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Compact Flash Memory and Data Recovery
Flash memory acquires its name due to its microchip arrangement in such a way, that its section of memory cells gets removed in a single action or "Flash".
Dr. Fujio Masuoka from Toshiba invented both NAND and NOR Flash memory in 1984. The name 'Flash' was recommended because the erasure procedure of the memory contents reminds a flash of a camera, and its name was created to prompt how much faster it could be deleted "in a flash". Dr. Masuoka presented the invention at the International Electron Devices Meeting (IEDM) held in San Jose, California in 1984 and Intel identifies the potentiality of the invention and announced the first marketable NOR type flash chip in 1988, with long erase and write times.
Flash memory is a form of non-volatile memory that can be electrically rewritten and erased, which means that it does not need power to keep the data stored in the chip. In addition, flash memory offers better shock resistance and fast read access times than hard disks. These features explain the reputation of flash memory for applications such as storage on battery-powered devices.
Flash memory is advanced from EEPROM (Electrically-Erasable Programmable Read-Only Memory) which permits multiple memory locations to be erased or written in one programming procedure. Different from an EPROM (Electrically Programmable Read-Only Memory) an EEPROM can be set and erased several times electrically. Normal EEPROM only permits one location at a time to be erased or written, meaning that flash can function at higher effective speeds when the systems using; it can read and write to different locations at the same time.
Referring to the type of logic gate used in each storage cell, Flash memory is constructed in two variations and named, NOR flash and NAND flash.
Flash memory stores one bit of data in an array of transistors, called "cells", though recent flash memory devices referred to as multi-level cell devices, can pile more than one bit per cell depending on the number of electrons located on the Floating Gate of a cell. NOR flash cell is like a semiconductor device (transistors), but it has two gates. The first one is the control gate (CG) and the second one is a floating gate (FG) that is protected or insulated all around by an oxide layer. Because the FG is separated by its shield oxide layer, electrons placed on it get locked in, and data is stored within. On the other hand, NAND Flash uses tunnel release for erasing and tunnel injection for writing.
NOR flash which was technologically advanced by Intel in 1988 with the exclusive feature of long erase and write times and its strength of erase cycles ranging from 10,000 to 100,000 makes it suitable for storage of program code that requires to be occasionally updated, like in digital cameras and PDAs. However, later cards mandate moved towards the cheaper NAND flash; NOR-based flash is previously the source of all the removable media.
Followed in 1989 Toshiba and Samsung form NAND flash with higher density, a lower cost per bit than NOR Flash with faster erase and write times, but it only allows sequence data access, not random like NOR Flash, which makes NAND Flash appropriate for mass storage device such as memory cards. SmartMedia was the first NAND-based removable media and many others are behind like Secure Digital, xD-Picture Cards, Memory Stick and MMC. Flash memory is often used to hold control code such as the simple input/output system (BIOS) in a computer. When BIOS needs to be altered (rewritten), the flash memory can be transcribed to in block rather than byte sizes, making it simple to update.
On the other hand, flash memory is not useful to random access memory (RAM) as RAM needs to be addressable at the byte (not the block) level. Therefore, it is used more as a hard drive than as RAM. Because of this particular exceptionality, it is used with specifically-designed file systems which extend writes over the media and deal with the long erase times of NOR flash blocks. The JFFS was the first file system, outdated by the JFFS2. Then YAFFS was released in 2003, dealing precisely with NAND flash, and JFFS2 was updated to support NAND flash too. Still, in run through most follows the old FAT file system for compatibility resolutions.
Even if it can be read or written a byte at a time in a random access fashion, the limitation of flash memory is, it must be removed a "block" at a time. Beginning with a newly erased block, any byte within that block can be programmed. But, once a byte has been programmed, it cannot be changed once more until the entire block is deleted. In other words, flash memory (specifically NOR flash) deals with random-access read and programming procedures, but cannot offer random-access rewrite or erase operations.
This effect is partly offset by some chip firmware or file system drivers by including the writes and dynamically remapping the blocks in order to extend the write procedures between the sectors, or by writing authentication and remapping to spare sectors in case of write failure.
Due to wear and tear on the insulating oxide layer around the charge storage mechanism, all types of flash memory wear down after a certain amount of erase functions ranging from 100,000 to 1,000,000, but it can be read an unlimited amount of times. Flash Card is effortlessly rewritable memory and overwrites without warning with a high possibility of data being overwritten and hence lost.
In spite of all these clear advantages, worse may happen due to system battery failure, failure, re-format, power surges, faulty electronics, accidental erasure, and corruption caused by hardware failure or software breakdowns; as a result, your data could be damaged or lost.
Flash Memory Data Recovery is a way of repairing data from the main storage media when it cannot be opened normally. Flash memory data recovery is a flash memory file recovery service that repairs all corrupted and erased photographs even if a memory card was re-formatted. This can be due to logical damage or physical damage to the storage device. Data even from damaged flash memory can be restored, and more than 90% of lost data can be recovered.