Information carrier- the physical environment directly storing information. The main carrier of information for a person is his own biological memory (human brain). A person's own memory can be called working memory. Here the word "operational" is synonymous with the word "fast". Learned knowledge is reproduced by a person instantly. We can also call our own memory internal memory because its carrier - the brain - is inside us.
Information carrier- a strictly defined part of a particular information system, which serves for intermediate storage or transmission of information.
The basis of modern information technologies- It's a computer. When we are talking about computers, then we can talk about storage media as external storage devices ( external memory). These data carriers can be classified according to various features, for example, according to the type of execution, the material from which the carrier is made, etc. One of the options for the classification of information carriers is shown in Fig. 1.1.
The list of storage media in fig. 1.1 is not exhaustive. Some storage media will be discussed in more detail in the following sections.
Data storage It is a way of disseminating information in space and time. The method of storing information depends on its carrier (a book is a library, a picture is a museum, a photograph is an album). This process is as ancient as the life of human civilization. Already in antiquity, man was faced with the need to store information: notches on trees so as not to get lost while hunting; counting objects with the help of pebbles, knots; images of animals and episodes of hunting on the walls of caves.
The computer is designed for compact storage of information with the ability to quick access To her.
Information system- this is a repository of information, equipped with procedures for entering, searching and placing and issuing information. The existence of such procedures main feature information systems that distinguish them from simple accumulations of information materials.
disk file drive information
TAPE STORAGE MEDIA
Magnetic tape- a magnetic recording medium, which is a thin flexible tape consisting of a base and a magnetic working layer. The working properties of a magnetic tape are characterized by its sensitivity during recording and signal distortion during recording and playback. The most widely used is a multilayer magnetic tape with a working layer of needle-shaped particles of magnetically hard powders of gamma-iron oxide (y-Fe2O3), chromium dioxide (CrO2) and gamma-iron oxide modified with cobalt, usually oriented in the direction of magnetization during recording.
DISK MEDIA
Disk media refer to machine media with direct access. The concept of direct access means that the PC can “access” the track on which the section with the required information begins or where new information needs to be written.
Disk drives are the most diverse:
Floppy disk drives (FPHD), they are also floppy disks, they are also floppy disks
Hard disk drives (HDD), they are also hard drives (popularly just "screws")
Optical CD drives:
CD-ROM (Compact Disk ROM)
There are other types of disk storage media, such as magnetic optical discs, but due to their low prevalence, we will not consider them. Floppy disk drives
Some time ago, floppy disks were the most popular means of transferring information from computer to computer, since the Internet was a rarity in those days, computer networks too, and CD-ROM readers were very expensive. Floppy disks are still used, but already quite rarely. Mainly for storing various keys (for example, when working with the client-bank system) and for transmitting various reporting information to state supervisory services.
Diskette- a portable magnetic storage medium used for multiple recording and storage of data of relatively small volume.
This type of media was especially common in the 1970s and early 2000s. Instead of the term “floppy disk”, the abbreviation GMD is sometimes used - “floppy magnetic disk” (respectively, the device for working with floppy disks is called NGMD - “floppy disk drive”, the slang version is a flop drive, floppy, floppar from the English floppy-disk or in general " cookie"). Usually a floppy disk is a flexible plastic plate coated with a ferromagnetic layer, hence the English name "floppy disk" ("floppy disk"). This plate is placed in a plastic case that protects the magnetic layer from physical damage. The shell is flexible or durable. Floppy disks are read and written using a special device - a disk drive (floppy drive). A floppy disk usually has a write protection feature that allows you to grant read-only access to data. Appearance 3.5” floppy disk is shown in fig. 1.2.
Information carriers are distributed according to four parameters: the nature of the carrier, its purpose, the number of write cycles and durability.
By nature, information carriers are material-objective and biochemical. The first ones are those that can be touched, picked up, moved from place to place: letters, books, flash drives, disks, finds of archaeologists and paleontologists. The latter are biological in nature and cannot be physically touched: the genome, any part of it - RNA, DNA, genes, chromosomes.
According to the purpose, information carriers are divided into specialized and general purpose. Specialized - these are those that are created for only one type of information storage. For example, for digital recording. And a broad purpose is a medium on which information can be written different ways: the same paper, they write and draw on it.
According to the number of recording cycles, the media can be single or multiple. On the first one, you can write information only once, on the second - a lot. An example of a one-time information carrier is a CD-R disc, and a CD-RW disc is already a multiple one.
The durability of the media is the period that it will store information. Those that are considered short-lived inevitably collapse: if you write something on the sand near the water, the wave will wash away the inscription in half an hour or an hour. And long-term ones can only be destroyed by a random circumstance - a library will burn down or a flash drive will suddenly fall into the sewer and lie in the water for many years.
They make storage media from four types of material:
In the past, the list was richer: information carriers were made from wax, fabric, birch bark, clay, stone, bone, and much more.
To change the structure of the material from which the information carrier is created, 4 types of influences are used:
Of the media of the past, punched cards and punched tapes, magnetic tapes, and then 3.5-inch floppy disks were the most popular.
Punched cards were made of cardboard, then they were pierced in the right places so that the holes in the cardboard resembled a pattern, and information was read from them. And punched tapes appeared later, were paper and were used in the telegraph.
Magnetic tapes reduced the popularity of punched cards and punched tapes to zero. Such tapes could both store and reproduce information - play recorded songs, for example. At the same time, tape recorders appeared on which it was possible to listen to both cassettes and reels. But the shelf life of magnetic tapes was modest - up to 50 years.
When floppy disks appeared, magnetic tapes became a thing of the past. Floppy disks were small, 3.5 inches, and could store up to 3 MB of information. However, they were sensitive to magnetic influences, and their capacity could not keep up with the needs of people - they needed media that could store much more data.
Now there are many such media: external hard drives, optical drives, flash drives, HDD box s and remote servers.
External hard drives are packaged in a compact case with one or two USB adapters and anti-vibration system. They can store up to 2 TB of information.
However, if the disk is in a rubberized metal case, then no one will hear the noise.
External hard drives are portable (2.5) and desktop (3.5). The interface can be exotic - firewire or bluetooth, but these are more expensive, they are less common and they need an additional power supply.
These are CDs, LaserDiscs, HD-DVDs, MiniDisks and Blu-ray. Information from such discs is read using optical radiation, which is why they are called so.
The optical disc has four generations:
CDs are almost never used anymore. They have a small volume - 700 MB, and the data from them is read by a laser beam. Compact discs were divided into two types: those on which nothing could be written (CD), and those on which it was possible to record (CD-R and CD-RW).
DVDs look the same as CDs, but they are much larger. DVDs come in several formats, the most popular being 4.37 GB DVD-5 and 7.95 GB DVD-9. Such discs are also R - for one-time recording, and RW - for multiple recordings.
Blu-ray discs, being the same size as CDs and DVDs, can store much more data - up to 25 and up to 50 GB. Up to 25 are discs with one information recording layer, and up to 50 are with two. And they are also subdivided into R - single entry, and RE - multiple entry.
A flash drive is a very small device that can store up to 64 GB or more. Flash drives are connected to the computer via a USB port, they have a high read and write speed, the case is plastic. Inside the flash drive is an electronic board with a memory chip.
A flash drive can be connected to a computer and TV, and if it is in Micro-cd format, then to a tablet or smartphone. Scratches and dust that could destroy optical discs are not terrible for a flash drive - it has a slight susceptibility to external influences.
This is an option that allows you to use regular hard drives desktop computers as external. HDD box is a plastic box with USB controller, where you can put the usual HDD and easily transfer information directly, avoiding additional copy and paste.
An HDD box is much cheaper than an external hard drive, and is very useful if you need to transfer it to another computer. a large number of information or even almost the entire hard disk partition.
This is a virtual way of storing data. The information will be on a remote server, which can be connected to from a computer, from a tablet, and from a smartphone, you just need to have access to the Internet.
With physical storage media, there is always a risk of losing data because a flash drive, hard drive or optical drive can break. But there is no such problem with a remote server - the information is stored securely and for as long as the user needs. In addition, remote servers have backup storage in case of unforeseen situations.
Information carrier- an object used by a person for long-term storage of information.
Disk-shaped storage media that can be read using a laser. Information is stored in the form of pits (pit - pit) and lands (land - earth) on a polycarbonate layer. If the light is focused between the pits (on the lens), then the photodiode registers the maximum signal. If light hits the pit, the photodiode registers a lower light intensity.
Compact Disc(CD)- developed by Sony and Phillips in 1979, used primarily for recording audio files. They have a volume from 650 MB to 900 MB. They are divided into CD-R(Compact Disc Recordable) for single recording and CD-RW(Compact Disc ReWritable) for multiple recording. Very common so far.
Digital Multipurpose Disc (DVD)- was announced in 1995. Due to the denser structure of the working surface and the possibility of applying it to both sides of the disc, it significantly outperforms CDs in volume from (1.46 GB to 17.08 GB). They are also divided into DVD-R and DVD-RW, DVD+R and DVD+RW, which are more advanced than the previous two, and DVD-RAM, which allows a much greater number of rewrites than DVD+RW. The most common optical discs at the moment.
Digital Multilayer Disc(DMD) is an optical disc developed by D Data Inc. The disc is based on 3D optical data storage technology, meaning the laser reads from several work surfaces at the same time. DMDs can store 22 to 32 GB of binary information. DMDs are coated with proprietary chemicals that react when a red laser illuminates a specific layer. At this point, the chemical reaction produces a signal that will later be read from the disk. Because of this, drives can potentially hold up to 100 GB of data.
Fluorescent Layered Disc(FMD)- format optical media, developed by Constellation 3D, which uses fluorescence instead of reflection to store data, which allows it to work according to the principles of large optical memory and have up to 100 layers. They allow you to accommodate up to 1 TB with the size of a regular CD. The pits on the disc are filled with fluorescent material. When coherent light from a laser is focused on them, they flash, emitting incoherent light waves of different wavelengths. As long as the disk is clear, light is able to pass through many layers unobstructed. Blank discs have the ability to filter laser light (based on wavelength and coherence) while achieving a higher signal-to-noise ratio than reflection-based discs. This allows you to have multiple layers.
Blu-ray Disc(BD)- an optical disc format used for high-density recording of digital data. The modern version of this disc was introduced in 2006. It got its name (blue ray - blue beam) by the technology of writing and reading using a short-wave blue laser, which made it possible to compact the data on the disk. Can hold from 8 to 50 GB.
High capacity DVD(HD DVD)- an analogue of the previous disk format with a capacity of up to 30 GB. Not supported since 2008 to avoid format wars.
High Capacity Multipurpose Layered Disk(HDVMD)- a format of digital media on optical discs, designed for storing high-definition video and other high-quality multimedia data. Up to 5 GB of data can be placed on one layer of an HD VMD, but due to the fact that the disks are multi-layered (up to 20 layers), their capacity reaches 100 GB. Unlike the previous two formats, it uses a red laser, which allows them to be read by drives that support CD and DVD discs.
Holographic Multipurpose Disc(HVD)- a promising optical disc format under development, which involves significantly increasing the amount of data stored on a disc compared to Blu-Ray and HD DVD. It uses a technology known as holography, which uses two lasers, one red and one green, combined into a single parallel beam. The green laser reads grid-encoded data from the holographic layer close to the surface of the disc, while the red laser is used to read auxiliary signals from the normal CD layer deep within the disc. Estimated capacity - up to 4 TB.
Hard disk drive- mass storage device, the main storage device in most computers. The principle of operation is based on a change in the magnetization vectors of domains (a small area of the disk) of a magnetic disk under the action of alternating current in a coil at the end of the read head. Widespread due to the very high capacity and speed of operation. Many hard drives make noise. Household disks usually store information in the amount of up to 1 TB. There are also external hard drives connected to the computer via a USB port, they do not provide the same speed as internal ones, but provide the same large capacity. In addition, hybrid hard drives with flash memory elements are being developed.
Flash memory- a kind of semiconductor technology of electrically reprogrammable memory. The operating principle of semiconductor flash memory technology is based on change and registration electric charge in an isolated region ("pocket") of the semiconductor structure. The advantages of such media are compactness, low cost, mechanical strength, large volume, speed of operation, and low power consumption. A serious disadvantage of this technology is the limited lifetime of media.
USB flash drive- a storage device invented in 2000. Very popular due to ease of use and versatility. Can store information without electricity for up to 10 years.
Memory card- a storage device of various varieties, used under certain device, such as Cell phones, PDA, car recorders. The most common standard is microSD.
The main types of storage media
Information carriers: living beings, inanimate objects and structures, signal, sign, symbol. Any object carries some information about itself and the objects surrounding it, that is, it is a carrier of information.
There is an idea that information carriers have real, material properties and properties of relations. The former imply the properties of the substances from which the carriers are made; the second are the properties of processes and fields, with the help of which carriers exist, and the third are elemental (species) properties that allow one to distinguish one carrier from another, for example, by shape and size. Real media are divided into: local (computer), alienable (portable disks and floppy disks) and distributed (communication lines). With regard to the latter, there is no unequivocal opinion, because communication channels can be represented as data carriers, but at the same time they are the medium for their transmission.
Usually under information carriers imply the generally accepted name of their form, that is: paper (book, brochure, etc.), plate (gramophone record, photographic plate), film (photo, film, x-ray film) audio cassette, floppy disk, microform (photographic film, microfilm, microfiche), video cassette, CD CD , DVD ) etc.
It has long been known, such media as: stone (rock paintings, stone slabs), clay tablets, parchment, papyrus, birch bark and others. Then the following media appeared: paper, plastic, photographic materials, magnetic and optical materials, and more.
Now they are divided into: traditional and machine-readable. Under traditional we will understand the following information carriers: paper, canvas, plastic (gramophone record), magnetic tape (audio and video cassette), photographic materials (photographic film, photographic plate, photographic print, microcarrier), etc. TO machine-readable media Let's include: floppy disks (floppy magnetic disks), hard magnetic and compact (optical, magneto-optical and other) disks, flash cards and other storage media intended for use in computer devices, complexes, systems and networks. Information is written to the media by changing the physical, chemical or mechanical properties of the storage medium.
A variant of the classification of information carriers used in computer technology is shown in Fig. 5-1.
Rice. 5-1. Classification of storage media used
in computer technology
Note that this division is conditional. So, for example, with the help of special devices on computers, you can work with ordinary audio and video cassettes, and devices for recording and long-term storage of data (streamers) use well-known magnetic media (magnetic tapes), etc. Therefore, we will refer to traditional media data of an analog nature, and to machine-readable, that is, used in computers, digital data or electronic data. informational resources(EIR).
Let's give them a brief description.
A magneto-optical disk (MO) is enclosed in a plastic envelope (cartridge). MO-disk is a universal, operational, highly reliable device for transferring and storing information. They are characterized by a high density of information recording. Disks with a diameter of 3.5 "have a capacity of 128 MB - 1.3 GB, and with a diameter of 5.25" - from 2.3 to 9.1 GB. Disc rotation speed - 2000 rpm.
Information carrier (data medium) is a material object or medium intended for data storage. Recently, information carriers are mainly called devices for storing data files in computer systems, distinguishing them from devices for input-output of information and devices for information processing.
Digital storage media - CDs, floppy disk, memory cards
Analog storage media - tape and cassette cassettes
By waveform used to record data distinguish between analog and digital media. To rewrite information from analog to digital media or vice versa, a signal is needed.
By appointment distinguish between carriers
According to the stability of the recording and the possibility of rewriting:
According to the physical principle
By design (geometric) features
Sometimes information carriers are also called objects, reading information from which does not require special devices - for example paper media.
The capacity of a digital medium means the amount of information that can be written to it, it is measured in special units - bytes, as well as in their derivatives - kilobytes, megabytes, etc., or in kibibytes, mebibytes like that. For example, the capacity of common CD media is 650 or 700 MB, DVD-5 - 4.37 GB, dual-layer DVD 8.7 GB, modern hard drives - up to 10 TB (for 2009).
