MultiMediaCard
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The MultiMediaCard (MMC) is a flash memory memory card standard. Unveiled in 1997 by Siemens AG and SanDisk, 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 CompactFlash. MMC is about the size of a postage stamp: 24 mm x 32 mm x 1.5 mm. 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 They have been more or less superseded by Secure Digital cards, but still see significant use because MMC cards can be used in any device which supports SD cards.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, although some can be found integrated into the computer itself), 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 8 GB, and are used in almost every context in which memory cards are used, like cellular phones, digital audio players, digital cameras and PDAs. Since the introduction of Secure Digital card few companies build MMC slots into their devices, but the slightly thinner, pin-compatible MMC cards can be used in almost any device that supports SD cards. An exception is some mobile devices like the Nokia 9300 communicator, where the smaller size of the MMC card is a benefit.
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[edit] Open standard
This technology is an open standard available to any company who wants to improve upon it or develop products for it.
[edit] Reduced-Size MultiMediaCard (RS-MMC)
MMC cards also come in a smaller form factor, of about half the size: 24 mm × 16 mm × 1.5 mm. This alternate form factor is known as Reduced-Size MultiMediaCard, 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. RS-MMC cards are currently available in sizes up to and including 8GB.
The only significant hardware licensors of RS-MMC cards are Nokia and Siemens, who often use RS-MMC in their Series 60 Symbian smartphones, the Nokia 770 Internet Tablet (Nokia), and generations 65 and 75 (Siemens).
[edit] MMCmobile
Newer RS-MMC cards, used in Nokia's newer phones (like the Nokia 6630 and Nokia 6680 and NokiaN70 ), support a lower voltage (1.8 V instead of 3 V) mode to reduce battery demand, and these lower-voltage RS-MMC cards, known as Dual-Voltage Reduced-Size MMC (DV RS-MMC), and can be marketed as MMCmobile when they meet the MMCmobile card standards. These low-voltage cards are backwards compatible with older RS-MMC devices. The dual voltage cards, and the MMCmobile are part of the MMC 4.x standards.
[edit] MMCmini
MMCmini is a mini-size version of MMC. With dimensions of 20 mm × 21.5 mm × 1.4 mm, it has roughly the same size as RS-MMC. Unlike MMC and RS-MMC, MMCmini has an 11-pin configuration and a maximum storage capacity of 2048 MB. The idea of using MMCmini on the hardware is to also reduce the size of the memory card slot rather than only reduce the size of the memory card itself.
[edit] MMCmicro
MMCmicro is a micro-size version of MMC. With dimensions of 14 mm × 12 mm × 1.1 mm, it is even smaller and thinner than RS-MMC. Like MMCmobile, MMCmicro supports dual voltage, is backward compatible with MMC, and can be used in full-size MMC and SD slots with a mechanical adapter.
[edit] MMC 4.x and SecureMMC
Standard 4.x (4.0, 4.1, etc.) was released in 2005 (MMCA System Specification 4.1). This new standard involves the higher performance MMC4 (with the same basic MMC form factor but more pins) called MMCplus, and RS-MMC4, marketed as MMCmobile. MMC/RS-MMC cards are generic names normally used for previous generation cards. Also in the works is SecureMMC, which will feature encryption features similar to Secure Digital or MagicGate Memory Sticks.
[edit] See also
[edit] External links
- MultiMediaCard Association
- Sandisk OEM Manual for MMC and RS-MMC (PDF)
- KingMax MMC technical document (PDF)
- MMC Wiki
- MMC pinout (tech.)
- Samsung Introduces High-Performance MMC Cards
| Memory cards |
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| CompactFlash (CF) | JEIDA | Memory Stick | MultiMediaCard (MMC) | PC card | SmartMedia | Secure Digital (SD) | xD-Picture |
| Comparison of memory cards |
