XD-Picture Card

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The xD-Picture Card is a type of flash memory memory card, used mainly in digital cameras. xD stands for extreme Digital. The cards were introduced into the market in July 2002 and developed by Olympus and Fujifilm. Toshiba Corporation and Samsung Electronics manufacture the cards for Olympus and Fujifilm. Other brands, including Kodak, SanDisk, and Lexar, now sell xD cards.

xD cards are used in Olympus and Fujifilm digital cameras and Olympus digital voice recorders; Fujifilm also made an MP3 player that used the cards. As of 2006, xD cards are available in these capacities: 16 MB, 32 MB, 64 MB, 128 MB, 256 MB, 512 MB, 1 GB, and 2 GB. An xD card is 20 mm × 25 mm × 1.78 mm and weighs 2.8 grams.

Contents 1 Type M and Type H cards 2 Theoretical transfer speeds 3 Comparison with rival formats 3.1 Advantages 3.2 Disadvantages 4 Detail specifications 5 See also

[edit] Type M and Type H cards

The original xD cards were available in 16 MB to 512 MB capacities. The Type M card, released in February 2005 [1], uses Multi Level Cell (MLC) architecture to achieve a theoretical storage capacity of up to 8 GB. As of August 2006, Type M cards are available in sizes from 256 MB to 2 GB. However, the Type M suffers slower read-write speeds than the original cards.

The Type H card, first released in November 2005 [2], offers higher data rates than Type M cards (theoretically as much as 3 times faster). As of 2006, Type H cards are only available in 256MB, 512MB, 1GB, and 2GB capacities (the 2GB type H card was initially only available in Japan, but is now available everywhere). Olympus says that its Type H xD cards support special "picture effects" when used in some Olympus cameras, though these software features are not intrinsically hardware-dependent. This dependence may be seen as a weak form of tying. However type H cards are required in newer models to capture video at high rate (640x480x30).

Due to changes in the cards' storage architecture, newer Type M and H cards may suffer compatibility issues with some older cameras (especially video recording). Compatibility lists are available for Olympus (PDF format) and Fujifilm. The newer cards are also incompatible with some card readers.

Pictures are transferred from the xD card to computer by plugging the camera into the PC (normally with USB) or removing the card and putting it into a card reader. In both these cases, the computer sees the card as a mass storage device with photos on it, although software or firmware can alter this. Card readers may be integrated into the PC or attached by cable. Adapters are available to allow an xD picture card to be plugged into other readers (and in some cases cameras), including PCMCIA, parallel port, CompactFlash and SmartMedia.

[edit] Theoretical transfer speeds

Type	Capacity	Write speed (MB/s)	Read speed (MB/s)
Standard	16 MB, 32 MB	1.3	5
	64 MB, 128 MB, 256 MB, 512 MB	3	5
M	256 MB, 512 MB, 1 GB, 2 GB	2.5	4
H	256 MB, 512 MB, 1 GB, 2 GB	4	5

[edit] Comparison with rival formats

The xD format primarily competes with formats such as Secure Digital card (SD), CompactFlash (CF), and Sony's Memory Stick.

[edit] Advantages

• xD cards are fast in comparison with older formats such as SmartMedia (SM), MultiMediaCard (MMC), and MemoryStick (MS).
• xD cards have a small form-factor in comparison with other formats (although both Micro SD and Memory Stick M2 are smaller).
• xD cards have a low power consumption.
• xD cards are very small, which allows devices to be smaller, especially USB flash drives. Owners of the 1GB or larger H-type xD card will find the Olympus MAUSB-200 USB flash drive to be the only compatible model.

[edit] Disadvantages

• Traditional xD cards have a fairly small theoretical maximum capacity in comparison with other formats, though with the introduction of Type H technology this is less of an issue.
• xD cards are much slower than their main competitor, SecureDigital (SD).
• xD cards are generally more expensive than cards of other formats.
• xD cards are less widely supported than many other formats, both by camera, reader, and accessory manufacturers.
• xD card is a proprietary format only used by Fujifilm and Olympus, much like the Memory Stick card is with Sony. This means that no public documentation or implementation is available. Compare this to the somewhat open SD, or the completely open MultiMediaCard and CompactFlash standards.
• xD cards could be lost or broken due to their small size (as with all smaller memory cards).^{[citation needed]}

[edit] Detail specifications

While the detailed specification for xD cards (needed to implement their use) is tightly controlled by Olympus and Fujifilm, it is known that xD cards (like SmartMedia cards) consist of a controller-less NAND flash memory chip embedded in plastic. Thus, xD cards (and SmartMedia cards) can be used by hobbyists as a common source of NAND flash memory chips for custom projects. For example, the Mattel Juice Box PMP can be booted into Linux using a modified cartridge containing an xD card with the boot image written to it.

Because of their higher cost and limited usage in products other than digital cameras as of 2005, xD has been losing ground to SD, which is broadly used by PDAs, digital audio players, and most other digital camera manufacturers.

Olympus branded xD cards are the only ones to support Olympus' panoramic function. Although they store data identically, this is an attempt by Olympus to sell more cards. A limited number of Olympus and Fujifilm cameras such as the Olympus E-500 and Fujifilm S9500 can use other formats such as CompactFlash in addition to xD.

[edit] See also

• Comparison of memory cards

v • d • e Memory cards
CompactFlash (CF) | JEIDA | Memory Stick | MultiMediaCard (MMC) | PC card | SmartMedia | Secure Digital (SD) | xD-Picture Comparison of memory cards