Comprehensive knowledge of mobile storage devices

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One, high capacity disk/drive
It is basically the same as the floppy disk structure, the capacity is more than 100MB. such as Iomega's Zip 100m/zip Plus 250m/jaz 2G, Compaq ls-120m, Fujitsu's HiFD 200m,castlewood's orb 2.2g,syquest SparQ 1g/ezflyer 230M, Nomai Nomai 540/datadrive 750. The disks of the above-mentioned disk drives are dedicated, they cannot be read and written on other drives, which can cause problems for users to transfer data. For example, if a user backs up data using Iomega's Zip Plus, the target computer is required to use zip Plus to transfer success. But the current domestic market situation is that any large-capacity disk drive market penetration is not too high. 1.44 the floppy drive has not been eliminated today, the root cause is almost 100% of its penetration.
This type of device is usually connected to a computer via a SCSI interface. This requires that the user's computer must be equipped with a SCSI card or motherboard integrated SCSI control chip. A user's desire to purchase will be suppressed by having to spend another amount of money on the SCSI device. There are some of these devices are USB interface or the same port connection, although the general computer has these two interfaces, but the transmission speed is much lower than SCSI, especially the joint port connection, greatly restricting the performance of the device to play.
A product can survive in the market, it must have its value, that is, the advantage. Although the above "grumble" a few shortcomings of the large-capacity disk drive, but it also has the advantage of others irreplaceable. The Zip 100M has been launched for a long time and is quite popular abroad, and has even become a standard configuration for some brand machines. If the imac has abandoned the other floppy drives a year ago, use only zip as a dedicated floppy drive. Therefore, the zip is very convenient in data exchange. The advantage of LS-120 is that it can be backwards compatible with 1.44MB floppy disk, and can be read at 720rpm speed, is twice times the normal floppy drive, which brings great convenience to users with a large number of 1.44MB floppy disks. Jaz 2g/orb 2.2g/sparq 1G and other larger capacity drives, due to the adoption of new technology, in the speed of a great advantage, is second only to the active hard drive of the mobile storage device.

Second, rewritable disc/drive
Rewritable discs generally refer to various cd-r/cd-rw/mo, with fixed specifications and capacities. CD-R/CD-RW for 600m/650m,mo capacity ranging from 128M to 2.6G, but generally commonly used 640M platters. CD-ROM drive capacity, performance and the use of the disk and other mobile storage has a fundamental difference, one is the principle of operation, the second is the use of storage media, the third is the speed requirements, but also far from the hard disk or mobile hard disk, at best can only be used as a tool to save data. However, because today's CD-ROM is already very popular, therefore, the optical disk media has other products can not be compared with the advantages of communication.
CD-R, simply speaking, refers to a disc burner that can be written and read multiple times. It works by "firing" a "data hole" on a blank CD disc, which is the reflection point of recording data. Therefore, all CD-R engraved platters can be read out on the ordinary CD-ROM, which is the biggest advantage of CD-R. The other major advantage of CD-R is that the disk is cheap, the bulk of the platter is generally 5 yuan to 7 yuan, the most expensive also more than 20 yuan, as well as the brand-name 1.44MB disks, which for the CD-R to ordinary users to get through the price bottleneck.
CD-RW refers to a rewritable disc burner that can be written multiple times and read multiple times. Compared with the CD-R, CD-RW can rewrite the CD-RW disc function, the other basic same, the price is not much more expensive. But CD-RW disc is too expensive, each about 100 to 200 yuan, and only support Mulit-read optical drive to read the CD-RW disc (in addition, CD-RW has a fatal weakness, low reflectivity.) Its reflectivity is less than 1/4 of the ordinary CD-ROM disc). In other words, discs burned by CD-RW may not be readable on ordinary CD-ROMs. However, for this issue, the United States Osta (Visual Storage Technology Alliance) has proposed a solution, CD-ROM drive standard multi-read will become the new standard of optical drive manufacturing industry, all MULTIREAD-compliant optical drive can be read out including CD, R, CD-RW platters. The shortcomings of CD-RW greatly limited its application range, but also because of the problem of reflectivity, CD-RW disc than the ordinary CD-ROM is more sensitive to physical damage.
Mo's full name is Magnetooptical, which is a repeatable erase storage technology that combines optics and electromagnetics. Mo drives on the market today are mainly 3-inch and 5-inch two, ranging in size from 128M to 2.6G, and more commonly 3-inch 640M of Mo. Because this MO already has the international standard, each big manufacturer's different capacity product can also be compatible with each other. But it's also a pity that MO drives cannot read CD-ROM discs, and CD-ROMs are not compatible with Mo platters. Mo Drive small size, good shockproof performance, no need to install any driver, easy to operate, and read faster than the fixed hard disk, large capacity floppy drive and other similar storage media, high stability, and relatively low storage cost advantage. Because the performance and capacity of Mo Drive is basically proportional, so, to the mo of about 2.6GB, it runs very close to the hard disk. In addition, MO backwards-compatible, small-capacity discs can be used on large-capacity drives.
In terms of price, the cheaper 3-inch 640M mo Drive only about 2500 yuan, the price of the platter is 150 yuan, is within the scope of consumers can bear. The price of 2.6GB MO drives is staggering, but it has a large disk size, with only 1/5 of the zip cost per megabyte, and a much smaller investment after the drive is purchased. Although Mo's overall performance is very good, but because of its low prevalence, is generally used by professionals, so the general home users may be inconvenient to use, also requires the source machine and target machine installed the same specification Mo driver, or the target machine installed higher-end MO to backward compatibility.

Three, active hard disk
The active hard disk is divided into two categories according to different connection methods. One class is a rack built-in active hard drive that can be placed on a 5-inch rack in the chassis, where power is provided by the chassis power supply. The hard drive is placed in a removable hard drive box that can be withdrawn and moved freely. This type of hard disk box generally built-in ordinary hard disk, the connection is also the same as the ordinary hard disk, so there is no special requirements for the system, transmission speed in all mobile storage solutions is the fastest. Rack built-in active HDD box is cheaper, one-time purchase of multiple computers equipped with data exchange requirements, but also a cost-effective solution. It is also important to note that the built-in active hard drive is a common hard disk, so the seismic resistance in the movement is poor, not suitable for the transfer of critical data.
The other is an external active hard drive, outside the chassis, powered by an external DC power supply, connected to the computer via a USB or IEEE1394 FireWire interface. This type of hard disk box is generally built into the laptop hard disk, in performance than the ordinary hard disk slightly worse, but high seismic resistance, while the cost of storage space per unit is also high.
Now almost every computer is equipped with a USB interface, so the external active hard drive box with USB interface is very convenient for data transfer, just bring the driver with you. However, due to the low transfer rate (12MB/S) of the USB interface, the overall performance of the enclosure is poor. The external HDD with IEEE1394 interface overcomes this shortcoming, and the transmission rate of IEEE1394 up to 400mb/s gives full play to the performance of external hard disk. However, at present, IEEE1394 is not popular, on the motherboard without the interface, users who want to use such equipment, must purchase a IEEE1394 interface card. However, compared to the SCSI interface card, the IEEE1394 interface card price is indeed not high. With the popularization of IEEE139, this kind of external active hard disk will become the mainstream of data mobile storage.

Four, Flash memory class
The storage medium of flash memory is different from the magnetic medium and optical medium of the above mobile memory, and is a semiconductor dielectric. The more famous products have Iomega clik! (PC Card), diamond Company's Rio (MP3 player), Sony's MemoryStick (Memory stick) and other USB readers (storage media for various flash cards).
CF memory cards and CF-card drives are the first storage media for digital cameras, and with the growing popularity of Cfⅰ/ⅱ slot applications, it is now possible to use the CF card not only in digital cameras, but also in PDAs and other devices with CF slots. In particular, IBM's CF micro-drive, in a small card can hold the largest number of gigabytes of data. CF card storage device has a good development prospects, but the shortcomings are also obvious, the scope of application is limited, the prevalence is not high.
Compared with other mobile memory, flash memory has the advantages of small size and high reliability. Flash chip is nonvolatile memory, that is, the storage data is not required to maintain the voltage, the energy consumption is mainly used in reading and writing data. Flash memory class storage reliability is relatively high, because it is a veritable "solid state storage Media", there is no collision between the head and the disk, so not afraid of bump, in the read and write operation can also resist the impact of up to 2000Gs, so users do not have to worry about their own mistakes to make data damaged.
The biggest disadvantage of flash memory is that storage media is expensive. At the time of last year even up to 100 yuan/mb, now although a lot of decline, but still more than the average user's affordability. This also results in a small capacity per unit of storage media (typically 32/64MB) and cannot be used for large-scale data transfers.

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Comprehensive knowledge of mobile storage devices