The Multi Media Card (known as MMC for short) is a flash memory card which was release in 1997 by Siemens AG and SanDisk, based on Toshiba's NAND-based flash memory which made it smaller than earlier systems based on Intel’s NOR-based memory such as Compact Flash at the time.
MMC is measures 24 mm x 32 mm x 1.4 mm and 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 They have been more or less superseded by Secure Digital cards (SD card), but still see significant use because MMCs can be used in most devices that support SD cards.
In 2005 MMCplus was introduced to address the slow transfer speeds of MMC, improving data transfer speeds to 52 MB per second. This is over 346x speed, one of the fastest transfer speeds available. 300x speed compact flash cards were the second fastest for a long time, but 600x speed compact flash cards were release by Transcend in the last half of 2009. Relegating the MMCplus to second place.
MMC cards have seen use in mobile phones, MP3 players, digital cameras and PDAs. Since the introduction of the Secure Digital card few companies build MMC slots into their devices (an exception is some mobile devices like the Nokia 9300 communicator, where the smaller size of the MMC is a benefit), but the slightly thinner, pin-compatible MMCs can be used in almost any device that supports SD cards if the software/firmware on the devices support them.
Since the MMC cards are thinner they can be used in all SD Memory Card slots making them the most compatible memory cards in the market. It is important to note that music stored on MMCplus or standard MMC cards my not be able to be played back when inserted into a SD Memory Card slot due to the copyright protection features supported by the SD slots.
The technology is a standard available to any company wanting to develop products based on it. There is no royalty charged for devices which host an MMC. A membership with the MMC Association must be purchased in order to manufacture the cards themselves.
As of July 2009, the latest specifications version 4.4 (dated March 2009) can be requested from the MMCA, and after registering, downloaded free-of-charge.
It is expected that the MMC card will eventually die out completely due to the popularity of SD cards.