A computer is a technical means of converting information, the basis of which is the same principles of processing electrical signals as in any electronic device:
- input information, represented by various physical processes, both electrical and non-electrical in nature (letters, numbers, sound signals, etc.), is converted into an electrical signal;
- the signals are processed in the processing unit;
- Using an output signal converter, the processed signals are converted into non-electrical signals (images on the screen).
The purpose of a computer is to process various types of information and present it in a form convenient for humans.
From a functional point of view, a computer is a system consisting of 4 main devices that perform certain functions: a storage device or memory, which is divided into operational and permanent, an arithmetic-logical unit (ALU), a control device (CU) and an input device. output (UVV). Let's consider their role and purpose.
A storage device (memory) is intended for storing information and program commands in a computer. The information that is stored in memory is numbers, symbols, words, commands, addresses, etc. encoded using 0 and 1.
By writing a number into memory we mean placing this number in a cell at a specified address and storing it there until fetched by a program command. The previous information that was in this cell is overwritten. When programming, for example, in Pascal or C, the cell address is associated with a variable name, which is represented by a combination of letters and numbers chosen by the programmer.
Reading a number from memory means sampling a number from a cell with a specified address. In this case, a copy of the number is transferred from memory to the required device, and the number itself remains in the cell.
Information forwarding means that information is read from one cell and written to another.
The cell address is generated in the control device (CU), then it enters the address sampling device, which opens the information channel and connects the desired cell.
Numbers, symbols, commands are stored in memory on an equal basis and have the same format. The type of data does not matter either for memory or for the computer itself. The types differ only when the data is processed by the program. The length, or bit depth, of a cell is determined by the number of binary digits (bits). Each bit can contain 1 or 0. In modern computers, the length of a cell is a multiple of 8 bits and is measured in bytes. The minimum length of a cell for which an address can be generated is 1 byte, consisting of 8 bits.
The following parameters are used to characterize the memory:
- memory capacity – the maximum amount of stored information in bytes;
- Memory speed is the memory access time, determined by the time it takes to read or write information.
Arithmetic logic unit (ALU). Performs arithmetic and logical operations.
It should be noted that any arithmetic operation can be implemented using the addition operation.
A complex logical problem is decomposed into simpler tasks, where it is enough to analyze only two levels: YES and NO.
The control device (CU) controls the entire course of the computational and logical process in the computer, i.e. performs the functions of a “traffic controller” of information. The control unit reads the command, decrypts it and connects the necessary circuits to execute it. The next command is read automatically.
In fact, the control unit performs the following cycle of actions:
- generating the address of the next command;
- reading a command from memory and decoding it;
- command execution.
In modern computers, the functions of the control unit and the ALU are performed by one device called the central processor.
Today, computer devices have become so firmly established in our lives that it seems impossible to imagine our existence without them. However, most users almost never think about how all these systems work. It will be discussed further (for “dummies”, so to speak). Of course, it won’t be possible to describe everything in detail and cover all the technical aspects (and most people don’t need this). Therefore, we will limit ourselves to the main aspects, speaking in simple “human” language.
Computer for dummies: basic components
When talking about the structure of any computer device, it should be clearly understood that it basically consists of hardware and software.
Hardware refers to all connected devices that, so to speak, can be touched with your hands (processors, memory sticks, hard drives, monitors, video, audio and sound adapters, keyboard, mouse, peripheral devices like printers, scanners, etc. .d.). People sometimes call all these components “computer hardware.”
The software part consists of many components, among which the leading role is played by the operating system, on the basis of which interaction is carried out between the hardware part and other programs and device drivers installed in it - special programs with the help of which the OS can interact with the hardware itself and use it when performing certain tasks.
From here it is easy to conclude that the main principle of operation of a computer of any type is the interaction of hardware and software components. But this is only the surface idea. These processes will be described a little later.
Computer hardware
In hardware, as many believe, the processor and RAM come first. In part, this is true. They ensure the execution of all program commands and make it possible to launch certain processes.
On the other hand, if you dig deeper, not a single “hardware” component in itself is worth anything, because in order to be used it must be connected somewhere. And here, paramount importance is given to the so-called motherboards (popularly known as “motherboards”) - special devices on which all other components, microcircuits, etc. are mounted. In this sense, the basic principle of computer operation (correct functioning without failures) is is to correctly connect all hardware components through the appropriate controllers to special slots or connectors on the board itself. There are rules here, for example, on the correct use of PCI buses, on connecting hard drives and removable drives using the Master/Slave principle, etc.
Separately, it is worth mentioning the information on which the information is recorded, as if forever, and the random access memory (RAM) used for executing software components.
Types of software
The software principle of computer operation implies the use of appropriate software to perform assigned tasks.
In the general understanding, software is divided into several categories, among which we can separately distinguish system software and include operating systems themselves, device drivers, and sometimes service utilities necessary to ensure the correct operation of the entire system. This is, so to speak, a common shell into which application programs and applications are embedded. Software of this type has a strict focus, that is, it is focused on performing a specific task.
But since we are talking about what the basic principles of computer operation are in a general sense, it is the system software that comes first. Next, let's look at how the entire computer system starts.
Computer science lesson. Computer: Turn on and check devices
Probably, many desktop PC users have noticed that when they turn on the computer, a characteristic sound from the system speaker is heard. Few people pay attention to it, but from the fact of its appearance we can conclude that all hardware devices are working normally.
What happens? The principle of operation of a computer is that when power is supplied to a special chip, called the primary input/output device, all devices are tested. The first step is to detect problems in the operation of the video adapter, because if it is not in order, the system simply will not be able to display visual information on the screen. Only then is the processor type and its characteristics, RAM parameters, hard drives and other devices determined. In fact, the BIOS initially stores information about the entire hardware.
Download options
There is also a system for selecting a boot device (hard drive, optical media, USB device, network, etc.). In any case, the further principle of the computer’s operation in terms of booting is that the device must have a so-called boot record, which is necessary to start the system.
Start of the operating system
To load the OS, you need a special bootloader, which initializes the system kernel recorded on the hard drive and places it in RAM, after which control of the processes is transferred to the OS itself.
In addition, the master boot record can have more flexible settings, giving the user the right to choose the boot system. If the start is made from removable media, the executable boot code is read from it, but loading in any case is carried out only if the BIOS determines the executable code as valid. Otherwise, a notification about the impossibility of starting will appear on the screen, such as that the boot partition was not found. In this case, a partition table is sometimes used, which contains information about all logical drives into which the hard drive can be divided. Among other things, access to information directly depends on the file organization structure, which is called the file system (FAT, NTFS, etc.).
Note that this is the most primitive interpretation of the loading process, since in reality everything is much more complicated.
launching programs
So, the operating system has loaded. Now let's focus on the functioning of programs and applications. The central processor and RAM are primarily responsible for their execution, not to mention the drivers of other devices involved.
The principle of operation of computer memory is that when an executable file of a program or other object is launched from ROM or removable media, when the application plays a complementary role, some associated components, most often dynamic ones, are placed into random access memory (RAM) through the system kernel libraries (although for simple programs their presence may not be provided), and device drivers necessary for operation.
They provide communication between the operating system, the program itself and the user. It is clear that the larger the RAM, the more components can be loaded into it and the faster their processing will occur. When interaction commands arrive, the central processor comes into play and performs all computational actions in the system. When the application finishes running or when the computer is turned off, all components from the RAM are unloaded. But this doesn't always happen.
Changing system settings
Some processes may reside in RAM permanently. Therefore they must be stopped manually. In Windows systems, many services start automatically, but they are completely unnecessary for the user. In this case, the autorun setting is applied. In the simplest version, optimizer programs are used that clean up unnecessary processes and remove computer junk automatically. But this is a separate conversation.
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 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 the desktop, on a bedside table near the 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 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 goes to 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 hovers 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.
All modern schoolchildren who have carefully listened to a computer science course know the components of a computer and their functions. Students enrolled in technical specialties related to computers are also well versed in this area. But if a person who has not received specific information in the educational program wants to understand the principles of operation of a modern computer, he will have to look for adequate sources of information. It is worth recognizing that some authors write as if for themselves: they use many terms that are unclear to a person far from this area. It is not difficult to understand how a personal computer (PC) works and works; you just need to take a responsible approach to the goal you have set for yourself. The world of computing is truly fascinating!
What is it about?
Before you can figure out what the basics of system software are, what a machine is made of, and how to program with it, you first need to figure out what the focus is on. Its name came to us from the English language. Nowadays, a computer is usually called an electronic machine that can be programmed to accumulate data, process information and transfer knowledge.
The most important, basic item on which a computer is built is a clock generator. It is he who produces signals at specified time intervals. The impulses further participate in the workflow of various internal and external devices for information input, processing and output. In fact, the control process involves distributing signals in such a way as to achieve the goal set for a person. There is no need to independently direct all signals where required: this happens automatically if there is appropriate software control. True, the result will be successful only if there is adequate code without errors.
How it works?
The key aspect that is always explained in computer courses for beginners: the software principle is the basis for the work process. We are talking about the presence of a specialized program in computer memory. This idea has become the most important for computer architecture at the current time. In (computer) courses for beginners, the main theses of the principle must be described:
- the computer program is written into electronic memory, where it is stored, like the original values;
- The sequences of commands formed into the program are encoded with numbers and do not differ in format.
The main postulate of the software principle of computer operation
A general description of a computer always begins with a declaration of this management principle, due to the presence of pre-written code that the machine must execute. This idea has become the basis for understanding the universality of computers: in a specific time period, a task is solved that is regulated by an updated program.
As soon as the result is obtained, you can proceed to the next program, carrying out calculations according to the algorithm described in it. This approach involves the use of software. The software principle of computer operation declares the presence of software mandatory for any modern user. What is curious is that people who create code (of course, not just any code, but still) also use programs, algorithms, which are software.
About terminology
As the name suggests, the basic concept for the modern approach to determining the principles of computer performance is a program. Through it, data is recorded, data is output from memory to an external device, any other operations - calculations, image construction, and so on. The term is usually used to denote an algorithmic notation that allows one to obtain a solution to a formulated problem by sequential execution of operations. The program is formulated using the operators of the selected language available for the computer. The main task of any modern program is to control the activity of hardware. The use of programs is the first sign of the software principle of computer operation.
How to use it?
Suppose, as part of solving a work problem, a person needs to analyze the work of the enterprise where he is employed, and in relation to this issue he needs to build examples of computer models. The software principle of the computer’s operation becomes an indispensable tool for him in achieving the task: there is no need to draw anything by hand and carry out extensive calculations, you just need to choose a program that, in the correct mode and in the established order, activates the hardware capabilities of the machine, ultimately outputting it to the information transfer device (monitor, printer) result.
On the other hand, the results will be correct only if debugged software is used. It should not require modification, that is, the user only launches the product and uses the functions that he understands, without having any special education regarding the internal structure of the software. All he needs is an understanding of the application and knowledge of the general description of the computer. The software operating principle of the computer provides for the availability of specialized documentation for all software used.
Software
This term is usually used to characterize a set of rules, procedural sets, software components, and official accompanying documentation that allows processing data and implementing the declared functionality of the system.
When understanding the essence of the software principle of computer operation, it is important to take into account that the software and hardware structure are constantly in close relationship, the functionality of one is determined by the clarity of the other. Software used on modern computers depends on technical parameters and is called software configuration.
Methodological approach
The software principle of the computer is based on the ideas expressed by Babbage and von Neumann. It is customary to talk about three key components:
- CPU;
- memory;
- devices that allow you to output and enter information.
Speaking about the processor, it is divided into two devices:
- manager;
- providing logical, arithmetic operations.
Classification system
It is customary to divide computers into several large categories:
- large;
- mini;
- micro;
Large - powerful devices, common in large organizations, often working for the benefit of the national economy. To service such devices, several dozen professionals are needed. Mainframe computers are a basic component of the formation of a computer center. In such a huge machine, it is absolutely impossible for a non-specialist to guess which device is intended for processing information!
Mini are computers that have small dimensions, relatively low performance, and low price. Often used by companies, scientific, research and educational institutions. They are entrusted with the functions of monitoring production processes. Micro are even smaller computers that are actively used not only in enterprises, but in computer centers as auxiliary equipment.
PC
Perhaps it is this category of technology that arouses such curiosity among the general public regarding the software principles of computer operation. The term usually refers to equipment used within the workplace, that is, intended for one person. Often, with the help of a PC, the educational and work process is made more efficient, but the functionality is not limited to this. International standardization has made it possible to introduce division into groups. The following categories are distinguished:
- mass;
- office;
- mobile;
- workers;
- gaming
Why are they needed?
Depending on the more or less broad focus on solving problems, it is customary to talk about the specialization of computers. Exist:
- universal;
- specialized.
The former are designed for a wide range of tasks; computing systems can be configured at will, selecting the optimal structural elements. The resulting computer will be efficient for workflows, editing text or music files, and so on. Specialized are machines created with a specific focus on work in mind. These include on-board computers installed in aircraft and cars. When examining such a machine, an inexperienced user will hardly be able to immediately figure out which device is intended for processing information! Many of them are distinguished by an abundance of screens, counters, sensors, lights - the eyes just run wild. Therefore, to use such a device in practice, you will first have to undergo a specialized development course.
Data: store and process
The software principle of computer operation is the execution of specified programs, which as a result produces useful information used by the user to solve the problems facing him. In fact, a computer is an executor of a set of template commands specified by a person, called an algorithm. Design ideas are based on Boolean algebra. In fact, a set of instructions is loaded into the machine in a computer-readable format, allowing you to sequentially perform a limited number of actions, which will result in the result the person needs. The algorithm is characterized by its name, starting point, and ending point.
An idea of what the essence of the software principle of a computer’s operation is can be obtained by analyzing the main characteristics of the algorithm:
- discreteness (a set of commands is formed by given actions, for which the order is declared);
- determinism (each action is strictly defined and cannot have more than one meaning);
- finiteness (actions individually, the algorithm as a whole necessarily have a completion path);
- efficiency (the absence of errors, proven by obtaining a result in a finite number of iterations);
- mass character (applicability to a large number of similar problems, differing in the spread of initial parameters).
Neumann's three principles
These postulates were translated into reality in 1946, when it was possible to build the first computer in human history. Neumann's principles:
- software control;
- homogeneity of memory;
- targeting.
How about more details?
The management principle presupposes the presence of a command set, sequentially executed by the processor in automatic mode.
Memory homogeneity involves the accumulation of information in one type of memory, which eliminates the need to determine the nature of the data in a given cell. Both programs and data are saved together, allowing the same sequence of actions to be applied to them. The user, skillfully using this feature, receives ample opportunities. Let's say, having launched the program, you can work on it, choosing the rules for obtaining parts.
Addressability says that computer memory is structured, formed by cells, each of them has its own unique number. The processor can require information from an arbitrary cell at any time; an ordered structure will provide the fastest possible access to the necessary information. Different areas of memory can be named differently, programs written in them are simply searched, and the accumulation of information about structure makes it possible to simplify the access procedure. In addition, using assigned names, it is easier to change the recorded information by executing the selected program set of actions.
Data and program representation
Any information can be processed by modern computers: graphics, pictures, text, sound. This is due to the possibility of converting into a format that is understandable at the hardware level. The processor receives an instruction on the basis of which it performs operations. Solving a problem is accompanied by a sequence of activities, often including an innumerable number of operations. It's called a program.
The software that a modern user has at his disposal did not appear overnight. It took the leading minds of our world several decades to develop the basic principles of program design, debugging optimal operations that allow us to quickly and efficiently obtain results with minimal hardware load. Modern computer software is a collection of such programs.
Software: features
Not a single ordinary modern user will be able to work if the computer is not equipped with system software. The main component of this complex is the operating system, recognized as the basic component of the software. This element is necessary; its absence makes it impossible for a computer to work in the understanding of an ordinary person. In addition to the OS, the system software category includes a variety of service projects and service programs. Some of them deal with disks, others compress data, resist malware attacks, and so on.
In order to be able to use a computer to solve the tasks assigned to the user, it is necessary to have software. Such projects help generate graphic information, pictures, sounds, texts, and allow you to perform operations with numerical data. The application software category is divided into:
- applications;
- programming systems.
Application software
Programming systems are necessary for professionals working in the field of creating new computer products. Several programming languages have been developed, the most widely used currently being the family for object-oriented programming. Visual environments are very popular. Even a beginner using such products can master basic coding operations and create their own working product.
Applications are a slightly different type of application software. Through it, text arrays, graphic and audio information, numbers and video are processed. You can use specialized programs for network work. Using the products does not require programming skills. General applications that allow you to solve classic problems are required by almost any user. These include text editors, graphics, tables, systems that allow centralized management of databases accumulating data. You should not lose sight of the products with which you can create presentations. Computer networks, which have been actively developing recently, have significantly increased the importance of programs for ensuring user communication.
What other applications are there?
Some propose to include anti-virus programs in a separate group, the importance of which is growing from year to year due to the increasing prevalence of malware. Professional software environments used by qualified users deserve attention. These are used to create animation and graphics, help develop projects, perform complex accounting calculations, and translate texts. Electronic dictionaries are extremely valuable for many modern users.
An important category of software is educational applications that allow you to improve your level in your chosen specialization without involving third parties. This is most relevant in relation to foreign languages. Tests and tutors programmed in electronic format are in demand.
OS: functionality
The OS works in close interaction with the computer hardware, controls the equipment, and transmits user commands in a format understandable to the machine. OS functionality:
- data exchange between devices;
- storing data and ensuring their availability;
- organization of work processes;
- error reporting, adequate response to an accident;
- monitoring equipment operation;
- access to system tools;
- ensuring mutual dialogue between the machine and the user.
GENERAL PRINCIPLES OF ORGANIZATION AND OPERATION OF COMPUTERS
What is a computer
Computer is a programmable electronic device capable of processing data and performing calculations and other symbol manipulation tasks.
There are two main classes of computers:
digital computers, processing data in the form of numeric binary codes;
analog computers, processing continuously changing physical quantities (electrical voltage, time, etc.), which are analogues of calculated quantities.
Nowadays, the vast majority of computers are digital.
The principle of operation of computers is to execute programs (Software) – predetermined, clearly defined sequences of arithmetic, logical and other operations.
Any computer program is a sequence of individual commands.
Team is a description of the operation that the computer must perform. As a rule, a command has its own code (symbol), initial data (operands) and result.
The result of the command is generated according to the rules precisely defined for this command, embedded in the design of the computer.
The set of commands executed by a given computer is called command system this computer.
Computers operate at very high speeds, ranging from millions to hundreds of millions of operations per second.
In any computer, the following can be distinguished: main devices:
memory(memory device - memory), consisting of renumbered cells;
CPU, including control device(UU)i arithmetic logic unit(ALU);
input device;
output device.
These devices are connected communication channels through which information is transmitted. The main devices of the computer and the connections between them are presented in the diagram (Fig. 1). Thin arrows show the paths and directions of information flow, and thick arrows show the paths and directions of transmission of control signals.
Memory functions:
– receiving information from other devices;
– remembering information;
– provision of information on request to other devices of the machine.
Rice. 1. General computer diagram
Processor functions:
– data processing according to a given program by performing arithmetic and logical operations;
– software control of the operation of computer devices.
The part of the processor that executes instructions is called arithmetic logic device(ALU), and its other part, which performs device control functions, is control device(UU).
Usually these two devices are distinguished purely conditionally; they are not structurally separated.
The processor contains a number of specialized additional memory cells called registers. The register performs the function of short-term storage of a number or command. Electronic circuits can perform manipulations on the contents of some registers, for example, “cutting” certain parts of an instruction for later use or performing certain arithmetic operations on numbers. The main element of the register is an electronic circuit called trigger, which is capable of storing one binary digit (bit). Register is a set of triggers connected to each other in a certain way by a common control system.
There are several types of registers, differing in the type of operations performed. Some registers have their own names, for example:
– adder– an ALU register that performs the summation of binary numbers;
– program counter– register CU, the contents of which correspond to the address of the next executed command; serves for automatic selection of a program from successive memory cells;
– command register– register CU for storing the command code for the period of time necessary for its execution. Some of its bits are used to store operation code, the rest are for storage operand address codes.
Principles of computer operation
The construction of the vast majority of computers is based on the following general principles, formulated in 1945 by an American scientist John von Neumann.
1. Program control principle . A program consists of a set of commands that are executed automatically by the processor in a certain sequence.
Retrieving a program from memory is done using program counter.This processor register sequentially increases the address of the next instruction stored in it by the instruction length. And since the program commands are located in memory one after another, a chain of commands is thereby organized from sequentially located memory cells. If, after executing a command, you need to move not to the next one, but to some other one, use the commands conditional or unconditional transition, which enter into the program counter the number of the memory cell containing the next command. Fetching commands from memory stops after reaching and executing the stop command.
Thus, the processor executes the program automatically, without human intervention.
2.The principle of memory homogeneity. Programs and data are stored in the same memory, so the computer does not distinguish between what is stored in a given memory cell - a number, text or command. You can perform the same actions on commands as on data.
This opens up a whole range of possibilities. For example, the program can also be revised during its execution, which allows you to set rules for obtaining some of its parts in the program itself (this is how the execution of cycles and subroutines is organized in the program).
Moreover, commands from one program can be obtained as results from the execution of another program. Based on this principle translation methods– translation of program text from a high-level programming language into the language of a specific machine.
3. The principle of targeting. Structurally, the main memory consists of renumbered cells. Any cell is available to the processor at any time.
This implies the ability to name memory areas so that the values stored in them can later be accessed or changed during program execution using the assigned names.
Computers built on the listed principles are of the type von Neumann But there are computers that are fundamentally different from von Neumann ones. For example, they may not follow the principle of program control, i.e. they may operate without a program counter indicating the currently executing program command. To access any variable stored in memory, these computers do not need to give it a name. Such computers are called not von Neumann.
Command and its execution
A command is a description of an elementary operation that the computer must perform.
In general, the command contains the following information:
– code the operation being performed;
– definition guidelines operands(or their addresses);
– instructions for placing the received result.
Depending on the number of operands, commands are:
– unicast;
– two-address;
– three-address;
– variable-address.
Commands are stored in memory cells in binary code.
In modern computers command length variable(usually two to four bytes), and the ways to specify variable addresses are very diverse.
The address part of the command may include:
– the operand itself (number or symbol);
– operand address (byte number from which the operand begins);
– address of the operand address (the byte number from which the operand address is located), etc.
Let's look at a few possible options for the addition command(English add - addition), and instead of digital codes and addresses we will use symbols.
1. Unicast commandadd x(cell contents X add with the contents of the adder, and leave the result in the adder):
2. Two-address commandadd x, y(cell contents X And at add and place the result in a cell at):
3. Three-address commandadd x, y, z(cell contents X add with cell contents y, place the amount in the cell z).
