USB flash drive

USB flash drive

Overview
A flash drive is a data storage device
Data storage device
thumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....

 that consists of flash memory
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

 with an integrated Universal Serial Bus
Universal Serial Bus
USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

 (USB) interface. flash drives are typically removable and rewritable, and physically much smaller than a floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

. Most weigh less than 30 g (1 oz). drives of 256 gigabyte
Gigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...

s (GB) are available, and storage capacities as large as 2 terabytes (TB) are planned, with steady improvements in size and price per capacity expected.
Discussion
Ask a question about 'USB flash drive'
Start a new discussion about 'USB flash drive'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Encyclopedia
A flash drive is a data storage device
Data storage device
thumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....

 that consists of flash memory
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

 with an integrated Universal Serial Bus
Universal Serial Bus
USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

 (USB) interface. flash drives are typically removable and rewritable, and physically much smaller than a floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

. Most weigh less than 30 g (1 oz). drives of 256 gigabyte
Gigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...

s (GB) are available, and storage capacities as large as 2 terabytes (TB) are planned, with steady improvements in size and price per capacity expected. Some allow up to 100,000 write/erase cycles (depending on the exact type of memory chip used) and 10 years shelf storage time
Non-volatile memory
Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, in the most basic sense, is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include read-only memory, flash memory, ferroelectric RAM, most types of magnetic computer...

.

USB flash drives are often used for the same purposes for which floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

s or CD-ROM
CD-ROM
A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....

s were used. They are smaller, faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts
Moving parts
The moving parts of a machine are those parts of it that move. Machines comprise both moving and fixed parts. The moving parts have controlled and constrained motions....

. Until approximately 2005, most desktop and laptop computers were supplied with floppy disk drives, but floppy disk drives have been abandoned in favor of USB ports.

Flash drives use the USB mass storage
USB mass storage device class
The USB mass storage device class, otherwise known as USB MSC or UMS, is a protocol that allows a Universal Serial Bus device to become accessible to a host computing device, to enable file transfers between the two...

 standard, supported natively by modern operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

s such as Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

, Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

, Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

, and other Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....

 systems. USB drives with USB 2.0 support can store more data and transfer faster than much larger optical disc drives like CD-RW or DVD-RW drives and can be read by many other systems such as the Xbox 360
Xbox 360
The Xbox 360 is the second video game console produced by Microsoft and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles...

, PlayStation 3
PlayStation 3
The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...

, DVD players and in some upcoming mobile smartphones.

Nothing moves mechanically in a flash drive; the term drive persists because computers read and write flash-drive data using the same system commands as for a mechanical disk drive, with the storage appearing to the computer operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 and user interface
User interface
The user interface, in the industrial design field of human–machine interaction, is the space where interaction between humans and machines occurs. The goal of interaction between a human and a machine at the user interface is effective operation and control of the machine, and feedback from the...

 as just another drive. Flash drives are very robust mechanically.

A flash drive consists of a small printed circuit board
Printed circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...

 carrying the circuit elements and a USB connector, insulated electrically and protected inside a plastic, metal, or rubberized case which can be carried in a pocket or on a key chain, for example. The USB connector may be protected by a removable cap or by retracting into the body of the drive, although it is not likely to be damaged if unprotected. Most flash drives use a standard type-A USB connection
Universal Serial Bus
USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

 allowing plugging into a port on a personal computer, but drives for other interfaces also exist.

USB flash drives draw power from the computer via external USB connection. Some devices combine the functionality of a digital audio player with USB flash storage; they require a battery only when used to play music.

Technology


Flash memory combines a number of older technologies, with lower cost, lower power consumption and small size made possible by advances in microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

 technology. The memory storage was based on earlier EPROM
EPROM
An EPROM , or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages...

 and EEPROM
EEPROM
EEPROM stands for Electrically Erasable Programmable Read-Only Memory and is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration...

 technologies. These had very limited capacity, were very slow for both reading and writing, required complex high-voltage drive circuitry, and could only be re-written after erasing the entire contents of the chip.

Hardware designers later developed EEPROMs with the erasure region broken up into smaller "fields" that could be erased individually without affecting the others. Altering the contents of a particular memory location involved copying the entire field into an off-chip buffer memory, erasing the field, modifying the data as required in the buffer, and re-writing it into the same field. This required considerable computer support, and PC-based EEPROM flash memory systems often carried their own dedicated microprocessor system. Flash drives are more or less a miniaturized version of this.

The development of high-speed serial data interfaces such as USB made semiconductor memory systems with serially accessed storage viable, and the simultaneous development of small, high-speed, low-power microprocessor systems allowed this to be incorporated into extremely compact systems. Serial access requires far fewer electrical connections for the memory chips than does parallel access
Random-access memory
Random access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in...

, which has simplified the manufacture of multi-gigabyte
Gigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...

 drives.

Computers access flash memory systems very much like hard disk drives, where the controller system
Flash memory controller
A flash memory controller manages the data stored on flash memory and communicates with a computer or electronic device. Flash memory controllers can be designed for operating in low duty-cycle environments like SD cards, CompactFlash cards, or other similar media for use in digital cameras, PDAs,...

 has full control over where information is actually stored. The actual EEPROM writing and erasure processes are, however, still very similar to the earlier systems described above.

Many low-cost MP3 players simply add extra software and a battery to a standard flash memory control microprocessor so it can also serve as a music playback decoder. Most of these players can also be used as a conventional flash drive, for storing files of any type.

Creator controversy


There are currently four entities who lay claim to inventing the USB flash drive: Dov Moran of M-Systems
M-Systems
M-Systems Ltd., was a Nasdaq-listed Israeli producer of Flash memory storage products founded in 1989 by Dov Moran and based in Kfar Sava, Israel. They were best known for developing and patenting the first flash drive, marketed in 1995 as DiskOnChip, and the first USB flash drive, marketed in...

, Pua Khein Seng of Phison
Phison
Phison Electronics Corporation is a public Taiwanese electronics company that primarily manufactures controllers for NAND flash memory chips. These are integrated into flash-based products such as USB flash drives, memory cards, and solid-state drives...

 Electronics, Trek Technology
Trek Technology
Trek 2000 International Ltd is a Singaporean Technology company that is public-listed on the Singapore Stock Exchange under the group name of TREK 2000 INT'L LTD. The company was founded by Henn Tan....

, and Netac Technology
Netac Technology
Netac Technology Co Ltd is a Shenzen consumer electronics company that claims to have invented the USB flash drive. It is a Chinese OEM/ODM.In 2006 it became the first Chinese company to initiate an overseas intellectual property infringement lawsuit when it sued PNY Technologies in the...

. Both Trek Technology and Netac Technology have tried to protect their patent claims. Trek won a Singaporean suit, but a court in the United Kingdom revoked one of Trek's UK patents. While Netac Technology has brought lawsuits against PNY Technologies
PNY Technologies
PNY Technologies, Inc is a manufacturer of flash memory cards, USB flash drives, solid state drives, memory upgrade modules, as well as consumer and professional graphics cards...

, Lenovo, aigo
Aigo
aigo is the trade name of Chinese consumer electronics company Beijing Huaqi Information Digital Technology Co Ltd. aigo should not be capitalized, much like "iPod".-History:...

, Sony
Sony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

, and Taiwan's Acer and Tai Guen Enterprise Co, most companies that manufacture USB flash drives do so without regard for Trek and Netac's patents.

Pua Khein-Seng
Pua Khein-Seng
Pua Khein-Seng |The Star]], the CEO of Phison Electronics Corp based in Taiwan claims to have incorporated the world's first single chip USB flash controller. Grown up in Sekinchan, Selangor, Malaysia, Pua received his undergraduate education in electrical control engineering at the National Chiao...

 from Malaysia claims to have incorporated the world's first single chip USB flash controller. He is currently the CEO of Phison
Phison
Phison Electronics Corporation is a public Taiwanese electronics company that primarily manufactures controllers for NAND flash memory chips. These are integrated into flash-based products such as USB flash drives, memory cards, and solid-state drives...

 Electronics Corp based in Taiwan.

First commercial product


Trek Technology
Trek Technology
Trek 2000 International Ltd is a Singaporean Technology company that is public-listed on the Singapore Stock Exchange under the group name of TREK 2000 INT'L LTD. The company was founded by Henn Tan....

 and IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 began selling the first USB flash drives commercially in 2000. The Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...

an Trek Technology
Trek Technology
Trek 2000 International Ltd is a Singaporean Technology company that is public-listed on the Singapore Stock Exchange under the group name of TREK 2000 INT'L LTD. The company was founded by Henn Tan....

 sold a model under the brand name "ThumbDrive", and IBM marketed the first such drives in North America with its product named the "DiskOnKey" which was developed and manufactured
Original Equipment Manufacturer
An original equipment manufacturer, or OEM, manufactures products or components that are purchased by a company and retailed under that purchasing company's brand name. OEM refers to the company that originally manufactured the product. When referring to automotive parts, OEM designates a...

 by the Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

i company M-Systems
M-Systems
M-Systems Ltd., was a Nasdaq-listed Israeli producer of Flash memory storage products founded in 1989 by Dov Moran and based in Kfar Sava, Israel. They were best known for developing and patenting the first flash drive, marketed in 1995 as DiskOnChip, and the first USB flash drive, marketed in...

. IBM's USB flash drive became available on December 15, 2000, and had a storage capacity of 8 MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

, more than five times the capacity of the then-common floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

s.

In 2000 Lexar
Lexar
Lexar Media, Inc. is an American manufacturer of digital media products based in Fremont, CA. Products manufactured by Lexar include SD cards, Memory Sticks, keydrives, CompactFlash cards and card readers. Lexar's Memory Stick Duos also have versions adapted for the PSP which includes a version of...

 introduced a Compact Flash (CF) card with a USB connection, and a companion card read/writer and USB cable that eliminated the need for a USB hub.

Second generation



Modern flash drives have USB 2.0 connectivity. However, they do not currently use the full 480 Mbit
Megabit
The megabit is a multiple of the unit bit for digital information or computer storage. The prefix mega is defined in the International System of Units as a multiplier of 106 , and therefore...

/s (60MB/s) which the USB 2.0 Hi-Speed specification supports because of technical limitations inherent in NAND flash. The fastest drives currently available use a dual channel controller, although they still fall considerably short of the transfer rate possible from a current generation hard disk, or the maximum high speed USB throughput.

File transfer speeds vary considerably and should be checked before purchase. Speeds may be given in Mbyte per second, Mbit per second or optical drive multipliers such as "180X" (180 times 150 KiB
Kibibyte
The kibibyte is a multiple of the unit byte for quantities of digital information. The binary prefix kibi means 1024; therefore, 1 kibibyte is . The unit symbol for the kibibyte is KiB. The unit was established by the International Electrotechnical Commission in 1999 and has been accepted for use...

 per second). Typical fast drives claim to read at up to 30 megabytes/s (MB/s) and write at about half that speed. This is about 20 times faster than USB 1.1 "full speed" devices which are limited to a maximum speed of 12 Mbit/s (1.5 MB/s).

Third generation



Like USB 2.0 before it, USB 3.0 offers dramatically improved data transfer rates compared to its predecessor. Even though it was announced in late 2008, consumer devices were not available until the beginning of 2010. The USB 3.0 interface specifies transfer rates up to 5Gbit/s, compared to USB 2.0's 480 Mbit/s. All USB 3.0 devices are downward compatible with USB 2.0 ports. Computers with USB 3.0 ports are becoming very popular and common. Many newer laptops and Desktops have at least one such port. USB 3.0 port expansion cards are available to upgrade older systems, and many newer motherboards feature two or more USB 3.0 jacks. Even though the USB 3.0 interface allows extremely high data transfer speeds, most USB 3.0 flash drives did not utilize the full speed of the USB 3.0 interface due to limitations of their memory controllers.

Design and implementation


One end of the device is fitted with a single Standard-A USB plug. Inside the plastic casing is a small printed circuit board. Mounted on this board is some power circuitry and a small number of surface-mounted
Surface-mount technology
Surface mount technology is a method for constructing electronic circuits in which the components are mounted directly onto the surface of printed circuit boards . An electronic device so made is called a surface mount device...

 integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

s (ICs). Typically, one of these ICs provides an interface between the USB connector and the onboard memory, while the other is the flash memory
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

.

Drives typically use the USB mass storage device class
USB mass storage device class
The USB mass storage device class, otherwise known as USB MSC or UMS, is a protocol that allows a Universal Serial Bus device to become accessible to a host computing device, to enable file transfers between the two...

 to communicate with the host.


Internals of a typical USB flash drive
1 USB Standard-A plug
2 USB mass storage controller device
3 Test points
4 Flash memory chip
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

5 Crystal oscillator
Crystal oscillator
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency...

6 LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

7 Write-protect
Write protection
Write protection is any physical mechanism that prevents modification or erasure of valuable data on a device. Most commercial software, audio and video is sold pre-protected.-Examples:...

 switch (Optional)
8 Space for second flash memory chip

Essential components



There are typically four parts to a flash drive:
  • Standard-A USB plug – provides a physical interface to the host computer.
  • USB mass storage controller – a small microcontroller
    Microcontroller
    A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM...

     with a small amount of on-chip ROM
    Read-only memory
    Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...

     and RAM.
  • NAND flash memory chip(s) – stores data (NAND flash is typically also used in digital camera
    Digital camera
    A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...

    s).
  • Crystal oscillator
    Crystal oscillator
    A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency...

     – produces the device's main 12 MHz clock signal
    Clock signal
    In electronics and especially synchronous digital circuits, a clock signal is a particular type of signal that oscillates between a high and a low state and is utilized like a metronome to coordinate actions of circuits...

     and controls the device's data output through a phase-locked loop
    Phase-locked loop
    A phase-locked loop or phase lock loop is a control system that generates an output signal whose phase is related to the phase of an input "reference" signal. It is an electronic circuit consisting of a variable frequency oscillator and a phase detector...

    .

Additional components


The typical device may also include:
  • Jumpers
    Jumper (computing)
    In electronics and particularly computing, a jumper is a short length of conductor used to close a break in or bypass part of an electrical circuit...

     and test pins – for testing during the flash drive's manufacturing or loading code into the microprocessor.
  • LEDs
    Light-emitting diode
    A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...

     – indicate data transfers or data reads and writes.
  • Write-protect
    Write protection
    Write protection is any physical mechanism that prevents modification or erasure of valuable data on a device. Most commercial software, audio and video is sold pre-protected.-Examples:...

     switches – Enable or disable writing of data into memory.
  • Unpopulated space – provides space to include a second memory chip. Having this second space allows the manufacturer to use a single printed circuit board for more than one storage size device.
  • USB connector cover or cap – reduces the risk of damage, prevents the entry of dirt or other contaminants, and improves overall device appearance. Some flash drives use retractable USB connectors instead. Others have a swivel arrangement so that the connector can be protected without removing anything.
  • Transport aid – the cap or the body often contains a hole suitable for connection to a key chain or lanyard
    Lanyard
    A lanyard is a rope or cord exclusively worn around the neck or wrist to carry something. Usually it is used where there is a risk of losing the object or to ensure it is visible at all times. Aboard a ship, it may refer to a piece of rigging used to secure objects...

    . Connecting the cap, rather than the body, can allow the drive itself to be lost.
  • Some drives offer expandable storage via an internal memory card
    Memory card
    A memory card or flash card is an electronic flash memory data storage device used for storing digital information. They are commonly used in many electronic devices, including digital cameras, mobile phones, laptop computers, MP3 players, and video game consoles...

     slot, much like a memory card reader
    Card reader
    A card reader is a data input device that reads data from a card-shaped storage medium. Historically, paper or cardboard punched cards were used throughout the first several decades of the computer industry to store information and programs for computer system, and were read by punched card readers...

    .

Size and style of packaging



Some manufacturers differentiate their products by using elaborate housings, which are often bulky and make the drive difficult to connect to the USB port. Because the USB port connectors on a computer housing are often closely spaced, plugging a flash drive into a USB port may block an adjacent port. Such devices may only carry the USB logo if sold with a separate extension cable.

USB flash drives have been integrated into other commonly carried items such as watches, pens, and even the Swiss Army Knife; others have been fitted with novelty cases such as toy cars or LEGO
Lego
Lego is a line of construction toys manufactured by the Lego Group, a privately held company based in Billund, Denmark. The company's flagship product, Lego, consists of colorful interlocking plastic bricks and an accompanying array of gears, minifigures and various other parts...

 bricks. The small size, robustness and cheapness of USB flash drives make them an increasingly popular peripheral for case modding
Case modding
Case modification is the modification of a computer chassis , or a video game console chassis. Modifying a computer case in any non-standard way is considered a case mod...

.

Heavy or bulky flash drive packaging can make for unreliable operation when plugged directly into a USB port; this can be relieved by a USB extension cable. Such cables are USB-compatible but do not conform to the USB standard.

File system


Most flash drives ship preformatted with the FAT
File Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...

 or FAT 32 file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...

. The ubiquity of this file system allows the drive to be accessed on virtually any host device with USB support. Also, standard FAT maintenance utilities (e.g. ScanDisk
SCANDISK
SCANDISK or ScanDisk is a utility in MS-DOS and Microsoft Windows systems which checks and repairs file systems and bad clusters on the hard drive. It was introduced in MS-DOS version 6.2...

) can be used to repair or retrieve corrupted data
Data corruption
Data corruption refers to errors in computer data that occur during writing, reading, storage, transmission, or processing, which introduce unintended changes to the original data...

. However, because a flash drive appears as a USB-connected hard drive to the host system, the drive can be reformatted
Disk formatting
Disk formatting is the process of preparing a hard disk drive or flexible disk medium for data storage. In some cases, the formatting operation may also create one or more new file systems...

 to any file system supported by the host operating system.

Defragmenting: Flash drives can be defragmented
Defragmentation
In the maintenance of file systems, defragmentation is a process that reduces the amount of fragmentation. It does this by physically organizing the contents of the mass storage device used to store files into the smallest number of contiguous regions . It also attempts to create larger regions of...

, but this brings little advantage as there is no mechanical head that moves from fragment to fragment. Flash drives often have a large internal sector size, so defragmenting means accessing fewer sectors. Defragmenting shortens the life of the drive by making many unnecessary writes.

Even Distribution: Some file systems are designed to distribute usage over an entire memory device without concentrating usage on any part (e.g. for a directory); this even distribution prolongs the life of simple flash memory devices. Some USB flash drives have this functionality
Wear leveling
Wear leveling is a technique for prolonging the service life of some kinds of erasable computer storage media, such as Flash memory used in solid-state drives and USB Flash drives...

 built into the software controller to prolong device life, while others do not, therefore the end user should check the specifications of his device prior to changing the file system for this reason.
Hard Drive: Sectors are 512 bytes long, for compatibility with hard drives, and the first sector can contain a Master Boot Record
Master boot record
A master boot record is a type of boot sector popularized by the IBM Personal Computer. It consists of a sequence of 512 bytes located at the first sector of a data storage device such as a hard disk...

 and a partition table
Partition table
The term partition table is most commonly associated with partition table but it may be used generically to refer to other "formats" that divide a disk drive into partitions, such as: GUID Partition Table, Apple partition map, or BSD disklabel.An alternative term to generically refer to partition...

. Therefore USB flash units can be partitioned as hard drives.

Longevity


Barring physical destruction of the drive, the memory or USB connector of a flash drive will eventually fail. Single-level cell (SLC) based memory is good for around 100,000 writes; more commonly used Multi-level cell
Multi-level cell
In electronics, a multi-level cell is a memory element capable of storing more than a single bit of information.MLC NAND flash is a flash memory technology using multiple levels per cell to allow more bits to be stored using the same number of transistors...

 (MLC) for around 10,000. The USB connector can withstand approximately 1,500 connect/disconnect cycles.

Fake products


Fake USB flash drives are sometimes sold, claiming to have higher capacities than they actually have. These are typically low capacity USB drives which are modified so that they emulate larger capacity drives (e.g. a 2 GB drive being marketed as an 8 GB drive). When plugged into a computer, they report themselves as being the larger capacity they were sold as, but when data is written to them, either the write fails, the drive freezes up, or it overwrites existing data. Software tools exist to check and detect fake USB drives. In some cases it is possible to repair these devices to remove the false capacity information and use them normally.

Uses



Personal data transport


The most common use of flash drives is to transport and store personal files such as documents, pictures and videos. Individuals also store medical alert information on MedicTag flash drives for use in emergencies and for disaster preparation.

Secure storage of data, application and software files


With wide deployment(s) of flash drives being used in various environments (secured or otherwise), the issue of data and information security remains of the utmost importance. The use of biometrics
Biometrics
Biometrics As Jain & Ross point out, "the term biometric authentication is perhaps more appropriate than biometrics since the latter has been historically used in the field of statistics to refer to the analysis of biological data [36]" . consists of methods...

 and encryption
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...

 is becoming the norm with the need for increased security for data; OTFE
OTFE
On-the-fly encryption , also known as Real-time Encryption, is a method used by some encryption programs, for example, disk encryption software...

 systems are particularly useful in this regard, as they can transparently encrypt large amounts of data. In some cases a Secure USB Drive may use a hardware-based encryption mechanism that uses a hardware module instead of software for strongly encrypting data. IEEE 1667
IEEE 1667
IEEE 1667 is a standard published and maintained by the IEEE that describes various methods for authenticating transient storage devices such as USB flash drives when they are inserted into a computer.Since the protocol is universal, it means that will be platform independent of operating...

 is an attempt to create a generic authentication platform for USB drives and enjoys the support of Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 with support in Windows 7 and in Windows Vista Service Pack 2 with a hotfix.

Application carriers


Flash drives are used to carry applications that run on the host computer without requiring installation. While any standalone application can in principle be used this way, many programs store data, configuration information, etc. on the hard drive and registry
Windows registry
The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, services, SAM, user...

 of the host computer

The U3
U3
U3 was a joint venture between SanDisk and M-Systems , producing a proprietary method of launching Windows applications from special USB flash drives. Flash drives adhering to the U3 specification are termed "U3 smart drives"....

 company works with drive makers (parent company SanDisk
SanDisk
SanDisk Corporation is an American multinational corporation that designs, develops and manufactures data storage solutions in a range of form factors using the flash memory, controller and firmware technologies. It was founded in 1988 by Dr. Eli Harari and Sanjay Mehrotra, non-volatile memory...

 as well as others) to deliver custom versions of applications designed for Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 from a special flash drive; U3-compatible devices are designed to autoload a menu when plugged into a computer running Windows. Applications must be modified for the U3 platform not to leave any data on the host machine. U3 also provides a software framework for independent software vendor
Independent software vendor
Independent software vendor is a business term for companies specializing in making or selling software, designed for mass marketing or for niche markets...

s interested in their platform.

Ceedo
Ceedo
Ceedo is a software virtualization platform developed by Israeli company Ceedo Technologies. The term "Ceedo" refers both to the company and to the virtual workspace client on which the company's products are based....

 is an alternative product with the key difference that it does not require Windows applications to be modified in order for them to be carried and run on the drive.

Similarly, other application virtualization
Application Virtualization
Application virtualization is an umbrella term that describes software technologies that improve portability, manageability and compatibility of applications by encapsulating them from the underlying operating system on which they are executed. A fully virtualized application is not installed in...

 solutions and portable application creators
Portable application creators
Portable application creators allow the creation of portable applications . They usually use application virtualization.- Creators of independent portable applications :...

, such as VMware ThinApp
VMware ThinApp
VMware ThinApp is an application virtualization and portable application creator suite by VMware that can package conventional applications so that they become portable applications...

 (for Windows) or RUNZ (for Linux) can be used to run software from a flash drive without installation.

In October 2010, Apple Inc. released their newest iteration of the MacBook Air
MacBook Air
The MacBook Air family is a line of Apple ultraportable Macintosh notebook computers.The first-generation MacBook Air was a 13.3"-only model, previously promoted as the World's Thinnest Notebook, introduced at the Macworld Conference & Expo on January 15, 2008. It featured a custom Intel Merom CPU...

, which had the system's restore files contained on a USB card drive rather than the traditional install CDs due to the Air not coming with an optical drive.

A wide range of portable application
Portable application
A portable application , sometimes also called standalone, is a computer software program designed to run independently from an operating system...

s which are all free of charge, and able to run off a computer running Windows without storing anything on the host computer's drives or registry, can be found in the list of portable software.

Computer forensics and law enforcement


A recent development for the use of a USB Flash Drive as an application carrier is to carry the Computer Online Forensic Evidence Extractor
Computer Online Forensic Evidence Extractor
Computer Online Forensic Evidence Extractor is a tool kit, developed by Microsoft, to help computer forensic investigators extract evidence from a Windows computer. Installed on a USB flash drive or other external disk drive, it acts as an automated forensic tool during a live analysis...

 (COFEE) application developed by Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

. COFEE is a set of applications designed to search for and extract digital evidence
Computer forensics
Computer forensics is a branch of digital forensic science pertaining to legal evidence found in computers and digital storage media...

 on computers confiscated from suspects. Forensic software should not alter the information stored on the computer being examined in any way; other forensic suites run from CD-ROM
CD-ROM
A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....

 or DVD-ROM, but cannot store data on the media they are run from (although they can write to other attached devices such as external drives or memory sticks).

Booting operating systems


Most current PC firmware permits booting
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...

 from a USB drive, allowing the launch of an operating system from a bootable flash drive. Such a configuration is known as a Live USB
Live USB
A live USB is a USB flash drive or a USB external hard disk drive containing a full operating system that can be booted. Live USBs are closely related to live CDs, but sometimes have the ability to persistently save settings and permanently install software packages back onto the USB device...

.

Original flash memory designs had very limited estimated lifetimes. The failure mechanism for flash memory cells is analogous to a metal fatigue
Fatigue (material)
'In materials science, fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values are less than the ultimate tensile stress limit, and may be below the yield stress limit of the material.Fatigue occurs...

 mode; the device fails by refusing to write new data to specific cells that have been subject to many read-write cycles over the device's lifetime. Premature failure of a "live USB" could be circumvented by using a flash drive with a write-lock switch as a WORM device
Write Once Read Many
A Write Once Read Many or WORM drive is a data storage device where information, once written, cannot be modified. On ordinary data storage devices, the number of times data can be modified is not limited, except by the rated lifespan of the device, as modification involves physical changes that...

, identically to a live CD
Live CD
A live CD, live DVD, or live disc is a CD or DVD containing a bootable computer operating system. Live CDs are unique in that they have the ability to run a complete, modern operating system on a computer lacking mutable secondary storage, such as a hard disk drive...

. Originally, this potential failure mode limited the use of "live USB" system to special purpose applications or temporary tasks, such as:
  • Loading a minimal, hardened kernel
    Kernel (computing)
    In computing, the kernel is the main component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources...

     for embedded applications (e.g. network router, firewall).
  • Bootstrapping an operating system install or disk cloning
    Disk cloning
    Disk cloning is the process of copying the contents of one computer hard disk to another disk or to an "image" file. Often, the contents of the first disk are written to an image file as an intermediate step, and the second disk is loaded with the contents of the image...

     operation, often across a network.
  • Maintenance tasks, such as virus scanning or low-level data repair, without the primary host operating system loaded.


As of 2011, newer flash memory designs have much higher estimated lifetimes. Several manufacturers are now offering warranties of 5 years, or more. That should make the device more attractive for more applications. By reducing the probability of the device's premature failure, flash memory devices can now be considered for use where a magnetic disk would normally have been required. Flash drives have also experienced an exponential growth in their storage capacity over time (following the Moore's Law
Moore's Law
Moore's law describes a long-term trend in the history of computing hardware: the number of transistors that can be placed inexpensively on an integrated circuit doubles approximately every two years....

 growth curve). As of 2011, single packaged devices with capacities of 64GB
Gigabyte
The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...

 are readily available, and devices with 8GB capacity are very economical. Storage capacities in this range have traditionally been considered to offer adequate space, because they allow enough space for both the operating system software and some free space for the user's data.

Windows 8
Windows 8
Windows 8 is the codename for the next version of the Microsoft Windows computer operating system following Windows 7. It has many changes from previous versions. In particular it adds support for ARM microprocessors in addition to the previously supported x86 microprocessors from Intel and AMD...

 is planned to have a feature called Windows To Go
Windows To Go
Windows To Go is a feature in Windows 8 that allows the entire system to run from USB mass storage devices such as flash drives and external hard drives....

, which will allow users to carry a bootable copy of Windows 8, alongside their documents and programs, in a USB drive.

Windows Vista and Windows 7 ReadyBoost


In Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

 and Windows 7, the ReadyBoost
ReadyBoost
ReadyBoost is a disk cache component of Microsoft Windows, first introduced with Microsoft's Windows Vista in 2006 and bundled with Windows 7 in 2009...

 feature allows use of flash drives (from 4 GB in the case of Windows Vista) to augment operating system memory.

Audio players


Many companies make small solid-state digital audio players, essentially producing flash drives with sound output and a simple user interface. Examples include the Creative MuVo
Creative MuVo
The Creative MuVo is a range of digital audio players produced by Creative Technology, launched in 2003...

, Philips GoGear
Philips GoGear
Philips GoGear is a series of small flash memory and hard drive-based personal electronic devices from Philips. The line includes digital cameras, digital audio players, and audio recorders. The GoGear line is named for the size of its products, all of which are rather small and portable...

 and the first generation iPod shuffle
IPod shuffle
The iPod Shuffle is a digital audio player designed and marketed by Apple Inc. It is the smallest model in Apple's iPod family, and was the first to use flash memory...

. Some of these players are true USB flash drives as well as music players; others do not support general-purpose data storage. Other applications requiring storage, such as digital voice or sound recording
Digital recording
In digital recording, digital audio and digital video is directly recorded to a storage device as a stream of discrete numbers, representing the changes in air pressure for audio and chroma and luminance values for video through time, thus making an abstract template for the original sound or...

, can also be combined with flash drive functionality.

Many of the smallest players are powered by a permanently fitted rechargeable battery, charged from the USB interface.

Music storage and marketing


Digital audio
Digital audio
Digital audio is sound reproduction using pulse-code modulation and digital signals. Digital audio systems include analog-to-digital conversion , digital-to-analog conversion , digital storage, processing and transmission components...

 files can be transported from one computer to another like any other file, and played on a compatible media player (with caveats for DRM
Digital rights management
Digital rights management is a class of access control technologies that are used by hardware manufacturers, publishers, copyright holders and individuals with the intent to limit the use of digital content and devices after sale. DRM is any technology that inhibits uses of digital content that...

-locked files). In addition, many home Hi-Fi and car stereo head units
Car audio
Car audio/video , auto radio, mobile audio, 12-volt and other terms are used to describe the sound or video system fitted in an automobile. While 12-volt audio and video systems are also used, marketed, or manufactured for marine, aviation, and buses, this article focuses on cars as the most common...

 are now equipped with a USB port. This allows a USB flash drive containing media files in a variety of formats to be played directly on devices which support the format.

Artists have sold or given away USB flash drives, with the first instance believed to be in 2004 when the German band WIZO
WIZO
Wizo is a punk rock band from Sindelfingen, Germany. The band was formed in 1985. Their messages run from political to humorous, and they are strongly opposed to Nazism, fascism, racism, and "all of that crap"...

 released the "Stick EP", only as a USB drive. In addition to five high-bitrate
Bitrate
In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....

 MP3
MP3
MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression...

s, it also included a video, pictures, lyrics, and guitar tablature
Tablature
Tablature is a form of musical notation indicating instrument fingering rather than musical pitches....

. Subsequently artists including Kanye West
Kanye West
Kanye Omari West is an American rapper, singer, and record producer. West first rose to fame as a producer for Roc-A-Fella Records, where he eventually achieved recognition for his work on Jay-Z's album The Blueprint, as well as hit singles for musical artists including Alicia Keys, Ludacris, and...

, Nine Inch Nails, Kylie Minogue
X (Kylie Minogue album)
X is the tenth studio album by Australian recording artist Kylie Minogue. It is her first release since the greatest hits compilation Ultimate Kylie , and her first studio album since Body Language . X was preceded by lead single "2 Hearts" and released worldwide in November 2007...

 and Ayumi Hamasaki
Next Level (Ayumi Hamasaki album)
Next Level is the tenth studio album by Japanese pop singer-songwriter Ayumi Hamasaki, released by Avex Trax on March 25, 2009 in Japan. It was released as a CD only version, a CD+DVD version, and a limited edition 2CD+DVD version with the second CD containing live songs taken from her New Year's...

 have released music and promotional material on USB flash drives. In 2009 a USB drive holding fourteen remastered Beatles albums in both FLAC
FLAC
FLAC is a codec which allows digital audio to be losslessly compressed such that file size is reduced without any information being lost...

 and MP3 was released.

Arcades


In the arcade game
Arcade game
An arcade game is a coin-operated entertainment machine, usually installed in public businesses such as restaurants, bars, and amusement arcades. Most arcade games are video games, pinball machines, electro-mechanical games, redemption games, and merchandisers...

 In the Groove
In the Groove (game)
In the Groove is the first game in the In the Groove franchise, published and developed by Roxor Games, and first released in video arcades around August 30, 2004.-Gameplay:...

and more commonly In The Groove 2
In the Groove 2
In the Groove 2 is the sequel to Roxor Games' 2004 arcade game In the Groove. It was released to arcades officially on June 18, 2005. It is available as an upgrade kit and as a dedicated cabinet developed by Andamiro...

, flash drives are used to transfer high scores, screenshots, dance edits, and combos throughout sessions. As of software revision 21 (R21), players can also store custom songs and play them on any machine on which this feature is enabled. While use of flash drives is common, the drive must be Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 compatible.

In the arcade games Pump it Up NX2
Pump It Up NX2
Pump it Up Next Xenesis is the 20th arcade game release in the Pump It Up series. It was released worldwide on January 21, 2008 after being made available in Mexico and Korea a couple months prior....

and Pump it Up NXA, a special produced flash drive is used as a "save file" for unlocked songs, as well as progressing in the WorldMax and Brain Shower sections of the game.

In the arcade game Dance Dance Revolution X
Dance Dance Revolution X
Dance Dance Revolution X, abbreviated DDR X or simply X, is a music video game, and a part of the Dance Dance Revolution series. DDR X was originally announced by Konami on May 15, 2008 for the North American PlayStation 2. The arcade version was announced on July 7, 2008, July 9, 2008 in Europe,...

, an exclusive USB flash drive was made by Konami for the purpose of the link feature from its Sony PlayStation 2 counterpart. However, any USB flash drives can be used in this arcade game.

Brand and product promotion


The availability of inexpensive flash drives has enabled them to be used for promotional
Promotion (marketing)
Promotion is one of the four elements of marketing mix . It is the communication link between sellers and buyers for the purpose of influencing, informing, or persuading a potential buyer's purchasing decision....

 and marketing
Marketing
Marketing is the process used to determine what products or services may be of interest to customers, and the strategy to use in sales, communications and business development. It generates the strategy that underlies sales techniques, business communication, and business developments...

 purposes, particularly within technical and computer-industry circles (e.g. technology trade shows
Trade fair
A trade fair is an exhibition organized so that companies in a specific industry can showcase and demonstrate their latest products, service, study activities of rivals and examine recent market trends and opportunities...

). They may be given away for free, sold at less than wholesale price, or included as a bonus with another purchased product.

Usually, such drives will be custom-stamped with a company's logo
Logo
A logo is a graphic mark or emblem commonly used by commercial enterprises, organizations and even individuals to aid and promote instant public recognition...

, as a form of advertising
Advertising
Advertising is a form of communication used to persuade an audience to take some action with respect to products, ideas, or services. Most commonly, the desired result is to drive consumer behavior with respect to a commercial offering, although political and ideological advertising is also common...

 to increase mind share
Mind share
Mind share, or the development of consumer awareness or popularity, is one of the main objectives of advertising and promotion. When people think of examples of a product type or category, they usually think of a limited number of brand names. For example, a prospective buyer of a college education...

 and brand awareness
Brand
The American Marketing Association defines a brand as a "Name, term, design, symbol, or any other feature that identifies one seller's good or service as distinct from those of other sellers."...

. The drive may be a blank drive, or preloaded with graphics, documentation, web links, Flash
Adobe Flash
Adobe Flash is a multimedia platform used to add animation, video, and interactivity to web pages. Flash is frequently used for advertisements, games and flash animations for broadcast...

 animation
Animation
Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement. The effect is an optical illusion of motion due to the phenomenon of persistence of vision, and can be created and demonstrated in several ways...

 or other multimedia
Multimedia
Multimedia is media and content that uses a combination of different content forms. The term can be used as a noun or as an adjective describing a medium as having multiple content forms. The term is used in contrast to media which use only rudimentary computer display such as text-only, or...

, and free or demonstration software. Some preloaded drives are read-only while others are configured with both read-only and user-writable segments, such dual-partition drives are more expensive.

Flash drives can be set up to automatically launch stored presentations, websites, articles, and any other software immediately on insertion of the drive using the Microsoft Windows AutoRun
Autorun
AutoRun and the companion feature AutoPlay are components of the Microsoft Windows operating system that dictate what actions the system takes when a drive is mounted....

 feature. Autorunning software this way does not work on all computers, and it is normally disabled by security-conscious users.

Backup


Some value-added reseller
Value-added reseller
A value-added reseller is a company that adds features or services to an existing product, then resells it as an integrated product or complete "turn-key" solution...

s are now using a flash drive as part of small-business turnkey
Turnkey
A turn-key or a turn-key project is a type of project that is constructed by a developer and sold or turned over to a buyer in a ready-to-use condition.-Common usage:...

 solutions (e.g. point-of-sale
Point of sale
Point of sale or checkout is the location where a transaction occurs...

 systems). The drive is used as a backup
Backup
In information technology, a backup or the process of backing up is making copies of data which may be used to restore the original after a data loss event. The verb form is back up in two words, whereas the noun is backup....

 medium: at the close of business each night, the drive is inserted, and a database
Database
A database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...

 backup is saved to the drive. Alternatively, the drive can be left inserted through the business day, and data regularly updated. In either case, the drive is removed at night and taken offsite.
  • This is simple for the end-user, and more likely to be done;
  • The drive is small and convenient, and more likely to be carried off-site for safety;
  • The drives are less fragile mechanically and magnetically than tapes;
  • The capacity is often large enough for several backup images of critical data;
  • And flash drives are cheaper than many other backup systems.


It is also easy to lose these small devices, and easy for people without a right to data to take illicit backups.

Operating system installation media


Some operating systems, especially some Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 distributions, Windows 7 and Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

 can be, or even have to be installed from a USB flash drive instead of a CD or a DVD. A common example of using USB flash drive as operating system is Mac OS X 10.7 which is only distributed via Internet (Mac App Store
Mac App Store
The Mac App Store is a digital distribution platform for Mac OS X applications developed by Apple Inc.. The platform was announced on October 20, 2010 at Apple's "Back to the Mac" event. Apple began accepting app submissions from registered developers on November 3, 2010 in preparation for its launch...

) or on USB Flash drives. A common example of employing USB Flash drive as the only way of operating system installation is MacBook Air
MacBook Air
The MacBook Air family is a line of Apple ultraportable Macintosh notebook computers.The first-generation MacBook Air was a 13.3"-only model, previously promoted as the World's Thinnest Notebook, introduced at the Macworld Conference & Expo on January 15, 2008. It featured a custom Intel Merom CPU...

 installing Windows with Boot Camp. MacBook Air is not shipped with an optical drive, hence rendering it impossible to install Windows through DVDs without an external SuperDrive
SuperDrive
SuperDrive is a trademark used by Apple Inc. for two different storage drives: from 1988–99 to refer to a high-density floppy disk drive capable of reading all major 3.5" disk formats; and from 2001 onwards to refer to a combined CD/DVD reader/writer....

 (due to limits in Apple EFI
Extensible Firmware Interface
The Unified Extensible Firmware Interface is a specification that defines a software interface between an operating system and platform firmware...

), so Windows 7 has to be installed to a MacBook Air with a USB Flash drive.

Security systems


Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

 uses USB Flash drive as a certificate carrier for BitLocker encryption
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...

 on system drives, on systems which do not support TPM
Trusted Platform Module
In computing, Trusted Platform Module is both the name of a published specification detailing a secure cryptoprocessor that can store cryptographic keys that protect information, as well as the general name of implementations of that specification, often called the "TPM chip" or "TPM Security...

s. Also some software uses a USB Flash drive with special hidden data written as a offline activiation method.

Advantages


Data stored on flash drives is impervious to scratches
Abrasion (mechanical)
Abrasion is the process of scuffing, scratching, wearing down, marring, or rubbing away. It can be intentionally imposed in a controlled process using an abrasive...

 and dust, and flash drives are mechanically very robust making them suitable for transporting data from place to place and keeping it readily at hand. Most personal computers support USB .

Flash drives also store data densely compared to many removable media. In mid-2009, 256 GB drives became available, with the ability to hold many times more data than a DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

 or even a Blu-ray disc
Blu-ray Disc
Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...

,

Compared to hard drives, flash drives use little power, have no fragile moving parts, and for most capacities are small and light.

Flash drives implement the USB mass storage device class
USB mass storage device class
The USB mass storage device class, otherwise known as USB MSC or UMS, is a protocol that allows a Universal Serial Bus device to become accessible to a host computing device, to enable file transfers between the two...

 so that most modern operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

s can read and write to them without installing device driver
Device driver
In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....

s. The flash drives present a simple block-structured logical unit to the host operating system, hiding the individual complex implementation details of the various underlying flash memory devices. The operating system can use any file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...

 or block addressing scheme. Some computers can boot up from flash drives.

Specially manufactured flash drives are available that have a tough rubber or metal casing designed to be waterproof and virtually "unbreakable". These flash drives retain their memory after being submerged in water, and even through a machine wash. Leaving such a flash drive out to dry completely before allowing current to run through it has been known to result in a working drive with no future problems. Channel Five's Gadget Show cooked one of these flash drives with propane, froze it with dry ice
Dry ice
Dry ice, sometimes referred to as "Cardice" or as "card ice" , is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue...

, submerged it in various acidic liquids, ran over it with a jeep and fired it against a wall with a mortar. A company specializing in recovering lost data from computer drives managed to recover all the data on the drive. All data on the other removable storage devices tested, using optical or magnetic technologies, were destroyed.

Disadvantages



Like all flash memory devices, flash drives can sustain only a limited number of write and erase cycles before the drive fails. This should be a consideration when using a flash drive to run application software or an operating system. To address this, as well as space limitations, some developers have produced special versions of operating systems (such as Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 in Live USB
Live USB
A live USB is a USB flash drive or a USB external hard disk drive containing a full operating system that can be booted. Live USBs are closely related to live CDs, but sometimes have the ability to persistently save settings and permanently install software packages back onto the USB device...

) or commonplace applications (such as Mozilla Firefox
Mozilla Firefox
Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. , Firefox is the second most widely used browser, with approximately 25% of worldwide usage share of web browsers...

) designed to run from flash drives. These are typically optimized for size and configured to place temporary or intermediate files in the computer's main RAM rather than store them temporarily on the flash drive.

Most USB flash drives do not include a write-protect mechanism, although some have a switch on the housing of the drive itself to keep the host computer from writing or modifying data on the drive. Write-protection makes a device suitable for repairing virus
Computer virus
A computer virus is a computer program that can replicate itself and spread from one computer to another. The term "virus" is also commonly but erroneously used to refer to other types of malware, including but not limited to adware and spyware programs that do not have the reproductive ability...

-contaminated host computers without risk of infecting the USB flash drive itself. A write-locked SD card in a USB flash card reader adapter is an effective way to avoid any writes on the flash medium. The SD card as a WORM
Write Once Read Many
A Write Once Read Many or WORM drive is a data storage device where information, once written, cannot be modified. On ordinary data storage devices, the number of times data can be modified is not limited, except by the rated lifespan of the device, as modification involves physical changes that...

 device has an essentially unlimited life.

A drawback to the small size is that they are easily misplaced, left behind, or otherwise lost. This is a particular problem if the data they contain are sensitive (see data security
Data security
Data security is the means of ensuring that data is kept safe from corruption and that access to it is suitably controlled. Thus data security helps to ensure privacy. It also helps in protecting personal data. Data security is part of the larger practice of Information security.- Disk Encryption...

). As a consequence, some manufacturers have added encryption hardware to their drives—although software encryption systems
Comparison of disk encryption software
-Background information:-Operating systems:-Features:* Hidden containers: Whether hidden containers can be created for deniable encryption...

 which can be used in conjunction with any mass storage
Mass storage
In computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. Devices and/or systems that have been described as mass storage include tape libraries, RAID systems, hard disk drives, magnetic tape drives, optical disc drives, magneto-optical...

 medium achieve the same thing. Most drives can be attached to keychains, necklaces and lanyards. The USB plug is usually fitted with a removable and easily lost protective cap, or is retractable.

USB flash drives are more expensive per unit of storage than large hard drives, but are less expensive in capacities of a few tens of gigabytes . Maximum available capacity is increasing with time, but is less than larger hard drives. This balance is changing, but the rate of change is slowing.

Tape


The applications of current data tape cartridges hardly overlap those of flash drives: on tape, cost per gigabyte is very low for large volumes, but the individual drives and media are expensive. Media has a very high capacity and very fast transfer speeds, but store data sequentially
Sequential access
In computer science, sequential access means that a group of elements is accessed in a predetermined, ordered sequence. Sequential access is sometimes the only way of accessing the data, for example if it is on a tape...

 and is very slow for random seek of data. While disk-based backup is now the primary medium of choice for most companies, tape backup is still popular for taking data off-site for worst-case scenarios and for very large volumes (more than a few hundreds of TB). See LTO
Linear Tape-Open
Linear Tape-Open is a magnetic tape data storage technology originally developed in the late 1990s as an open standards alternative to the proprietary magnetic tape formats that were available at the time. Hewlett-Packard, IBM and Seagate initiated the LTO Consortium, which directs development...

 tapes.

Floppy disk



Floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

 drives are rarely fitted to modern computers and are obsolete for normal purposes, although internal and external drives can be fitted if required. Floppy disks may be the method of choice for transferring data to and from very old computers without USB or booting
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...

 from floppy disks, and so they are sometimes used to change the firmware on, for example, BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....

 chips. Devices with removable storage like older Yamaha music keyboards are also dependent on floppy disks, which require computers to process them. Newer devices are built with USB flash drive support.

Optical media


The various writable and rewritable forms of CD and DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

 are portable storage media supported by the vast majority of computers as of 2008. CD-R, DVD-R, and DVD+R can be written to only once, RW varieties up to about 1,000 erase/write cycles, while modern NAND-based flash drives often last for 500,000 or more erase/write cycles. DVD-RAM
DVD-RAM
DVD-RAM is a disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders and personal video recorders since 1998.-Design:DVD-RAM is one of three competing...

 discs are the most suitable optical discs for data storage involving much rewriting.

Optical storage devices are among the cheapest methods of mass data storage after the hard drive. They are slower than their flash-based counterparts. Standard 12 cm optical discs are larger than flash drives and more subject to damage. Smaller optical media do exist, such as business card CD-Rs which have the same dimensions as a credit card, and the slightly less convenient but higher capacity 8 cm recordable MiniCD and MiniDVD
MiniDVD
MiniDVD is a DVD disc having 8 cm in diameter.The 8 cm optical disc format was originally used for music CD singles, hence the commonly used names CD single and miniCD...

. The small discs are more expensive than the standard size, and do not work in all drives.

Universal Disk Format
Universal Disk Format
Universal Disk Format is an implementation of the specification known as ISO/IEC 13346 and ECMA-167 and is an open vendor-neutral file system for computer data storage for a broad range of media. In practice, it has been most widely used for DVDs and newer optical disc formats, supplanting ISO 9660...

 (UDF) version 1.50 and above has facilities to support rewritable discs like sparing tables and virtual allocation tables
File Allocation Table
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...

, spreading usage over the entire surface of a disc and maximising life, but many older operating systems do not support this format. Packet-writing utilities such as DirectCD and InCD
InCD
InCD is a packet writing software developed by Nero AG for Microsoft Windows.InCD allows optical discs to be used in a similar manner to a floppy disk...

 are available but produce discs that are not universally readable (although based on the UDF
Universal Disk Format
Universal Disk Format is an implementation of the specification known as ISO/IEC 13346 and ECMA-167 and is an open vendor-neutral file system for computer data storage for a broad range of media. In practice, it has been most widely used for DVDs and newer optical disc formats, supplanting ISO 9660...

 standard). The Mount Rainier
Mount Rainier (packet writing)
Mount Rainier is a format for writable optical discs which provides the packet writing and defect management. Its goal is the replacement of the floppy disk...

 standard addresses this shortcoming in CD-RW media by running the older file systems on top of it and performing defect management for those standards, but it requires support from both the CD/DVD burner and the operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

. Many drives made today do not support Mount Rainier, and many older operating systems such as Windows XP and below, and Linux kernels older than 2.6.2, do not support it (later versions do). Essentially CDs/DVDs are a good way to record a great deal of information cheaply and have the advantage of being readable by most standalone players, but they are poor at making ongoing small changes to a large collection of information. Flash drives' ability to do this is their major advantage over optical media.

Flash memory cards


Flash memory cards, e.g. Secure Digital card
Secure Digital card
Secure Digital is a non-volatile memory card format developed by the SD Card Association for use in portable devices. The SD technology is used by more than 400 brands across dozens of product categories and more than 8,000 models, and is considered the de-facto industry standard.Secure Digital...

s, are available in various formats and capacities, and are used by many consumer devices. However, while virtually all PCs have USB ports, allowing the use of USB flash drives, memory card readers are not commonly supplied as standard equipment (particularly with desktop computers). Although inexpensive card readers are available that read many common formats, this results in two pieces of portable equipment (card plus reader) rather than one.

Some manufacturers, aiming at a "best of both worlds" solution, have produced card readers that approach the size and form of USB flash drives (e.g. Kingston
Kingston Technology
Kingston Technology Company, Inc. is an American privately held, multinational computer technology corporation that develops, manufactures, sells and supports flash memory products and other computer-related memory products. Headquartered in Fountain Valley, California, USA, Kingston Technology...

 MobileLite, SanDisk
SanDisk
SanDisk Corporation is an American multinational corporation that designs, develops and manufactures data storage solutions in a range of form factors using the flash memory, controller and firmware technologies. It was founded in 1988 by Dr. Eli Harari and Sanjay Mehrotra, non-volatile memory...

 MobileMate.) These readers are limited to a specific subset of memory card formats (such as SD, microSD, or Memory Stick
Memory Stick
Memory Stick is a removable flash memory card format, launched by Sony in October 1998, and is also used in general to describe the whole family of Memory Sticks...

), and often completely enclose the card, offering durability and portability approaching, if not quite equal to, that of a flash drive. Although the combined cost of a mini-reader and a memory card is usually slightly higher than a USB flash drive of comparable capacity, the reader + card solution offers additional flexibility of use, and virtually "unlimited" capacity. The ubiquity of SD cards is such that, circa 2011, due to economies of scale
Economies of scale
Economies of scale, in microeconomics, refers to the cost advantages that an enterprise obtains due to expansion. There are factors that cause a producer’s average cost per unit to fall as the scale of output is increased. "Economies of scale" is a long run concept and refers to reductions in unit...

, their price is now less than an equivalent capacity USB flash drive even with the added $2 (Canadian) cost of a USB SD card reader.

An additional advantage of memory cards is that many consumer devices (e.g. digital camera
Digital camera
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...

s, portable music players) cannot make use of USB flash drives (even if the device has a USB port) whereas the memory cards used by the devices can be read by PCs with a card reader.

External hard disk


Particularly with the advent of USB, external hard disks have become widely available and inexpensive. External hard disk drives currently cost less per gigabyte than flash drives and are available in larger capacities. Some hard drives support alternative and faster interfaces than USB 2.0 (e.g. IEEE 1394 and eSATA). For consecutive sector writes and reads (for example, from an unfragmented file) most hard drives can provide a much higher sustained data rate than current NAND flash memory though mechanical latencies seriously impact hard drive performance.

Unlike solid-state memory, hard drives are susceptible to damage by shock, e.g., a short fall, vibration, have limitations on use at high altitude, and although they are shielded by their casings, they are vulnerable when exposed to strong magnetic fields. In terms of overall mass, hard drives are usually larger and heavier than flash drives; however, hard disks sometimes weigh less per unit of storage. Hard disks also suffer from file fragmentation
Fragmentation (computer)
In computer storage, fragmentation is a phenomenon in which storage space is used inefficiently, reducing storage capacity and in most cases reducing the performance. The term is also used to denote the wasted space itself....

 which can reduce access speed.

Obsolete devices


Audio tape cassette
Compact Cassette
The Compact Cassette, often referred to as audio cassette, cassette tape, cassette, or simply tape, is a magnetic tape sound recording format. It was designed originally for dictation, but improvements in fidelity led the Compact Cassette to supplant the Stereo 8-track cartridge and reel-to-reel...

s and high-capacity floppy disks (e.g. Imation
Imation
Imation is a US based multi-national technology corporation that designs, manufactures and sells recordable data storage media, consumer electronics products and accessories.The company is a 1996 spin off of 3M and is headquartered in Oakdale, Minnesota...

 SuperDisk
SuperDisk
The SuperDisk, sometimes marketed as LS-120 and a later variant LS-240, is a high-speed, high-capacity alternative to the 90 mm , 1.44 MB floppy disk. The Superdisk hardware was introduced by 3M's storage products group circa 1997...

), and other forms of drives with removable magnetic media such as the Iomega Zip
Zip drive
The Zip drive is a medium-capacity removable disk storage system that was introduced by Iomega in late 1994. Originally, Zip disks launched with capacities of 100 MB, but later versions increased this to first 250 MB and then 750 MB....

 and Jaz drive
Jaz drive
The Jaz drive was a removable disk storage system, introduced by the Iomega company in 1995. The system has since been discontinued.The Jaz disks were originally released with a 1 GB capacity in a 3½-inch form factor, which was a significant increase over Iomega's most popular product at the time,...

s are now largely obsolete and rarely used. There are products in today's market which will emulate these legacy drives for both tape and disk (SCSI1/SCSI2, SASI, Magneto optic, Ricoh ZIP, Jaz, IBM3590/ Fujitsu 3490E and Bernoulli for example) in state-of-the-art Compact Flash storage devices – CF2SCSI.

Encryption and Security



As highly portable media, USB flash drives are easily lost or stolen. All USB flash drives can have their contents encrypted using third party disk encryption software, which can often be run directly from the USB drive without installation (for example, FreeOTFE
FreeOTFE
FreeOTFE is an open source on-the-fly disk encryption computer program for PCs running Microsoft Windows, and personal digital assistants running Windows Mobile . It creates virtual drives, or disks, to which anything written is automatically encrypted before being stored on a computer's hard or...

) although some, such as TrueCrypt, require the user to have administrative rights on every computer it's run on.

Archiving software can achieve a similar result by creating encrypted ZIP
ZIP (file format)
Zip is a file format used for data compression and archiving. A zip file contains one or more files that have been compressed, to reduce file size, or stored as is...

 or RAR files.

Some USB flash drive manufacturers have produced USB flash drives which use hardware based encryption as part of the design, removing the need for third-party encryption software; though a number of these have been shown to have security problems, and are typically more expensive than software based systems which are available for free.

A minority of flash drives support biometric fingerprinting to confirm the user's identity. As of mid-, this was an expensive alternative to standard password protection offered on many new USB flash storage devices. Most fingerprint scanning drives rely upon the host operating system to validate the fingerprint via a software driver, often restricting the drive to Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 computers. However, there are USB drives with fingerprint scanners which use controllers that allow access to protected data without any authentication.

Some manufacturers deploy physical authentication tokens
Dongle
A software protection dongle is a small piece of hardware that plugs into an electrical connector on a computer and serves as an electronic "key" for a piece of software; the program will only run when the dongle is plugged in...

 in the form of a flash drive. These are used to control access to a sensitive system by containing encryption keys or, more commonly, communicating with security software on the target machine. The system is designed so the target machine will not operate except when the flash drive device is plugged into it. Some of these "PC lock" devices also function as normal flash drives when plugged into other machines.

Security threats


Flash drives may present a significant security challenge for some organizations. Their small size and ease of use allows unsupervised visitors or employees to store and smuggle out confidential data with little chance of detection. Both corporate and public computers are vulnerable to attackers connecting a flash drive to a free USB port and using malicious software such as keyboard loggers or packet sniffer
Packet sniffer
A packet analyzer is a computer program or a piece of computer hardware that can intercept and log traffic passing over a digital network or part of a network...

s.

For computers set up to be bootable from a USB drive it is possible to use a flash drive containing a bootable portable operating system to access the files of a computer even if the computer is password protected. The password can then be changed; or it may be possible to crack the password with a password cracking program, and gain full control over the computer. Encrypting files provides considerable protection against this type of attack.

USB flash drives may also be used deliberately or unwittingly to transfer malware
Malware
Malware, short for malicious software, consists of programming that is designed to disrupt or deny operation, gather information that leads to loss of privacy or exploitation, or gain unauthorized access to system resources, or that otherwise exhibits abusive behavior...

 and autorun worms
Computer worm
A computer worm is a self-replicating malware computer program, which uses a computer network to send copies of itself to other nodes and it may do so without any user intervention. This is due to security shortcomings on the target computer. Unlike a computer virus, it does not need to attach...

 onto a network.

Some organizations forbid the use of flash drives, and some computers are configured to disable the mounting of USB mass storage devices by users other than administrators; others use third-party software to control USB usage. The use of software allows the administrator to not only provide a USB lock but also control the use of CD-RW, SD cards and other memory devices. This enables companies with policies forbidding the use of USB flash drives in the workplace to enforce these policies. In a lower-tech security solution, some organizations disconnect USB ports inside the computer or fill the USB sockets with epoxy
Epoxy
Epoxy, also known as polyepoxide, is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of applications, including fiber-reinforced plastic materials and general purpose adhesives....

.

Naming


In 2005, Microsoft was using the term "USB Flash Drive" as the common name for these devices when they introduced the Microsoft USB Flash Drive Manager application. Alternative names are commonly used conversationally with many of them listed as trademarks of various manufacturers.

The following names are trademarks used on the USB flash drives manufactured by these companies:
  • ClipDrive - Originally filed by Memory Experts International Corporation, now owned by Imation Corporation
    Imation
    Imation is a US based multi-national technology corporation that designs, manufactures and sells recordable data storage media, consumer electronics products and accessories.The company is a 1996 spin off of 3M and is headquartered in Oakdale, Minnesota...

  • Cruzer
    SanDisk Cruzer
    The SanDisk Cruzer is a range of USB flash drives manufactured by SanDisk. As of April 2011, the flash drives have a capacity range from 2 to 64 Gigabytes. There are a broad range of products, from small low-capacity flash drives designed to very portable, to large high capacity ones made for data...

     - SanDisk Corporation
    SanDisk
    SanDisk Corporation is an American multinational corporation that designs, develops and manufactures data storage solutions in a range of form factors using the flash memory, controller and firmware technologies. It was founded in 1988 by Dr. Eli Harari and Sanjay Mehrotra, non-volatile memory...

  • DiskOnKey - Originally filed by M-Systems Flash Disk Pioneers, Ltd.
    M-Systems
    M-Systems Ltd., was a Nasdaq-listed Israeli producer of Flash memory storage products founded in 1989 by Dov Moran and based in Kfar Sava, Israel. They were best known for developing and patenting the first flash drive, marketed in 1995 as DiskOnChip, and the first USB flash drive, marketed in...

    , now owned by SanDisk
  • Jump Drive - Originally registered by Lexar Media, Inc.
    Lexar
    Lexar Media, Inc. is an American manufacturer of digital media products based in Fremont, CA. Products manufactured by Lexar include SD cards, Memory Sticks, keydrives, CompactFlash cards and card readers. Lexar's Memory Stick Duos also have versions adapted for the PSP which includes a version of...

    , now owned by Micron Technology
    Micron Technology
    Micron Technology, Inc. is an American multinational corporation based in Boise, Idaho, USA, best known for producing many forms of semiconductor devices. This includes DRAM, SDRAM, flash memory, SSD and CMOS image sensing chips. Consumers may be more familiar with its consumer brand Crucial...

  • Thumbdrive - Trek 2000 International Ltd.

Current and future developments


Semiconductor corporations have worked to reduce the cost of the components in a flash drive by integrating various flash drive functions in a single chip, thereby reducing the part-count and overall package-cost.

Flash drive capacities on the market increase continually. , few manufacturers continue to produce models of 1 GB and smaller; and many have started to phase out 2 GB capacity flash memory. High speed has become a standard for modern flash drives and capacities of up to 256 GB have come on the market, as of 2009.,

Lexar
Lexar
Lexar Media, Inc. is an American manufacturer of digital media products based in Fremont, CA. Products manufactured by Lexar include SD cards, Memory Sticks, keydrives, CompactFlash cards and card readers. Lexar's Memory Stick Duos also have versions adapted for the PSP which includes a version of...

 is attempting to introduce a USB FlashCard
USB FlashCard
USB FlashCard is a flash memory card format developed by Lexar, and announced on December 13, 2004.There is a wide range of existing memory card formats such as SD, xD, and CompactFlash; the major advantage of USB FlashCard is that the cards are in fact standard USB flash drives...

, which would be a compact USB flash drive intended to replace various kinds of flash memory cards. Pretec introduced a similar card, which also plugs into any USB port, but is just one quarter the thickness of the Lexar model. Until 2008, SanDisk manufactured a product called SD Plus, which was a SecureDigital card with a USB connector.

SanDisk has also introduced a new technology to allow controlled storage and usage of copyrighted materials on flash drives, primarily for use by students. This technology is termed FlashCP
FlashCP
FlashCP is a copyright enforcement technology for the storage of electronic materials . Originally developed under the trademark "BootLocker", SanDisk acquired the technology in 2005 with the purchase of Israeli-based MDRM....

.

See also

  • Dead Drop (USB)
  • Portable application
    Portable application
    A portable application , sometimes also called standalone, is a computer software program designed to run independently from an operating system...

  • Readyboost
    ReadyBoost
    ReadyBoost is a disk cache component of Microsoft Windows, first introduced with Microsoft's Windows Vista in 2006 and bundled with Windows 7 in 2009...

  • USB Flash Drive Alliance
    USB Flash Drive Alliance
    The 'USB Flash Drive Alliance', founded in December 2003 bySamsung, Lexar Media, Kingston Technology and others, is a group of companies promoting the use of USB flash drives ....


External links