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The MultiMediaCard (MMC) is a memory card standard used for solid-state storage. Unveiled in 1997 by SanDisk and Siemens AG, 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 × 32 mm × 1.4 mm. MMC originally used a 1-bit serial interface, but newer versions of the specification allow transfers of 4 or 8 bits at a time. MMC can be used in most devices that can use SD cards. Typically, an MMC is used as a storage medium 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 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 additionally read MMCs if the operating system drivers can. MMCs are available in sizes up to and including 128 GB. They 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 (SD) cards, few companies build MMC slots into their devices (an exception is some mobile devices like the Nokia 9300 communicator in 2004, 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 can use SD cards if the software/firmware on the device is capable. While few companies build MMC slots into devices today (SD cards are more common), the embedded card (eMMC) is still widely used in the industry as a primary means of integrated storage in portable devices. It provides a low-cost flash memory system with a built-in controller that can reside inside an Android or Windows phone or low-cost PC and appear to its host as a bootable device, in lieu of a more expensive form of solid-state storage, like the traditional solid-state drive. While drives are generally better than cards, they cost more and take up more space. ==Open standard== This 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 with MMCA, can be downloaded free-of-charge. Older versions of the standard, as well as some optional enhancements to the standard such as MiCard and SecureMMC, must be purchased separately. A highly detailed version is available on-line that contains essential information for writing an MMC driver. As of 23 September 2008, the MMCA group has (turned over ) all specifications to the (JEDEC organization ) including embedded MMC (e-MMC) and miCARD assets. JEDEC is an organization devoted to standards for the solid-state industry. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「MultiMediaCard」の詳細全文を読む スポンサード リンク
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