- 1.1 Introduction to U Disk
- Flash drive (English: USB flash drive), also known as pen drive, is a small portable storage device that uses a USB interface to connect to a computer and usually uses flash memory for data storage. Generally, U disks are actively small, light, and rewriteable. After they are released, they quickly become popular and replace traditional floppy disks and floppy disk drives. Sometimes the card reader is also classified as a USB flash drive, but the memory chip of such devices is not built-in, but a removable memory card.
- Compared with other portable storage devices (especially floppy disks), U disks have many advantages: they take up less space, can store more data, have faster read and write speeds, and will not be unusable due to scratches or mold. This type of USB storage device uses the USB mass storage device standard and has built-in support in modern operating systems such as Windows, macOS, Linux and Unix.
- U disks usually use a plastic or metal shell with a small printed circuit board inside, so that the size of the U disk is so small that it can be placed in a pocket like a key ring or string on a neck strap. Only the USB connector protrudes from the protective shell and is usually covered by a small cover. Most USB flash drives use a standard Type-A USB connector, which allows them to be plugged directly into the USB interface on a personal computer.
- To access the data of the USB flash drive, you must connect the USB flash drive to the computer; either directly connected to the computer’s built-in USB controller or a USB hub. Only when it is inserted into the USB port, the U disk will boot, and the required power is also supplied by the USB connection port for DC+5V.
- 1.2 U Disk History
- 1.2.1 Patent disputes over USB flash drives
- From 1998 to 2000, many companies claimed that they were the first to invent the USB flash drive. There are some different companies claiming to be the first to conceive or explain in detail, or to manufacture, or to apply for a patent; some companies claim to be the first to sell this kind of USB flash drive on the market. Tracing back to the development history of USB flash drives, in 2000, at least five companies around the world were selling USB flash drives, including Israel’s M-system, Singapore’s Trek, Netac USB, Ruben Easy Drive and South Korea’s Flash Driver.
- Netac technology argument
- China’s Netac Technology Co., Ltd. claimed that its U disk was the first in the world in 1999 [and passed the patent on November 14, 1999, and became the first inventor of the U disk recognized by mainland China. . In 2004, the US National Patent Office also approved Netac’s patent application. Netac, which had a patent in hand, subsequently launched a patent war against various U-disk manufacturers in the US market. In 2006, Netac sued Sony for patent infringement, and finally Sony compensated 10 million U.S. dollars. In 2008, Netac sued the U.S. PNY for patent infringement, and PNY compensated 7.71 million U.S. dollars. Netac’s patent wars have been won repeatedly. It can be said that Netac has been recognized as an inventor in the patent offices of the two major countries in China and the United States. However, the patent has been invalid since the 20-year patent period of technology products has passed.
- Phison electronic argument
- Taiwan Phison Electronics Pan Jiancheng is regarded by the locals as the “father of USB flash drives.” In 2001, Taiwan Phison Electronics produced the world’s first USB flash memory type system control microcontroller in the basement of the Industrial Research Institute’s incubation center and launched the Pen Drive product. For a while, Pen Drive became synonymous with U disk.
- M-Systems argument
- M-Systems from Israel (now SanDisk) has been developing this equipment since 1998. They registered the domain name of diskonkey.com in October 1999 and clearly pointed out that this brand-new USB flash memory device is being developed. In 2000 Dan Huckbee joined the M-System team and led the development of DiskOnKey. The product designed by Ziba for industrial design won the IDEA Award in 2001. M-System strictly describes this new device in the patent description. IBM’s invention document RPS8-1999-0201 (September 1999) is the earliest known document that accurately and completely describes USB-FD, but it is only limited to USB-FD. M-Systems helped IBM OEM DiskOnKey, and IBM first sold this product in North America in late 2000.
- Trek argument
- Trek claimed that they were the first company to conceive and manufacture a thumb drive (ThumbDrive), but the patent they applied for did not detail this new meaning of USB flash memory, but only called a data storage device in the general sense. The company’s CEO Henin Dan once said: “When we first launched the thumb disc in the first half of 2000, we believed that this small device could change the way customers around the world store and exchange data.” “Its potential makes Trek willing to invest and protect its intellectual property rights.” At present, Trek has patent rights for thumb discs in Japan, Taiwan, South Korea, the United Kingdom, New Zealand and Singapore. The British court overturned a British patent of Trek. Even so, the patent ownership of the USB flash drive is still controversial. According to the Straits Times, many other companies started selling similar equipment at the time. M-Systems calls their products DiskOnKey and Diskey. Electec is the importer of M-System, and FE Global is its distributor in Singapore. Trek sued four manufacturers of infringing its patents, and the four manufacturers responded by requesting the invalidation of the patent to be abolished. In the end, the Singapore court confirmed the validity of Trek’s thumb disc patent, which was considered “novel and creative” in the judgment published by The Straits Times. The Singapore Supreme Court also rejected the requests of four companies-Israeli companies M-Systems, Electroc, FE Global Electronics and Singapore company Ritronics Components, and prohibited them from continuing to sell similar equipment. This judgment affects the legal proceedings of Trek Group in the United Kingdom, Japan and Taiwan.
- Lexar argument
- At the same time, Lexar also claimed to have created a USB flash drive product. In 2000, they introduced a CompactFlash card with built-in USB function. Lexer also provides a set of card readers and USB cables so that users do not need to prepare another USB hub. They think this is a prototype of a USB flash drive, but few people agree with this statement.
- 1.2.2 The Past and Present of U Disk
- In the 1990s, 1.44M floppy disks, at that time DOS software was only a few tens of K, a few hundreds of K, the mainstream hard disk back then was a few hundred M;
- After 1997, WIN95 and WIN97 began to enter people’s field of vision, and the software began to grow larger. Software with more than tens of megabytes began to appear. Many softwares could not be copied completely with one floppy disk, and several floppy disks were needed to separate copies. At that time, 5.1G hard drives were quite large. At this time, the concept of multimedia computers has become popular. In addition to work, everyone buys a computer and adds more entertainment concepts, a compressed movie in REAL format, a dozen M;
- After 2000, the XP system became popular and hundreds of megabytes of software abound. 1.44M floppy disks were completely eliminated. People began to use U disks and rewritable CDs as mobile storage devices. At that time, the U disks were 128M, and CDs Generally, it is about 650M. At that time, the largest hard drive on the market was IBM’s, with a size above 10G. At this time, our mobile hard drives are all 2G-4G;
- From 2011 to 2015, the mainstream of hard drives were above 500G, or even terabytes. Many game software often had a few gigabytes, and a high-definition movie was more than 30 gigabytes. In 2011, the mainstream U disks were 4G, 8G, and 16G, while mobile hard drives were mainstream. 500G will dominate the world;
- 2015-now, with the development of smart phones, the data is getting bigger and bigger, the mainstream U disk 32G, 64G;
- Future development: mobile storage, cross-platform, larger capacity and faster speed.
- 1.3 Influencing factors of U disk speed
- The speed of the USB flash drive will be limited by the main control performance of the USB flash drive, dual-layer MLC NAND performance and the supported USB protocol. The theoretical transmission speed of USB 2.0 is 480Mbit/S, but is limited by the transmission protocol, the actual speed will not exceed 35MByte/S. USB 3.0 can support higher transmission speeds, but is limited by the performance of the main control and MLC flash memory. The writing speed of ordinary USB 3.0 U disks on the market in 2013 generally does not exceed 20MB/S. Some high-speed USB 3.0 U disks on the market have surpassed the aforementioned speed limits by using multi-channel controllers or SATA-to-USB controllers with faster NAND chips. If the USB 3.0 U disk is plugged into the USB 2.0 interface, data can only be transferred in the USB 2.0 mode. However, because the USB 3.0 U disk uses a higher frequency crystal oscillator and a faster flash memory, even if it is plugged into the USB 2.0 interface Also faster than ordinary USB 2.0 U disk. The actual transmission speed of the USB flash drive is also related to the transmitted files, and fragmented files require longer transmission time.
- 1.4 U Disk Composition
- Composition of U Disk
- U disk is composed of two parts: shell + semi-finished products
- There are two main types of semi-finished products: UDP (black colloid) and PCB
- The UDP chipset adopts PIP packaging technology, which directly encapsulates the various parts (including controllers, flash memory, integrated circuits, basic materials, electronic components) required by the U disk into a small black box. It is waterproof and high-voltage resistant. High temperature, speed and stability are better than PCB-type USB flash drives. And due to the high entry barrier, fraud costs and difficulties are greater.
- Black colloid size
- 11.3mm wide and 1.4mm thick
- There are three kinds of length: 15mm, 20mm, 25mm
- What we commonly use is 25mm long black colloid
- The surface of the black colloid
- There are 4 golden fingers on the front front,
- Respectively represent power, data +, data -, ground
- There are 2 or 4 golden dots on the back of the front, which can be used to connect lights or expand the phone U disk
- One end of the device is a Type-A USB plug. There is a printed circuit board in the plastic case. In addition to simple power circuits on the circuit board, there are also some integrated circuits (IC) soldered on the circuit board. Generally speaking, there are at least two ICs on the USB flash drive. The larger one is the flash memory chip, which is far away from the USB port. It is usually packaged in TSOP48 or BGA. The other is the main control of the USB flash drive. The power supply circuit and crystal oscillator are sometimes affected. Integrated in the main control.
- Necessary components
- Usually a U disk has three parts:
- Type-A USB plug
- Provide an interface to connect to the computer
- USB mass storage device controller
- Provide USB device controller and interface to communicate with flash memory. This controller contains a RISC microprocessor and some ROM (Read-Only Memory) and RAM (Random Access Memory).
- Flash memory: used to store data. Flash memory is also commonly used in digital cameras. The firmware and file system information of the USB flash drive is usually also located in the flash memory. Before the U disk leaves the factory, the manufacturer writes firmware (In System Programing) and initializes to the U disk in batches. This process is called card opening or mass production. Most U disks currently on the market use memory chips similar to flash memory in solid state drives.
- SLC = Single-Level Cell, 1bit/cell, fast speed, long life, super expensive, about 100,000 erase and write life
- MLC = Multi-Level Cell, that is 2bit/cell, the speed is generally average, the life is average, the price is average, about 3000—10000 erasing and writing life
- TLC = Trinary-Level Cell, that is, 3bit/cell, with slow speed and short lifespan, low price, about 500 erase and write lifespan
- Related reading: How about QLC particles? Comparison knowledge of solid state hard disk QLC, SLC, MLC, TLC particle difference
- Quartz oscillator
- Composition of U Disk
- Additional components
- The USB flash drive may also contain:
- Micro USB/USB Type-C plug
- Some U disks have Micro USB or USB Type-C plugs, which can be used on mobile devices (such as mobile phones and tablets) that support OTG. Corresponding adapters or adapter cables are also available on the market.
- Jumper wires and test pins
- It can be tested during production or used to load code into a microprocessor.
- Light Emitting Diode (LED) (indicating that data is being transmitted or is reading or writing.)
- Write protection switch (Provide “write protection mode” function to prevent data from being rewritten.)
- Unused space (Providing space for the second memory chip, allowing manufacturers to use the old printed circuit boards to make USB flash drives with different storage sizes to meet market needs.)
- The cover of the USB connector (reduces the chance of damage to the USB flash drive due to static electricity, and makes the overall appearance more beautiful. Some USB flash drives do not provide a cover, but the connector is made hidden and removed when needed. Other USB flash drives Provide a rotating cover attached to the body to avoid loss of the cover.)
- Small ring (sometimes there is a small ring on the body or cover that allows key rings, necklaces, or other things to help carry and store USB flash drives through it.)
- 1.5 Advantages and disadvantages of U disk
- Pros and cons
- U disks are less likely to allow water or dust to penetrate (especially black colloidal U disks), and are not afraid of being scratched and moldy. These are serious problems in old portable storage devices (such as optical discs and floppy disks). The solid-state storage design used by U disks allows them to resist unintentional external impacts to a greater extent. These advantages make the U disk very suitable for carrying personal data or work files from one place to another, such as from home to office, or generally, various places where personal data needs to be carried and accessed. Since USB is almost ubiquitous in today’s personal computers, USB flash drives can be used everywhere. However, the small size of the U disk also makes them often misplaced, forgotten or lost.
- Although the U disk is small, it has a relatively large storage capacity. At present, all commercially available U disks can store more data than a single CD (700MB). In 2019, the cheapest 16GBU disk storage is about to catch up with the data of a double-sided double-layer DVD (17GB). At present, the maximum capacity of commercially available flash drives can be as high as 1TB, and the read speed exceeds 250MB/s
- U disk uses the category of USB mass storage devices, which means that most modern operating systems can read and write to U disk without installing additional drivers. The U disk is displayed as a block-like logic unit in the operating system, hiding the complex details required by the internal flash memory. The operating system can use any file system or block addressing method. Some computers can also be booted by U disk.
- Like other flash memory devices, U disks also have a limit on the total number of reads and writes. When the U disk becomes old, the writing operation will take more time. When we use a U disk to run applications or operating systems, we have to consider this point. Some program developers have written special versions of operating systems (such as Linux) and software (such as Portable Apps) for U disks in response to this feature and capacity limitations. They usually optimize the space used and store temporary files in the main memory of the computer instead of a USB flash drive.
- U disks are more tolerant of external impacts than mechanical disks, but they may still fail or lose data due to severe physical damage. In a self-assembled computer, the wrong USB connection port wiring may also damage the circuit of the U disk. Compared with other peripherals, USB flash drives are more prone to failure, so data backup should be done.
- Pros and cons
- 1.6 Working Principle of U Disk
- The USB port is responsible for connecting to the computer, which is the channel for data input or output; the main control chip is responsible for the coordinated management of various components and issuing various action instructions, and makes the computer recognize the U disk as a “removable disk”, which is the principle of the U disk. “The brain”; the principle of the FLASH chip is basically the same as that of the memory module in the computer. It is the entity that saves data. Its characteristic is that the data will not be lost after power failure and can be stored for a long time. connected together. After the U disk is recognized by the operating system and the user issues an action command for data access, the work of the USB removable storage disk includes these processes.
- A floating shelf for storing electrons is formed on the semiconductor in which current conducts unidirectionally between the source and drain. The floating gate is wrapped with a layer of silicon oxide film insulator. Above it is the selection/control gate that controls the conduction current between the source and drain. The data is 0 or 1 depending on whether there are electrons in the floating gate formed on the silicon substrate. If there is an electron, it is 0, and if there is no electron, it is 1. Just like its name, flash memory is initialized by deleting data before writing. Specifically, electrons are derived from all floating gates. Some data will be returned to “1” soon. When writing, only write when the data is 0, and do nothing when the data is 1. When writing 0, a high voltage is applied to the gate electrode and the drain to increase the electron energy conducted between the source and the drain. In this way, electrons will break through the oxide film insulator and enter the floating gate. When reading data, a certain voltage is applied to the gate electrode, the current is 1 when the current is large, and the current is 0 when the current is small. When the floating gate has no electrons (data is 1), a voltage is applied to the drain when a voltage is applied to the gate electrode, and a current is generated between the source and the drain due to the movement of a large amount of electrons. When there are electrons in the floating gate (the data is 0), the number of electrons conducted in the channel will decrease. Because the voltage applied to the gate electrode is absorbed by the floating gate electrons, it is difficult to affect the channel.
- The storage principle of the U disk is: the computer converts the binary digital signal into a composite binary digital signal (adding instructions for allocation, verification, stacking, etc.) to read and write to the USB chip adapter interface, and store the corresponding address allocated to the EPROM2 memory chip through the chip processing signal Binary data, realize data storage.
- 1.7 U Disk Test Utility Tool
- H2&chipgenius
- H2
- H2testw, a U-disk test tool from Germany. You can check storage media such as hard disks or flash drives for errors. The software will find out whether the storage device actually provides enough storage space as described by the manufacturer.
- chipgenius
- Chipgenius is a USB device chip model detection tool, which can automatically query the main control chip model, manufacturer, brand of all USB devices such as U disk, MP3/MP4, card reader, mobile hard disk, and provide the download address of related materials. Of course You can also query the VID/PID information, device name, interface speed, device version, etc. of the USB device.
- application:
- 1. Quickly repair the U disk, you can query the chip model of the U disk without disassembling the machine, and quickly find the corresponding mass production tool.
- Second, identify the copycat U disk (better with H2&mydisktest)
- application:
- Chipgenius is a USB device chip model detection tool, which can automatically query the main control chip model, manufacturer, brand of all USB devices such as U disk, MP3/MP4, card reader, mobile hard disk, and provide the download address of related materials. Of course You can also query the VID/PID information, device name, interface speed, device version, etc. of the USB device.
- 1.8 U Disk Production Process
- QC engineering drawing
- Chip production process (silicon ingot-silicon wafer-forming silicon wafer with chips-silicon wafer testing-cutting into chips-packaging-finished product testing)
- Chip production process (silicon ingot-silicon wafer-forming silicon wafer with chips-silicon wafer testing-cutting into chips-packaging-finished product testing)
- U disk production flow chart (chip test-SMT patch-mass production-H2 test-formatting-sample production / copy file-assembly-finished product test-main assembly-quality inspection = packagin
- Copy file process V4.12
- 1, file access
- 1.1 When the business places a production order, indicate the customer’s file copy requirements.
- 1.2 The business obtains documents from customers and understands customer needs. Submit the files and requirements to the R&D project, complete the files and copy the file attributes.
- 1.3 The following file copy methods are currently supported:
- A single disk {ordinary disk (single standard), read-only disk (single warranty, that is, single disk write protection), encrypted disk (single encryption, that is, single disk encryption), auto play (single self, that is, single disk auto play, currently Known to support this type of copying are SMI, Chipsbank and some Jianrong masters)}
- B dual disk {normal disk + normal disk (dual standard), read-only disk + normal disk (reinsurance), encrypted disk + normal disk (separate encryption), auto play disk + normal disk (separate from), read-only disk + Read-only disk (double security), auto-play disk + read-only disk (self-protection), auto-play disk + encrypted disk (self-encryption, currently known to support this type of copying is part of the SMI master)}
- 2. Document confirmation
- 2.1 The R&D project will perform corresponding checks on the files provided by the customer, including the file name garbled, whether the file can be opened (the file can be opened, and the video can be opened to the end without exception. The correctness of more complex file content cannot be judged by the project. Therefore. Customers are responsible for the accuracy of the documents they provide)
- 2.2 After the R&D project confirms that the file is normal, and the corresponding configuration is improved (for example, the autorun file may need to be produced for the automatic playback disk, etc.), make a screenshot of the corresponding file attributes and send it to the customer for confirmation through the corresponding business.
- 2.3 After the customer confirms, the business publishes the document confirmation information in the “Caiyue Electronics” group, with a screenshot of the document attribute confirmed by the customer provided by the previous project (not allowed to arbitrarily add pictures).
- 3, computer settings
- 3.1 Copy file naming rules;
- The first level: folder naming {copy type (two characters, see 1.3 for details) + order number}.
- The second layer: folder naming {normal copy files/undeletable files/encrypted files/autoplay files}. At the same time, “Copy File Properties” is located on this layer.
- The third layer: the customer copied files are located in this layer.
- 3.2 The copied files are stored for each business and year. Files older than 1 year will be deleted according to the hard disk space. Saved in the engineering computer D disk/business production order
- 3.3 After the business publishes the document confirmation information in the “Caile Electronics” group, the R&D project will produce the “Copy File Attributes” according to the documents confirmed by the customer, save it on the D disk of the engineering computer/copy the file attributes and save them synchronously in the production order. At the same time, first self-check the number and size of the documents, after the inspection, print the signature and then the business signature, hand over the production line project for signature, and submit the copy of the file to the production line project for setting.
- 3.4 The production line project arranges the copy files according to the semi-finished product arrival and testing conditions, and sets the corresponding mass production tools in the super workstation (when setting the SMI mass production tools, the scanning method must be confirmed by the R&D project to the SMI project), and copy the files 1PCS, check the number, size and copy method of files in accordance with “Copy File Properties”. After confirmation, upload the configuration to the server to arrange a copy.
- 4, file copy
- Semi-finished products are tested in accordance with the production line engineering settings, mass production and signing, testers are not allowed to change the tools privately, if there is an abnormality in the middle (such as computer crash, power failure, etc.), you need to find the production line engineering to reopen the corresponding tools.
- 5, document inspection
- The finished product and quality control shall perform full inspection or random inspection and signature on the finished product in accordance with the “Copy File Attributes” and the order requirements (check the number of files, size and write protection, and the encrypted disk needs to check the password).
- 6, exception handling
- 6.1 When the parties involved in any of the above links should be absent or unable to complete the corresponding actions, the corresponding personnel should take the initiative to consciously supplement them, and complete the corresponding actions including signing. The specific methods of replenishment are as follows: R&D engineering: production line engineering production line engineering: research and development engineering
- Order clerk: assign other clerk for order business. Quality control, semi-finished product testing, finished product testing: other personnel on the production line
- 6.2 Any substitution action is limited to personnel substitution, and no substitution is made in the workplace under special circumstances. For example, the semi-finished product copy must be copied in the semi-finished product copy area in principle, even if the operator is a finished product inspector. For example, making screenshots of documents must in principle be completed on the engineering computer, even if the operator is an order salesperson.
- 6.3 After receiving the information provided by the previous link in any link, it must be checked and signed.
- Black colloid testing and production process (take card U disk as an example)
- Chip semi-finished products & assembly and finished products
- Packaging
- Semi-finished product test. A comprehensive test is carried out on the semi-finished product through the H2 test tool and QA test tool (the test includes U disk read and write speed, real capacity, reliability, security, etc.)
- Attached:
- Common capacity standards Single test Batch test
- 16G 15000M-15720M write>10M/S write>2M/S
- 32G 30000M-31440M read>20M/S read>3M/S
- File copy. According to the needs, some special production is carried out on the U disk through QA or mass production tools (including ordinary copy, partition copy, non-deletable copy, automatic playback copy, change drive letter name, change serial number, etc.)
- Attachment: Except for the auto play mode, the length of the USB drive letter name in other modes can only contain up to 11 characters (1 Chinese character counts as 2 characters, and special symbols cannot be included).
- When copying files with single disk write protection or partition write protection, the locked disk space must be larger than the copied file size. It is recommended to reserve 200M-500M more space according to the file size to ensure that the file copy will not be wrong.
- Assemble the casing. The black glue is fixed with the casing through 3M glue (mainly used for cards, keys, window grilles and other casings) or plastic parts (mainly used for tube metal casings). The assembly process is relatively simple.
- Attachment: First, pay attention to the aspects of black colloid, including front and back, front and back.
- Second, when using 3M glue to fix, be sure to apply a certain pressure directly above the black colloid to ensure that the glue on the back of the black colloid is perfectly combined with the shell and sticks firmly.
- Finished product testing. The assembled finished product is tested on the U disk through QA tools or document comparison tools, confirmed that it is correct, and the order requirements are met, and the surface of the U disk shell is cleaned (mainly use wiper water to wipe the dust and finger marks on the surface Go), put it in the packaging.
- Attachment; First, check whether the capacity and mode of the U disk are consistent with the order
- The second is to check whether the file on the U disk is correct and whether it is the same as the source file.
- 1. Manually open all documents and perform manual inspections, including whether the audio has sound, whether the video can be played to the end, etc. (sampling)
- 2. Use QA to check the number of files and whether the size is the same as the source file. (Full inspection)
- 3. Use file comparison tools and source files for comparison. (Sampling inspection)
- QC engineering drawing
- 1.9 Details of the U Disk
- Engineering system
- Detection system
- Chip trends
- Custom style
- 2.0 Common Questions of U Disk
- Question 1: Why the U disk I purchased is 16GB, but the actual capacity is not 16G when inserted into the computer?
- Answer: Because the bottom layer of the computer uses binary 1MB=1024KB; but storage manufacturers use the decimal system for convenience when making U disks, hard disks and other storage devices, so this difference is caused; GB to MB to KB to B to b. A total of 4 conversions are required: 1000/1024, which is 90.9%. In addition, the U disk itself needs to make room for storing its own information and as a spare area, so the actual capacity of the U disk is smaller than the nominal capacity of the U disk.
- Question 2: So what should the actual capacity of the U disk be reasonable?
- Answer: The answer to comprehensive question 1, the storage industry standard: the actual capacity of the U disk is not less than 90% of the nominal capacity is a qualified product. The actual capacity range of some common capacity USB flash drives is listed below. 1GB(900M-960M); 2GB(1860M-1960M); 4GB(3680M-3860M); 8GB(7680M-7800M); 16GB(14.4GB or more); 32GB(28.8GB or more); 64GB(57.6GB or more); 128GB (Above 115.2GB) The actual capacity is in parentheses.
- Question 3: What are the file formats of the USB flash drive?
- Answer: Generally speaking, there are 3 formats of USB flash drives, which are produced because of their different needs. FAT, FAT32, exFAT; Early USB flash drives had a smaller capacity, which was in FAT16 format, or FAT format for short. Now USB flash drives of 2GB and below are in this format;
- As the file size becomes larger, the size of some single files exceeds 2GB. The FAT format of this type of file is not supported, so the FAT32 format appears. Now 4GB-32GB U disks are in this format;
- Subsequently, a single file with a size of more than 4GB appeared. This type of file FAT32 format is not supported. So the FAT64 format, or exFAT for short, appeared. Now 64G and above U disks are in this format;
- A small-capacity USB flash drive can be made into a large format, such as 16GB can also be made into an exFAT format, which will not have a significant impact on the use of the USB flash drive. This solution can be used to store a single file of more than 4GB. Conversely, a large-capacity U disk can also be made into a small format, but when the file size exceeds the standard, the corresponding file cannot be stored and should not be used;
- In addition, U disk can be made into NTFS hard disk format and CDFS disc format when encountering some special situations.
- Question 1: Why the U disk I purchased is 16GB, but the actual capacity is not 16G when inserted into the computer?
- Question 4: I obviously bought a brand new empty U disk. Why is there a small amount of space in it that is used and cannot be processed after formatting? Is it a virus?
- Answer: FAT32 and exFAT format U disks require a small amount of space to store some information on the U disk itself;
- Of course, the occupied space has a certain range. If it exceeds this range, be careful about whether there is a virus, and you can perform anti-virus formatting processing. The standards are as follows;
- 2GB or less: FAT format, occupying space 0 bytes
- 4GB-32GB: FAT32 format, occupying space 4KB– 32KB
- 64GB and above: ExFAT format, 384KB and above (not more than 1MB)
- Question 5: Why I bought a 128GB USB flash drive that cannot be opened on my XP system computer, but it can be used normally on my friend’s W7 system?
- Answer: The 128GB U disk is in exFAT format. This format was developed later, while XP is an older operating system; in the early version and the now popular GHOST version with reduced functions on the Internet, exFAT format is not supported Yes; but it does not matter, you can go to the Internet to download an exFAT patch package for the XP system; it can be solved by installing it on the computer. The patch package is small and easy to find, and Baidu has it.
- Question 6: Can the drive letter name of the USB flash drive be changed at will?
- Answer: The drive letter name of the U disk without write protection can be changed freely, but there are the following restrictions: The length of the drive letter name cannot exceed 11 characters (1 Chinese character counts as 2 characters, and spaces are counted as characters). Some characters are too special and cannot be recognized by the computer.
- Question 7: Will the USB flash drive be broken if dropped on the ground?
- Answer: As we all know, the vibration of a mechanical hard disk falling on the ground can easily damage the precision parts inside and cause the hard disk to be damaged. Unlike the USB flash drive, it uses FLASH storage and does not have any precision parts. Therefore, under normal circumstances, dropping will not have any impact on the function of the U disk;
- As for the shell of the USB flash drive, except for fragile shells (such as glass), the shell of the USB flash drive should not fall apart or break if it falls within one meter. It is inevitable that it will be scratched;
- Packing should pay attention to the box with 4 layers, safe transportation to prevent rollover during express delivery.
- Question 8: Why are some U disks that I purchased cannot be used in the car or other non-computer equipment, and some are OK?
- Answer: The reason why the computer supports USB flash drives is because there is a complete USB protocol. When other devices that support USB flash drives are developed and designed, many of them only use incomplete USB protocols, which will lead to some main control types. U disk cannot support;
- From another perspective: there is a computer first, then a U disk. U disk first, then other USB devices; this is also one of the reasons for this situation;
- There is no good solution to this, only to find a supported U disk master control category, and then purchase it.
- It is recommended to test the sample first before mass production
- Question 9: Is the USB flash drive waterproof?
- Answer: U disk is divided into 2 categories. PCB board and UDP board (ie black colloid)
- PCB boards are not waterproof. After falling into the water, you need to find a way to completely clean the water that enters the U disk before using it, otherwise it will cause a short circuit. The U disk may be damaged in the slightest, and the main board of the computer may be damaged in the severe case. (You can use a hair dryer to quickly blow off a large amount of water, and then wrap it in a paper towel and place it in a dry place. Note that the hot air of the hair dryer should not blow for too long)
- The UDP board is waterproof, but also pay attention to the surface, especially the water on the gold finger, before using it.
- Question 10: The USB flash drive suddenly loses power while transferring data, and then it cannot be read. What should I do?
- Answer: Sudden power failure will cause a sudden change in current; U disk will have a power failure protection mechanism.
- At this time, after plugging and unplugging the USB flash drive again, the USB flash drive can still be opened, but the content cannot be written into it. After copying the backup contents to the computer, format the U disk.
- If it cannot be formatted or still cannot open the U disk. Then it can only be returned to the factory for repair.
- Question 11: What are the main components of the price of U disk?
- The main control + flash memory chip accounts for most of the cost of the USB flash drive and is the most critical factor; generally speaking, a factory with a fab will produce a complete wafer, although it is the same wafer, but each part The quality of the wafer is different. A complete wafer will be cut, and some complete particles will be cut and packaged to make a qualified storage disk, and the remaining scraps are called black chips. The original factory considers the quality and defines these particles as waste products for disposal. Generally speaking, the price difference between qualified and scrap is very large. In terms of quality assurance, the latter is difficult to use normally for a long time. However, because someone in the market turned it out and repackaged it, it caused the user’s data security storage and use risks;
- Shell + LOGO is the second major element: the shell of the same style has different requirements for mold precision, production technology, and surface treatment, and it is normal for a difference of RMB0.3-RMB1.2;
- Labor + service is the third major element: choosing a professional manufacturer can avoid many hidden dangers such as patent infringement, file copying and burning, and product quality and delivery. It is recommended that customers be affected by the company’s reputation, product safety and stability, and after-sales communication. The manufacturer cooperates with a comprehensive evaluation of collaboration intentions and capabilities from multiple perspectives and makes a prudent decision.
- Question 12: How to quickly eliminate unqualified suppliers?
- Cannot quickly provide the company’s basic qualifications and related file-building materials; (check whether the company has precipitation and accumulation)
- Can’t quickly answer specific questions about product specialty & can’t quickly quote; (inspect professionalism and competitiveness)
- Mentioned that after using H2 to test the test goods, they dare not accept the inspection or want to change the price; (inspect the integrity, quality control system)
- The work is not rigorous enough, not meticulous enough; (avoid hidden problems later)
- 1.2.1 Patent disputes over USB flash drives
