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Flash Memory is digital electronic memory that is non-volatile - that is it keeps its contents without the need for power - and can be written to and read from many times. This means that digital photos can be stored in flash memory, and will not be lost when the camera has no battery - and the photos can be deleted and the memory space reused for further photos. For this use it is sometimes called digital film, although unlike film, it can be re-used - and many cameras go through their lives without changing the flash memory.
Flash memory is used as the storage medium in most digital cameras - but is also used for may other purposes, such as MP3 players, mobile phone internal and SIM-card storage, and firmware on computer motherboards or embedded devices such as set-top boxes. Many small laptop and palmtop computers rely on flash memory in place of hard disk drives.
Some lower-end flash-equipped cameras have their memory built-in and fixed, whilst most have removable "cards", allowing the photographer to simply change the card when the memory is full and continue taking pictures.
For photographic use, it is normally formatted and accessed as a disk drive. This makes it simple to move whole flash cards from a camera to a computer - which then needs no extra software to read the card. Cards can be connected via the camera itself, or a card reader. Some computers have built-in card readers, but these are readily-available as USB devices for almost any computer.
There are numerous types of flash memory card, some of them (more-or-less) open standards, and some proprietary - such as
|CompactFlash, SmartMedia, SD and xD cards|
image by AWCam (Image rights)
- PC Card (PCMCIA), type I, type II, type III
- CompactFlash (CF)
- Sony Memory Stick
- MultiMediaCard (MMC)
- SD (Secure Digital), up to 2gb
- SDHC (Secure Digital, High Capacity), up to 32gb
- SDXC (Secure Digital, eXtended Capacity), up to 2 terabytes
- Mini SD
- xD-Picture card, up to 2gb