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XD-Picture Card

From Academic Kids

The title of this article is incorrect because of technical limitations. The correct title is xD-Picture Card.
Missing image
XD_Picture_Card_with_penny.jpg
xD-Picture Card compared in size with a US 1 cent coin

The xD-Picture Card is a flash memory memory card format developed and introduced to the market in July 2002 by Olympus and Fujifilm, and manufactured by the Toshiba Corporation. (Kodak, SanDisk, and Lexar now also sell xD cards.) xD cards are in Olympus and Fujifilm digital cameras, and are available in a range of sizes, from 16 MB to 1 GB. xD stands for "extreme digital." In 2005 xD-Picture Card Type M came out.

A higher-performance xD card known as Type M came out in 2005, and uses Multi Level Cell (MLC) architecture. The 1GB Type M card is called the M1GB (M-XD1GM). Type M will availbe in sizes up to 8 GB eventually, though the cards are not compatible with all older models.

PCMCIA and CompactFlash adapters are available for xD-Picture cards, enabling them to be used in readers and cameras which do not have native support for the xD format. Olympus also has models that use CF in addition to xD as of 2005, though support is tapering (formerly, Olympus and Fujifilm primarily used SmartMedia and CF in there cameras). zD primarily competes with formats such as Secure Digital Card (SD), CompactFlash (CF), and Sony Memory Sticks.

Typically, an xD card is used as storage media for a digital camera, in a form that can easily be removed for access by a PC or uploaded off the camera directly. A digital camera would use an xD card for storing image files. With an xD reader (typically a small box that connects via USB or some other serial connection), a user could copy the pictures on the xD-Picture card directly to their computer. Laptops and desktops were slow to have built-in xD slots, though dedicated xD-Picture card readers gradually became more common. The aformentioned xD to CF adapter meant that the xD could be used in the very common CF type I slots in the interim.

An xD card is is 20 by 25 by 1.78 mm and weighs about 2.8 g, making it significantly smaller than the nearly matchbook-sized CF card and about half the size of the SD/MMC card. As far as size goes, it is much closer to miniSD or RS-MMC, both which are generally used in cell phones rather than digital cameras.

The manufacturer's listed write speeds for xD-Picture Cards are: for the 16 MB and 32 MB card, 1.3 MB/s. The 64 MB and higher cards achieve 3 MB/s. Both offer a read speed of 5 MB/s. For comparison, CompactFlash memory uses a 150 kB/s baseline, and so a 64 MB xD-Picture Card is equivalent to a 20x CompactFlash card; one limit of CF is 80x(The CF3.0 card standard is up to 66MB/s). The xD Type M cards have a faster standard rate of 4.0MB/s for reading and 2.5MB/s for writing.

Contents

xD-Picture card feature comparison

xD cards offer both advantages and disadvantages in comparison to some of their competitors.

One potential disadvantage for a consumer is their somewhat more limited availability and support. xD cards are only used in Olympus and Fuji cameras as of 2005 (though some Olympus models also offer support for CF). xD card readers are slightly more difficult to find, as well, though this does not have big impact due to the xD to CF adapter. The xD-Picture Card to CF adapter enables xD to be used directly in CompactFlash slots, which is one of the most common, if not the most common, memory card slot. In fact xD is more reusable then even Memory stick and Memory Stick Pro, because there is no direct adapter to CF for them just a oversize adapter/reader that can use a CF port but not fit entirely inside (only the smaller more expensive Duo type have direct adapters availble). There are also readers that connect to a SmartMedia slot, and can read the smaller capacity xD cards.

Another issue is their greater cost as compared to some other bigger formats, due to a variety of factors (such as there smaller size, lower economies of scale, and licensing required to manufacture them). In general, an xD card costs approximately twice as much per-megabyte as a basic SD card as of 2005. However, xD cards are avaible from a wide variety of manufacturers, they are not the most expensive format, and they also offers some advantges as well.

As of June 2005, they have lower maximum capacity then some other standards, but the same or higher then others: xD cards are available in sizes up to one gigabyte, while Memory Stick Pro (Up to 4 GB), SD/MMC (up to 2 GB), and Compact Flash (Multi-GB) have more. However, those large sizes are top of line and expensive models, and have a larger form factor. Memory Stick Pro Duo is larger (about the size of SD/MMC) but also only peaks at 1GB. Many smaller formats such as RSS-MC, MiniSD (tops at 1 GB also), etc. which match xD's size more closely have lower or the same capacity.

xD has a lower theoretical capacity then some formats, as well; without a format change, xD cards can scale up to 8 gigabytes, whereas some can go up to 128 gigabytes (in the case of SD and CF) or 32 GB eventually (in the case of the Memory Stick Pro according to Sony). However, both are larger form factors, and Memory Stick Pro cannot be used with a CompactFlash adaptor. The 8 GB max, if not broken, is still higher then a number other (albeit outdated) formats including the original Memory Stick (128 MB), Memory Stick Duo (128 MB), Memory Stick Select (2*128 MB), and SmartMedia (128 MB). In terms of newer formats, it has kept pace with form factors that are the same size or smaller, and will potentially have higher capacity some of the new Micro card formats. As mentioned earlier (as of 2005), it can match or beat miniSD, microSD, and RSS-MC in terms of highest capacities available.

The detail specification for xD cards (needed to implement their use) is tightly controlled by Olympus and Fujifilm. This not so much a disadvantage, but a trait of the current batch of memory cards. Its main competitors, and memory cards in general, are also quite controlled. Memory Stick and its dervatives are tightly managed by Sony for example. Even the more open ones like SD, CF, etc. are controlled by groups which charge for access to the exact standards, or certain technical features.

Some newer Olympus digital cameras need a Olympus-branded xD card to use the panoramic mode feature, and that some older camera's cannot use the new Type M cards without a firmware update (or at all). However, xD cards are noted for high-reliablity and are made to certain qualities. So if a third-party card is used, it could cause errors when using the panoramic mode, which is avoided by having the feature disabled alltogether. Also, in general, many old digital cameras cannot take advantage of advances in memory cards or speeds, and is not something unique to xD format; the older xD memory cards are still usable in later cameras too.

Other adapters and readers

There are a varity of other readers aside from the previously mentioned xD-Picture Card to CompactFlash and xD to PCMICA adapters.

There are oversized/external xD-Picture card to SmartMedia adapter, that allows to xD cards to use a SM port (but does not fit entirely inside a SM slot). There is a limit on how big of a memory capcity xD card can be used in this type of adapter (sometimes 128 MB or 256 MB), and the device is subject to the restrictions of the SmartMedia reader as well. Since the adapter is oversized, xD cards cannot be used directly as a SmartMedia card (unlike the xD to CF adapter which is the same size as a CF type I card) unless open space is left for the extra section on the adapter.

Other major adapters are a xD-Picture card reader that plugs into a USB port and various type of PC Card (PCMCIA) adapters. For example there is a combination SmartMedia and xD-Picture card to PCMCIA adapter.

Aside from these, there are a number of xD-Picture card readers that connect to many major PC connection standards, including USB, Parallel, etc. Furthermore, xD-Picture has slowy gained more prominence and is becoming more common on third-party multi card readers (such as 10 in 1 readers).

Conclusion

Overall, xD has size and performance advantages over a number of its competitors. Some of its drawbacks are not unique to it, but are also in other memory cards too. With its ability to be used in a xD to CF card adapter, the increasing numbers of dedicated xD card readers, and continued development of higher performance cards, the xD format continues to offer notable competition to other memory card formats.

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External links

ja:XDピクチャーカード

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