A memory card (sometimes called a flash memory card or a storage card) is a small storage medium used to store data such as text, pictures, audio, and video, for use on small, portable or remote computing devices. Most of the current products use flash memory, although other technologies are being developed. There are a number of memory cards on the market, including the SD card (secure digital card), the CF card (CompactFlash card), the SmartMedia card, the Memory Stick, and the MultiMediaCard (MMC). These cards are of varying sizes, and each is available in a range of storage capacities that typically corresponds directly to the price. The CompactFlash card is about the size of a matchbook, while the MultiMediaCard and Secure Digital card are each about the size of a postage stamp. The latter two are expected to reach storage capacities up to 1 gigabyte (GB) by the end of 2002.
Most available cards have constantly powered nonvolatile memory, which means that data is stable on the card, is not threatened by a loss of power source, and does not need to be periodically refreshed. Because memory cards are solid state media, they have no moving parts, and therefore, are unlikely to suffer mechanical difficulties. Earlier removable storage media, such as the PC card, the smart card, and similar cards used for game systems, can also be considered to be memory cards. However, the newer cards are smaller, require less power, have higher storage capacity, and are portable among a greater number of devices. Because of these features, memory cards are influencing the production of an increasing number of small, lightweight and low-power devices.
Memory cards offer a number of advantages over the hard disk drive: they're much smaller and lighter, extremely portable, completely silent, allow more immediate access, and are less prone to mechanical damage. In comparison, however, the hard disk still offers a compelling advantage: currently, a memory card (for example, CompactFlash) with a 192MB capacity typically costs more than a hard drive with a capacity of 4OGB.