brief introduction
storage principle
Application mode
Use problem
The purpose of USB flash drive
Related websites
[Edit this paragraph] Introduction
U disk is the abbreviation of U disk, and U disk is just the homonym of U disk. U disk is a kind of flash memory, so it is also called flash disk. The biggest features are: small and portable, large storage capacity and low price. It is a kind of mobile storage device. Generally, the capacities of USB flash drives are 64M, 128M, 256M, 5 12M, 1G, 2G, 4G, 8G, etc. Take the most common 1G as an example, you can buy it around 40 yuan. 2G Kingston 65 yuan. The capacity of U disk has been greatly improved, such as 4G, 8G, 16G. Easy to carry, it belongs to mobile storage equipment, and of course it will not be inserted in the box. We can hang it on our chests, on key chains, or even in our wallets.
[Edit this paragraph] Storage principle
The computer converts the binary digital signal into a composite binary digital signal (adding instructions such as allocation, check and stack), reads and writes it to the U disk chip adapter, and passes through the chip.
[Edit this paragraph] Usage
U disk has a USB interface and is a USB device. If the operating system is Windows 2000/XP/2003/Vista or Apple, the system will automatically identify the U disk by inserting it directly into the USB interface on the front panel or the back of the chassis. If the system is Windows 98, you need to install a USB driver to use it. You can find the driver on the attached CD or the manufacturer's website.
The first time you use a USB flash drive on a computer (when you plug in a USB interface), the system will report "New hardware found". After a while, you will be prompted: "The new hardware has been installed and can be used". (Sometimes it may need to be restarted) At this time, open "My Computer" and you will see an additional icon called "Removable Disk". After this step, if you use a USB flash drive in the future, you can directly open "My Computer". At this point, notice that a small icon will appear in the lower right corner of the screen, indicating a USB device. U disk is one of USB devices. Next, you can save and delete the files on the USB flash drive as usual. However, it should be noted that after using the USB flash drive, close all windows, especially those about the USB flash drive. Right-click the USB device icon in the lower right corner before correctly unplugging the USB flash drive, then left-click "Remove Hardware Safely", press the "Stop" button, and then click "OK" in the pop-up window. When the prompt "You can safely remove the drive now" appears in the lower right corner, you can unplug the USB flash drive from the chassis. There is a more convenient way to unplug it. Click the extra icon directly, and then click Stop USB Interface. After the prompt "You can safely remove the drive now", click OK to unplug it.
From 1998 to 2000, many companies claimed that they were the first to invent USB flash drives. Include China Netac Technology, Israeli M-Systems and Singapore Trek Company. However, the real patent for the basic invention of U disk is China Netac. In July 2002, Netac's "Flash electronic external storage method and device for data processing system" (patent number: ZL 99 1 17225.6) was officially authorized by China National Intellectual Property Administration. This patent fills the gap of invention patent in the field of computer storage in China for 20 years. The acquisition of this patent right caused a great shock to the entire storage industry, including the Israeli M-Systems Company immediately filed an invalid reexamination with China National Intellectual Property Administration, China, which once became a patent dispute that shocked China and foreign countries in the global flash memory field. However, on June 7, 2004, Netac obtained the basic invention patent of flash disk officially authorized by the US National Patent Office, with the US patent number of US6829672. The acquisition of this patent right finally ended the struggle. China Netac was the first person to invent USB flash drive in the world. On February 10, 2006, US time, Netac entrusted American lawyer Morgan Lewis to file a complaint with the US Federal Court for the Eastern District of Texas, accusing PNY of infringing Netac's US patent (US Patent No.6,829,672). In February 2008, Netac and PNY reached an out-of-court settlement. Netac signed a patent license agreement with PNY, and PNY paid Netac a patent license fee of $654.38+million. This is the first time that a China enterprise has obtained a huge patent license fee in the United States, which further proves that Netac is the global inventor of U disk.
Now all flash drives support USB2.0 standard; However, due to the technical limitation of NAND flash memory, their reading and writing speed can not reach the maximum transmission speed of 480Mbit/s supported by the current standard. At present, the fastest flash drive has used dual-channel controller, but compared with the current generation of hard disks, or the maximum transmission rate that USB2.0 can provide, it is still a little worse. At present, the highest transmission rate is about 20-40MB/s, while the general file transmission rate is about100 MB/s. The transmission rate of the older "full speed" 12mbit/s devices is only about 1MB/s at most. Among them, Hong Kong Company, Shenzhen Netac Company, M-Systems Company and Singapore Trek Company are the best in the industry. U disk, USB interface, plug and play. Generally speaking, USB is one of the interface types between peripheral devices and computer hosts. In addition to USB interface, there are parallel bus and other interfaces. But USB interface has a great advantage that it is very popular in this field, that is, devices with this interface can be plugged and played on computers (sometimes called hot plug). When the computer is turned on, the peripheral equipment should be turned on first, and then the host power supply should be turned on, and the order of turning off is just the opposite. The reason why we should follow this startup sequence is that before the computer starts, we must turn on the power of all peripheral devices to get ready, and then wait for the host to check these devices one by one and install the corresponding software. Only in this way can the computer run normally, otherwise the peripheral equipment may be unavailable or the computer cannot recognize the peripheral equipment. However, the appearance of USB interface changed this situation. If a device is a USB interface, it can be plugged into the computer host at any time, no matter what state the computer is in at this time, and if you want to take this device away, you can safely take it out of the computer according to the standard operation, which undoubtedly provides great convenience for people's study and life. So it can be seen from the name of the U disk that this storage disk is a USB interface, because this storage disk is a USB interface. So this storage disk can be plugged and played on the computer, which means that this storage disk is a mobile storage disk and can be carried around. So the generalized U disk actually refers to the mobile storage device.
However, the narrow sense of U disk only refers to flash disk. Flash disk refers to a mobile storage disk that uses flash technology to store data information. Flash memory technology is a storage technology that has just emerged in the computer field for several years. Compared with the traditional electromagnetic storage technology, it has many advantages: first, this storage technology has no mechanical movement in the process of storing information, which makes its operation very stable, thus improving its seismic performance. Make it the most shockproof device among all storage devices. Secondly, because it doesn't have a high-speed rotating disk like floppy disk, hard disk and CD-ROM, its size can often be made very small. Now MP3 players can be made very small because of this storage technology. For example, some people say that he has a USB flash drive, which may be just an ordinary mobile hard disk or a micro hard disk that has just appeared in recent years. There may also be a flash drive. Of course, as mentioned above, the current USB flash drive generally refers to a flash drive, so we usually understand it as a USB flash drive. Related software and virus Vista ReadyBoost ReadyBoost is a new technology in windows vista, which uses the advantages of random reading and writing of flash memory and fragmentary file reading and writing to improve system performance. If your USB flash drive meets the specifications, you can speed up the system by starting ReadyBoost. Online storage-"Network USB flash drive" has the functions of "upload" and "download" of breakpoints, which not only realizes the download of large files, but also has the function of continuous transmission of breakpoints, which can transmit files in segments and greatly save transmission time. However, the upload/download speed is slow, and it is not practical for files over 200M m. A kind of "U disk parasite" is a worm virus that spreads by using mobile devices such as U disk and is triggered by automatically playing the autorun.inf file, which generally exists in the root directory of U disk, MP3, mobile hard disk and hard disk partition. When a user double-clicks a device such as a USB flash drive, the file will use the automatic playback function of Windows system to execute the virus program to be loaded first, thus damaging the user's computer and causing losses to the user's computer.
[Edit this paragraph] Use problems
Expert advice: users must scan the USB flash drive with anti-virus software before using it, and then open it after confirming that it is non-toxic. Faults and maintenance of the following faults: during maintenance, first of all, eliminate the damage of USB interface, virtual welding of PCB board and normal USB extension cable, and then make maintenance judgment.
USB flash drive failure.
U disk faults are generally divided into soft faults and hard faults, of which soft faults are the most common.
Soft fault mainly refers to the bad block of the U disk, which causes the U disk to be recognized by the computer, but there is no drive letter, or there is a drive letter, but when you open the U disk, you are prompted to format, and the formatting cannot be successful. Early signs may include: slow reading and writing of USB flash drive, file loss but still occupying space, etc. This kind of bad USB flash drive can generally be repaired by software. At present, the commonly used low-level repair tool is Mformat (it can be searched and downloaded on the Internet, which is extremely convenient to use and can be repaired in less than one minute). Of course, some U disk manufacturers will also provide some similar software. The author thinks that since it is a low standard, the fault type is the same, and the low standard tool Lformat of hard disk can also be used, but it is relatively troublesome because Lformat runs under dos, and I have not tried it specifically, so it is not recommended.
Hard failure mainly refers to the situation that the hardware of the USB flash drive fails, the computer will find new hardware after plugging in the USB flash drive, but the drive letter cannot appear, and the USB flash drive is disassembled without any traces of circuit board burning or other damage, which cannot be solved by the soft failure method. I had a USB flash drive a long time ago, because I couldn't get the drive letter and went to the after-sales service department for repair. Because I was there, I watched them plug in for a long time, and I didn't even try the soft repair. I said it was impossible to repair it, so I just changed it. Fortunately, it also shows their ignorance. ) A hard fault is generally that the crystal oscillator in the U disk is damaged due to violent vibration. Readers can try to buy a crystal oscillator with the same frequency in the electronic market for less than one yuan instead of the original crystal oscillator.
Next, let's explain the file recovery problem of bad U disk. The recovery of the U disk file only exists when the U disk can be identified as a soft fault, but the prompt format is unsuccessful. Readers can download some file recovery software similar to EasyRecover on the Internet. The author has used this software many times to solve the file recovery of U disk and hard disk.
1.The USB flash drive does not respond when inserted into the machine.
Maintenance ideas: according to the fault phenomenon, the U disk machine does not work, and the conditions that the U disk tool should have are the focus of our maintenance. No matter what scheme of USB flash drive wants to work, the following conditions must be met:
(1) power supply is divided into power supply required by master control and power supply required by FLASH. These two are keys, and the U disk circuit is very simple. If there is no power supply, it is generally the fuse inductor or the 3.3V voltage stabilizing block that is damaged. Speaking of voltage stabilizing blocks, let's stop here. It has three pins, namely power input (5V), grounding and power output (3.3). The working principle is that when the input pin inputs 5V voltage. As long as we find a place without power supply, this problem will be well solved.
(2) Clock, because the host can only work at a certain frequency, and the communication with FLASH also needs to be transmitted by clock signal, so if there is no clock signal, the host will definitely not work. When checking this circuit, in fact, the clock generation circuit is very simple, just check the crystal oscillator and its peripheral circuits, because the crystal oscillator is afraid of rubbing and the U disk is easy to fall to the ground, which will damage the crystal oscillator, so just replace the same crystal oscillator. Note: the crystal oscillator cannot be measured, and the best way to judge its quality is to change a good crystal oscillator.
(3) Master control. If the above two conditions are normal, the master control chip is damaged. Just change the main control.
2. Insert the USB flash drive into the computer and prompt "Unrecognized device".
Maintenance ideas: for this phenomenon, first of all, it shows that the circuit of the U disk is basically normal, but there is a fault in communication with the computer. For communication, you need to check the following points:
(1) USB interface circuit, this circuit has no special components, just two data lines D+ D-, so when checking this circuit, you only need to measure whether the line between the data lines and the main control circuit is normal. Generally, two resistors with small resistance are connected in series between the data line and the main control circuit for protection, so it is necessary to check whether the resistance values of these two resistors are normal.
(2) Clock circuit, because the communication between the USB flash drive and the computer should be carried out at a certain frequency. If the working frequency of the USB flash drive and the computer can't be synchronized, then the system will think that this is an "unrecognizable device". At this time, the crystal oscillator will be changed. And there are many examples of crystal vibration damage in actual maintenance!
(3) Host, if the above two checks are normal, it can be judged that the host is damaged.
3. You can recognize the USB flash drive, but when you open it, you will be prompted "The disk is unformatted" but the system cannot format it, or you will be prompted "Please insert the disk". Open the USB flash drive, the content is garbled, and the capacity does not match itself.
Maintenance ideas: for this phenomenon, it can be judged that there is not much problem with the hardware of the U disk itself, but there is a problem with the software.
Solution: Just find the repair tool of the master control scheme. This depends on everyone, what is the main control scheme of the USB flash drive.
The failure of U disk is generally due to the poor performance of flash memory or the phenomenon that bad blocks can't be written and stored in files. Unlike MP3, USB flash drives don't have firmware, but some manufacturers put their own software in them. If they are low, they will be gone. Tell you a very simple method, that is, when the main control is damaged or the corresponding repair tool can't be found, you can use the USB flash drive kit to make a new USB flash drive. The method is to remove the flash of the faulty machine and put it on a new PCB. U disk kit includes (PCB with main controller (1. 1/2.0) and a set of shell), which is very simple to maintain and more convenient for data recovery.
life
The erasable times of the USB flash drive are the normal life of the USB flash drive. Generally, the U disk with MLC particles can be erased more than 1000 times, and the life of the U disk with SLC particles is as long as 1000 times. Maintenance and correct plugging and unplugging of U-disk: Never unplug the U-disk when the indicator light of U-disk flashes rapidly, because the U-disk is reading or writing data at this time, and unplugging it halfway may cause damage to hardware and data. Don't close the related program immediately after backing up the document, because the indicator light on the U disk was still flashing, indicating that the program was not completely finished. At this time, pulling out the USB flash drive will easily affect the backup. Therefore, after the file is backed up to the U disk, it will take some time to close the relevant programs to prevent accidents; Similarly, when the system prompts "Cannot stop", don't pull out the USB flash drive easily, which will also cause data loss. Pay attention to place the U disk in a dry environment, and don't expose the interface of the U disk to the air for a long time, otherwise it will easily cause surface metal oxidation and reduce the sensitivity of the interface. Don't always plug a long-term unused U disk into the USB interface, otherwise, on the one hand, it will easily lead to aging of the interface, and on the other hand, it will be a loss to the U disk.
correlation technique
Generally speaking, USB is one of the interface types between peripheral devices and computer hosts. In addition to USB interface, there are parallel bus and other interfaces. However, USB interface has a great advantage that makes it very popular in this field, that is, devices with this interface can be plugged and played on computers (sometimes called hot plug).
When the computer is turned on, the peripheral equipment should be turned on first, and then the power of the host computer should be turned on, and the order of turning off is just the opposite. The reason why this boot sequence should be followed is that before the computer starts, all peripheral devices must be powered on to get ready, and then wait for the host to check these devices one by one and install the corresponding software. Only in this way can the computer run normally, otherwise the peripheral equipment may be unavailable or the computer can't recognize the peripheral equipment.
However, the appearance of USB interface changed this situation. If a device is a USB interface, it can be plugged into the computer host at any time, no matter what state the computer is in at this time. If you want to take this device away, you can safely remove it from your computer according to standard operation. This undoubtedly provides great convenience for people's study and life.
Therefore, from the name of the U disk, we can see that this storage disk is USB interface, because this storage disk is USB interface, so this storage disk can be inserted into a computer to play, which means that this storage disk is a mobile storage disk and can be carried around. Therefore, in a broad sense, a U disk actually refers to a mobile storage device. In a narrow sense, U disk only refers to USB flash drive.
Flash disk refers to a mobile storage disk that uses flash technology to store data information. Flash memory technology is a storage technology that has just emerged in the computer field for several years. Compared with the traditional electromagnetic storage technology, it has many advantages: first, this storage technology has no mechanical movement in the process of storing information, which makes it run very stably, thus improving its seismic performance and making it the most anti-vibration device among all storage devices. Second, because it doesn't have high-speed rotating disks like floppy disks, hard disks and optical disks. Its volume can usually be made very small. The reason why MP3 players can do very little now is because of this storage technology. For example, some people say that he has a USB flash drive, which may be just an ordinary mobile hard disk, or a micro hard disk that has just appeared in recent years, or a USB flash drive. Of course, as mentioned above, the current USB flash drive generally refers to a USB flash drive, so we usually understand that what he owns is a USB flash drive.
Matters needing attention
1.USB flash drives generally have write protection switches, but they should be switched before the USB flash drive is plugged into the computer interface, not when the USB flash drive is working. 2. The USB flash drive has a working status indicator. If it is an indicator light, it will light up when it is plugged into the host interface, and when it flashes, it means that data is being read and written. If there are two indicator lights, there are generally two colors, one is on when the computer is turned on, and the other is on when the USB flash drive reads and writes data. After the system copy progress bar disappears, some USB flash drives are still working. It is forbidden to pull the USB flash drive when the read-write status light is on. Do not unplug the USB flash drive until the reading and writing status indicator light stops flashing or goes out. 3. Some brands and models of USB flash drives have little space reserved in the file allocation table, and it is easy to report errors when copying a large number of single small files. At this time, you can stop copying and adopt the method of compressing multiple small files into one large file. 4. In order to protect the USB interface and USB flash drive of the motherboard, prevent deformation and reduce friction, if there is no requirement for copying speed, you can use a USB extension cable, which is usually given with the USB flash drive. If you need to buy, try to choose famous brands, and the thicker the lines, the better. But it can't exceed 3 meters, otherwise it is easy to make mistakes when copying data. Note that if the USB extension cable is USB1.1(full speed of USB 2.0), the speed will be very slow. 5. The storage principle of U disk is very different from that of hard disk, so don't defragment it, otherwise it will affect its service life. 6. There may be a virus in the USB flash drive, so it is best to disinfect the USB flash drive when inserting it into the computer.
Brand and purchase
The data transmission speed of U disk is generally related to the data interface and the quality of U disk, because U disk uses flash memory, unlike the storage speed of hard disk, it is only related to the interface type of USB; The USB 1. 1 and USB2.0 standards used to distinguish speeds have been changed to USB2.0 full speed (corresponding to the previous USB 1. 1) and USB2.0 high speed (corresponding to the previous USB 2.0). There is also USB2.0 Nolmal Speed, which is generally used on keyboards and mice. These standards may also be displayed as USB2.0 (FS) and USB2.0 (HS) in some test software, so it must be confirmed as the interface of HS when purchasing. If the unified USB2.0 does not indicate the speed, it must be tested on site. Generally speaking, the speed of HS can reach 5~ 10M/S, while that of FS is 0. Introduce several popular USB flash drive brands: LG SanDisk Kingston Patriot Amber Bolesse Jinbang Langke Lenovo BenQ Newman Tsinghua Hi-Tech Ziguang Digital China Ziming Youbeite IBM. But yes, because the work of memory is very simple, the core is just a flash memory. In addition, basically all over the world will make flash memory, and Hyundai and several other factories are willing to make it and sell it. The memory particles themselves are of good quality. Therefore, memory is generally no different from any brand, and it is basically not bad. The only difference is that the products of big factories may read and write faster and have better after-sales service. It is not necessary for us. Just stick it in for a second. Why spend tens of dollars more? At present, the inferior brand memory on the market generally provides a one-month or one-year warranty, which shows that the quality is still very good. Don't drop it as long as it doesn't get into the water. It won't break.
U disk system (the first prayayan v3 in China)
Prayaya V3 is a virtual operating system (also known as V3 pocket system, with a total installation capacity of only 9M), which can install and use applications on any non-windows system partition or mobile storage device.
1: Install V3 on this computer (non-system disk) and install commonly used software into V3. The advantage is that all the registry information and post-upgrade files of those software, including the record files left after use, are automatically saved in the V3 virtual system, so that your windows system can be completely liberated, and you don't have to worry about the increasingly bloated and aging WINDOS, eliminating the trouble of always backing up, optimizing and cleaning up the system; If your windows is being reinstalled or restored, the programs in the V3 directory do not need to be reinstalled, and all previous data (favorites, cookie, history, chats, VoIP records, emails) will be kept intact.
2. Install the V3 virtual system on the mobile storage device, install the commonly used software to V3, and plug and play can be realized. Replace the public computer with your own computer, input method, QQ, MSN, stock operation, and everything remains the same.
3. official website Download Center lists thousands of V3-compatible software programs, which can be installed directly.
4.Playaya V3' s unique openurl function makes it extremely convenient for your favorite programs to run on it, as convenient as windows.
5. In terms of security, the latest right-click encryption function makes you no longer worry about the leakage of important files (using the latest AES256 algorithm in the United States).
6: V3 can install a variety of anti-virus software at the same time to ensure that the virus is not invaded to the maximum extent, and can also be used to make anti-virus disks.
Playa V3 can bring great convenience to your life, work and entertainment. On the other hand, because the data transmission speed of mobile storage devices is very different (some are faster than the local hard disk, some are inferior and defective, and may be slower than the local hard disk 10%), sometimes we don't expect them to run as fast on the external mobile storage devices as on the local hard disk, so we also recommend that you install them on the local hard disk and high-speed external storage devices, such as the mobile hard disk and high-speed USB flash drive, to back up each other.
installation instructions
After downloading the installation program, insert the removable storage medium into the location where you want to install V3. The installer will first list the drive letter of removable storage for you to choose (local disk installation can directly specify the drive letter), and then specify the root directory of this drive letter.
V3 is a green virtual system. After installation, no files will be written in the registry and windows system directory. In order to facilitate the application, you will be prompted to create a shortcut on the desktop.
For the installation of the local hard disk, it is recommended to set-> In security, turn off Allow V3 to create autorun.inf. Run PrayayaV3 directly from the desktop shortcut.
[Edit this paragraph] The use of U disk
1, used as a disk for storing files.
2, used as a boot disk to start DOS
3. Used as an optical disk drive system
4. Used as a hard disk installation system
5. Use it as a hard disk and put the system inside.
6, used for computer encryption