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Flash memory is a non-volatile memory chip used for storage and for transfering data between a personal computer (PC) and digital devices. It has the ability to be electronically reprogrammed and erased. It is often found in USB flash drives, MP3 players, digital cameras and solid-state drives.
Flash memory is a type of electronically erasable programmable read only memory (EEPROM), but may also be a standalone memory storage device such as a USB drive. EEPROM is a type of data memory device using an electronic device to erase or write digital data. Flash memory is a distinct type of EEPROM, which is programmed and erased in large blocks.
Flash memory incorporates the use of floating-gate transistors to store data. Floating-gate transistors, or floating gate MOSFET (FGMOS), is similar to MOSFET, which is a transistor used for amplifying or switching electronic signals. Floating-gate transistors are electrically isolated and use a floating node in direct current (DC). Flash memory is similar to the standard MOFSET, except the transistor has two gates instead of one.
Flash memory was first introduced in 1980 and developed by Dr. Fujio Masuoka, an inventor and mid level factory manager at Toshiba Corporation (TOSBF). Flash memory was named after its capability to erase a block of data “"in a flash.” Dr. Masuoka’s objective was to create a memory chip preserving data when the power was turned off. Dr. Masuoka also invented a type of memory known as SAMOS and developed a 1Mb dynamic random access memory (DRAM). In 1988, Intel Corporation produced the first commercial NOR-type flash chip, which replaced the permanent read-only memory (ROM) chip on PC motherboards containing the basic input/output operating system (BIOS).
A flash memory chip is composed of NOR or NAND gates. NOR is a type of memory cell created by Intel in 1988. The NOR gate interface supports full addresses, data buses and random access to any memory location. The shelf life of NOR flash is 10,000 to 1,000,000 write/erase cycles.
NAND was developed by Toshiba a year after NOR was produced. It is faster, has a lower cost per bit, requires less chip area per cell and has added resilience. The shelf life of a NAND gate is approximately 100,000 write/erase cycles. In NOR gate flash every cell has an end connected to a bit line and the other end connected to a ground. If a word line is “high” then the transistor proceeds to lower the output bit line.
Flash memory has many features. It is a lot less expensive than EEPROM and does not require batteries for solid-state storage such as static RAM (SRAM). It is non-volatile, has a very fast access time and has a higher resistance to kinetic shock compared to a hard disc drive. Flash memory is extremely durable and can withstand intense pressure or extreme temperatures. It can be used for a wide array of applications such as digital cameras, mobile phones, laptop computers, PDAs (personal digital assistants), digital audio players and solid-state drives (SSDs).