 Multi Media Card A Multi Media Card (MMC) is a solid state disk or flash memory data storage device. It is based on Toshiba's NAND-based flash memory, and is therefore much smaller than earlier systems based on Intel NOR-based memory such as Compact Flash. MMC is about the size of a postage stamp: 24mm x 32mm x 1.5mm. MMC originally used a 1-bit serial interface, but newer versions of the specification allow transfers of 4 or sometimes even 8 bits at a time.
MMC is a popular storage medium for very small electronic devices, like mobile phones, PDAs and digital audio players (MP3 players). It comes in 16MB, 32MB, 64MB, 128MB, 256MB, 512MB, and 1GB sizes as of 2004. In addition, a 2GB card has been announced.
Most of the Nokia smartphones in 2004 use a smaller version of MMC cards called Reduced Size MMC, or RS-MMC. They are half the height of a normal MMC card: 24mm x 16mm x 1.5mm. RS-MMC cards can be used in a MMC slot or a card reader with an adapter (which merely elongates the card so that it can be removed from the MMC slot - the MMC connector itself stays the same).
Another development in MMC cards is the Dual Voltage Reduced Size MMC or DV-RS-MMC, used by the Nokia 6630. It supports operating at both 1.8 V and 3.0 V, the latter being the traditional MMC card voltage. The lowered voltage allows for longer battery life in the electronic device. Likewise, a DV-RS-MMC card can be used in an MMC slot with an adapter.
Toshiba has responded to complaints from copyright holders by including additional hardware to perform on-system encryption, thus making it impossible to directly copy songs from one MMC to another. The resulting system, Secure Digital Card, has since emerged as a competitor to the MMC.
See also
Compact Flash, Memory Stick, Secure Digital, SmartMedia, XD-Picture Card
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