External data storage devices appeared a very long time ago, in fact, at the dawn of the computer era, all data storage devices were external. This approach to connectivity was largely due to the storage technology used at the time and the general level of development of the semiconductor industry. However, over time, data drives have moved inside the nice and compact personal computer (PC) cases.
Progress is progress, miniaturization reaches new and new heights. However, for some tasks there is still a need for external data storage devices. For example: a designer who has to transfer large files to a customer or needs to work with this material at home. Again, it may be necessary to absolutely protect your information from access by strangers: disconnect the disk and take it with you - what is called absolute protection :).
Below I will consider the main ways to connect external data drives and their characteristic features - a kind of historical tour.
Naked interface
Initially, the only way to connect an external storage device to a PC was to use the SCSI interface. It is worth noting that the SCSI interface implemented the ability to connect not only data drives, but also all kinds of external peripherals. For the first time, I had a chance to deal with external storage devices on the example of a hard drive and a CD-ROM with a SCSI interface back in 1992. The disk and CD-ROM were convenient and not very large boxes that could be disconnected from one PC and quickly connected to another PC without disassembling them. Well, if the operating system was perfect enough, then this could be done in a "hot" mode. The classic appearance of such a case can be seen in the photo.
True, for this method of connection it was required that both machines had a SCSI interface, and at that time this pleasure cost a lot of money. However, for some tasks, this ability to quickly transfer and connect storage media of large amounts of data was simply invaluable. As an interface, SCSI had and still has a lot of possibilities, but they are all locked into a rigid framework of high price. However, this method of connection has other disadvantages. Perhaps the main ones can be considered the use of thick and bulky 50-core connecting cables and the low prevalence of the SCSI interface. The photo shows SCSI and USB interface cables for comparison.
The IDE interface, which began its triumphal march on the PC market a little later, was very primitive in its capabilities, but had a huge advantage over SCSI - it was very cheap. But the old rule that “cheap is not good” has not stopped working. The wider the IDE interface spread to the PC, the more urgently there was a need to implement such functions that SCSI already had, including the ability to use the IDE to connect external storage media. The industry took the shortcut to solve this problem. This, as you guessed, is about the so-called Mobile Rack devices. This is a primitive basket that houses a hard drive and a socket, which is usually installed in a 5 inch slot on the front of the PC.
This whole design allows you to connect / disconnect the hard drive without disassembling the computer. To call such a method of connecting data drives "external" the language does not turn, however, without fish and cancer - a fish, it turns out, although not very convenient, but cheap. Moreover, for a very narrow range of tasks, this method is almost ideal. Over time, the possibilities provided by new operating systems even made it possible to implement the primitive ability to hot-swap IDE drives. But too frequent cases of disk failure with such a connection sharply limit both the scope of this method and the number of users who want to risk their hardware. In addition, Mobile Rack baskets made by different companies were often physically incompatible with the jacks due to the non-standard location of the connectors. However, the Mobile Rack connection method is still alive and well.
But let's go back a little. The possibilities that the primitive Mobile Rack provided, of course, could not fully satisfy users, and the computer industry once again launched the process of evolution.
building bridges
So, the industry had to evolve within the framework of certain requirements for external data storage.- Devices must be hot-pluggable/unpluggable
- It is necessary to use existing technologies
- The solution must be cheap and massive
In the following, I will mainly use IDE device examples, since it is more common. But everything that will be said about the IDE can just as well be said about SCSI, since the ideology remains the same regardless of the interface.
This approach - using the LPT interface - was certainly not ideal, but it worked nonetheless. So, what the user could get in the end.
- Ability to connect external storage devices to any PC.
- No need to upgrade your computer.
- Cheapness.
- Ease of connection.
- Low speed, several orders of magnitude lower than that of SCSI or IDE (with direct connection).
- The need to install drivers.
- A primitive set of commands and features.
Well, the first pancake always turns out lumpy. Nevertheless, it is important for us that the industry first applied bridge technology in practice. This was the first step in the development of a whole class of similar devices.
However, as time went on, the capacity of hard drives grew, and the amount of data grew. The speed provided by the LPT interface has become sorely lacking. The industry began to look for new ways to connect faster and more capacious drives.
The idea of connecting devices through bridges began to develop in new directions. By that time, almost all more or less modern computers were equipped with such a peripheral data transfer bus as USB. Although USB was the most common bus, it also turned out to be the most unclaimed at that time. A rather promising development, integrated by INTEL into its chipsets and therefore practically worthless, it was present on many motherboards, but the lack of devices that could work with this bus turned it into a beautiful toy. Now the time has come. In fact, USB was developed as a peripheral bus for connecting computer peripherals outside the machine case according to the plug "n" play standard. The old man LPT simply could not resist such pressure. So, what could users get when switching from an LPT-IDE bridge to a USB-IDE bridge.
- Significant increase in speed. USB - 750-950 Kb/s versus 250-300 Kb/s for LPT
- Ideal hot-pluggable/unpluggable.
- No setup issues, completely P&P.
- Convenient cables for connection.
It was impossible to pass by such an opportunity to use USB, and users received a whole range of IDE devices capable of working via USB 1.1. Here are some examples.
USB-IDE bridge board - what is called a do-it-yourself constructor. The user can, if desired, easily convert any external storage enclosure he has.
External case for 3-inch hard drive.
External case for 2-inch hard disk, with some models of hard disks, even operation without external power is possible.
Integration is a curious process
A small lyrical digression. Despite the fact that the methods of connecting drives using a bare interface and using a bridge have fundamental differences, the market is a market, and if there are unoccupied niches in it, then they should be taken. Apparently, guided by such motives, some companies have developed such curious combi devices that can work in different guises.
Allows you to work in two modes: as a universal Mobile Rack for computer devices, and as an external device connected using a USB bridge. In the first case, you have the ability to quickly remove the data carrier from the computer without disassembling it, and in the second case, you can easily connect the removed media to any computer that does not have a Mobile Rack slot, but has a USB bus.
The bridge must be wide!
Agree, it's a shame to have a hard drive that can, for example, issue a transfer of 20 Mb / s, and connect it via a USB bridge at a speed of 900Kb / s. Not everyone has the patience to, say, rewrite 10 GB of information at that speed. Faced with such problems, the computer industry turned to the FireWire (IEEE 1394) peripheral data bus, which came to the PC world from the world of MAC computers. Possessing outstanding characteristics and capabilities, this tire initially, due to the policy of the Apple developer, was not widely used in the world. But what a chance Apple had to become a leader in this area! However, if there is a need for speed, then it is necessary to satisfy it somehow. Incidentally, the fact that the industry has chosen to use FireWire in this way has had a positive effect on the cost of FireWire devices. During the year, their price has decreased by more than three times. With the transition from USB 1.1 to FireWire, users have received the following key benefits.- Increased maximum transfer rate from 10 MBit/s (USB) to 400 MBit/s (FireWire).
- Ability to power external devices from the bus 1.25A/12V (FireWire) against the maximum 500 mA/5V (USB).
Again, a small example. Here is the case for the 2" hard drive.
However, unlike USB, the user does not have to puzzle over how to find a suitable hard drive that will work without additional power. Power is taken directly from the bus (1.25A 12V = 15W), so absolutely any hard drive will do.
However, progress does not stand still, and clouds hang over FireWire in the form of USB 2.0. Possessing somewhat better characteristics, it is able to become its serious competitor. The main trump cards in the fight were to be an increase in speed from 10 MBit / s to 480 MBit / s and support for all old USB 1.1 devices. True, when introducing USB 2.0 to the market, some bewilderment is caused by the policy of Intel. Previously, the corporation actively promoted this bus, but, contrary to the expectations of users, did not integrate it into their latest i845D and i850 chipsets. Why this did not happen remains a mystery. However, there is already everything that is needed for the widespread adoption of USB 2.0 in the PC market. Firstly, the market is more than provided with chips for creating expansion cards to support USB 2.0, and secondly, external storage devices that use USB 2.0-IDE bridges are actively moving into the market.
Here, for example, is a bridge on a chip from In-System. It is designed in such a way that it can very easily replace the previous generation bridge (photo a little higher in the text). And that's not all, the company's pricing policy is such that the cost of a USB 2.0 bridge is almost equal to the cost of the previous USB 1.1 model.
Bridge to the bridge of strife
The market is a market, and if there is a demand, then everyone who can will try to get into this niche in the market. Therefore, it is not surprising that a natural process of competition was observed in this segment of the market. As usual, competing firms presented their products one after another. This is where we get some differences in transmission speed for practically similar products, but using bridges from different companies.
For USB 1.1, this difference was not so fatal due to the low transfer rate. The values of the maximum possible transmission speed, as a rule, ranged from 750-950 Kb/s. However, a 20% difference looks quite large.
Much more interesting was the situation on the market for high-speed IDE-FireWire bridges. Here the maximum speed could differ several times. Moreover, I observed such a difference in devices of the same company, assembled on different chips of FireWire-IDE bridges. Curiously, both chips were from the same manufacturer. Below you can take a look at the comparison results.
Chip Oxford semi. OXFW910
Chip Oxford semi. OXFW911
|
Well, is the difference impressive? I can understand those who, for example, need to connect a CD-RW recorder through a similar bridge. By and large, they will not give a damn about speed, but what about those who want to connect a modern high-speed hard drive? So, as they say, be careful when choosing such a device for yourself. Below I will give the test data of some of the most commonly used chips on the basis of which IDE-FireWire bridges are built. Data obtained from Skymaster. This company is engaged in the production of all kinds of USB and FireWire devices. An IBM DTLA-307020 hard disk was used as a test device; testing was carried out under OS Windows 2000.
Unfortunately, there is no way to compare at least two USB 2.0-IDE bridges, since at the moment only In-System supplies such devices to the market. But recently, two more large companies - NEC and ALI - have announced similar devices, so let's see what they get, and in the future we will try to compare them.
Bridges of all countries, unite!
In one place you have FireWire, in another you only have USB, and you want, for example, to bring a friend a couple of new films in DVD format, but rewritten to a hard drive. However, you have a FireWire drive, and your friend only has USB 1.1, well, he shouldn’t get a FireWire controller for this. Well, the controller can and should be started, especially since peripheral manufacturers have long been hinting at the need for all widely used peripheral buses in every computer. Just take a look at this universal hub, isn't it cute and practical?
But this card can make you happy with two high-speed buses at once - USB 2.0 and FireWire.
Well, versatility is a sacred thing, - the manufacturers decided and, without thinking twice, they set about developing bridges with combined interfaces. In principle, the main difficulty is to compactly place all the necessary components on the bridge board and try at the same time so that the cost of such a device does not turn out to be excessively high. The first bird was such a FireWire / USB1.1 bridge - IDE.
And this is just the beginning, as the FireWire/USB2.0 -IDE versions are ready and will soon be put into production. Here the user can afford to forget about the compatibility of his external drive with computers, since the computer has some kind of peripheral bus for sure :).
Bridges, say ... well, well
This year was marked by the final version of the Serial ATA interface. And although for now it is intended only to replace the outdated IDE, it already has the manners of Napoleon. Judge for yourself, this interface is almost identical in its functions to both a FireWire device and USB 2.0, but at the same time even faster. The data transfer rate of Serial ATA can reach 150 Mb/s. Of course, it will be some time before it hits the market in all its glory. Although for now it is positioned exclusively as an internal interface, it nevertheless has all the makings of an interface for connecting external devices. See for yourself, the interface uses a star topology to connect devices. So you can bring out one or two connectors for connecting external devices without any problems, and at the same time the devices will function similarly to internal ones. The maximum cable length is 1 meter - this is also quite enough to connect most external devices.
The cable consists of two pairs of data wires and three ground wires, so the cable is very compact and convenient. Of course, the future will show whether this interface will invade the external storage market or not, but this possibility must be kept in mind.
Let's say right away that "data drives" is an official term that is rarely used in everyday life. True, they tried to revive it with the introduction of the concept of "solid-state drive". Apparently, someone needed it. However, people still say "SSD", rarely using clerical terms.
Well, okay, let's move on to devices for storing digital information. Life forces us to understand all this at least a little.
Ancient data drives
Once upon a time, computers did not fit in your pocket or bag. They were the size of a two-story house. Programs were entered into them using paper tapes with holes punched into them (punched tapes), and information was recorded on tapes. Yes, on ordinary tape recorders! But only instead of sound - signals of zeros and ones.
Tape recorders lasted quite a long time, even for a while after the invention of floppy disks. Don't know what a floppy disk is? It's a plastic disc with a floppy disk inside. The disk was magnetic, it was possible to record all the same zeros and ones on it. A special "tape recorder" was built into the computer. That's what it was called: "floppy drive".
Hard drives
As opposed to flexible, there are hard drives (hard drives, "hard drives", hence the slang "hard" and "screw"). Metal, in cases, with their own motors and microcircuit controllers. They are used to this day, moreover, as the main keepers of information. They are built into laptops and desktop computers, they record the operating system, and also store all sorts of files.
However, there are not only built-in bowels of the computer, but also external hard drives connected to the USB port. These are small boxes that fit easily into a bag and even into a rather spacious jacket pocket. It is very convenient if you need to take fifty films to a friend, for example.
Optical discs
These are CD, DVD and Blueray. As data stores, CDs are now used to place drivers for various devices on them. We bought a printer, and in the box - a disk from which you need to install these drivers.
DVDs are the most popular because they are not much more expensive than CDs and they hold six times as much data. If you urgently need to make a backup copy of, say, forty gigabytes, then it is cheaper to purchase a dozen blank DVDs than any other drives of sufficient capacity.
Well, for the time being, Blueray discs record mainly high-definition films. Just as CDs were previously audio discs and DVDs were video, so Blueray has not yet matured to mass use as arbitrary data drives, although the process has already begun.
It is better to purchase rewritable discs (labeled as RW). They are more practical, and the quality is always higher.
Flash drives
These are not only ordinary flash drives, but also flash memory players, and a variety of microSD for cameras, mobile phones and other compact devices. In short, there are quite a few variations.
Of course, a flash drive is the most popular type of such drives when it comes to working with computers. Plugged into a USB port - record, copy, view, do whatever you want. At least launch the operating system from it and install it on your hard drive (this is true for Linux-based OS).
However, it should be remembered that flash drives are not designed for an infinite number of writes and erasures. Maybe three years is enough, and then you have to buy a new one.
SSD
Solid-state drive, abbreviated SSD - these are the same solid-state drives mentioned in the preamble. At the moment - the highest stage of the evolution of flash memory.
SSD drives are commonly found in netbooks and tablet computers instead of hard drives.
They work faster than any disks in general, they are not afraid of vibrations (therefore they are used at the International Space Station), and in general they are utterly progressive ...
What? Do you think there is a slight irony in my words? Yes there is a bit. Why? Now I will explain.
First, SSD is not cheap. Secondly, only modern operating systems are optimized to work with them. Why optimize? This is third.
The fact is that SSD is an advanced, but still flash technology. Solid-state drives wear out too quickly if the netbook torrented for days, constantly downloading something, giving it away, picking up files piece by piece, writing and overwriting. And these are not flash drives, not external devices; to replace them, you will have to carry the computer for repair.
Therefore, it is necessary to optimize the work with data. For example, Windows 7 does not apply defragmentation.
conclusions
Optical discs are too early to send to the museum of computer technology, where there are already floppy disks.
Yes, you need a program to burn data. Yes, not as convenient as simply connecting the device to USB. Not for the lazy. But very economical.
Of course, the future is for the SSD, but it has not yet arrived. Inexpensive options for such drives are designed for a miserable ten thousand rewrite cycles. Long enough for a flash drive, which you remember one and a half times a day, but not for an operating system carrier on a heavily used computer. So hard drives (including external ones) have not yet become history either.
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In most laptops, you cannot insert a second hard drive, and changing the main one is not always easy. External storage devices come to the rescue.
External drives are used to store, transfer and back up data in computer systems. The main types of such drives are devices based on hard drives and flash memory. In some cases, external optical drives are used as such drives, but since most computers have internal drives for reading and writing CD, DVD or Blu-ray, such drives are of limited distribution and we will not dwell on them here (more on optical drives, see a separate article).
Flash drives
Due to the decrease in prices for flash memory, external drives based on it are becoming more common. A typical flash drive is a small device, about the size of a disposable lighter, equipped with a built-in USB connector. At the same time, the volume of such miniature drives can vary in a very wide range: from one to 128 GB. To date, the most popular models with a capacity of 8 to 16 GB can be purchased for 500-900 rubles, modifications in protected rubberized and sealed aluminum cases are slightly more expensive. As a rule, 8-16 gigabyte flash drives are purchased not for storage and backup, but for quick data transfer.
High-capacity flash drives are significantly more expensive: 64 GB models are already estimated at about 5,000 rubles, and 128 GB models at 11,000 rubles and more. It is easy to calculate that the cost of a gigabyte of disk space in such drives is about one and a half times higher (from 85 rubles) than in drives of a small capacity. In addition, an external mini-hard drive of the same volume will cost about three times cheaper, so consumers prefer it.
External HDs
Hard drives have been the best solution for storing and backing up large amounts of data for several decades now. Modern hard drives are distinguished by high reliability, high capacity and low cost of data storage: in the best models it is from 3 to 4 rubles per gigabyte.
External hard drives can be divided into four broad categories: drives based on 2.5-inch drives, drives based on 3.5-inch drives, multimedia drives and NAS systems.
Drives based on 2.5-inch "notebook" hard drives are the smallest: they are considered portable and easily fit into a shirt pocket. However, compared to 3.5-inch drives, they have significantly lower write and read speeds, limited capacity, and the cost of a gigabyte of storage is one and a half to two times higher. A typical read speed for such disks is 35 MB / s, writes - 30 MB / s, for the best models, read and write speeds can reach 50 MB / s.
The volume of 2.5-inch external hard drives is from 120 to 500 GB, the cost of storing a gigabyte of data is, on average, from 8 to 12 rubles.
As a rule, 2.5-inch hard drives are equipped with a USB 2.0 interface, sometimes eSATA, and almost never support FireWire, with the exception of ZIV-branded drives. In many cases, USB power is sufficient for these drives.
It is also worth mentioning models based on 1.8-inch "subnotebook" hard drives, which are even smaller than 2.5-inch ones. Typically, the capacity of such drives is limited to 120 GB and they are equipped exclusively with a USB 2.0 interface. These discs are rarely found in stores, usually they are distributed at various events as souvenirs.
The most popular and popular category is external drives based on standard 3.5-inch hard drives. They can consist of one or two hard drives placed in one case, and in the latter case, it is usually possible to organize RAID arrays of levels 0 (disk pooling) and 1 (mirroring).
For drives based on 3.5-inch hard drives, a read speed of 70-90 MB / s and a write speed of 60-80 MB / s are typical. For the most productive models, the read speed can reach 120 MB / s, and the write speed - 110 MB / s. The volume of such drives is usually from 500 GB to 2 TB in single-drive models and up to 4 TB in dual-drive models. The cost of storing one gigabyte, on average, is from 4 to 8 rubles, for the best models - from 3 to 4 rubles.
3.5-inch external drives can be equipped with a full range of a wide variety of modern interfaces: in addition to the obligatory USB 2.0, they are equipped with eSATA, FireWire 400 and FireWire 800 controllers, as well as a promising USB 3.0 interface.
Multimedia drives are a special category of external hard drives based on 2.5- or 3.5-inch hard drives, which are equipped with a built-in decoder for popular audio and video formats, as well as a software media player with hardware controls. In fact, these drives are hard disk-based multimedia players and are usually equipped with a remote control.
Such devices can be directly connected to the TV and audio system and they will act as a stand-alone multimedia player that is not connected to a computer. To do this, they are equipped with "household" video interfaces (composite, component, HDMI), as well as analog and digital audio outputs. In many cases, a card reader is built into these devices, which allows direct playback of multimedia content from removable flash cards. There are modifications designed exclusively for connecting removable hard drives, purchased separately.
In the standard arsenal of multimedia drives - support for MPEG-1 / 2/4, DivX and XviD video formats, MP3, WAV, AAC audio formats, as well as JPEG digital images. The possibility of working with other formats should be clarified separately when choosing each specific model.
At the same time, of course, such devices can also be used as ordinary computer external drives - usually via USB 2.0 and eSATA interfaces.
The most complex and expensive type of external drives are NAS systems, that is, network storage devices. These are external devices with one or more 3.5-inch hard drives, equipped with an Ethernet network interface (for all modern models - gigabit) and having the functionality of a mini-server.
NAS drives are networked computers, the main function of which is to provide access to the data stored in them for any computer that is part of the local network. At the same time, many of these devices have the extended functionality of a "real" server that can connect to the Internet and exchange data via FTP and HTTP protocols.
Some NAS have built-in multimedia servers that allow you to play and broadcast content stored on hard drives over a local network, as well as print servers: printers connected to the NAS will be available to all computers on the network. Many models are equipped with data backup software.
However, the most requested feature, for which NAS drives are most often purchased or assembled, is the built-in peer-to-peer client, thanks to which you can upload and download files from the BitTorrent and eMule networks without turning on the computer. Such devices are able to work around the clock, consuming much less electricity than a full-fledged PC, and making almost no noise (however, this depends on the specific design).
Despite the fact that NAS drives are usually built on the basis of 3.5-inch drives, in terms of speed they are often inferior even to 2.5-inch external hard drives. Manufacturers rely on reliability, rightly believing that the low speed of access via a local network makes it pointless to use drives with high speed characteristics. Of course, when directly connected to a computer via USB 2.0 or eSATA interfaces, the drives demonstrate quite typical performance for 3.5-inch hard drives.
Prices for NAS drives vary quite widely: extremely simple single-disk models without an FTP / HTTP server cost about 4,000 rubles, and multifunctional systems with support for five hot-swap hard drives can cost more than 30,000 rubles. At the same time, for quite a bit of money, you can independently assemble a NAS from an old computer or from inexpensive components for nettops. For such "self-assembly", a special and completely free assembly of the FreeBSD operating system, called FreeNAS, is often used. This software allows you to set up a network storage device with almost any required functionality.
Accumulators and carriers of information.
Information storage - a device that reads and/or writes information.
Information storage devices are:
· internal and external:
· with removable and non-removable storage media;
· stationary and portable.
Internal drives are located in the PC system unit and are connected to special connectors on the motherboard.
External and portable storage is in its own case and connects to the computer through standard input / output ports. External storage media are used to back up and store information, as well as to transport data from one computer to another.
Information carrier - this is a device on which information is directly recorded (stored), for example, a disk, a magnetic tape cassette, etc.
The drive and the information carrier can be made in the same housing, i.e. form one whole, for example, a hard disk HDD (Fig. 13).
Rice. 13. Hard Disk Drive HDD
The drive may have removable media, for example:
at the FDD drive removable media - floppy disk floppy disk);
at DVD drive - RW (Fig. 14) removable storage medium - DVD disc.
Rice. 14. DVD-RW drive
In some cases, the division into storage and media is conditional. For example, the internal storage of information is random access memory ( RAM ) and portable storage FLASH A card is both a storage device and a carrier of information.
Main drives and storage media
|
Storage device |
Russian designation |
International designation |
Drive type |
Carrier |
Media type |
|
RAM |
interior |
she is |
|||
|
Persistent memory |
ROM BIOS |
interior |
she is |
||
|
HDD hard drive (hard disk drive) |
interior |
HDD |
fixed built-in |
||
|
FDD drive (floppy disk drive) |
interior |
diskette (floppy disk) |
removable portable |
||
|
CD-ROM, CD-RW - drive for reading and writing CDs |
CD-ROM CD-RW |
interior |
CD-disk (compact disc) |
removable portable |
|
|
DVD-RW - drive for reading and writing CDs and DVDs |
DVD-R |
interior |
DVD disc |
removable portable |
|
|
FLASH card |
FLASH |
external, portable |
she is |
The main characteristic of a carrier (drive) is its capacity, i.e. the maximum amount of information that can be written to this device. Drive capacity is measured in the following units:
|
designation |
International designation |
|
|
kilobyte |
||
|
megabyte |
||
|
gigabyte |
Recently floppy disks and CDs - disks are outdated, they will no longer be used in the near future and are being actively replaced by more capacious media FLASH -cards (Fig. 15) and DVD discs.
Rice. 15.. FLASH card
The capacity of the main media (drives).
|
Media / Drive |
Note |
|
|
Removable storage media |
||
|
Floppy disk or floppy disk |
1.44 Mb |
are falling into disuse |
|
CD disc |
650 Mb, 700 Mb |
are falling into disuse |
|
DVD disc |
4.7 Gb, 9 Gb |
DVDs can be single or double sided, single layer or double layer. |
|
FLASH card |
256 Mb , 512 Mb , 1 Gb , 2 Gb |
|
|
Internal media / storage media |
||
|
RAM memory |
512 Mb 1 GB |
standard for Windows XP standard for Windows Vista |
|
HDD hard drive |
120 - 300 Gb |
Typical HDD capacity of a modern PC |
Any electronic computers include memory drives. Without them, the operator would not be able to save the result of his work or copy it to another medium.
Punch cards
At the dawn of its appearance, punched cards were used - ordinary cardboard cards with printed digital markings.
One punched card contained 80 columns, each column could store 1 bit of information. The holes in these columns corresponded to the unit. The data was read sequentially. It was impossible to re-record anything on a punch card, so a huge number of them were required. It would take 22 tons of paper to store a 1 GB data array.
A similar principle was used in perforated tapes. They wound on a reel, took up less space, but often torn and did not allow you to add and edit data.
floppy disks
The advent of floppy disks was a real breakthrough in information technology. Compact, capacious, they allowed to store from 300 KB on the earliest samples to 1.44 MB on the latest versions. Reading and writing were carried out on a magnetic disk enclosed in a plastic case.
The main disadvantage of diskettes was the fragility of the information stored on them. They were vulnerable to action and could be demagnetized even in public transport - a trolleybus or tram, so they tried not to use them for long-term data storage. Floppy disks were read in disk drives. At first there were 5-inch floppy disks, then they were replaced by more convenient 3-inch ones.
Flash drives have become the main competitor of floppy disks. Their only drawback was the price, but as microelectronics developed, the cost of flash drives dropped dramatically and floppy disks became history. Their production was finally discontinued in 2011.
streamers
Streamers were previously used to store archived data. They were similar to video cassettes in appearance and in principle. A magnetic tape and two reels made it possible to sequentially read and write information. The capacity of these devices was up to 100 MB. Such drives have not received mass distribution. Ordinary users preferred to store their data on hard drives, and it was more convenient to keep music, movies, programs on CDs and later DVDs.
CD and DVD
These storage media are still in use today. An active, reflective and protective layer is applied to the plastic substrate. Information from the disc is read by a laser beam. A standard disk has a capacity of 700 MB. This is enough for example to record a 2-hour movie in average quality. There are also double-sided discs where the active layer is deposited on both sides of the disc. Mini-CDs are used to save a small amount of information. Drivers, instructions for computer products are now written on them.
DVDs replaced CDs in 1996. They allowed to store information already in the amount of 4.7 GB. Their advantage was also that the DVD drive could read both CDs and DVDs. At the moment it is the most massive memory storage device.
Flash drives
The CD and DVD drives discussed above have a number of advantages - cheapness, reliability, the ability to store large amounts of information, but they are designed for one-time recording. You cannot make changes, add or remove unnecessary things on a recorded disc. And here a fundamentally different drive comes to our aid - flash memory.
For some time he competed with floppy disks, but quickly won this race. The main limiting factor was the price, but now it has been reduced to an acceptable level. Modern computers are no longer equipped with disk drives, so the flash drive has become an indispensable companion for everyone dealing with computer technology. The maximum amount of information that can fit on a flash drive reaches 1 Tb.
Memory cards
Phones, cameras, e-books, photo frames and much more require memory drives to work. Due to their relatively large size, USB sticks are not suitable for this purpose. Memory cards are specially designed for such cases. In fact, this is the same flash drive, but adapted for small-sized products. Most of the time, the memory card is in an electronic device and is removed only to transfer the accumulated data to a permanent medium.
There are many standards for memory cards, the smallest of them are 14 by 12 mm. On modern computers, instead of a disk drive, a card reader is usually installed, which allows you to read most types of memory cards.
Hard drives (HDD)
Memory drives for a computer are inside it there are metal plates coated on both sides with a magnetic composition. The motor rotates them at a speed of 5400 for older models or 7200 rpm for modern devices. The magnetic head moves from the center of the disk to its edge and allows you to read and write information. The volume of the hard drive depends on the number of disks in it. Modern models allow you to store up to 8 Tb of information.
There are practically no shortcomings of this type of memory drives - they are very reliable and durable products. The cost of a unit of memory in hard drives is the cheapest among all types of drives.
Solid state drives (SSD)
No matter how good hard drives are, they have almost reached their ceiling. Their performance depends on the speed of disk rotation, and its further increase leads to physical deformation. Flash technology, which is used in the manufacture of solid-state memory drives, is devoid of these disadvantages. They do not contain moving parts, so they are not subject to physical wear and tear, are not afraid of shock and do not make noise.
But there are still serious shortcomings. First of all - the price. The cost of a solid state drive is 5 times higher than a hard drive of the same size. Another significant drawback is a short service life. Solid state drives are usually chosen for installing the operating system, and a hard drive is used for data storage. The cost of solid-state drives is steadily declining, and there is progress in increasing their resource. In the near future, they should replace traditional hard drives, just as flash drives replaced floppy disks in their time.
External drives
Internal storage and internal memory are good for everyone, but often you need to transfer information from one computer to another. Back in 1995, the USB interface was developed, which allows you to connect a wide variety of devices to a PC, and memory drives are no exception. Initially, these were flash drives, later DVD players with a USB connector appeared, and finally HDD and SSD drives.
The attractiveness of the USB interface is in its simplicity - just plug in a USB flash drive or other storage device and you can work, no driver installation or other additional steps are required. The development of the interface and the appearance of USB 2.0 first, and then USB 3.0, dramatically increased the speed of data exchange over this channel. The performance now differs little from the internal one, and their size cannot but rejoice. An external memory drive fits easily in the palm of your hand, while it allows you to store hundreds of gigabytes of information.