Multi Media Card

The Multi Media Card (MMC) is a flash memory memory card standard. 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. They have been more or less superceded by Secure Digital cards, but still see significant use because MMC cards can be used in any device which supports SD cards.

Typically, an MMC card is used as storage media for a portable device, in a form that can easily be removed for access by a PC. For example, a digital camera would use an MMC card for storing image files. With an MMC reader (typically a small box that connects via USB or some other serial connection), a user could copy the pictures taken with the digital camera off to his or her computer. Modern computers, both laptops and desktops, often have SD slots, which can read MMC cards.

MMC cards are currently available in sizes up to and including 1 GB, and are used in almost every context in which memory cards are used, like cell phones, mp3 players, digital cameras, and PDAs. Since the introduction of Secure Digital few companies build MMC slots into their devices, but the slightly-thinner, pin-compatible MMC cards can be used in any device that supports SD cards. A handful of companies, most notably Nokia, still support MMC exclusively, however.

Reduced-Size Multi-Media Card (RS-MMC)

MMC cards also come in a smaller form factor, of about half the size: 24mm x 16mm x 1.5mm. This alternate form factor is known as Reduced-Size Multi-Media Card, or RS-MMC, and was introduced in 2004. RS-MMC cards are simply smaller MMC cards; by using a simple mechanical adapter to elongate the card, an RS-MMC card can be used in any MMC (or SD) slot.

The only significant hardware licensor of RS-MMC cards is Nokia, who often uses RS-MMC in their Series 60 Symbian smartphones. Newer RS-MMC cards, used in Nokia's newer phones (like the Nokia 6630 and Nokia 6680), support a lower voltage (1.8 V instead of 3 V) mode to reduce battery demand, and these lower-voltage RS-MMC cards, officially known as Dual Voltage Reduced Size MMC, are occasionally marketed as MMCmobile. These low-voltage cards are backwards compatible with older RS-MMC devices.

See also

Compact Flash, Memory Stick, Secure Digital Card, SmartMedia, XD-Picture Card

External links

• Multi Media Card Association