USB Flash Drive Detailed

Summary: u disk, address the earliest from NETAC company production of a new type of storage equipment, called "USB", using USB interface to connect. USB interface connected to the computer's host, the data can be exchanged with the computer USB. And then the production of similar technology equipment because the NETAC has been patented, and can not be called "USB", and renamed the "U Disk" homophonic. Later, the name of the USB flash drive is widely known for its simplicity and ease of use, and until now the two have been common and are no longer distinguishable from one of the mobile storage devices. The biggest advantage of the U disk is: Small and easy to carry, large storage capacity, cheap, reliable performance. The volume of the flash drive is small, thumb-like size, very light weight, generally around 15 grams, especially suitable for carry-on, we can hang it on the chest, hanging on the keychain, or even put into the purse. The general U disk capacity of 1G, 2G, 4G, 8G, 16G, 32G, etc., the most common price of 4Gb for example, about 70 yuan can be bought. There is no mechanical device in the disk, the anti-seismic performance is very strong. In addition, the flash disk also has moisture-proof, anti-magnetic, high and low temperature characteristics, safety and reliability is very good.

u disk, full name "USB flash drive", English "USB flash disk". It is a USB interface with no physical drive micro high-capacity mobile storage products, can be connected via USB interface to the computer for Plug and play. The name of the USB flash drive originated from NETAC Company, a new type of storage equipment, known as "USB", using USB interface to connect. USB interface connected to the computer's host, the data can be exchanged with the computer USB. And then the production of similar technology equipment because the NETAC has been patented, and can not be called "USB", and renamed the "U Disk" homophonic. Later, the name of the USB flash drive is widely known for its simplicity and ease of use, and until now the two have been common and are no longer distinguishable from one of the mobile storage devices.

Advantages
The biggest advantage of the U disk is: Small and easy to carry, large storage capacity, cheap, reliable performance. The volume of the flash drive is small, thumb-like size, very light weight, generally around 15 grams, especially suitable for carry-on, we can hang it on the chest, hanging on the keychain, or even put into the purse. The general U disk capacity of 1G, 2G, 4G, 8G, 16G, 32G, etc., the most common price of 4Gb for example, about 70 yuan can be bought. There is no mechanical device in the disk, the anti-seismic performance is very strong. In addition, the flash disk also has moisture-proof, anti-magnetic, high and low temperature characteristics, safety and reliability is very good.

Storage principle
    computer to convert binary digital signal to compound binary digital signal (add assignment, check, stack and other instructions) read and write to the USB chip adapter interface, through the chip processing signal allocated to the EEPROM memory chip corresponding address store binary data, Implements the storage of data. EEPROM data memory, the control principle is voltage control gate transistor voltage high and low value, the junction capacitance of the gate transistor can hold the voltage value for a long time, the reason why the data can be saved after power failure is to add the floating gate and the selection grating on the original transistor. A floating shed for storing electrons is formed on a semiconductor that conducts unidirectional currents between the source and drain poles. The floating grille is encased in a layer of silicon oxide film insulator. Above it is the selection/control grille that controls conduction currents between the source and the drain poles. The data is 0 or 1 depending on whether there is an electron in the floating grille formed on the silicon baseplate. There are electrons for 0, no electrons for 1. Flash memory, like its name, deletes data before it is written to initialize. In particular, the electrons are exported from all floating grids. There will be some data for "1". Write only when the data is 0 o'clock, and when the data is 1, nothing is done. At 0 o'clock, a high voltage is applied to the gate electrode and drain, which increases the electrical energy conduction between the source and drain poles. In this way, the electrons will break through the oxide film insulator and enter the floating gate. When the data is read, a certain voltage is applied to the gate electrode, the current is 1, and the current is set to 0. The floating gate does not have the state of the electrons (data 1), the voltage is applied to the drain when the gate electrode is applying a voltage, and the current is generated between the source and the drain due to the large amount of electrons moving between the poles. In the case of a floating gate having an electronic state (data 0), the electrons in the channel are reduced. Because the voltage applied to the gate electrode is absorbed by the floating gate electrons, it is difficult to influence the channel.

Improve Performance methods
Under the Windows XP operating system, after the USB flash drive is working, right-click the removable disk in My Computer, select Properties------Hardware-----Select the move disk in all disk drives, click Properties, and select Policy in the New dialog box.
If you select "Optimize for quick Delete", this device will not use the disk's write cache, so you can unplug the device without "safe delete".
If you select "Optimize for performance", this device will use disk write cache to improve disk performance, incoming and outgoing speed will be greatly improved, but to disconnect the device is to click on the "Safe removal of hardware", or the data on the USB flash drive is likely to be lost.
Ordinary u disk does not have encryption function. If you have encryption requirements, you can choose a USB flash drive with encryption. General software encryption is easy to crack. Simple point file encryption method you can choose to use the encryption features included with software such as Windows Optimizer. The way you're talking about storing data is software implementation. Embodied in the disk drive and other storage media, is a form of a file. Simply say that you are operating the same as your hard drive.

Lifetime Maintenance
U disk can erase the number of times is the normal life of the U disk, the general use of MLC particles of the U disk can erase more than 10,000 times, and the use of SLC particles of the U Disk Service life is up to 100,000 times.
Never unplug the flash drive when the flashing light is flashing, as the USB flash drive is reading or writing data, and unplugging may cause hardware and data damage. Do not close the relevant program immediately after the backup document, because that time the flash drive on the light is still flashing, indicating that the program is not completely finished, then unplug the USB flash drive, it is easy to affect the backup. Therefore, after the file backup to the flash disk, it should be some time before closing the relevant procedures to prevent accidents, the same reason, when the system prompts "can not stop" do not easily unplug the USB flash drive, which will also cause data loss. Note that the USB stick is placed in a dry environment, do not let the USB port interface for a long time exposure to the air, otherwise prone to surface metal oxidation, reduce interface sensitivity. Do not use a long time to plug the USB stick on the interface, otherwise it is easy to cause the interface aging, on the other hand is also a loss of u disk.

Considerations
1. Generally have write protection switch U disk, should be in the USB stick before inserting the computer interface to switch, do not switch in the operating state of the U disk.  
2. The USB stick has a working status indicator, if it is a light, when the host interface is plugged in, the light indicates the power supply, when the light flashes indicate that the data is being read and written. If it is two LEDs, usually two colors, one on the power-on, one on the USB drive to read and write data on the light.  
Some USB sticks are still working after the system copy progress bar disappears, it is forbidden to unplug the USB flash drive when the reading and writing status light is on. Must wait for the read-write status led to stop flashing or out before unplugging the USB flash drive.  
3. Some brand models of the U disk for the file allocation table reserved space is small, when copying a large number of individual small files prone to error, you can stop the copy, take a number of small files first compressed into a large file method to solve.  
4. In order to protect the motherboard and USB interface, prevent deformation to reduce friction, if the copy speed is not required, you can use a USB extension cable, (usually with a USB flash drive is presented.) If you need to buy, try to choose well-known brands, the thicker the better. But not more than 3 meters, otherwise it is easy to copy data error. Note that if the USB extension is USB1.1 (USB2.0 full speed), it will be slow.  
5. U disk storage principle and hard drive has a great discrepancy, do not defragment, otherwise affect the service life.  
6.U disk may have a USB stick virus, the best way to plug in the computer antivirus.  
7. The new U disk to buy the best to do a U disk virus immunity, can be very good to avoid the U disk poisoning  
       8.U disk does not start on the computer (after entering the desktop) do not plug in the computer, Otherwise, your computer may not start properly.

USB flash drive to extend system cache
Under the Microsoft Windows Vista operating system, the ReadyBoost feature allows you to simply plug in the USB flash memory and slightly configure to improve system performance. and using USB 2.0 Flash to speed up Vista PC performance, use the space of the USB memory as system memory.
Of course, the prerequisite for using the ReadyBoost feature is that the USB flash memory must meet certain performance and capacity requirements: at least 2.5mb/s transfer, 4K Random read speed, 1.75mb/s transmission, 512K random write speed, 64MB to 8GB of free space , the total capacity is at least 256MB or more. This is only the basic parameters given by Microsoft, and it requires more high-performance flash memory to be a perfect experience for readyboost performance.

USB USB port and Plug and Play
In layman's words, USB is one of the interface types that peripherals connect to a computer host. In addition to the USB interface, there are interfaces such as parallel buses.
However, the USB interface has a great advantage to make it very popular in this field, that is, the device with this interface can be Plug and Play on the computer (Plug and Play is sometimes called Hot plug). When the computer is turned on the peripheral equipment to open the host power, and the order of the shutdown is the opposite. The reason to follow this boot order is because before the computer starts, all peripherals must be powered on and ready, Then wait for the host to check each of these devices and install the appropriate software. Only in this way can the computer function properly, otherwise the peripheral device may not be available or the computer will not be able to recognize the peripheral device. The appearance of the USB interface has changed this situation, if a device is a USB interface, then it can be inserted at any time the computer host regardless of the state of the computer at this time, and if you want to take away this device, just follow the standard operation can be safe to remove the device from the computer. This undoubtedly provides people with great convenience in their study and life.
From the name of the USB flash drive, we can see that this storage disk is a USB interface, because this storage disk is a USB interface, so this storage disk can be Plug and Play on the computer, that is, the storage disk is Removable Storage disk, it can carry. Therefore, the generalized USB stick is actually refers to the mobile storage device.

USB Drive Storage Specification
The USB flash drive belongs to the mass storage class, and its storage specification includes 4 independent sub-specifications, namely CBI transfer, BULK-ONLY transmission, ATA command block, UFI Command specification. The first two protocols define the data/command/State transfer method on the USB bus, the BULK-ONLY transport protocol uses only the BULK endpoint to transmit the data/command/state, and the CBI transport protocol uses control/bulk/interrupt three types of endpoints for data/command/ The delivery of the state. The latter two protocols define the operational commands for the storage media, the ATA protocol for the hard disk, the UFI protocol for USB Removable Storage, and the design of the USB drive reader to follow the Bulk-only transport protocol and UFI Command specification. The UFI command block specification is designed for USB Removable Storage, which defines a total of 19 12-byte operation commands.

Related software and viruses
Vista ReadyBoost
ReadyBoost is a new technology in Windows Vista that leverages the advantages of Flash random read-write and fragmented file read and write to improve system performance. If your USB stick is up to spec, you can boost the system speed by starting ReadyBoost.
Prayaya v3
Prayaya v3 is a USB stick boot system. Mini Office software. You can install the software you need on the USB stick. Achieve Mobile Office purpose
U disk parasite (Checker/autorun)
The "U-disk Parasite" is a worm that uses mobile devices such as a USB stick to propagate and use Autorun.inf to automatically play files. Autorun.inf files usually exist in the root directory of the USB flash drive, MP3, mobile hard disk and hard disk partitions, when the user double-clicks the USB flash drive and other devices, the file will take advantage of the Windows System AutoPlay function, priority to execute the virus program to be loaded, thereby destroying the user's computer, Make the user's computer suffer losses.
Expert advice: Users before using the U disk, must first use anti-virus software to scan, confirm non-toxic and then open. You can set up a Autorun.inf folder in a USB flash drive and read-only hide it.
You can use the batch command in CMD to establish Autorun.inf, as follows:
@echo off
MD Autorun.inf
CD Autorun.inf
MD ABC.. \
Pause
Copy the above command into Notepad to save as bat or cmd file format, run on the USB stick, you can no longer let the USB stick virus run.
If you want to delete this folder, run the following command line:
@echo off
CD Autorun.inf
RD ABC.. \
Cd..
Rd Autorun.inf
Pause
Copy the above command into Notepad and save it as a bat or cmd file format and run it on a USB drive to delete the Autorun.inf folder.
You can use Group Policy gpedit.msc to disable the operation of executable files on a USB flash drive:
Enter "Gpedit.msc" in "Run"
Computer Configuration---Windows Settings---Security settings---software restriction policies---other policies---right-click the new path rule----Add the drive letter you want to restrict---OK
In this way, all the executable files on the USB stick will not run, to run, repeat the above actions, set to unrestricted.
Unable to stop ' universal volume ' device solution
When you safely delete a USB flash drive, you will often encounter the prompt "Unable to stop the universal volume" device, please stop the device later. ”
Can you forcibly unplug the USB flash drive in this case? Of course you can't! At this time if forcibly removed, it is easy to damage the computer u port or your USB stick. If you have important information on your USB stick, it is likely that it will be destroyed. So what should we do?
Here I write several commonly used solutions, I hope to be helpful to everyone.
The first method (which is also the most common method that I suggest to you):
Often we in the file or data to take out the flash drive, are used by the "copy" "Paste" way, and if the copy is a USB flash drive file, this file will always be placed in the system's clipboard, in the state of waiting. And if in this case we want to remove the USB flash drive, it will appear above the unable to stop the USB flash drive prompt.
The corresponding solution is: empty your clipboard, or on your hard disk to copy a file and then paste the operation, then you go to delete the USB flash drive prompt to see if it was successfully deleted?
The second method:
If you feel that the above method is not valid, you can use the following method:
At the same time press the keyboard "Ctrl" + "Alt" + "Del" key combination, the Task Manager window appears, click the "Process" tab, in "Image name" in the "rundll32.exe" process, select the "rundll32.exe" process, and then click "End Process" , a Task manager warning pops up asking you to determine if you want to close the process and click "Yes" to turn off the "rundll32.exe" process. Then delete the USB flash drive can be deleted normally. When using this approach, note that if you have more than one "rundll32.exe" process, you need to close more than one "rundll32.exe" process.
The third method:
This method also uses the Task Manager, while pressing the keyboard "Ctrl" + "Alt" + "Del" key combinations, the Task Manager window appears, click "Process", Look for "explorer." EXE "process and end it. At this time you will find your desktop is missing, please do not panic, continue to do the following, in the Task Manager, click on "File"-"New Task"-Enter explorer.exe--OK. Then remove the USB flash drive and you will find it safe to delete.
The fourth method:
This is the simplest, but most time consuming, way to restart your computer.
The Fifth method:
Installing Unlocker Software
If you feel that there is a problem to solve some of the trouble, you can use the following early precautionary measures:
Turn off the preview feature of the system.
Method: Double-click My Computer--tools--Folder Options--general--tasks--Use the Windows Traditional Style folder, then click OK. So once and for all.
Tips: Some of the current U disk technology is in place, and some U disk directly Plug and pull can also. However, no matter how good the U disk, there is a time is absolutely not directly plug and draw, that is, carefully look at your u disk of the small lamp, small lights in the flashing time indicates that is constantly reading and writing data, it must not be pulled, otherwise light damage data, heavy u disk scrap.
Working relationship commonly used U disk, forever learned the above several methods, hope to everyone will be helpful.
Main Specifications and functions:
* USB2.0 interface (compatible with USB1.1) is currently used. Hot-swappable, plug-and-play support
* No external power supply required. With LED light display
* Capacity: 128M (currently obsolete), 256M (currently obsolete), 512M (currently obsolete), 1G, 2G, 4G, 8G, 16G, 32G
* Use a variety of operating platforms WIN98/SE/ME/2000/XP/VISTA/7, MAC Os8.6&higher, UNIX, LINUX2.4 or later
(WIN98 must install the driver)
* Electronic storage media. No mechanical parts, anti-vibration, anti-electromagnetic interference
* Support software encryption, dual boot function
* Keep data safe for a long time (more than 10 years)
* Read and Write fast:
O USB 1.1:
+ Write Speed: 0.75-1mb/s
+ Read speed: 1.5-2.5mb/s
O USB 2.0:
+ Write Speed: 4.5-7mb/s
+ Read speed: 15.5-16mb/s
* Can be carried with you
* Operating Ambient temperature:-40°c ~ + 70°c
* Storage Temperature:-50°c ~ + 80°c
* Main purpose of U disk: Storage of file information, production system Startup disk

USB Flash Drive Detailed