XD-Picture Card

The xD-Picture Card is a type of flash memory memory card, for use mainly in digital cameras. xD stands for extreme Digital.

History

It was developed by Olympus and Fujifilm, who introduced it to the market in July 2002. Toshiba Corporation and Samsung Electronics manufacture the cards for Olympus and Fujifilm. Other brands, including Kodak, SanDisk, and Lexar, now sell xD cards. The Type M was released in 2005.

Description

xD cards are used in Olympus, and Fujifilm digital cameras, and Olympus digital voice recorders. Currently they are available in these capacities: 16 MB, 32 MB, 64 MB, 128 MB, 256 MB, 512 MB and 1GB (Type M). An xD card is 20 mm × 25 mm × 1.78 mm and weighs 2.8 grams. The 16 MB and 32 MB models write at 1.3 MB/s and read at 5 MB/s. The 64 MB, 128 MB, 256 MB and 512 MB models write at 3 MB/s and read at 5 MB/s. The 1 GB (Type M) model writes at 2.5 MB/s and reads at 4.0 MB/s.

Type M and Type H cards

The Type M uses Multi Level Cell (MLC) architecture to achieve higher storage capacity than the 512MB. Although Type M capacity will eventually stretch to 8GB, the 1GB card is currently the only card in this range. The Type M suffers some compatibility issues with older cameras (especially video recording) and marginally slower readwrite speeds than the 512MB card. The newer Type H cards claim to offer speed increases over Type M cards, as well as include special "picture effects", although most of these are only available in use with Olympus digital cameras.

Picture transfer

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 Smart Media.

Comparison with rival formats

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

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.
xD cards have a low power consumption.

Disadvantages

xD cards have a fairly small theoretical maximum capacity in comparison with other formats.
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 cards are so small that they can be harder to handle for some people, and risk being misplaced more easily than larger format cards
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 CompactFlash standard.

Copy warnings

Never format, copy files to, or erase pictures from, an xD card via a card reader/writer connected to a computer, only do so via the camera. xD-Picture cards are specially formatted with certain proprietary tags and flags. Formatting or otherwise altering the contents of the card via a card reader/writer connected to a computer will render the card unusable in a camera or erase the special Olympus signature to enable panoramic mode. Not true for SanDisk card readers as SanDisk manufactures the xD cards of both Olympus and Fujifilm.

Fujifilm does not do this.

Detail specifications

While the detail 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 limited usage in products category other than digital camera 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. As of 2005, some cameras such as the Olympus E-500 and Fujifilm S9500 use CF in addition to xD, though support is tapering.

External links

Solid-state computer storage media

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