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The difference between EPROM and EEPROM lies in the way that the memory programs and erases. EEPROM can be programmed and erased electrically using field electron emission (more commonly known in the industry as "Fowler–Nordheim tunneling"). EPROMs can't be erased electrically and are programmed by hot-carrier injection onto the floating gate.
EPROM programming is slow compared to other forms of memory. Because higher-density parts have little exposed oxide between the layers of interconnects and gate, ultraviolet erasing becomes less practical for very large memories. Even dust inside the package can prevent some cells from being erased. [13]
EEPROM (Electrically erasable programmable read-only memory) – In this type the data can be rewritten electrically, while the chip is on the circuit board, but the writing process is slow. This type is used to hold firmware , the low level microcode which runs hardware devices, such as the BIOS program in most computers, so that it can be ...
Modern EEPROM based on Fowler-Nordheim tunnelling to erase data was invented by Bernward and patented by Siemens in 1974. [22] And further developed between 1976 and 1978 by Eliyahou Harari at Hughes Aircraft Company and George Perlegos and others at Intel. [23] [24] This led to Masuoka's invention of flash memory at Toshiba in 1980.
Other examples of non-volatile memory include read-only memory (ROM), EPROM (erasable programmable ROM) and EEPROM (electrically erasable programmable ROM), ferroelectric RAM, most types of computer data storage devices (e.g. disk storage, hard disk drives, optical discs, floppy disks, and magnetic tape), and early computer storage methods such ...
A computer's firmware may be manually updated by a user via a small utility program. In contrast, firmware in mass storage devices (hard-disk drives, optical disc drives, flash memory storage e.g. solid state drive) is less frequently updated, even when flash memory (rather than ROM, EEPROM) storage is used for the firmware.
The bit cell is programmed by applying a high-voltage pulse not encountered during a normal operation across the gate and substrate of the thin oxide transistor (around 6 V for a 2 nm thick oxide, or 30 MV/cm) to break down the oxide between gate and substrate. The positive voltage on the transistor's gate forms an inversion channel in the ...
Non-volatile random-access memory (NVRAM) is random-access memory that retains data without applied power. This is in contrast to dynamic random-access memory (DRAM) and static random-access memory (SRAM), which both maintain data only for as long as power is applied, or forms of sequential-access memory such as magnetic tape, which cannot be randomly accessed but which retains data ...