information and files. Including OS (operating system), programs, browsers, photos, music, etc. In other words, this is computer memory (like a flash drive in a phone).
There is also SSD. The essence and principle are the same, but an SSD works many times faster and costs an order of magnitude more. If you use an SSD as a system drive for the OS, then your computer will run much faster.
Drive
If you need to view/copy information from a disk, then you need a disk drive. Nowadays, you rarely see this device in new computers; the drive has been replaced by USB drives (flash drives). They take up much less space than disks, are easier to use, and are reusable. Nevertheless, disk drives are still used, and I couldn’t help but write about it.
Sound card
A computer needs a sound card to play audio files. Without it, there will be no sound on the computer. If you go back to the "motherboard" section for a second, you will see that it is already built into every motherboard.
As you can see in the photo above, there are additional sound cards. They are necessary for connecting more powerful speaker systems and provide better sound in contrast to integrated (built-in) ones.
If you use ordinary small speakers, then the difference will not even be noticeable. If you have a subwoofer or home theater, then of course you need to install a decent sound card.
Additional computer devices
Everything I said above necessary for the operation of the system unit, and now let's look at additional computer devices that expand its capabilities and add functionality.
External hard drive
Unlike an HDD, an external hard drive is portable. If the HDD and SSD need to be installed in the case and secured there, then the external one is connected with just one USB cable. This is very convenient for all occasions that there is no point in describing. An external HDD is like a flash drive, only with more memory.
Uninterruptable power source
Absolutely every computer is afraid of voltage surges, I would even say more than any other equipment. An uninterruptible power supply will provide stable voltage and protect your power supply from surges.
Voltage can jump for various reasons, and it is not always noticeable. For example, if you have weak wiring, then when you turn on other equipment in the house, the voltage may jump. Or maybe the neighbors have something powerful... In general, I strongly recommend that everyone use a power supply.
TV tuner
A TV tuner is a special chip that allows you to watch TV on a computer. Here, rather, as in the case of the disk drive, it still works, but is no longer relevant. To watch TV on a computer, you don’t have to insert special boards; we now have it and on my blog there is a whole section dedicated to this topic.
Computer peripherals
As Wikipedia says:
Peripherals are hardware that allows information to be entered into or output from a computer. Peripheral devices are optional for system operation and can be disconnected from the computer.
But, I don't agree with her. For example, we don’t even need a computer without a monitor, and without a keyboard, not everyone can turn on a computer, only the most experienced users can do without a mouse, and without speakers you can’t watch or listen to anything. These are not all devices yet, so let's look at each of them separately.
Personal computer monitor
Let me repeat a little - we don’t need a computer without a monitor, otherwise we won’t see what’s going on there. Perhaps in the future they will come up with some kind of hologram or special glasses, but for now this is just my sick fantasy).
The monitor is connected to the video card with a special cable, of which there are 2 types: VGA (obsolete connector) and HDMI. HDMI provides a better image and also transmits sound parallel to the image. So, if your monitor has built-in speakers and is high resolution, you definitely need to use an HDMI cable.
Keyboard
The keyboard is needed to enter information, call commands and perform actions. There are different types of keyboards: regular, silent, multimedia and gaming.
- Regular - the simplest keyboard with only standard buttons.
- Silent – rubber/silicone keyboards, when working with which not a single sound is heard.
- Multimedia. In addition to the standard buttons, the keyboard has additional keys for controlling audio/video files, volume, touchpad (possibly), and more.
- Gaming – Additional buttons for different games, the main buttons for the game have a different color and other goodies.
Mouse
The main task of a computer mouse is to control/move the cursor on the screen. You can also select and open files/folders and call the menu with the right button.
Now there are many different mice for computers. There are wireless, small, large, with additional buttons for convenience, but its main function remains the same after decades.
Acoustic system
As mentioned above, the speaker system is connected to the sound card. The signal is transmitted through the sound to the speakers, and you hear what they say in the video and sing in the song. Acoustics can be different, but without any, a computer with all its capabilities becomes an ordinary working tool, in front of which it is boring to spend time.
MFP - Multifunction devices
An MFP is more necessary for office and study. Typically contains: scanner, printer, copier. Although these are all in one device, they perform completely different tasks:
- Scanner – makes an exact copy of a photograph/document in electronic form.
- Printer – prints an electronic version of a document, photographs, pictures onto paper.
- Xerox – Makes an exact copy from one paper to another.
Gamepad or joystick
A gamepad is also a joystick in the past. Only needed for comfort in some games. There are wireless ones and vice versa. Usually they contain no more than 15 buttons, and there is no point in using them in non-games.
