With the advent of computers, the issue of storing information, which was originally supplied in digital form, became very acute. And now this problem is very relevant, because you want to save the same photos or videos for a long memory. That is why you will initially have to find the answer to the question of what devices and media serve for long-term storage of information. You should also fully appreciate all their advantages and disadvantages.
The concept of information and methods of its storage
There are several basic types of information data that can be found on computers today. The most common forms are text, graphics, audio, video, mathematical and other formats.
In the simplest version, information is stored on the hard drives of computers on which the user saves the file initially. But this is only one side of the coin, because in order to view (extract) this information, you need at least an operating system and appropriate programs, which, by and large, also represent information data.
It is interesting that in schools in computer science lessons, when choosing the correct answer to such questions, there is often a statement that, they say, RAM is used for long-term storage of information. And schoolchildren who are not familiar with the specifics and principles of its work consider this the right answer.
Unfortunately, they are wrong, because the RAM stores only information about the programs that are running in this moment processes, and when they are terminated or the system is rebooted, RAM is completely cleared. This is similar to the once-popular children's drawing toys, when you could first draw something on the screen and then shake the toy and the drawing would disappear, or when the teacher erased the text written in chalk from the blackboard.
How information was stored in the past
The very first method of storing information in the form of rock paintings (by the way, graphics) has been known since time immemorial.
Much later, with the advent of speech, the preservation of information began to be a process, so to speak, of transmission from mouth to mouth (myths, legends, epics). Writing led to the fact that books began to appear. Do not forget the paintings or drawings. With the advent of photography, sound and video recording technologies, corresponding media appeared on the information field. But all this turned out to be short-lived.
Device for long-term storage of information: basic requirements
As for computer systems, it should be clearly understood what requirements modern media must meet in order for information to be stored on them for as long as possible.
The most important requirement is durability and resistance to wear and physical or other damage. And in relation to any type of carriers, one can speak about time intervals very relatively, because, as you know, "nothing lasts forever under the Moon."
What media are used for long-term storage of information
Now let's go directly to devices on which data of any type can be stored, if not forever, then at least for a long time. So, what types of media are used for long-term storage of information?
Among the most commonly used for computer technology distinguish the following:
- internal and removable hard and ZIP drives of computers;
- optical CDs, DVDs and Blu-ray media;
- flash memory of any type;
- floppy disks (now used extremely rarely).
Media Advantages and Disadvantages
As can be seen from the above list, only hard drives built into computers are classified as internal devices data storage. All other media are external.
But all of them are more or less subject to aging or external influences. In this sense, floppy disks or the same CDs or media of a different format are the most unsafe, although optical media in this respect seem to be more durable. But how long can they last? 5-10 years? But if the information stored on them is viewed very often, the service life is reduced.
Flash drives and hard drives have a longer service life, but they are not immune to wear, damage and aging.
Hard drives begin to “crumble” (this is a natural process), flash drives can be exposed to the same sunlight, moisture, or even delete data if removed incorrectly or software failures. In addition, there are many more additional factors that can lead to device inoperability.
Nevertheless, speaking of the fact that the devices listed above are used for long-term storage of information, it should be borne in mind that such a classification is given solely for the current state of affairs in the computer world. Who knows, maybe even in the foreseeable future, completely new carriers using other technologies will be invented, because, as stated, the creation of quantum computers is not far off.
Reliable storage of information is a problem familiar to most modern enterprises, the solution of which always raises the question: how to get a high-quality result at a relatively low cost? Storage of documentation in in electronic format ensures not only its safety, but also unimpeded availability in real time.
For long-term and reliable storage of archival information in electronic form, various types of storage media are used. The main requirement for such media is the exclusion of the possibility of physically making changes to archived data or deleting them. The information carrier must provide a single record and at the same time be able to read information multiple times. These requirements are met by an information carrier of the WORM type - Write Once, Read Many (write once, read many times). Other basic requirements for information media include durability and maximum archival storage capacity.
Hard drives.
The use of hard drives allows you to organize the so-called "operational" storage of archival data, which provides permanent on-line access to archival documents. The core of such storage is a tiered archive storage architecture, in which frequently requested archive data is stored on "fast" hard drives with an external Fiber Channel (FC) or Serial Attached SCSI (SAS) interface, and infrequently requested archive data is stored on "slow" hard drives. external Serial ATA (SATA) and NL-SAS drives.
There is an opinion that systems Reserve copy- this is a burden for the IT budget, and for the IT department, so to speak, an extra headache. But ... Manufacturers of data storage systems (SHD) on hard drives of all levels still recommend using backup systems to tape media as part of such solutions, with the help of which a copy of data is created, from which, in case of failure of the storage system, it will be possible to recover data.
Tape media.
The main purpose of tape media is to create backup copies of operational data (backup). On the basis of tape media, you can also organize archival storage of information. Tape solutions provide non-real-time (near-line) access to archived information. The basis of this solution is a robotic tape drive. Today, the volume of data storage on one tape medium in the LTO-5 format is 1.5 TB (3 TB with the possibility of data compression). Therefore, tape storage systems are used to securely store information of large amounts of archived data. These solutions also have a number of serious drawbacks. Tapes are demagnetized, torn, it is necessary to constantly rewind the tape in cartridges, it takes a lot of time to search for a specific file, while the tape in the cartridge is rewound to the right place, the fragility of the media forces you to periodically transfer data from the old tape to a new tape. When organizing off-line storage, cartridges with archival data must be stored in rooms with certain environmental requirements or in specialized cabinets.
optical media.
To organize long-term storage of archival data, it is necessary to use optical disk drives. Such drives ensure the fulfillment of all requirements for archival storage and archival data storage. High reliability, long periods of storage of archival data, contactless work with media, authenticity and immutability of archived data, fast random access to archived data, high capacity of optical media, organization of off-line storage of archived data are important parameters when choosing optical media.
Today, the most popular optical media recording format is the Blu-ray format, which provides a high archiving density of up to 100 GB per optical media. Support for WORM at the hardware level allows you to store archived data recorded on optical media, which cannot be deleted or changed later. And the "open" recording format of the UDF type allows you to read archival information in any device that supports working with such optical media. The main task is to store rarely requested and unchangeable archived data. Practice shows that the amount of such data is about 80% of the total amount of data stored on the operational (on-line) storage. At the same time, 20% of these archived data will never be in demand. By sending such data to archival storage based on optical media, the Customer can free up to 80% of the storage volume on the operational (on-line) storage, which will entail a reduction in the volume and size of the backup window.
Solutions on optical media provide non-real-time (near-line) access to archival information. The volume of archival data storage in the drive on optical media and the number of readers is determined according to the terms of reference. Various types of building archival solutions are supported, up to the "mirroring" of archival data between geographically distributed drives on optical media. Non-contact work with optical media eliminates the possibility of damage to the working surfaces of optical media. Provides backward compatibility with previous types of optical media such as CD\DVD. When organizing archival data storage based on an optical media drive, it is not necessary to create backups this data.
Advantages and disadvantages
Hard drives
- Online access to archival information
- Random access to archived information
- Solution Popularity
- High power consumption
- Expensive solution
- Required to back up archived data
- Minimum "terms" of life (maximum 3 years)
- If the mechanical part of the hard drive fails, data recovery is almost impossible.
- Not intended for organizing off-line storage
Tape media
- Large volumes of archival data storage
- High-speed recording of information on tape media
- Low power consumption
- High total cost of ownership
- Minimum "terms" of life (on average up to 5 years)
- "Closed" format for recording information on tape media
- Low read access time (minimum 5 min)
- Loss of information when exposed to electromagnetic radiation
- Possibility of mechanical damage (tape rupture)
Optical media
- Non-volatility of optical media
- Storage period of archival information from 50 years
- Support for the WORM function at the hardware level (immutability of archived data)
- Possibility of organizing off-line storage of archival data
- "Open" recording format (UDF) on optical media
- Low total cost of ownership
- Low power consumption
Conclusion
Most specialists in the field of building archival solutions agree that for archival storage of information with the possibility of online access to it, it is best to use a multi-level structure of archival data storage. The main criterion in choosing a solution should not be cheapness, but the mechanism for saving and protecting archived data, which is implemented in this solution. Before making a final choice, it is necessary to check all hardware and software for compatibility.
electronic computing device for processing numbers;
a device for storing information of any kind;
multifunctional electronic device for working with information;
device for processing analog signals.
2. Computer performance (speed of operations) depends on:
monitor screen size
clock frequency of the processor;
supply voltage;
keystroke speed;
the amount of information being processed.
3. Processor clock speed is:
the number of binary operations performed by the processor per unit of time;
the number of cycles performed by the processor per unit of time;
the number of possible processor accesses to RAM per unit of time;
the speed of information exchange between the processor and the input / output device;
speed of information exchange between the processor and ROM.
4. The "mouse" manipulator is a device:
input of information;
modulation and demodulation;
reading information;
to connect the printer to a computer.
5. Read-only storage device is used for:
storing the user program during operation;
recordings of especially valuable application programs;
storage of constantly used programs;
storage of computer boot programs and testing of its nodes;
permanent storage of especially valuable documents.
6. For long-term storage of information is used:
RAM;
CPU;
magnetic disk;
drive.
7. Storing information on external media is different from storing information in RAM:
the fact that information can be stored on external media after the computer is turned off;
volume of information storage;
the possibility of protecting information;
ways to access stored information.
8. During performance application software stored:
in video memory
in the processor
in RAM;
in ROM.
9. When the computer is turned off, the information is erased:
from RAM;
from ROM;
on a magnetic disk;
on CD.
10. A floppy drive is a device for:
processing commands of the executable program;
reading/writing data from external media;
storing commands of the executable program;
long-term storage of information.
11. To connect a computer to telephone network used:
modem;
plotter;
scanner;
a printer;
monitor.
12. Program control computer operation involves:
the need to use operating system for synchronous operation of hardware;
execution by the computer of a series of commands without user intervention;
binary encoding of data in a computer;
the use of special formulas for the implementation of commands in the computer.
13. File is:
an elementary information unit containing a sequence of bytes and having a unique name;
an object characterized by a name, value and type;
set of indexed variables;
set of facts and rules.
14. The file extension, as a rule, characterizes:
file creation time;
file size;
the space occupied by the file on the disk;
the type of information contained in the file;
the location where the file was created.
15. Full path to the file: c:\books\raskaz.txt. What is the name of the file?
books\raskaz;.
raskaz.txt;
books\raskaz.txt;
txt.
16. The operating system is -
a set of basic computer devices;
programming system in a low-level language;
software environment that defines the user interface;
a set of programs used for operations with documents;
programs to destroy computer viruses.
17. Programs for pairing computer devices are called:
loaders;
drivers;
translators;
interpreters;
compilers.
18. System diskette is required for:
for emergency boot of the operating system;
file systematization;
storing important files;
computer virus treatment.
19. Which device has the highest information exchange rate:
CD-ROM drive;
HDD;
floppy disk drive;
RAM;
processor registers?
volatile.
e) Faster access.
g) Slower access.
2. What Memory in bytes will take the next binary
3. Text in volume 1024 bits located in random access memory, starting from byte number 10 . What will be the address last byte
4. List at least five devices you know external memory.
5. What difference disks CD- ROM, CD- RW And CD- R?
Urgently needed. Very. 1. Which of the following characteristics relate to RAM and which to external memory? but)It is volatile.
b) Its volume is measured in tens and hundreds of gigabytes.
c) Used for long-term storage of information.
d) Its volume is measured in hundreds of megabytes or several gigabytes.
e) Faster access.
f) Used for temporary storage of information.
g) Slower access.
2. How much memory in bytes will the following binary code take: ? Explain your answer.
3. A text of 1024 bits is located in RAM, starting from byte number 10. What will be the address of the last byte that is occupied by this text?
4. List at least five external memory devices you know.
5. What is the difference between CD-ROM, CD-RW and CD-R discs?
Homework No. 5 Topic: Computer memory 1. Which of the following characteristics relate tooperational, and which - to external memory?
a) It is volatile.
b) Its volume is measured in tens and hundreds of gigabytes.
c) Used for long-term storage of information.
d) Its volume is measured in hundreds of megabytes or several gigabytes.
e) Faster access.
f) Used for temporary storage of information.
g) Slower access.
2. What Memory in bytes will take the next binary the code: ? Explain your answer.
3. Text in volume 1024 bits located in random access memory, starting from byte number 10 . What will be the address last byte, which is occupied by the given text?
4. List at least five devices you know external memory.
COURSE WORK
in the discipline "Informatics"
Devices for long-term storage of information
Introduction
1. Basic concepts
2. Classification of devices for long-term storage of information
3. Detailed characteristics of devices for long-term storage of information
3.2 Optical discs
3.3 Flash memory
4. Practical part
Conclusion
Bibliography
INTRODUCTION
The main types of memory used in storage computers are internal memory, cache memory, and external memory. In addition, a computer may contain various specialized types of memory that are characteristic of certain devices of a computing system, for example, video memory.
In the theoretical part of this course work, devices for long-term storage of information will be considered. Such devices refer to the external memory of the computer and allow you to save information for later use, regardless of whether the computer is turned on or off.
Modern society is characterized by intensive development of hardware and software. On the basis of timely replenishment, accumulation, processing of the information resource, rational management and making the right decisions is possible. This is especially important for the economic sector. The constant growth of information flows places increased demands on the use of data storage devices. In this regard, consideration of the issue concerning the means of long-term storage of information seems to be very relevant.
This topic will be covered with the following questions:
1. Basic concepts;
2. Classification of devices for long-term storage of information;
3. Detailed characteristics of devices for long-term storage of information.
In the practical part of the course work, the following problem will be solved:
The organization maintains a journal for calculating income tax on employee salaries from the point of view of departments. The types of subdivisions are shown in fig. 1. In this case, the following rule works:
All deductions are provided according to the table (Fig. 2) only to employees of the “main” place of work, other employees pay tax on the total amount.
This course work was carried out on an IBM PC of a standard configuration, including system unit, monitor, keyboard, mouse with the following specifications: AMDAthlonIIX3 3.0 GHz 64-bit microprocessor, 8192 MB RAM, NVIDIA GeForceGTX 550 Ti 1024 MB graphics card, 2 TB WD hard drive, DVD-RWNEC, LG 22" monitor with a resolution of 1920x1080 The work was carried out in Windows 7 Ultimate using text editor Microsoft Office Word 2010, spreadsheet Microsoft Office Excel 2010 included in the integrated PPP Microsoft Office 2010 Professional Plus.
INTRODUCTION
Information storage devices (external memory) are computer components that allow you to store large amounts of information for almost unlimited time without consuming electricity (non-volatile).
The first such devices for PCs were Floppy disk drives (FDD) and removable floppy disks - first five-inch (5.25 ") with a capacity of 360 Kb and 1.2 Mb, then three-inch (3.5") with a capacity of 1.44 Mb. Currently, they are rarely used due to the widespread use of flash memory devices with a capacity of several gigabytes.
A characteristic feature of external memory is that its devices operate with blocks of information, but not bytes or words, as RAM allows. These blocks usually have a fixed size, a multiple of a power of 2. The block can be rewritten from internal memory to external memory or back only in its entirety, and to perform any exchange operation with external memory, it is required special procedure(subroutine). Procedures for exchanging with external memory devices are tied to the device type, its controller, and the way the device is connected to the system (interface).
External memory used for long-term storage of large amounts of information. In modern computer systems, the most commonly used external memory devices are:
* hard disk drives (HDD)
* floppy disk drives (FPHD)
* optical disc drives
* magneto-optical storage media.
1. BASIC CONCEPTS
External memory is memory implemented in the form of external, relatively motherboard, devices with different principles of information storage and types of media, designed for long-term storage of information. In particular, all computer software is stored in external memory. External memory devices can be placed both in the computer system unit and in separate cases. Physically, external memory is implemented in the form of drives.
Drives are storage devices designed for long-term (which does not depend on power supply) storage of large amounts of information. The capacity of drives is hundreds of times greater than the capacity of RAM, or even unlimited when it comes to drives with removable media.
The media is the physical medium for storing information. appearance can be disk or tape. According to the principle of storage, magnetic, optical and magneto-optical media are distinguished. Tape media can only be magnetic; disk media uses magnetic, magneto-optical and optical methods of writing and reading information.
2. CLASSIFICATION OF DEVICES FOR LONG-TERM STORAGE OF INFORMATION
External storage devices are used as information storage devices, which are implemented in the form of appropriate technical means for storing information. All drives used in PCs are unified in design. Their standard sizes are standardized: the width and height of devices are most rigidly set, the depth is limited only by the maximum allowable value. Such standardization is necessary to unify the structural compartments of PC cases.
External memory can be random access and sequential access. Random access memory devices allow an arbitrary block of data to be accessed in approximately the same access time. Sequential memory devices allow data to be accessed sequentially, i.e. in order to read the desired block of memory, it is necessary to read all the previous blocks.
There are the following main types of memory devices:
1. Hard disk drives (hard drives, HDD) - non-removable hard magnetic disks. They refer to external memory with direct access to data and are divided into internal, installed in the system unit of the computer and external (portable) in relation to the system unit.
2. Floppy disk drives (floppy drives, floppy disk drives) - devices for writing and reading information from small removable magnetic disks (floppy disks) packed in a plastic envelope (flexible - for 5.25 inch diskettes and hard for 3.5 inch diskettes) ). They refer to external storage devices with direct (random) access to data stored on a magnetic disk and are designed for long-term storage of relatively small amounts of information.
3. Information storage devices on optical disks are external storage devices with direct (random) access to data and are designed for long-term storage of relatively large amounts of information (hundreds of megabytes and tens of gigabytes).
4. Information storage devices based on flash memory are external storage devices with direct (random) access to data and are designed for long-term storage of relatively small amounts of information (a few gigabytes).
5. Magnetic tape drives (NML) - devices for reading data from a magnetic tape, which are external storage devices with serial access. Such drives are quite slow, although they have a large capacity. Modern devices for working with magnetic tapes - streamers - have an increased write speed of 4-5 MB per second. There are also devices that allow you to record digital information on video cassettes, which allows you to store 2 GB of information on 1 cassette. Magnetic tapes are commonly used to create data archives for long-term storage of information.
6. Punched cards - cards made of thick paper and punched tape - reels with paper tape, on which information is encoded by punching (perforating) holes. Serial access devices are used to read data.
Currently, devices with sequential access to floppy data are obsolete and are not used, so we will not consider them in detail.
3. DETAILED CHARACTERISTICS OF DEVICES FOR LONG-TERM STORAGE OF INFORMATION
3.1 Hard disk drives
Rice. 1 Hard drive (hard drive)
A hard disk drive, or hard drive, is a volatile, rewritable computer storage device. The data stored on the hard drive is not lost when the computer is turned off, making the hard drive ideal for long-term storage of programs and data files, as well as the most important operating system (OS) programs. This ability of his allows you to get a hard drive from one computer and insert it into another.
Inside a sealed hard drive are one or more hard drives coated with metal particles. Each disc has a head (electromagnet) built into an articulated arm that moves over the disc as it rotates. The head magnetizes the metal particles, causing them to line up to represent ones and zeros. binary numbers(Fig. 1). The motors that move the disc and lever are usually subject to wear. Only the head can avoid wear because it never comes into contact with the disc surface.
The drive received the name "hard drive" thanks to IBM, which in 1973 released the model 3340 hard drive, which for the first time combined disk platters and reading heads in one all-in-one case. During its development, engineers used the short internal name "30-30", which meant two modules (in the maximum layout) of 30 MB each. Kenneth Haughton, project leader, in consonance with the designation of the popular hunting rifle "Winchester 30-30", suggested calling this disc a "Winchester".
New hard drives must be formatted before use. This process consists of laying out magnetic concentric tracks and breaking them into small sectors, like slices in a cake. But if data was recorded on the hard disk, then formatting it will lead to their complete destruction.
Due to more tracks on each side of discs and a large number disks, the information capacity of a hard disk can reach 150-200 GB. The speed of writing and reading information from hard drives is quite high (can reach 133 MB / s) due to the fast rotation of the disks (up to 7500 rpm).
Other parameters include:
1) cache memory capacity - all modern disk drives have a cache buffer that speeds up data exchange; the larger its capacity, the higher the probability that the cache will contain the necessary information that does not need to be read from disk (this process is thousands of times slower); cache buffer capacity different devices can vary from 64 KB to 2 MB;
2) average access time - the time (in milliseconds) during which the block of heads is shifted from one cylinder to another. Depends on the design of the actuator and is approximately 10-13 ms;
3) delay time - this is the time from the moment of positioning the block of heads on the desired cylinder to positioning a specific head on a specific sector, in other words, this is the search time for the desired sector;
4) exchange rate - determines the amount of data that can be transferred from the drive to the microprocessor and in the opposite direction for certain periods of time; the maximum value of this parameter is equal to the bandwidth of the disk interface and depends on which mode is used.
Hard disks use fairly fragile and miniature elements (carrier platters, magnetic heads, etc.), therefore, in order to preserve information and performance, hard disks must be protected from shock and sudden changes in spatial orientation during operation.
Market leaders in 7200/3.5” drives from Seagate, Maxtor and WD also produce external hard drives in a separate case with a power supply, USB or IEEE1394 (FireWire) interface.
A hard drive, whether or not a floppy drive is present, is always referred to as "C".
3.2 Optical discs
In addition to floppy disk drives, the personal computers usually included are devices for working with optical (laser) discs, which have a diameter of 5.25 inches (133 mm).
CD-ROM drive
Rice. 3. CD
In 1995, the first optical disc drive appeared in the basic PC configuration - CD-ROM (CompactDiskReadOnlyMemory, compact disc read only memory) (Fig. 2). The device used multilayer CDs with a diameter of 120 mm and a thickness of 1.2 mm, the disc capacity was 650-700 MB.
A CD consists of 4 layers (from top to bottom):
2) Layer for recording information;
3) Reflective layer;
4) Polycarbonate base.
The manufacturing process of a disc consists of sputtering a silver or gold reflective layer onto the base, applying a transparent layer on it to record information, and squeezing recesses on it that form a spiral track going from the center of the disc to its edge. For stamping a disk, a prototype matrix (master disk) of the future disk is used. After that, a protective layer of transparent plastic is applied to the surface of the disc.
CD-ROM reads information from a disc using a laser beam with a wavelength of 780 nm, which reflects differently from the surface of the disc (land) and depressions on the surface (pit). The minimum pit size is 0.88 µm, the track pitch is 1.5 µm.
Key Features of CD-ROM:
1) Data transfer rate - measured in multiples of the speed of an audio CD player and characterizes the maximum speed at which the drive transfers data to the computer's RAM;
2) Access time - the time required to search for information on the disk, measured in milliseconds.
CD-RW drive
The device is used to record information on CD-R (write once) and CD-RW (CD-ReWritable - rewritable discs).
Outwardly, it looks like a CD-ROM and is compatible with it in terms of disc sizes and recording formats. Data recording is carried out using special software or operating system tools.
A CD-R or CD-RW has 4 layers (top to bottom):
1) Polycarbonate protective layer;
2) Active layer for recording information;
3) Reflective layer;
4) Polycarbonate base.
DVD-ROM drive
Further development of CD manufacturing technologies led to the creation of high-density discs, which were called Digital Versatile Disks (DVD - Digital Versatile Disk). Such disks use a spiral track for writing - reading data with reduced gaps between adjacent turns. In addition, the pits and protrusions are smaller compared to CDs. This made it possible to increase the amount of information on the disk up to 4.7 GB.
According to the data structure, DVDs are:
§ DVD-Video (read-only) - contain movies (video, sound);
§ DVD-Audio - contain high quality audio data;
§ DVD-Data - contain any data.
How DVD media are:
§ DVD-ROM - discs made by injection molding (injection molding from durable polycarbonate plastic);
§ DVD-R - Write-Once Disc - a format developed by Pioneer. The recording technology is similar to CD-R and is based on an irreversible change under the influence of a laser of the spectral characteristics of the information layer coated with a special organic compound. On the DVD-R discs can be recorded as computer data, multimedia programs, and video, audio information;
§ DVD+RW -- multiple (RW -- ReWritable) recording discs. DVD+RW discs record video, sound, and computer data. DVD+RW discs can be rewritten about 1000 times;
§ DVD-RW is a rewritable format developed by Pioneer. DVD-RW discs hold 4.7 GB per side, are available in single-sided and double-sided versions, and can be used to store video, audio, and other data. DVD-RW discs can be rewritten up to 1000 times and are readable on first generation DVD-ROM drives;
§ DVD-RAM - rewritable discs (RAM - RandomAccessMemory) - a format developed by Panasonic, Hitachi, Toshiba. The first generation of DVD-RAM discs held 2.6 GB per side. Disks of the current - second - generation carry 4.7 GB per side or 9.4 GB for double-sided modification. The most important advantages of DVD-RAM discs are rewriting 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, Sharp and Pioneer at a joint press conference announced the creation and promotion of a new high-capacity optical disc format called Blu-RayDisk - the next generation rewritable disc with standard 12 cm CD/DVD with a maximum recording capacity per layer and one side up to 27 GB.
The HDDVD format was proposed by Toshiba and NEC at the August 2003 DVD Forum session. In February 2008, it became known about the actual victory of Blu-Ray over HDDVD: Toshiba announced the complete curtailment of work in this direction. Movies and other HDDVD programs have also been discontinued.
Blu-Ray and HD technologies were created primarily for recording, storing and playing video and audio information, but you can also write data to these discs. The Blu-Ray format involves working with a video stream of resolution up to 1080p, sound up to 7.1 and support for the HDCP information protection protocol. Supported video encoding algorithms - MPEG-2 HD, VC1 (Video Codec 1, based on Windows Media Video 9) and H.264/MPEG-4 AVC, audio formats - AC3, MPEG1, MPEG Layer 2. For Blu-Ray digital video players, decoding will be done in hardware, for computer drives - in software.
Blu-ray devices have a high data transfer rate. According to specification maximum speed data transfer between the Blu-ray drive and the target device can reach 36 Mbps.
3.3 Flash memory
Rice. 3. Flash memory
computer information memory disk
Flash memory appeared quite a long time ago (the first samples were developed by Toshiba back in 1984), but its mass use began with the widespread use of digital cameras. Today, manufacturers produce several types of flash memory:
§ Flash cards (Figure 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;
§ The USB flash memory is self-sufficient and does not require the use of additional devices for writing and reading information; it has a connector for connecting to a PC USB port.
Flash memory is a type of EEPROM, its full name Flash Erase EEPROM (Electronically Erasable Programmable ROM) can be translated as "fast electrically erasable programmable read-only memory". In other words, flash memory is a volatile (not consuming power while storing data) rewritable memory, the contents of which can be quickly erased.
As a fast and versatile storage device for transferring a sufficiently large amount of data, it is convenient to use a USB flash memory.
4. PRACTICAL PART
General characteristics of the task
The organization maintains a journal for calculating income tax on employee salaries from the point of view of departments. The types of subdivisions are shown in fig. 4. In this case, the following rule works:
All deductions are provided according to the table (Fig. 5) only to employees of the “main” place of work, other employees pay tax on the total amount.
1. Build tables according to the data below (Fig. 4-6).
2. Organize inter-table links to automatically fill in the column of the document “Journal of calculation of personal income tax (PIT)” “Name of the unit”, “PIT” (Fig. 6).
3. Set up a check in the "Type of place of work" field for input values with an error message.
4. Determine the monthly amount of tax paid by the employee (for several months).
5. Determine the total amount of personal income tax for each unit.
6. Determine the total amount of personal income tax transferred by the organization for the month.
7. Build a histogram based on the pivot table data.
Rice. 4 List of organizational units
Rice. 5. Benefit and tax rates
Rice. 6 Tabular data of the journal for calculating personal income tax
The solution of the problem
1. Run the spreadsheet MSExcel.
2. Sheet 1 is renamed into a sheet with the name "Subdivisions".
3. On the "Subdivisions" worksheet, create a table of the list of organization's subdivisions (Fig. 7).
Rice. 7. Location of the table "List of departments of the organization" on the worksheet "Departments" MSExcel
4. Rename sheet 2 to a sheet with the name Rates, on which we create a table “Best and tax rates” and fill it in according to the condition (Fig. 8).
Rice. 8 Location of the Benefit and Tax Rates table on the MSExcel Rates worksheet
5. We rename sheet 3 into a sheet with the name of personal income tax, on which we create the table "Journal of calculation of personal income tax" and fill it with the initial data (Fig. 9).
Rice. 9 Location of the table "Journal of calculation of personal income tax" on the personal income tax worksheet MSExcel
6. We organize inter-table links to automatically fill in the columns of the journal for calculating personal income tax: “Name of the unit”, “NDFL”.
To do this, fill in the column Name of the subdivision of the table "Journal of calculation of personal income tax", located on the personal income tax sheet as follows:
Enter the formula in cell E3:
VIEW($D$3:$D$22;Departments!$A$3:$A$7;Departments!
We multiply the formula entered in cell E3 for the remaining cells (from E3 to E22) of this column.
Thus, a cycle will be executed, the control parameter of which is the subdivision code of the table “Journal of calculation of income tax from individuals” (Fig. 10).
Rice. 10. Filling in the column of the journal for calculating the tax on income from individuals "Name of the unit"
7. Set up a check in the "Type of place of work" field for input values with an error message. To do this, select "Data Validation" in MSExcel. In the "Data type" column, select "List", "Source" - "Type of place of work" (main / non-main) (Fig. 11).
Rice. 11. Setting up a check in the "Type of place of work" field for input data with an error message
We multiply the formula entered in cell G3 for the remaining cells (from G3 to G22) of this column. Now, when you enter extraneous values into the cell data, the program will display an error message (Fig. 12).
Rice. 12 Error message when entering an extraneous value in a cell
We enter the formula in cell J3:
IF(G3="non-main";F3;(F3-(Bets!$B$3)-(p*(Bets!$C$3))-
(IF(I3="disabled",Bets!$D$3))))*(Bets!$A$3)%
We multiply the formula entered in cell J3 for the remaining cells (from J3 to J22) of this column.
Thus, a loop will be executed, the control parameter of which is the Disability Benefit column of the Personal Income Tax Calculation Log table and the columns of the Benefit and Tax Rates table on the MSExcel Rates worksheet (Fig. 13).
Rice. 13 Filling in the column of the journal for calculating personal income tax "Personal Income Tax"
9. In order to determine the total amount of personal income tax for each unit and the total amount of personal income tax transferred by the organization for the month, it is necessary to create a summary table based on the data of the completed table “Journal of calculation of personal income tax” (Fig. 14).
Rice. 14 Creating a pivot table on the worksheet "personal income tax" MSExcel
10. Sheet 4 is renamed into a sheet with the name "Results", on which the pivot table is built (Fig. 15).
Rice. 15. Pivot table on the worksheet "Results" MS Excel
11. In order to present the results of calculations graphically, we will build a histogram according to the data of the pivot table (Fig. 16).
Rice. 16.Creating a histogram based on the data of the pivot table on the MSExcel Totals worksheet
Graphical calculation results are shown in Fig. 17
Rice. 17Worksheet MSExcel Summary
CONCLUSION
So, in the theoretical part of the course work, devices for long-term data storage on a PC were considered.
To work with external memory, you must have a drive (a device that provides recording and (or) reading information) and a storage device - a carrier.
The main types of drives:
* floppy disk drives (FPHD);
* drives on hard magnetic disks (HDD);
*drives CD-ROM, CD-RW, DVD;
They correspond to the main types of media:
* floppy disks (FloppyDisk) (3.5"" in diameter and 1.44 MB in diameter; 5.25" in diameter and 1.2 MB in capacity 5.25 "", also discontinued)), disks for removable media;
*hard magnetic disks (HardDisk);
*CD-ROMs, CD-Rs, CD-RWs, DVDs;
*flash memory.
To date, the optimal devices for long-term data storage, depending on the timing, volume and purpose of storage, are: DVD-ROMs, hard drives, Flash-memory.
LIST OF USED LITERATURE
1. Groshev A.S. Informatics: Textbook for universities. - Arkhangelsk, Arkhang. state tech. un-t, 2010.
2. Informatics: Laboratory workshop for 2nd year students of all specialties. - M.: Vuzovsky textbook, 2006.
3. COPRs in informatics.
4. Odintsov B.E., Romanov A.N. Informatics in Economics: Proc. allowance. - M.: High school textbook, 2008.
5. Yashin V.M. Informatics: PC hardware: Proc. allowance. - M.: INFRA-M, 2008.
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A variant of the classification of information carriers used in computer technology Information carriers for computers Magnetic tape carriers Optical disk carriers Magneto-optical flash carriers
The main type of external memory is magnetic memory. Magnetic Recording At the end of 1898, the Dane Valdemar Poulsen proposed a device for magnetically recording sound on steel wire. Thirty years later, the German engineer Fritz Pfleumer introduced a sound recording device with a paper tape carrier coated with a thin steel coating. In 1932, the German company AEG demonstrated the first sound recording device, which was called "Magnetophon". Magnetic tape has the main disadvantage - the ability to demagnetize during long-term storage and has an uneven frequency response (different sensitivity to recording at different frequencies). In addition, any magnetic tape has its own noise (the physical properties of the magnetic layer and methods of sound recording and playback).
The principle of magnetic recording is the effect of an electromagnetic field on the ferromagnetic material of a magnetic tape, which is carried out during recording, as well as rewriting an analog signal. The magnetic field during the recording process changes in accordance with changes in electrical signals. Electrical vibrations from a sound source are fed to the recording head and excite a magnetic field of sound frequency (20 Hz - 20 kHz) in it. Under the action of this field, individual sections of the magnetic tape are magnetized, uniformly moving along the recording, erasing and playback heads (Fig.).
For recording-playback, as well as the use of various data on machine-readable data carriers, the conversion of an analog (sound and video) signal into digital form is used. This technology is called digitization of information. The principle of digitization (coding) of sound consists in converting continuous audio and video signals of different magnitude into an encoded sequence of numbers representing discrete values of the amplitudes of this signal, taken after a certain period of time. To do this, it is necessary to measure the signal amplitude at certain time intervals and determine the average signal amplitude at each time interval. According to the Shenon (Kotelnikov) theorem, this time interval (frequency) must be at least twice the maximum frequency of the transmitted sound signal(Rice.).
This frequency is called the sampling rate. Discretization is the process of taking samples of a signal continuous in time at equally spaced points in time that make up the sampling interval. The sampling process measures and stores the level of the analog signal. Amplitude Frequency (Hz) Fig. 13. Convert analog signal to digital. The rarer (smaller) the time intervals, the higher the quality of the encoded signal.
Tape drives Tape media is used for backup purposes to ensure data integrity. As such devices, a streamer is used (Fig.), And as an information carrier, they use magnetic tapes in cassettes and tape cartridges. Typically, a tape is recorded byte by byte, with the domain corresponding to a binary one. If the reader does not detect it, then the resulting value is zero.
The system for recording on magnetic disks and floppy disks is somewhat similar to the system for recording on records. Unlike the latter, the recording is not carried out in a spiral, but on concentric circles - tracks ("tracks" - traks), located on two sides of the disk and forming, as it were, cylinders. Circles, in turn, are divided into sectors (Fig.). Each sector of the floppy, regardless of the size of the track, has the same size, equal to 512 bytes, which is achieved by different recording densities: less at the periphery and more closer to the center of the floppy.
Magneto-optical information carrier is an external highly reliable device for transferring and storing information. Magneto-optical disks (MOs) appeared in 1988. MO disk is enclosed in a plastic envelope (cartridge) and is a random access device. It combines the magnetic and optical principles of information storage and is a polycarbonate substrate (layer) 1.2 mm thick, on which several thin-film magnetic layers are deposited (Fig.). Recording with a laser at a temperature of about 200 o. C on the magnetic layer occurs simultaneously with the change in the magnetic field. Rice. The composition of the MO disk.
Data recording is carried out by a laser in a magnetic layer. Under the influence of temperature at the heating point in the magnetic layer, the resistance to polarity change decreases, and the magnetic field changes the polarity at the heated point by the corresponding binary unit. At the end of heating, the resistance increases, but the established polarity is maintained. Erasure creates the same polarity in the magnetic field, corresponding to binary zeros. In this case, the laser beam sequentially heats the area to be erased. The reading of the recorded data in the layer is performed by a laser with a lower intensity, which does not lead to heating of the read area. At the same time, unlike CDs, the surface of the disc is not deformed.
A compact optical disc (CD) is a specially coated plastic disc that contains digitally recorded information. Due to the change in the speed of its rotation, the track moves relative to the reading laser beam at a constant linear speed. At the center of the disk, the speed is higher, and at the edge it is slower (1.2–1.4 m/s). The CD uses a laser with a wavelength of radiation = 0.78 μm. The digital information “burned” by the laser is stored in the form of “pit” - lines 0.6–0.8 µm wide and 0.9–3.3 µm long. There are three main types of CDs: ● CD-ROMs, which are usually recorded in the factory by stamping from a matrix; ● CD-Rs used for single or multiple laser recording sessions; ● CD-RWs designed for multiple write/erase cycles.
In CD-R (Compact Disk Recordable), on top of a reflective layer of gold, silver or aluminum, there is an organic layer of a special fusible plastic. In view of this, such a disc is sensitive to heat and direct sunlight. CD-RW also uses an organic compound as an intermediate layer, but it is capable of changing from a crystalline (transparent to a laser) state to an amorphous state upon strong heating. Slight heating returns it back to the crystalline state. This is how the rewrite is done.
DVD In early 1997, a compact disc standard called DVD (Digital Video Disc) appeared, intended primarily for recording high-quality video programs. In the future, the abbreviation DVD received the following meaning - Digital Versatile Disc (universal digital disc), as it more fully meets the capabilities of these discs for recording sound, video, text information, PC software, etc. DVD provides more high quality images than CD. They use a laser with a shorter radiation wavelength = 0.635–0.66 µm. This makes it possible to increase the recording density, i.e., to reduce the geometric dimensions of the pit to 0.15 μm and the track pitch to 0.74 μm.
The recording density of optical discs is determined by the wavelength of the laser, that is, the ability to focus a beam with a spot on the surface of the disc, the diameter of which is equal to the wavelength. After DVD, at the end of 2001, Blu-Ray devices appeared, allowing you to work in the blue region of the spectrum with a wavelength = 450–400 nm.
To increase the capacity, fluorescent discs are also used - FMD (Fluorescent Multilayer Disk). The principle of their operation is to change the physical properties (the appearance of a fluorescent glow) of some chemicals under the influence of a laser beam (Fig.). Here, instead of CD and DVD technologies that use a reflected signal, under the influence of a laser, light is emitted directly from the information layer. These discs are made of transparent photochrome. Under the influence of laser radiation, a chemical reaction occurs in them, and individual sections of the information layer (“pitas”) are filled with fluorescent material. This method can be considered as a bulk data recording method. To a greater extent, such a recording is possible using three-dimensional holography, which now makes it possible to place up to 1 Tb of data in a crystal the size of a sugar cube.
There are two main types of Flash memory used: NAND and NOR (NOR logic function) and NAND (NAND logic function). The NOR structure consists of elementary information storage cells connected in parallel. This organization of cells provides random access to data and byte-by-byte recording of information. The NAND structure is based on the principle of serial connection of elementary cells forming groups (16 cells in one group), which are combined into pages, and pages into blocks. With such a construction of a memory array, access to individual cells is impossible. Programming is carried out simultaneously only within one page, and when erasing, access occurs to blocks or groups of blocks.
NOR chips work well together RAM RAM, so are more commonly used for BIOS. When working with relatively large data arrays, the write / erase processes in NAND memory are much faster than in NOR memory. Since 16 adjacent NAND memory cells are connected in series without contact gaps, a high density of cells on a chip is achieved, which allows you to get a large capacity at the same technological standards. Since the mid 1990s. NAND chips appeared in the form of solid state disks (Solid State Disk, SSD). For comparison, the access time for SDRAM is 10–50 µs, for flash memory it is 50–100 µs, and for hard drives it is 5000–10000 µs.
Samsung solid state hard drive. The read speed from such a disk is 57 MB / s, and the write speed to it is 32 MB / s. SSD power consumption is less than 5% of that of traditional hard drives, increasing more than 10% of the time battery life portable PCs. SSDs provide ultra-high storage reliability and perform well in extreme temperatures and humidity. Petersburg firm “Prosto. Soft” suggested the Flash driver. RAID for combining two flash drives into a RAID array.
Flash memory is a portable, non-volatile storage device. Commonly used flash memory standards are: Compact. Flash, Smart. Media, Memory Stick, Floppy Disks, Multi. Media Cards, etc. They can be used instead of floppy disks, laser and magneto-optical compact, small hard drives. Modern removable flash memory devices provide high data transfer rates (Ultra High Speed) - more than 16.5 Mbps. To connect to the USB port of a computer, special USB Flash Drives (Fig.) are used, which are mobile small-sized data storage devices that do not have moving and rotating mechanical parts.
Holography is a photographic method of recording, reproducing and transforming wave fields. It was first proposed in 1947 by the Hungarian physicist Dennis Gabor. In the 1960s, with the advent of the laser, it became possible to accurately record and reproduce volumetric images in a lithium niobate crystal. Since the 1980s, with the advent of compact discs, holographic information storage devices based on laser optics have become one of the external memory technologies. Holographic memory represents the entire volume of the storage medium of the carrier, while the data elements are accumulated and read in parallel.
Modern holographic storage devices are called HDSS (holographic data storage system). They contain: a laser, a beam splitter for splitting the laser beam, mirrors for directing the laser beams, a liquid crystal panel used as a spatial light modulator, lenses for focusing the laser beams, a lithium niobate crystal or a photopolymer as a storage device, a photodetector for reading information (Fig.) .