Compact Flash Memory and Data Recovery

 Compact Flash Memory and Data Recovery

Flash memory gets its name owing to its microchip organization in such a way that its portion of memory cells is wiped in a single action, or “Flash”.

Both NOR and NAND flash memory were designed by Dr. Fujio Masuoka from Toshiba in 1984. The term 'Flash' was suggested because the erasing process of the memory contents resembles the flash of a camera, and its name was created to represent how much quicker it could be wiped "in a flash". Dr. Masuoka presented the concept at the International Electron Devices Meeting (IEDM) held in San Jose, California, in 1984, and Intel realized the potentiality of the innovation and created the first commercial NOR-type flash chip in 1988, with extended erase and write times.

 

Flash memory is a sort of non-volatile memory that can be electrically wiped and rewritten, which implies that it does not need electricity to keep the data contained in the chip. In addition, flash memory offers rapid read access times and superior stress tolerance compared to hard drives. These properties explain the appeal of flash memory for applications such as storage on battery-powered devices.

 

Flash memory is an advanced kind of EEPROM (Electrically Erasable Programmable Read-Only Memory) that allows numerous memory areas to be wiped or written in one programming process. Unlike an EPROM (Electrically Programmable Read-Only Memory), an EEPROM may be programmed and wiped several times electrically. Normal EEPROM only permits one spot at a time to be erased or written, meaning that flash can work at greater effective rates when the system employs it; it reads and writes to various locations at the same time.

 

Referring to the sort of logic gate utilized in each storage cell, flash memory is manufactured in two types, termed NOR flash and NAND flash.

Flash memory holds one bit of information in an array of transistors, termed "cells", although modern flash memory technologies, dubbed multi-level cell devices, may store more than 1 bit per cell depending on the number of electrons deposited on the floating gate of a cell. The NOR flash cell appears similar to semiconductor devices like 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 covered or insulated all around by an oxide layer. Because the FG is isolated by its shield oxide layer, electrons deposited on it get caught, and data is kept therein. On the other side, NAND Flash employs tunnel injection for writing and tunnel release for erasing.

 

NOR flash, which was invented by Intel in 1988, has the unique property of long erase and write times and a durability of erase cycles ranging from 10,000 to 100,000, making it excellent for storing program code that has to be seldom updated, like in digital cameras and PDAs. Though later card demand migrated towards the cheaper NAND flash, NOR-based flash is hitherto the source of all portable media.

 

In 1989, Samsung and Toshiba created NAND flash with better density, a cheaper cost per bit than NOR flash, and quicker erase and write times, but it only enables sequence data access, not random access like NOR flash, which makes NAND flash appropriate for mass storage devices such as memory cards. SmartMedia was the first NAND-based removable media, and countless others are behind, like MMC, Secure Digital, xD-Picture Cards, and Memory Stick. Flash memory is widely used to retain control code, such as the basic input/output system (BIOS) in a computer. When BIOS has to be altered (rewritten), the flash memory may be written to in blocks rather than byte sizes, making it easier to update.

On the other hand, flash memory is not feasible for random access memory (RAM), as RAM has to be accessible at the byte (not the block) level. Thus, it is employed more as a hard drive than as RAM. Because of its special distinctiveness, it is employed with specifically designed file systems that prolong writes throughout the medium and deal with the extended erase durations of NOR flash blocks. JFFS was the first file system, superseded by JFFS2. Then YAFFS was launched in 2003, dealing exclusively with NAND storage, and JFFS2 was modified to include NAND flash too. Still, in reality, most use outdated FAT file systems for compatibility considerations.

 

Although it may be read or written a byte at a time in a random access method, the restriction of flash memory is that it must be erased one "block" at a time. Starting with a newly erased block, any byte inside that block can be programmed. However, once a byte has been programmed, it cannot be modified again until the entire block is wiped. In other words, flash memory (particularly NOR flash) supports random-access read and programming operations but cannot give random-access rewrite or erase operations.

 

This impact is somewhat countered by certain chip firmware or file system drivers by counting the writes and dynamically remapping the blocks in order to distribute the write operations throughout the sectors, or by write verification 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 forms of flash memory dissolve after a specific number of erase functions ranging from 100,000 to 1,000,000, yet they can be read an indefinite number of times. A flash card is readily rewritable memory and overwrites without notice, with a high possibility of data being erased and consequently lost.

 

In spite of all these evident advantages, worse may occur due to system failure, battery failure, unintentional erasure, re-format, power surges, defective electronics, and corruption caused by hardware breakdowns or software faults; as a consequence, your data might be lost and harmed.

 

Flash memory data recovery is the process of recovering data from a primary storage medium when it cannot be accessed normally. Flash memory data recovery is a flash memory file recovery solution that restores all damaged and lost images, even if a memory card was re-formatted. This might be due to physical damage or logical harm to the storage device. Data even from damaged flash memory may be retrieved, and more than 90% of lost data can be restored.