Compact Flash Memory and Data Recovery

Both NOR and NAND Flash memory was invented by Dr. Fujio Masuoka of Toshiba in 1984.The name ‘Flash’ was suggested because the process of erasing the memory content is like a flash of a camera, and its name was coined to express how much faster could be erased in an instant. ” Dr. Masuoka presented the invention at the International Electron Devices Meeting (IEDM) held in San Jose, California in 1984 and Intel recognizes the potentiality of the invention and introduced the first commercial or flash chip in 1988, with long writing and erasing.

Flash memory is a form of nonvolatile memory that can be electrically erased and rewrite, which means it does not need energy to keep the data stored on the chip. Additionally, flash memory offers fast read access times and better shock resistance of the hard disks. These characteristics explain the popularity of flash memory for applications such as storing battery-powered devices.

The flash memory is advancing EEPROM (electrically erasable programmable read-only memory) that allows multiple memory locations to be erased or written in one programming operation. Unlike an EPROM (electrically programmable read-only memory) an EEPROM can be programmed and erased multiple times electrically. Normal EEPROM only allows one location at a time to be erased or written, meaning that flash can operate at high speeds when the effective use of systems, but that reads and writes in several places at once.

Regarding the type of logic gate used in each storage cell, Flash memory is based on two varieties, named, or flash and NAND flash. Flash memory stores one bit of information in a matrix of transistors, called “cells”, however recent flash memory devices referred to as multi-level cell devices, can store more than 1 bit per cell depending on the amount of electrons Floating in the cell door. NOR flash cell is similar to the semiconductor device such as transistors, but has two doors.

First is the control gate (CG) and the second is a floating gate (FG) as a shield or insulation around an oxide layer. Because the FG was withdrawn by its shield oxide layer, electrons are being trapped and the data is stored inside. Moreover NAND Flash uses tunnel injection for writing and tunnel release for erasing.

NOR flash that was developed by Intel in 1988 with the unique feature of write and erase over time and their resistance to erase cycles ranges from 10,000 to 100,000 makes it suitable for storage of program code that needs to be updated infrequently, as in digital cameras and PDAs. However, later moved to the demand for the cards cheaper NAND flash, NOR-based flash is hitherto the source of all removable media.

Followed in 1989 by Samsung and Toshiba form NAND flash with higher density, lower cost per bit then NOR Flash with faster erase and write times, but only allows access to the data sequence, not random like NOR Flash, which makes NAND Flash suitable for mass storage device such as memory cards. SmartMedia NAND was based on removable media and are behind many others like MMC, Secure Digital, xD-Picture Cards and Memory Stick. Flash memory is often used to maintain control code base, such as input / output system (BIOS) on a computer. When the BIOS has to be changed (again), flash memory can be written in the block rather than byte sizes, making it easy to upgrade.

On the other hand, flash memory is not practical to random access memory (RAM) of RAM to be addressable at the byte (not the block) level. Therefore, it is used more as a hard drive as a RAM. Because of this uniqueness, which is specifically designed file systems which extend writes over the media and address the long time to erase or flash blocks. JFFS was the first file systems obsolete by JFFS2. YAFFS was later released in 2003, dealing specifically with NAND flash, and JFFS2 was updated to support NAND flash too. However, in practice most follows old FAT file system for compatibility purposes.

Although you can read or write one byte at a time in a random access, the limitation of flash memory is erased to be a “block” at a time. From a freshly erased block, any byte within that block can be programmed. However, once a byte has been programmed, can not 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 can not offer random-access rewrite or erase operations.

This effect is partly offset by some chip firmware or file system drivers by counting the writes and dynamically remapping the blocks in order to spread write operations between sectors, or by writing to the verification and reallocation of spare sectors in case of writing.

Due to the wear of the insulating oxide layer around the charge storage mechanism, all types of flash memory erode after a certain number of functions that will erase 100,000 to 1000000, but you can read an unlimited number of times. Flash Card is easily rewritable memory and overwrites without warning with a high probability of data overwritten and therefore lost.

Despite all these clear advantages, worse may occur due to system failure, battery failure, accidental erasure, re-format, electrical, electronics defective and corruption caused by failure of hardware or software malfunction, so their data could be lost and damaged.

Flash Memory Data Recovery is the process of restoring data from primary storage media when it can not be accessed normally. Flash memory data recovery is a flash memory file recovery service that restores all corrupted and deleted photographs even if a memory card is reformatted. This may be due to physical or logical damage to storage. Details of damage, including the flash memory can be recovered, and over 90% of data loss can be restored.