 A USB Flash Memory Device Flash memory is a form of EEPROM (Electrically-Erasable Programmable Read-Only Memory) that allows multiple memory locations to be erased or written in one programming operation. In layman's terms, it is a form of rewritable memory chip that, unlike a Random Access Memory chip, holds its content without the need of a power supply. It is also an example of a Non-Volatile Read Write Memory (NVRWM). The memory is commonly used in memory cards, USB flash drives, MP3 players, digital cameras and mobile phones. Download high resolution version (2592x1944, 982 KB) Wikipedia does not have an article with this exact name. ...
Download high resolution version (2592x1944, 982 KB) Wikipedia does not have an article with this exact name. ...
Note: USB may also mean upper sideband in radio. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
The terms storage (U.K.) or memory (U.S.) refer to the parts of a digital computer that retain physical state (data) for some interval of time, possibly even after electrical power to the computer is turned off. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
A 32 MB High Speed CompactFlash Type I card A memory card or flash memory card is a solid-state electronic flash memory data storage devices used with digital cameras, handheld and laptop computers, telephones, music players, video game consoles, and other electronics. ...
A USB drive, shown with a 24 mm US quarter coin for scale. ...
A digital audio player (DAP) is a device that stores, organizes and plays digital music files. ...
A SiPix digital camera next to a matchbox to show scale. ...
Overview Flash memory is non-volatile, which means that it does not need power to maintain the information stored in the chip. In addition, flash memory offers fast read access times (though not as fast as volatile DRAM memory used for main memory in PCs) and better shock resistance than hard disks. These characteristics explain the popularity of flash memory for applications such as storage on battery-powered devices.
Principles of operation Flash memory stores information in an array of floating gate transistors, called "cells", each of which traditionally stores one bit of information. Newer flash memory devices, sometimes referred to as multi-level cell devices, can store more than 1 bit per cell, by varying the number of electrons placed on the floating gate of a cell. The floating gate transistor is a variant of transistor that is commonly used for non-volatile storage such as flash, EPROM and EEPROM memory. ...
Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ...
In NOR flash, each cell looks similar to a standard MOSFET transistor, except that it has two gates instead of just one. One gate is the control gate (CG) like in other MOS transistors, but the second is a floating gate (FG) that is insulated all around by an oxide layer. The FG is between the CG and the substrate. Because the FG is isolated by its insulating oxide layer, any electrons placed on it get trapped there and thus store the information. When electrons are on the FG, they modify (partially cancel out) the electric field coming from the CG, which modifies the threshold voltage (Vt) of the cell. Thus, when the cell is "read" by placing a specific voltage on the CG, electrical current will either flow or not flow, depending on the Vt of the cell, which is controlled by the number of electrons on the FG. This presence or absence of current is sensed and translated into 1's and 0's, reproducing the stored data. In a multi-level cell device, which stores more than 1 bit of information per cell, the amount of current flow will be sensed, rather than simply detecting presence or absence of current, in order to determine the number of electrons stored on the FG. The metal oxide semiconductor field-effect transistor (MOSFET), is by far the most common field-effect transistor in both digital and analog circuits. ...
Assorted component transistors The transistor is a solid state semiconductor device which can be used for amplification, switching, voltage stabilization, signal modulation and many other functions. ...
In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ...
A NOR flash cell is programmed (set to a specified data value) by starting up electrons flowing from the source to the drain, then a large voltage placed on the CG provides a strong enough electric field to suck them up onto the FG, a process called hot-electron injection. To erase (reset to all 1's, in preparation for reprogramming) a NOR flash cell, a large voltage differential is placed between the CG and source, which pulls the electrons off through quantum tunneling. In single-voltage devices (virtually all chips available today), this high voltage is generated by an on-chip charge pump. Most modern NOR flash memory components are divided into erase segments, usually called either blocks or sectors. All of the memory cells in a block must be erased at the same time. NOR programming, however, can generally be performed one byte or word at a time. In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
Quantum tunneling is the quantum-mechanical effect of transitioning through a classically-forbidden energy state. ...
A charge pump is an electronic circuit that uses capacitors as energy storage elements to convert DC voltages into other DC voltages. ...
NAND Flash uses tunnel injection for writing and tunnel release for erasing. NAND flash memory forms the core of the removable USB interface storage devices known as keydrives. Tunnel injection is the effect used to program NAND flash memory. ...
Type A USB connector Dual images of the two Type B USB connectors, mini and full size, side and front view, compared with a U.S. ¢5; piece (nickel) in both images for scale. ...
A USB keydrive, shown with a US quarter coin for scale. ...
History Flash memory was invented by Dr. Fujio Masuoka while working for Toshiba in 1984. According to Toshiba, the name 'Flash' was suggested by Dr. Masuoka's colleague, Mr. Shoji Ariizumi, because the erasure process of the memory contents reminded him of a flash of a camera. Dr. Masuoka presented the invention at the IEEE 1984 Integrated Electronics Devices Meeting held in San Jose, California. Intel saw the massive potential of the invention and introduced the first commercial NOR type flash chip in 1988. Toshiba Corporation (æ±èŠ, TÅshiba) (TYO: 6502) is a Japanese high technology electrical and electronics manufacturing firm, headquartered in Tokyo, Japan. ...
1984 (MCMLXXXIV) is a leap year starting on Sunday of the Gregorian calendar. ...
Toshiba Corporation (æ±èŠ, TÅshiba) (TYO: 6502) is a Japanese high technology electrical and electronics manufacturing firm, headquartered in Tokyo, Japan. ...
In photography, a flash is a device that produces an instantaneous flash of light (typically around 1/1000 of a second) to help illuminate a scene. ...
The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ...
Intel Corporation (NASDAQ: INTC, HKEx: 4335), founded in 1968 as Integrated Electronics Corporation, is a U.S.-based multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ...
1988 (MCMLXXXVIII) was a leap year starting on a Friday of the Gregorian calendar. ...
NOR-based flash has long erase and write times, but has a full address/data (memory) interface that allows random access to any location. This makes it suitable for storage of program code that needs to be infrequently updated, such as a computer's BIOS or the firmware of set-top boxes. Its endurance is 10,000 to 1,000,000 erase cycles. NOR-based flash was the basis of early flash-based removable media; Compact Flash was originally based on it, though later cards moved to the cheaper NAND flash. In computer science, random access is the ability to access a random element of a group in equal time. ...
This article is about the software. ...
In computing, firmware is software that is embedded in a hardware device. ...
CompactFlash (CF) was originally a type of data storage device, used in portable electronic devices. ...
NAND flash from Samsung and Toshiba followed in 1989. It has faster erase and write times, higher density, and lower cost per bit than NOR flash, and ten times the endurance. However its I/O interface allows only sequential access to data. This makes it suitable for mass-storage devices such as PC cards and various memory cards, and somewhat less useful for computer memory. The first NAND-based removable media format was SmartMedia, and numerous others have followed: MMC, Secure Digital, Memory Stick and xD-Picture Cards. A new generation of these formats is becoming a reality with RS-MMC (Reduced Size MultiMedia Card), the TransFlash and miniSD variants of Secure Digital and the new USB/Memory card hybrid Intelligent Stick. The new formats exhibit a greatly reduced size, usually under 4 cm². Samsung Group is one of the largest South Korean business groupings. ...
Toshiba Corporation (æ±èŠ, TÅshiba) (TYO: 6502) is a Japanese high technology electrical and electronics manufacturing firm, headquartered in Tokyo, Japan. ...
1989 (MCMLXXXIX) is a common year starting on Sunday of the Gregorian calendar. ...
In computer science sequential access means that a group of elements (e. ...
The PCMCIA is the Personal Computer Memory Card International Association, an industry trade association that creates standards for notebook computer peripheral devices. ...
A 32 MB High Speed CompactFlash Type I card A memory card or flash memory card is a solid-state electronic flash memory data storage devices used with digital cameras, handheld and laptop computers, telephones, music players, video game consoles, and other electronics. ...
A 32MB SmartMedia flash memory card (on keyboard for scale) SmartMedia is a flash memory card standard owned by Toshiba. ...
A 32 MB Multi Media Card Multi Media Card A 128 MB RS-MMC card and an adapter The Multi Media Card (MMC) is a flash memory memory card standard. ...
16Mb SD Card Secure Digital, or SD, is a flash memory data storage device based on Toshibas earlier Multi Media Cards (MMC). ...
128 MB Memory Stick with MagicGate support 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. ...
xD-Picture Card compared in size with a US 1 cent coin The xD-Picture Card is a type of flash memory memory card. ...
Limitations One limitation of flash memory is that although it can be read or programmed a byte or a word at a time in a random access fashion, it must be erased a "block" at a time. Starting with a freshly erased block, any byte within that block can be programmed. However, once a byte has been programmed, it cannot be changed again until the entire block is erased. In other words, flash memory (specifically NOR flash) offers random-access read and programming operations, but cannot offer random-access rewrite or erase operations. When compared to a hard disk drive, a further limitation is the fact that flash memory has a finite number of erase-write cycles, so that care has to be taken when moving hard-drive based applications, such as operating systems, to flash-memory based devices such as CompactFlash. This effect is partially offset by some chip firmware or filesystem drivers by counting the writes and dynamically remapping the blocks in order to spread the write operations between the sectors, or by write verification and remapping to spare sectors in case of write failure. Typical hard drives of the mid-1990s. ...
In computing, an operating system (OS) is the system software responsible for the direct control and management of hardware and basic system operations. ...
A 64 MB CompactFlash Type I card CompactFlash (CF) was originally a type of data storage device, used in portable electronic devices. ...
Interestingly, the Tungsten T5 PDA and Treo 650 smartphone from PalmOne, released in late 2004, use NAND flash to back up the contents of main memory during normal operations. PalmOne names this technique "non-volatile file system" (NVFS). It gives the illusion of a RAM storage pool that does not lose any of its data when power is removed. This PalmOne knowledge base article explains how this technique works on the Treo 650. The Tungsten T5 is a Personal Digital Assistant made by palmOne, Inc. ...
This article is in need of improvement. ...
The palmOne Treo 650 is a combination hybrid PDA/cellphone officially announced on October 24, 2004 as the successor to the companys hugely successful Treo 600. ...
Nokia 3620/3660 A smartphone is any electronic handheld device that integrates the functionality of a mobile phone, personal digital assistant or other information appliance. ...
The title given to this article is incorrect due to technical limitations. ...
2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ...
NVFS File System, in which it is an acronym of Non-Volatile File System is a Flash-Style Memory File System introduced in the release of the two palmOne Personal Digital Assistant handheld models Tungsten T5 and Treo 650. ...
The cost per byte of flash memory remains significantly higher than the corresponding cost of a hard disk drive, and that (on top of finite number of erase-write cycles previously mentioned) has prevented flash from becoming a solid state replacement for the hard disk drive on normal desktop and laptop computers. Typical hard drives of the mid-1990s. ...
In physics, the solid state is one of the three phases of matter (solid, liquid, and gas). ...
A desktop is the horizontal surface of a desk. ...
Laptop with touchpad. ...
Low-level access Low-level access to a physical flash memory by device driver software is different from accessing common memories. Whereas a common RAM memory will simply respond to read and write operations by returning the contents or altering them immediately, flash memories need special considerations, especially when used as program memory akin to a read-only memory (ROM). A device driver, often called a driver for short, is a computer program that enables another program, typically, an operating system (OS) (e. ...
Read-only memory (ROM) is used as a storage medium in computers. ...
While reading data can be performed on individual addresses on NOR memories (not on NAND memories) unlocking (making available for erase or write), erasing and writing operations are performed block-wise on all flash memories. A typical block size will be 64, 128, or 256 KiB. A kibibyte (a contraction of kilo binary byte) is a unit of information or computer storage, commonly abbreviated KiB (never kiB). 1 kibibyte = 210 bytes = 1,024 bytes The kibibyte is closely related to the kilobyte, which can be used either as a synonym for kibibyte or to refer to...
NOR memories The read-only mode of NOR memories is similar to reading from a common memory, provided address and data bus is mapped correctly, so NOR flash memory is much like any address-mapped memory. NOR flash memories can be used as execute-in-place memory, meaning it behaves as a ROM memory mapped to a certain address.
When unlocking, erasing or writing NOR memories, special commands are written to the first page of the mapped memory. These commands are defined as the common flash interface (defined by Intel) and the flash circuit will provide a list of all available commands to the physical driver. Intel Corporation (NASDAQ: INTC, HKEx: 4335), founded in 1968 as Integrated Electronics Corporation, is a U.S.-based multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ...
Apart from being used as a ROM memory, the NOR memories can of course also be partitioned with a file system and used as any storage device. In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ...
NAND memories NAND flash memories cannot provide execute-in-place due to their different construction principles. These memories are accessed much like block devices such as hard disks or memory cards. When executing software from NAND memories, virtual memory strategies are used: memory contents must first be paged into memory-mapped RAM and executed there, making the presence of a memory management unit (MMU) on the system absolutely necessary. In computing (specifically data transmission and data storage), block size indicates a nominal size, usually expressed in bytes or bits, of a block of data. ...
Typical hard drives of the mid-1990s. ...
A 32 MB High Speed CompactFlash Type I card A memory card or flash memory card is a solid-state electronic flash memory data storage devices used with digital cameras, handheld and laptop computers, telephones, music players, video game consoles, and other electronics. ...
The memory pages of the virtual address space seen by the process, may reside non-contiguously in primary, or even secondary storage. ...
In computer operating systems, paging memory allocation algorithms divide computer memory into small partitions, and allocates memory using a page as the smallest building block. ...
MMU, short for Memory Management Unit, is a class of computer hardware components responsible for handling memory accesses requested by the CPU. Among the functions of such devices are the translation of virtual addresses to physical addresses (i. ...
For this reason some systems will use a combination of NOR and NAND memories, where the NOR memory is used as software ROM and the NAND memory is partitioned with a file system and used as a random access storage area. In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ...
Flash file systems Because of the particular characteristics of flash memory, it is best used with specifically-designed file systems which spread writes over the media and deal with the long erase times of NOR flash blocks. The basic concept behind flash file systems is: When the flash store is to be updated, the file system will write a new copy of the changed data over to a fresh block, remap the file pointers, then erase the old block later when it has time. In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ...
One of the earliest flash file systems was Microsoft's FFS2 (presumably preceded by FFS1), for use with MS-DOS in the early 1990's. Around 1994, the PCMCIA industry group approved the FTL (Flash Translation Layer) specification, which allowed a flash device to look like a FAT disk, but still have effective wear levelling. Other commercial systems such as FlashFX by Datalight were created to avoid patent concerns with FTL. Microsoft Corporation (NASDAQ: MSFT, HKEx: 4338) is the worlds largest software company, with 2005 global annual sales of 40 billion US dollars and nearly 60,000 employees in 85 countries and regions. ...
Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ...
File Allocation Table (FAT) is a patented file system (patents apply to technology supporting Long File Names within the file system, but not the core file system itself) that was developed by Microsoft for MS-DOS and is the primary file system for consumer versions of Microsoft Windows up to...
Wear levelling (also written -levelling) is a technique for prolonging the service life of some kinds of eraseable computer storage media, e. ...
JFFS was the first flash file system for Linux, but it was quickly superseded by JFFS2, originally developed for NOR flash. Then YAFFS was released in 2003, dealing specifically with NAND flash, and JFFS2 was updated to support NAND flash too. However, in practice most flash media is used with the old FAT filesystem for compatibility purposes. The Journaled Flash File System (or JFFS) is a log-structured file system for use on NOR flash memory devices. ...
...
This article needs to be cleaned up to conform to a higher standard of quality. ...
File Allocation Table (FAT) is a patented file system (patents apply to technology supporting Long File Names within the file system, but not the core file system itself) that was developed by Microsoft for MS-DOS and is the primary file system for consumer versions of Microsoft Windows up to...
A special issue is flash memory booting. An Internet payphone loading Windows XP In computing, booting is a bootstrapping process that starts operating systems when the user turns on a computer system. ...
Capacity Common flash memory parts (individual internal components or "chips") range widely in capacity from kilobits to hundreds of megabits each. A kilobit is a unit of information storage, abbreviated kbit or sometimes kb. ...
The megabit is a unit of information storage. ...
Toshiba and SanDisk have developed a NAND flash chip capable of storing 8 gigabits (1 gigabyte) of data using MLC (multi-level cell) technology, capable of storing 2 bits of data per cell. Toshiba Corporation (æ±èŠ, TÅshiba) (TYO: 6502) is a Japanese high technology electrical and electronics manufacturing firm, headquartered in Tokyo, Japan. ...
...
A gigabit is a unit of information or computer storage, abbreviated Gbit or sometimes Gb. ...
A gigabyte (derived from the SI prefix giga-) is a unit of information or computer storage equal to one billion bytes. ...
In September 2005, Samsung Electronics, by far the world's largest manufacturer of NAND flash with ~40% of bit market share, announced that it had developed the world’s first 16 gigabit NAND flash memory chip. A gigabit is a unit of information or computer storage, abbreviated Gbit or sometimes Gb. ...
With the introduction of Samsung's 16 gigabit chips came the iPod nano, a flash device available in 2 GB and 4 GB capacities, which use two 1 gigabyte Toshiba chips and one 4 gigabyte Samsung chips respectively, according to the autopsies done by Ars Technica, Systm and Inpress Direct. The iPod nano is Apples fourth digital audio player, combining features of the iPod shuffle and iPod. ...
A gigabyte (derived from the SI prefix giga-) is a unit of information or computer storage equal to one billion bytes. ...
A gigabyte (derived from the SI prefix giga-) is a unit of information or computer storage equal to one billion bytes. ...
Up to date NAND spot pricing is available at dramexchange.
In efforts to focus on increasing capacities, 64 MB and smaller capacity flash memory has been largely discontinued, 128 MB capacity flash memory is being given a large discount to attract entry level buyers (people who do not generally require one, or uses it only once in a long time), 256 MB capacity flash memory is the normal storage space for any people who do not extensively use flash memory, while more and more people are adopting 512 MB or 1 GB flash drives, 2 GB flashdrives are still very expensive for a normal consumer.
External links |
Feeds |
Contact