What is the Difference Between MMC & SD Cards
The Multimedia Card (MMC) and Security Digital (SD) Card are two very similar, very popular flash memory devices. The MMC debuted in 1997 through a joint venture by Siemens AG and SanDisk, and quickly became the standard for memory card technology. SD cards debuted in 2006 through a joint venture by SanDisk, Panasonic and Toshiba, and was an improvement of the original MMC. Though the improvement in technology makes a tremendous difference between the two cards, the MMC and SD card feature the same small and durable design, and can thus be used interchangeably in memory card-supporting devices.
History
The MMC was the industry standard for portable flash memory cards. The SD card superseded the MMC, offering greater storage capacity and higher data transfer speeds in the same postage stamp-sized form.
Capacity
The MMC is available in capacities of 128, 256 and 512 MB. The SD cards are currently (2009) available in 1 and 2 GB, with 4 and 8 GB models in development.
Transfer Speed
The MMC has a slow data transfer speed of 2.5 MB per second, while the SD card features speeds up to 22 MB per second.
Considerations
While SD card transfer speeds make the product more attractive than MMCs, a higher-performance MMCPlus debuted in 2005. It featured the highest transfer speed available in the memory card industry: 52 MB per second.
Physical Features
Both the MMC and the SD card have the same compact and durable physical design. However, the SD card has a sliding security tab on the left edge of the card, and nine, rather than seven, electrical connectors for power reception and data transfer.
Security
The SD card improved on the MMC by incorporating an optional security feature: a small sliding tab, positioned in the left-hand corner, that permits the user to trigger write-protection of data stored on the card.
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