Frankfurt  - You can find them in cell phones, digital cameras and navigation systems. They are digital storage cards, and they can be enormous - at least in a digital sense - holding hundreds of photos or a plethora of large documents. To transfer their data onto a computer, you can either connect the mobile device to a computer using a USB cable or you can stick the memory card into a card reader. That is a simpler, and in many cases quicker, solution.

"What's important is that the device can read all current cards," says Michael Tafelmaier, editor-in-chief at Colour Foto magazine. "Four or five slots are standard today," he says. The storage cards are slid into these slots, and then the data transfer is set to go.

All modern operating systems automatically recognize the card readers as external hard drives. They assign the devices a drive letter of their own.

"Only older operating systems could have problems in this regard," Tafelmaier says. "Be sure to check the compatibility when making a purchase."

The computer also requires a free USB port if an external card reader is to be used. The device is then simply plugged into it. "The devices require no electricity from a power supply of their own," explains Volker Schanz, managing director at the Information Technology Society (ITG) in Frankfurt. They are powered by the bus - that is, they draw their power from the USB port.

Top transfer speeds are achieved by minding the USB standards. "The current standard is USB 2.0, and it's fastest," Schanz says. Just how fast the data transfers to the computer also depends on the card reader and card type. A read-through of the card reader's packaging and information from the storage card maker are required here.

Card readers can be installed internally into the computer using a free expansion slot. Experts tend to prefer external devices, though.

"They're quite easy to bring along and can be connected to various computers," photo expert Tafelmaier notes.

Card readers destined for on-the-go use should be well built. "The device should really be robust." Consumers should hence avoid overly thin plastic devices.

Simple versions of these products are often available for as little as 10 dollars. As with all low-end products, consumers shouldn't expect too much from them, though. In many cases they can only read two different card formats.

"On average 50 dollars will get you a good device," Tafelmaier stays.

Martin Knapp, chairman of the Working Group for Digital Photography, can list off the five storage card formats users should look for: Secure Digital (SD), Compact Flash (CF), MultiMediaCard (MMC), Extreme Digital (xD-Picture-Card) and Memory Stick (MS). A good card reader should be able to handle any of those formats.

Some manufacturers boast of "150 in 1" readers or the ability to read "1001" storage card formats. "There aren't even that many formats at all," Knapp says. The manufacturers are clearly counting the individual product descriptions of the individual cards and their storage sizes as well. Consumers shouldn't be fooled. "Devices that can handle the five important formats are sufficient," Knapp adds. Multiple card slots don't mean that a device can write from one card to the other. Those details should be checked prior to purchase. (dpa)