For long storage of information serves. For long-term storage of information serve what carriers? Main types of modern devices

Funds long-term storage And data accumulation (external storage device) provide record and reading large information arrays, which can be used: texts in languages \u200b\u200bin languages high level, programs in machine codes, data files, etc. As external storage devices in PEVM, drives are mainly used on flexible magnetic disks (NGMD) and storage devices on hard magnetic disks (NMD) type "Winchester".

The drives on flexible magnetic disks are the main devices of the external memory of the PC. The carrier of information in NGMD is flexible magnetic disk (GMD) made from a synthetic film covered with wear-resistant ferrolac. Information on gmd is placed in a consecutive code on concentric circles (tracks), each of which is divided into sectors. The sector is a unit of data exchange between OP and NGMD. In one sector, 128.256, 512 or 1024 data bytes can be posted. In PEVM, the listed data formats can be installed software.

The gmd has a mounting hole (UO) to fix the disk in the drive and the index hole (IO) to identify the start of the tracks. To protect against the adverse effects of the external environment, the gmd is placed in a rectangular envelope, which has a slot for the supply of magnetic heads (PMG), slot of the index hole (PIO) and a hole for fastening gmd in a drive (OKD). Information that is recorded on the GMD, in its intended purpose, is divided into service and working. Service information is used to control and synchronize the work of NGMD. It in turn is divided into information, an indentation of the track, and information that the sector indentigress. Work information represents user data.

The NGMD capacity in the PEVM is 160 KB and more depending on the number of magnetic heads in the drive and the data record density on the GMD. There are the following varieties of NGMD: with a single and double record density; One-way - with one and double-sided - with two mg. In bilateral NGMDs, both surfaces of the GMD can be used to record and read data. In accordance with the varieties of NGMD, the corresponding marking of the GMD is adopted: SS is a single density unilateral disk; SD - one-sided disc of double density; DD - double-density double-dens.

Along with the NGMD, developed PC models are also equipped with drives on "Winchester" type magnetic disks. Their distinctive features - Hermetically closed single disk design, magnetic read-write heads and their drive, a small gap (compared to conventional NDMs) between the magnetic heads and the surface of the disk (0.5 μm), a slight pressure of the clips of the magnetic head (10 g Compared with 350 g in conventional NMDs), a small thickness of the magnetic disk.

Hermetically closed design increases 2 times the reliability of operation compared to the usual NMD. Reducing the gap between the surface of the disk and magnetic heads significantly increases the longitudinal and transverse record density. NMD type "Winchester" is considered the third generation of NMD and have close to limit characteristics. Thus, NMD with a diameter of 356 mm on one surface may include up to 1770 tracks (1300 MB of information).

Development of modems.

The first information processing systems in which telegraph equipment was used to connect subscribers to computer, were created in the early 60s. In such systems, the transfer was carried out using conventional telegraph equipment at relatively low speeds, not exceeding 110 bits / s.

The next step in the development of data transmission systems was the development of modems, providing the possibility of transferring binary information on telephone lines.

Modem- an electronic device endowed with data modulating functions on the transmitting end of the communication line and demodulation on the receiving end of the communication line. Modifying the signal means converting the signal to the form that allows it to transmit it to long distances. For example, a typical acoustic modem is equipped with two cup-shaped receptors to which the handset is mounted. The modem is connected to the computer from which it receives information in the form of a sequence of binary signals - bits. However, the phone is designed to transmit sound frequency, and binary bits are only electrical impulses, not heard by the human ear. Therefore, the electrical pulses are previously converted to the modem into sound frequency signals, and then transmitted on telephone lines. On the other end there is a reverse process transfers of sound frequency signals into a sequence of binary electrical pulses - bits suitable for computer operation. Such transformations are called modulating and demodulation, the device described is just the simplest modem.

The first modem samples had relatively low speed Data transmission, however, in the future, the transmission rate over switched channels has increased to 1,200 bits / s in duplex mode - simultaneously input and output information or up to 9600 bps in half-duplex mode - mode intended for alternate input and information output.

Since the mid-60s, the intensive development of specialized information processing systems based on selected channels begins. Such systems are created to ensure the needs of individual organizations owning both computing resources and communication channels. However, the operation of such systems has shown that computational resources and communication channels used in them are not effectively used, the systems are expensive and few adapted to changing conditions. The need for many users has emerged to refer to powerful computing machines for relatively short periods of time.

All this led to the development of collective use data transmission systems, in which many users can connect through the network of public relations in their choice to various information processing tools.

Keyboard.

Keyboard an important and universal information input device into a computer.

By the location of the keys, the desktop keyboards are divided into two main types, not inferior to each other functionally. In the first embodiment, the function keys are located in two vertical rows, and there are no individual groups of the cursor keys. In total, in such a keyboard 84 keys.

The second option of the keyboard, which is customized with an improved, has 101 or 102 keys. The keyboard of this type is supplied today almost all desktop personal computers. Professionals do not like this keyboard due to the fact that the function keys have to have far to reach, to the topmost key of the keys through the entire letter keyboard. However, the number of function keys in the enhanced keyboard is not 10, but all 12.

IN portable Computer The keyboard is usually built-in part of the design.

Location of alphabetic keys on computer keyboards standard. Today QWERTY standard applies everywhere - first Six Latin alphabetic keys of the top row. It corresponds to the domestic standard of Yatsuken Kirillic keys, almost a similar location of the keywords on the typewriter.

Standardization in the size and arrangement of the keys is needed so that the user on any keyboard can work without re-switching the "blind method". Blind-ten-legged work method is the most productive, professional and efficient. Alas, the keyboard due to the low user productivity turns out to be today the most "bottleneck" of the high-speed computing system.

Working with the keyboard is very simple and visual. To make a specific software byte keyboard character, use a special ASCII Code Table (American Standart Code for Information Interchange) -American code for sharing information used on most computers.

After pressing the key, the keyboard sends the interrupt signal processor and causes the processor to pause its operation and switch to the keyboard interrupt processing program.

In this case, the keyboard in its own special memory remembers which key is pressed (usually up to 20 codes of the keys pressed in the keyboard memory, if the processor does not have time to respond to the interrupt). After passing the code, the processor key pressed this information from the keyboard memory disappears.

In addition to pressing the keyboard, it also marks the release of each key, sending the processor to its interrupt signal with the appropriate code.

Entering characters from the keyboard is carried out only at the point of the screen, where the cursor is located. The cursor is a rectangle or a contrast color line in one character.

Special keyboard keys: Special (service) keys perform the following main functions: (ENTER) - command commands for execution of the processor; (ESC) - Acting any action; (TAB) - Move the cursor to the tab position; (Ins) - Put the symbol insertion mode in the cursor position in the symbol slaughter ramp in the cursor position;

(DEL) -Engthen the symbol in the cursor position;

(Backspace) -Engthen the symbol to the left of the cursor;

(HOME) - Moving the cursor to the beginning of the text;

(END) - Cursor-inserted to the end of the text;

(PGUP) - Move the cursor to one on-screen text page up;

(PGDN) - Move the cursor to one on-screen page by text down;

(ALT) and (Ctrl) - while simultaneously pressing these keys from any other, the change in the last action is caused;

(SHIFT) - hold this key in the prescribed state ensures the change of the register;

(CAPS LOCK) -Fixation / Diffixation of the register of capital letters;

External memory is used for long-term storage of information solid media storage drives on rigid magnetic disks (HDD, HDD) hardware implementation of magnetic tape drives - "Streamers" drives on laser disks (CD, Compact Disk, etc.) Media information - Wednesday Recording / reading and storing information.

Option classification of media used in computer technician Media information for computer Ribbon media Magnetic disk carriers Optical Flash carriers Magneto optical

The main type of external memory is the magnetic memory Magnetic recording at the end of 1898 Dane Valdemar Polesen (Valdemar Poulsen) suggested a device for a magnetic sound recording on steel wire. After 30 years, the German engineer Fritz Pleimer (Fritz Pfleumer) presented a sound recording device with a carrier in the form of a paper tape, which caused a thin steel coating. In 1932, the German company AEG demonstrated the first recording apparatus, which was called "Magnetophon". The magnetic tape has the main disadvantage - the ability to demagnetize during long-term storage and has an uneven frequency response (different sensitivity to record at different frequencies). In addition, any magnetic tape has its own noise (the physical properties of the magnetic layer and the methods of recording-play sound).

The principle of the magnetic record consists in the effects of the electromagnetic field on the ferromagnetic material of the magnetic tape, carried out when recording, as well as overwriting an analog signal. The magnetic field in the recording process varies in accordance with the changes in the electrical signals. Electrical oscillations from the sound source are fed to the recording head and excit the magnetic field of the sound frequency (20 Hz - 20 k. Hz). Under the action of this field, there is a magnetization of individual sections of the magnetic tape, evenly moved along the recording heads, erasing and playback (Fig.).

To record playback, as well as the use of various data on computer-readable data media, use analog (sound and video) signal to digital form. Such a technology was named the digitization of information. The principle of digitization (encoding) of the sound is to convert continuous different over the amplitude of the amplitude audio and video signals into the encoded sequence of numbers representing the discrete values \u200b\u200bof the amplitudes of this signal, taken after a certain period of time. To do this, it is necessary to measure the amplitude of the signal at certain intervals and at each time of the segment to determine the average amplitude of the signal. According to the Shanon Theorem (Kotelnikov), this period of time (frequency) should be at least double the maximum frequency of transmitted sound signal (Fig.).

This frequency is called the sampling frequency. Discretization is the process of taking the references of the signal continuous in time in equivalent from each other by the time of points constituting the sampling interval. During the sampling process, the level of analog signal is measured and remembered. Amplitude frequency (Hz) Fig. 13. Convert analog signal into digital. The less often (less) time intervals, the quality of the encoded signal is higher.

Streamers Tape media are used to back up in order to ensure the safety of data. As such devices, a streamer is used (Fig.), And the carrier of information in them is used magnetic tapes in cassettes and tape cartridges. Usually, the recording is carried out to the magnetic tape, the domain corresponds to binary unit. If the reader does not detect it, the value obtained corresponds to zero.

The record system for magnetic discs and diskettes are somewhat similar to the record of the record on the record. Unlike last record It is carried out not on the helix, but on the concentric circles - the tracks ("Tracts" - TRAKS) located on two sides of the disk and forming cylinders. Circle, in turn, are divided into sectors (Fig.). Each floppy sector, regardless of the size of the track, has same sizeequal to 512 bytes, which is achieved by different recording density: less on the periphery and more closer to the center of the floppy disk.

Magneto optical information carrier External high-spirits and storage devices. Magneto-optical disks (MO) appeared in 1988. The monitor is enclosed in a plastic envelope (cartridge) and is an arbitrary access device. It combines the magnetic and optical principles of storage of information and represents a polycarbonate substrate (layer) with a thickness of 1, 2 mm, which causes several thin-film magnetic layers (Fig.). Recording a laser with a temperature of about 200 o. The magnetic layer occurs simultaneously with the change in the magnetic field. Fig. The composition of the Disk.

Data recording is carried out by a laser in a magnetic layer. Under the influence of temperature at the heating site in the magnetic layer, the resistance to the change in polarity is reduced, and the magnetic field changes the polarity at a heated point to the corresponding binary unit. At the end of heating, the resistance increases, but the installed polarity is preserved. Erasing creates the same polarity in a magnetic field corresponding to binary zeros. In this case, the laser beam consistently heats the washed plot. Reading recorded data into the layer is produced by a laser with a smaller intensity that does not lead to the heating of the readable area. At the same time, in contrast to CDs, the disc surface is not deformed.

Compact optical disk (CD) is a plastic disk with a special coating on which recorded information is in digital form. Due to the change in the speed of its rotation, the track relative to the reading beam of the laser moves with a constant linear speed. At the center of the disk the speed is higher, and the edge is slower (1, 2- 1, 4 m / s). The CD use a laser with a radiation wavelength \u003d 0, 78 microns. The "burnable" laser digital information is preserved in the form of "pit" - cigroxks width 0, 6-0, 8 μm and a length of 0, 9-3, 3 μm. There are three main types of CD: ● CD-ROM to which the entry, as a rule, is carried out by the factory method of stamping from the matrix; ● CD-Rs used for one or non-slip laser recording sessions; ● CD-RW intended for multiple recording cycles.

In the CD-R (Compact Disk Recordable) on top of the reflective layer of gold, silver or aluminum, there is an organic layer of special light-melting plastic. In view of this, such a disk is sensitive to heating and exposure to direct sunlight. In CD-RW, an organic composition is also used as an intermediate layer, but it is capable of moving from a crystalline (transparent for laser) in amorphous with a strong heating. Weak heating returns it back to the crystalline state. Thus, overwriting is carried out.

DVD In early 1997, a CD standard called DVD (Digital Video Disc) appeared, designed mainly to record high-quality video programs. In the future, the DVD abbreviation received the following value - Digital Versatile Disc (universal digital disc), as more fully meets the capabilities of these disks to write sound, video, textual information, PC software, etc. DVD provides higher image quality than CD. They use a laser with a shorter radiation wavelength \u003d 0, 635-0, 66 μm. This allows you to increase the record density, i.e. reduce the geometric sizes of PIT up to 0, 15 μm and the pathway up to 0, 74 μm.

The density of the optical disc recording is determined by the laser wavelength length, that is, the possibility to focus on the disc surface of the beam with a stain, the diameter of which is equal to the wavelength. Following the DVD, at the end of 2001, Blu-ray devices appeared, allowing to operate in the blue region of the spectrum with a wavelength \u003d 450-400 nm.

Fluorescent Multilayer Disk (Fluorescent Multilayer Disk) is used to increase the tank. The principle of their action consisting in changing the physical properties (the appearance of fluorescent luminescence) of some chemicals under the influence of the laser beam (Fig.). Here, instead of CD and DVD technologies using reflected signal, under the influence of a laser, the light is emulsioned directly information. Such discs are made of transparent photochromas. Under the influence of laser radiation, they include a chemical reaction, and individual sections of the information layer ("Petes") are filled with fluorescent material. This method can be considered by the method of data recording. In the greater degree, such a record is possible when using three-dimensional holography, which is now in a crystal size with a sugar cube, to accommodate up to 1 TB of data.

Two main types of Flash memory are used: NAND and NOR (logical or-no) and Nand (logical function and non). The NOR structure consists of parallel enabled elementary storage cells. Such the organization of the cells provides random access to the data and the delete record of information. The NAND structure is based on the principle of a serial connection of elementary cells forming groups (16 cells in one group), which are combined into pages, and pages in blocks. With such a construction array, an appeal to individual cells is impossible. Programming is performed simultaneously only within one page, and when erasing, the circulation occurs to blocks or block groups.

NOR chips work well jointly with RAM RAM, so more often used for BIOS. When working with relatively large data arrays, recording / erasing processes in the NAND memory are performed much faster than in the NOR memory. Since the 16 adjacent Nand memory cells are connected in series, without contact gaps, a high density of cell location on a crystal is achieved, which makes it possible to obtain a large container with the same technological standards. From the mid-1990s. NAND microcircuits appeared in the form of solid-state disks (SOLID STATE DISK, SSD). To compare the access time in the SDRAM it is 10-50 μs, the flash memory is 50-100 μs, and the hard drives - 5000 - 10,000 μs.

Salted Samsung hard drive. The speed of reading from such a disc is 57 MB / s, and the recording speed is 32 MB / s. SSD power consumption is less than 5% of the indicators of traditional hard drives, increasing more than 10% time autonomous work Portable PC. SSD provide ultra-high reliability of data storage and have proven itself in extreme temperatures and humidity conditions. Petersburg firm "Just. Soft "offered Flash driver. RAID to combine two flash drives in a RAID array.

Flash memory is a portable non-volatile drive. The following Flash Memory Standards are commonly used: Compact. Flash, Smart. Media, Memory Stick, Floppy disks, Multi. Media Cards, etc. They can be used instead of floppy disk, laser and magneto-optical compact, small hard drives. Modern replaceable flash memory devices provide high speed Data exchange (Ultra High Speed) - more than 16, 5 Mbps. To connect to the USB port of the computer, special USB Flash. DRIVE (Fig.), Which are mobile small-sized storage devices that do not have mobile and rotating mechanical parts.

Holography is a photographic method of recording, playback and conversion of wave fields. For the first time he was proposed in 1947 by the Hungarian physicist Dennis Gabor. In 1960, with the advent of the laser, it was possible to accurately record and reproduce volume images In the Crystal of Niobate Lithium. Since the 1980s, with the advent of CDs, holographic information storage devices based on laser optics have become one of the external memory technologies. Holographic memory represents the entire volume of storage medium of the medium, and the data elements accumulate and read in parallel.

Modern holographic storage devices were called HDSS (Holographic Data Storage System). They contain: laser, beam discriminator for separating a laser beam, mirrors for the direction of laser rays, a liquid crystal panel used as a spatial light modulator, lenses for focusing laser rays, a lithium niobate crystal or a photopolymer as a storage device, a photodetector for reading information (Fig.) .

And information. Clear things, things like wedding photos or videos, I want to save for a long memory. However, how to do it?

Concept

Informatics determines that for long-term storage of information, it is all possible drives and carriers that can only be represented. As you understand, it is possible to ensure security and the safety of data. Let's determine which form storage forms exist.

Graphic / Fine. The most ancient way adapted for it appeared in prehistoric times in the form of rock paintings, passed the stage of painting and turned into the art of photography. In addition, the information in graphical form appears in the form of drawings and schemes.
Text. The most common way to store data is today. Various books and recordings, libraries. If we talk about reliability, this method of storage is not only not protected from theft, but also is short-lived. It is best to preserve except culinary books that are initially printed on materials adapted to the aggressive environment.
The next step after the invention of writing - mathematics , Numerical form storage information. A sufficiently highly specialized area is used to determine the quantitative characteristics of a subject, surrounding space.
Sound recording. The ability to store sounds appeared only in 1877 with the invention of sound recording devices.
Video information. The next step in the storage of graphic information appeared with the creation of cinema.

Information processes

Informational processes imply search, storage, transmission, use and basic and primary business is to save data. What is the difference, can we get or transfer the information if we can not save it?

The main is the process of storing information. This is a way to transfer data in space and time. For long-term storage of information, a device or device depends on the type of stored data is used. Information systems serve as information systems to ensure the ordering of this process. Any such system is equipped with search procedures, placement and input / output of data. The main distinguishing feature of the information system is the presence of all these key procedures. For example, comparable two libraries. The private library at your home in the closet is not an information system, because it is only oriented you. On the other hand, the public urban library, in which everything is ordered on the card file and there are standardized procedures for issuing books, undoubtedly is a system.

Computer Century

With the development of not even a computer, and the Internet information systems are upgraded. The storage process has simplified due to the possibility of its translation into digital form. And despite the beliefs of some people that e-books or paintings do not carry the souls, for long-term storage of information, this method of preserving data is much more efficient than the rest, and includes all possible information, unless you can translate it into digital view.

Modernity

For long-term storage of information, a personal computer and its external devices are served. They are divided into several types depending on the recording method.

optical discs;
hard drives;
flash memory.

Have the most different volume and are best adapted for transferring and storing information. Hard disks are designed to store large amounts of data, but their reliability leaves much to be desired. And, of course, flash drives. They are middle link between rigid and optical discs, provide storage of information in sufficient volumes and for a sufficiently long period, just do not wet them. In any case, the storage method choose you.

In order to store information for long time and transfer from one data media to another, devices are used on hard disks, DVD, CD-equipment, flash drives, drives on flexible disks.

Winchester is a means of constant saving information, programs in the computer.

Flexible magnetic disk is the principle of data recording on magnetic tapes. Such a device can accommodate information up to 600 pages of a text document.

CD is the principle of an optical record. You can write even the encyclopedia that contains many volumes. Flash memory is a device that does not need food from electricity.

Many are thinking: what does it serve for long-term storage of information? So, the structure of my story is as follows:

what serves for long-term storage of information;
types of information.

What serves for long-term storage of information

The main thing information process It is the process of saving information, that is, the method due to which it is possible to transmit data on space and time. In order to save information, devices or devices that depend on the type of stored information are used. In order to ensure the ordering of this process, the availability of information systems equipped with a search procedure, placement, as well as editing information. Main distinctive feature of information systems - data Key procedures.

Programmers are determined by: in order to save information, external storage devices should be used. It can be a drive or a carrier of all sorts of types, which may be imagined to yourself.

Types of information

In addition to the foregoing, it should be said about what information types are. So information may be as follows:

textual;
visual;
numerical;
sound recorder;
video.

The most common in today the method of saving information is the text type. True, this storage method is not reliable and durable. Graphic, or the pictorial type - the most ancient storage method of information, these are all sorts of schemes, graphics and drawings.

COURSE WORK

in the discipline "Informatics"

Long-term storage devices

Introduction

1. Basic concepts

2. Classification of long-term storage devices

3. Detailed characteristics of devices of long-term storage of information

3.2 Optical disks

3.3 Flash Memory

4. Practical part

Conclusion

Bibliography

Introduction

In information storage computers allocate the following main types of memory: internal memory, cache memory and external memory. In addition, various specialized types of memory may be present in EUM characteristic of certain computing system devices, such as video memory.

In the theoretical part of this course work will be considered devices of long-term storage of information. Such devices relate to the external memory of the computer and allow you to save information for subsequent use regardless of whether the computer is turned on or off.

Modern society is characterized by the intensive development of technical and software. Based on timely replenishment, accumulation, recycling of the information resource, rational management is possible and the adoption of certain solutions. This is especially important for the sector of the economy. Permanent growth of information flows places increased requirements for the application of storage devices. In this regard, the consideration of the issue concerning the means of long-term storage of information is very relevant.

This topic will be disclosed using the following questions:

1. Basic concepts;

2. Classification of devices of long-term storage of information;

3. Detailed characteristics of devices of long-term storage of information.

In the practical part of the course work, the task will be solved:

The organization includes a magazine calculation of income tax with employee wages from the point of view of divisions. Types of divisions are presented in Fig. 1. At the same time, the following rule works:

All deductions are provided according to the table (Fig. 2) Only the employees of the "main" job place, the remaining workers pay tax with the total amount.

This term paper was performed on an IBM standard configuration PC, including system unit, monitor, keyboard, mouse with the following characteristics: 64-bit microprocessor AMDATHLONIIX3 3.0 GHz, RAM 8192 MB, NVIDIAGEFORCEGTX 550 TI 1024 MB video card, WD hard drive with a volume of 2 TB, DVD-RWNEC, LG 22 monitor with a resolution of 1920x1080 . The work was carried out in Windows 7 maximum OS using text editor Microsoft. Office Word. 2010, MICROSOFT table processor Office Excel 2010 included in the integrated PPP Microsoft Office. 2010 Professional Plus.

Introduction

Information storage devices (external memory) are computer components that allow virtually unlimited time to maintain large amounts of information without electricity consumption (non-volatile).

The first such devices for PCs were floppy drives (FDD) and replaceable floppy disks - at the beginning of the five-year (5.25 ") capacity of 360 KB and 1.2 MB, then three-tie (3.5") capacity of 1, 44 MB. Currently, it is rarely applied due to the wide distribution of flash memory devices with a container of several gigabytes.

A characteristic feature of the external memory is that its devices operate with blocks of information, but not by bytes or words, as whether the RAM allows. These blocks usually have a fixed size, a multiple degree of numbers 2. The unit can be rewritten from internal memory In external or back only entirely, and to perform any external memory exchange operation requires a special procedure (subroutine). Exchange procedures with external memory devices are tied to the device type, its controller and method of connecting the device to the system (interface).

External memory is used to long-term storage of large amounts of information. In modern computer systems as external memory devices, the most commonly applied:

* Storage devices on hard magnetic disks (NGMD)

* Drives on flexible magnetic disks (NGMD)

* Drives on optical disks

* Magneto optical media.

1. Basic concepts

External memory is the memory implemented in the form of external motherboard, devices with different storage principles and media types intended for long-term storage of information. In particular, all computer software is stored in the external memory. The external memory devices can be placed both in the computer's system unit and in separate cases. Physically, the external memory is implemented in the form of drives.

Drives are storage devices intended for long (which does not depend on power) storage of large amounts of information. The capacity of the drives hundreds of times the capacity of RAM or is generally unlimited when it comes to drives with interchangeable media.

The carrier is a physical storage environment, appearance It may be disk or tape. According to the principle of memorization, magnetic, optical and magneto-optical media differ. Ribbon carriers can only be magnetic, in disk carriers use magnetic, magneto-optical and optical methods for recording-reading information.

2. Classification of long-term storage devices

As information storage devices, external memory are used, which are implemented in the form of relevant technical means for storing information. All drives used in PCs are unified in constructive execution. Their sizes are standardized: the width and height of the devices is most rigid, the depth is limited only to the maximum permissible value. Such standardization is necessary for the unification of structural compartments of PC cases.

External memory can be with arbitrary access and consistent access. Random Access Memory Devices allow you to access an arbitrary data block in approximately the same access time. Memory devices with allegant access allow access to data sequentially, i.e. In order to read the desired memory block, you need to consider all previous blocks.

Allocate the following main types of memory devices:

1. Hard magnetic drives (Winchesters, HDD) - non-removable hard magnetic discs. They refer to external memory with direct access to data and are divided into internal, installed in the system block of the computer and external (portable) relative to the system unit.

2. Drives on flexible magnetic disks (floppy drives, NGMD) - devices for recording and reading information from small removable magnetic disks (floppy disks) packed in a plastic envelope (flexible - 5.25 inch diskettes and hard 3.5 inch ). Reference to external memory with direct (arbitrary) access to data stored on a magnetic disk and are intended for long-term storage relative to small amounts of information.

3. Information drives on optical disks are external (arbitrary) access to the data and are intended for long-term storage of relatively large amounts of information (hundreds of megabytes and tens of gigabytes).

4. Flash-memory-based information storage devices refer to external memory with direct (arbitrary) data access and are intended for long-term storage relative to small amounts of information (gigabyte units).

5. Magnetic tape drives (NML) - data reading devices from magnetic ribbons, which belong to external memory with sequential access. Such drives are sufficiently slow, albeit a large tank. Modern devices for working with magnetic ribbons - streamers - have an increased recording speed of 4-5 MB in sec. There are also devices allowing you to record digital information on video tapes, which allows you to store on 1 magazine 2 GB of information. Magnetic ribbons are usually used to create data archives for long-term storage of information.

6. Perfoocards - Dense paper cards and Perflectors - Coils with a paper tape, in which the information is encoded by penetrating (perforation) holes. Sequential access devices are used to read the data.

Currently, devices with sequential access to the NGMD data are morally outdated and do not apply, therefore we will not consider them in detail.

3. Detailed characteristics of devices of long-term storage of information

3.1 Hard magnetic drive drives

Fig. 1 Hard Drive (Winchester)

Drive on hard magnetic disks, or hard drive is an energy-dependent, rewritable computer storage device. The data stored on the hard disk is not lost when the computer is turned off, which makes the hard drive ideal for long-term storage of programs and data files, as well as the most important programs. operating system (OS). This its ability allows you to get a hard drive from one computer and insert to another.

Inside sealed hard disk There are one or more unbending disks covered with metal particles. Each disk has a head (electromagnet), built into the hinge lever, which moves above the disk during its rotation. The head magnetizes metal particles, forcing them to line up for the presentation of zeros and units binary numbers (Fig. 1). Motors, moving disk and lever, are usually deposited. Avoid wear manifest only the head, since it never comes into contact with the surface of the disk.

The name "Winchester" received the drive thanks to IBM, which in 1973 released hDD Models 3340, first combined the disc plate in one indefinite case and read heads. When developing it, engineers used the brief internal name "30-30", which meant two modules (in the maximum layout) of 30 MB each. Kenneth Hoton, Project Manager, on Winchester 30-30, with the designation of the popular hunting rifle "Winchester 30-30" suggested calling this drive "Winchester".

Before use, new hard drives must be formatted. This process is in laying magnetic concentric tracks and in their breakdown to small sectors, like pieces in the cake. But if data was recorded on the hard disk, its formatting will result in their full destruction.

Due to more Roads on each side of the disks and large number Disc Information Capacity Hard Disk can reach 150-200 GB. The recording speed and reading of information from hard drives is large enough (can reach 133 MB / s) due to speed rotation of the disks (up to 7500 revolutions / min).

Other parameters note:

1) Cache-memory capacity - in all modern disk drives, a cache buffer is installed, accelerating data exchange; The more its capacity, the higher the likelihood that in the cache memory will be the necessary information that does not need to be read from the disk (this process is thousands of times slower); Cache buffer capacitance in different devices It may vary within the borders from 64 KB to 2 MB;

2) The average access time is the time (in milliseconds), during which the head block is shifted from one cylinder to another. Depends on the design of the drive of the heads and is approximately 10-13 ms;

3) the delay time is the time from the moment of positioning the head block to the desired cylinder before positioning the specific head to the specific sector, in other words, is the time of searching for the desired sector;

4) exchange rate - determines the amount of data that can be transmitted from the drive to the microprocessor and in reverse direction During certain intervals; maximum value This parameter is equal bandwidth disk interface and depends on what mode is used.

In hard drives, sufficiently fragile and miniature elements are used (carrier plates, magnetic heads, etc.), therefore, in order to save information and performance, hard drives must be protected from shocks and sharp changes in spatial orientation during operation.

Class 7200 / 3.5 Disk Market Leaders, CompaniesSeagate, Maxtor and WWD, also produce external hard drives, made in a separate case with a power supply, USB orIEEEE1394 interface (FireWire).

Hard disk, regardless of the presence or absence of a drive for flexible disks, is always customary called "C".

3.2 Optical disks

In addition to drives for working with flexible discs personal computers Usually include devices for working with optical (laser) discs, which have a diameter of 5.25 inches (133 mm).

CD-ROM drive

Fig. 3. CD

In 1995, the first optical disk drive appeared in the PC basic configuration - CD-ROM (COMPACTDiskReadonlyMemory, a constant storage device of CDs) (Fig. 2). The device used multi-layer CDs with a diameter of 120 mm and a thickness of 1.2 mm, the capacity of the disk 650-700 MB.

The CD consists of 4 layers (top-down):

2) layer for record information;

3) reflective layer;

4) base of polycarbonate.

The process of making a disc consists of operations by spraying silver or gold of a reflective layer to the base, applying a transparent layer to it for recording information and squeezing on it of recesses forming a spiral track, running from the center of the disk to its edge. For disk stamping, the prototype matrix (master disc) of the future disk is used. After that, a protective layer of transparent plastic is applied to the surface of the disk.

CD-ROM reads information from a disk using a laser beam with a wavelength of 780 nm, which is different from the surface of the disk (Land) and recesses on the surface (PIT). The minimum size of the pit is 0.88 microns, the step of the tracks is 1.5 microns.

The main characteristics of CD-ROM:

1) the data transfer rate - is measured in multiple shares of the speed of the audio CD player and characterizes the maximum speed with which the drive forwards data into the computer's operational memory;

2) Access time - the time required to search for information on the disk is measured in milliseconds.

CD-RW Drive

The device is used to record information on cD-R discs (Single recording) and CD-RW (CD-Rewritable is a rewritable disk).

Externally, it looks like a CD-ROM and compatible with it to the size of the disks and recording formats. Data recording is carried out using special software or operating system.

CD-R or CD-RW has 4 layers (top-down):

1) a protective layer of polycarbonate;

2) an active layer for recording information;

3) reflective layer;

4) base of polycarbonate.

DVD-ROM drive

Further development of CD making technologies led to the creation of high-density discs, which were called digital universal disks (DVD - Digital Versatile Disk). In such disks, a spiral track of recording - reading data with reduced gaps between adjacent turns is used. In addition, the depressions and protrusions have a smaller size compared to CDs. This made it possible to increase the amount of information on the disk to 4.7 GB.

According to the DVD data structure, there are:

§ DVD-Video (read-only) - contain movies (video, sound);

§ DVD-AUDIO - contain audio data high quality;

§ DVD-DATA - contain any data.

How do DVD media happen:

§ DVD-ROM drives made by injection molding (casting under pressure from durable polycarbonate plastic);

§ DVD-R - Operating Discs - the format developed by Pioneer. The technology of the record is similar to CD-R and is based on an irreversible change under the influence of the laser of the spectral characteristics of the information layer, covered with a special organic composition. On the dVD-R discs can be recorded both computer data, multimedia programs and video, audio information;

§ DVD + RW - multiple wheels (RW - Rewritable) entries. On the dVD disks+ RW write and video, and sound, and computer data. DVD + RW discs can be overwritten about 1000 times;

§ DVD-RW - multiple recording format developed by Pioneer. DVD-RW discs contain 4.7 GB to one side, are available in one-sided and double-sided modifications and can be used to store video, audio and other data. DVD-RW discs can be overwritten up to 1000 times and are read on the first generation DVD-ROM drives;

§ DVD-RAM - repeated recording wheels (RAM - RandomaccessMemory) - format developed by Panasonic, Hitachi, Toshiba. First generation dVD disks-Ram accompanied 2.6 GB to the side. Modern - second-generation discs are 4.7 GB on the side or 9.4 GB for bilateral modification. The most important advantages of DVD-RAM disks are overwriting up to 100,000 times, the presence of a recording error correction mechanism.

Blu-ray and HD drives

In 2002, representatives of nine leading high-tech companies Sony, Panasonic, Samsung, LG, Philips, Thomson, Hitachi, SharPioneer at a joint press conference announced the creation and promotion of a new high-capacity optical disk format called Blu-Raydisk - a rewritable disc next generation Standard CD / DVD size 12 cm with a maximum recording capacity of one layer and one side up to 27 GB.

The HDDVD format was proposed by TOSHIBA and NEC at the 2003 DVD Forum session. In February 2008, it became known about the actual victory of Blu-Raynad HDDVD: Toshiba reported on full folding of work in this direction. The production of films and other programs on HDDVD also stopped.

TechnologyBlu-RayyHD was created primarily for recording, storing and playing video and audio information, however, these discs can be recorded and simply data. Blu-ray format involves working with a resolution video stream up to 1080p, sound up to 7.1 and support for HDCP information protection protocol. Video coding algorithms - MPEG-2 HD, VC1 (Video Codec 1, based on Windows Media Video 9) and H.264 / MPEG-4 AVC, sound formats - AC3, MPEG1, MPEG Layer 2. For digital video players of Blu- format Raydecoding will be done hardware for computer drives - software.

Blu-ray devices have high data transfer speeds. According to the specification, the maximum data transfer rate between Blu-ray drive and the target device can reach 36 Mbps.

3.3 Flash Memory

Fig. 3. Flash memory

computer information memory disc

Flash memory has appeared for a long time (the first samples were developed by Toshiba back in 1984), but its mass use began with the wide distribution of digital cameras. Today manufacturers produce flash memory of several types:

§ Flash cards (Fig. 3) Compact Flash (CF), Smart Media (SM), Multi Media Card (MMC), Secure Digital (SD), Memory Stick Pro (MSPRO), Memory Stick (MS) and XD-Picture (XD) - To work with them, you need a flash card reader;

§ USB flash memory self-sufficient and does not require applications additional devices To record and read information, has a connector for connecting to the USB port of the PC.

Flash memory is a type of esappa, its full name Flash Erase Eeprom (Electronically Erasable Programmable ROM) can be translated as "quickly electrically erasable programmable constant memory." In other words, the flash memory is an energy-dependent (not consuming energy when storing data) overwritten memory, the contents of which can be quickly erased.

As a high-speed and universal storage device for transferring a sufficiently large amount of data, it is convenient to use USB flash memory.

4. Practical part

General characteristic of the task

The organization includes a magazine calculation of income tax with employee wages from the point of view of divisions. Types of divisions are presented in Fig. 4. At the same time, the following rule works:

All deductions are provided according to the table (Fig. 5) only employees of the "main" job place, the remaining workers pay tax with the total amount.

1. Build tables according to the data below (Fig. 4-6).

2. Organize interstabilities to automatically fill the graph of the document "Log for calculating income tax individuals (NDFL) "" Name of the division "," NDFL "(Fig. 6).

3. Configure the check in the "Opening Place" field on the entered values \u200b\u200bwith the error message output.

4. Determine the monthly amount of the tax paid by an employee (in a few months).

5. Determine the total amount of personal income PFFs for each subdivision.

6. Determine the overall listed Ndfl amount listed in the month.

7. Build a histogram according to the summary table.

Fig. 4 List of organization divisions

Fig. 5. Betting benefits and taxes

Fig. 6 Table data of the magazine calculation of income from individuals

The solution of the problem

1. Run the MSExcel tabular processor.

2. Sheet 1 Rename into a sheet with the name "Division".

3. On the work sheet of the "division" we create a table of the list of units of the organization (Fig. 7).

Fig. 7. Location of the table "List of units of the organization" on the work sheet "Divisions" Msexcel

4. Sheet 2 rename to a sheet with the name of the bet, on which we create a table of "betting and taxes" table and fill it according to the condition (Fig. 8).

Fig. 8 Location of the table "Betting and taxes" on the work sheet MSEXCEL rates

5. Sheet 3 rename to a sheet with the name of NFFL, on which we create a table "The magazine calculation of income from individuals" and fill it with the source data (Fig. 9).

Fig. 9 Location of the Table "Magazine Calculation of Revenues from Individuals" on the work sheet of the NDFL MSEXCEL

6. We organize interstabilities to automatically fill in the Count of the Magazine Calculation of income from individuals: "Name of the Unit", "NDFL".

To do this, fill the Count the name of the division of the table "The magazine for calculating income tax from individuals", located on a list of NDFL as follows:

We enter the E3 formula:

View ($ D $ 3: $ D $ 22; divisions! $ A $ 3: $ A $ 7; Divisions!

The formula for the remaining cells (s E3 in E22) introduced into the E3 cell is E3.

Thus, a cycle will be performed that controls the parameter of which is the code division code "The magazine calculation of income from individuals" (Fig. 10).

Fig. 10. Filling the graph of the magazine calculation of the tax on income from individuals "Name of the division"

7. Configure the check in the "View of Work" field on the entered values \u200b\u200bwith the error message output. To do this, in MSExcel, select "Data Check". In the Count "Type of Data", choose the "list", "source" - "view of the place of work" (basic / not basic) (Fig. 11).

Fig. 11. Setting up the check in the "Workshop" field on the entered data with the error message output

Split-entered in the cell G3 formula for the remaining cells (with G3 in G22) of this graph. Now, when entering foreign values \u200b\u200bto the cell data, the program will issue an error message (Fig. 12).

Fig. 12 Error message when entering an extraneous value in the cell

We enter the J3 formula:

If (g3 \u003d "not basic"; F3; (F3- (bets! $ B $ 3) - (P * (rates! $ C $ 3)) -

(If (i3 \u003d "disabled"; rates! $ D $ 3)))) * (bets! $ A $ 3)%

The formula entered into the cell introduced into the cell for the remaining cells (with j3 in j22) of this graph.

Thus, a cycle will be performed, the control parameter of which is the graph of the failure of the table of the table "The magazine for calculating income from individuals" and the columns of the "Betting and Tax rates" table on the MSExcel bet worksheet (Fig. 13).

Fig. 13 Filling the chart of the magazine for calculating tax on income from individuals "NDFL"

9. In order to determine the total amount of personal income tax on each unit and the total listed organization, the amount of NDFL in a month must be created a summary table based on the data of the table "The magazine for calculating the income tax from individuals" (Fig. 14).

Fig. 14 Creating a summary table on the workstate "NDFL" MSEXCEL

10. Sheet 4 Rename into a list with the name "Results", on which a consolidated table is built (Fig. 15).

Fig. 15. Summary table on the work sheet "Results" MSEXCEL

11. In order for the results of the calculation results graphically, we construct a histogram according to the summary table (Fig. 16).

Fig. 16. Creation of a histogram according to the summary table on the work list the results of MSExcel

Graphic results of calculations are presented in Fig. 17.

Fig. 17 Works Leaf Results MSExcel

Conclusion

So, in the theoretical part of the course work, devices for long-term storage of data on PC were considered.

To work with the external memory, it is necessary to have a drive (device that provides the record and (or) reading information) and storage devices.

Main types of drives:

* storage devices on flexible magnetic disks (NGMD);

* storage drives on hard magnetic disks (NGMD);

* CD-ROM drives, CD-RW, DVD;

They correspond to the main types of media:

* Flexible magnetic discs (floppydisk) (3.5 "diameter" and a capacity of 1.44 MB; with a diameter of 5.25 "" and a capacity of 1.2 MB (currently outdated and practically not used, the release of drives intended for disks with a diameter 5.25 "", also stopped)), discs for interchangeable carriers;

* Hard Magnetic Disks (harddisk);

* CD-ROM discs, CD-R, CD-RW, DVD;

* Flash memory.

To date, optimal devices for long-term data storage, depending on the timing, volume and storage objectives, are: DVDs, hard drives, flash memory.

List of used literature

1. Groshev A.S. Informatics: Textbook for universities. - Arkhangelsk, Arkhang. State tehn University, 2010.

2. Informatics: laboratory workshop for students of 2 courses of all specialties. - M.: The university tutorial, 2006.

3. Kopras on computer science.

4. Odintsov B.E., Romanov A.N. Informatics in the economy: studies. benefit. - M.: School Textbook, 2008.

5. Yashin V.M. Informatics: PC hardware: studies. benefit. - M.: Infra-M, 2008.