Category:Flash memory

Flash memory is solid-state non-volatile computer memory, which can be read and written and keeps its values even with power off. Common uses include Solid-State Drive, thumb drives, and many other devices which uses it for storage. A type of "managed Flash memory" is Secure Digital (SD).

The two main types are NAND and NOR, named after the logic gates they resemble. NAND memory is written or read in blocks, so it is suitable for substituting for disk drives (which read and write in sectors). NOR memory can read or write single bytes, so it can substitute for RAM.

Before flash memory, non-volatile memory consisted of either Eraseable Programmable Read Only Memory (EPROM) which could only be reprogrammed via exposing the transparent window to ultra-violet light, or Electronically Eraseable Programmable Read Only Memory (EEPROM) which could be rewritten in small blocks or single bytes, but were slow. Once data is written, these behaves like Read Only Memory(ROM)

Links

• Wikipedia article
• NAND flash applications design guide (Toshiba)]
• Compact Flash interface card for Apple I
• Compact Flash interface card for Apple II