What is the difference between NAND and NOR Flash?
by Toshiba -- 3/28/2006 9:19:00 PM
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What is the difference between NAND and NOR Flash?
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Though they are both considered leading non-volatile
Flash memory technologies, NAND and NOR Flash meet completely different design
needs based on their individual attributes. NOR offers faster read speed and
random access capabilities, making it suitable for code storage in devices
such as PDAs and cell phones. However, with NOR technology, write and
erase functions are slow compared to NAND. NOR also has a larger memory
cell size than NAND, limiting scaling capabilities and therefore achievable
bit density compared to NAND. Since code storage tends to require lower
density memory than file storage, NOR’s larger cell size is not considered
a concern when used in these applications.
Conversely, NAND offers fast write/erase capability and is slower than NOR in the area of read speed. NAND is, however, more than sufficient for a majority of consumer applications such as digital video, music or data storage. NAND’s fast write/erase speed combined with its higher available densities and a lower cost-per-bit than NOR make it the favored technology for file storage in a host of consumer applications. Offering users the ability to rewrite data quickly and repeatedly, NAND is typically used for storing large quantities of information in devices such as Flash drives, MP3 players, multi-function cell phones, digital cameras and USB drives. The following diagram compares typical NOR and NAND read, program and erase speeds:
1. For purposes of measuring
data transfer rate in this context, megabits per second MB/s and/or MBps =
1,000,000 bytes per second.
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