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Q. I notice labels like “Class 2” and “Class 4” on Secure Digital memory cards. What do these mean?

A. The class rating specified on the Secure Digital card refers to the minimum sustained speed at which the card can continuously record video data. While this may not mean much for snapping random pictures, the sustained transfer rate is more important for camcorders and cameras that can shoot movie clips.

The number in class rating — commonly Class 2, Class 4, Class 6 or, recently, Class 10 — refers to the rate of megabytes transferred.

For example, a Class 2 card moves a minimum of two megabytes of data per second, while a Class 10 card can transfer a minimum of 10 megabytes per second. (The SD Card Association has the technical details on class ratings at www.sdcard.org/developers/tech/speed_class.)

Depending on the camera and its own specifications, using a card with a lower rating when trying to shoot high-definition video could result in error messages, dropped frames and uneven playback. Check the manual for your camera or camcorder to see what cards are recommended for your model; for high-definition video, a Class 4 card or higher may be required.

The class rating is separate from the card’s speed rating, which is also printed somewhere on the packaging or label. The speed rating looks something like “up to 15MB/s Read, 9MB/s Write” in the card’s fine print.

These numbers refer to the maximum transfer speed for data being read and written to the card. Read speed (in this case, 15 megabytes per second) is the amount of time it takes to transfer photos and videos from memory card to computer. Write speed (9 megabytes per second in this example) refers to how quickly data can be recorded onto the card from the camera.

Like class ratings, memory-card speed ratings may not matter as much for casual photography with point-and-shoot cameras.

Cards with faster speed ratings are sometimes recommended for digital S.L.R. cameras that can shoot high-resolution pictures in continuous bursts.

Transcend Launches Extreme Plus 600X CF Memory Cards – Transcend has declared the launch of its Extreme Plus 600X CF (Compact Flash) memory cards in India. These memory cards are new cards more intended for performance based conscious photographers utilizing advanced Turbo Multi Level Cell NAND Flash Chips (MLC) technology.

Transcend arrogates, these memory cards offers the best and fast performance needed by professional photographers and even enthusiasts, who meant to use digital SLR cameras. In addition, the company claimed that these new cards will provide transfer speed of up to 92 MB/sec while reading and 87 MB/sec while writing to the memory card.

The cards can be operated in quad-channel mode and could be twice as much faster as 300X cards, highly useful in storing, saving and recording high resolution images and videos. Transcend proffers Extreme Plus 600X memory cards in 8GB and 16GB capacities. The costing would be Rs. 8,000 and 16,000 respectively. Along with smart pricing, the new cards carry Lifetime International Warranty.

A few months ago Wii owners were blessed with a system update that expanded the functionality of the SD card increasing the size limitation from 2GB to a exceptionally large 32GB of high capacity space, and the capability of playing VC/Wiiware directly from the memory card. Apparently that was just one step as Nintendo will begin to allow actual Wii game data to stream from a trusty SDHC card.

This means that Downloadable content will no longer need to occupy the HDD and will load them straight on an SD card and leave it there. These benefits come right as Guitar Hero 5 goes gold next month – essentially becoming the first title to take advantage of the latest feature.

Keep reading for all the details!

As IGN properly explains:

“All the tricks used for both Guitar Hero and Rock Band in the past – leaving internal memory open- is gone. Instead, straight-up booting off the SD card is available, and that means easier downloads, larger expansions, and quicker loads when bringing in song data from the SDHC card into GH5.”

Of course what this mean is that full DLC is now a reality for the little console as full albums and other features are now available with ease and without size limitations, as well as the ability to import your favorite song from Guitar Hero World Tour just like the Xbox 360 and PlayStation 3 versions.

It’s taken Nintendo a while to find a viable solution to their storage issues, but this good news for Guitar Hero followers and its even better for the Wii in general, especially when you consider how inadequate things were compared to the other powerhouse consoles that sport hard drives.  A quick look online finds that 32GB SD cards (the highest capacity the Wii console currently supports) can be had for roughly $59 and up, and with prices sure to keep dropping perhaps Nintendo will put this new resource to proper – and more mainstream – use soon.  Playable game demos, anyone?

Toshiba’s announced a new card based on the SDXC spec, which will eventually allow SD cards to reach 2TB capacities. Microsoft owns the file system used by the new cards, so it’s unknown when, if ever, the new format will be supported by OSX.

The continuing capacity ramping of Secure Digital cards will continue basically uninterrupted through the next few years, as the flash card vendors introduce yet another extension to the SD specification, called Secure Digital Extended Capacity. This week, Toshiba announced the first card to launch on the new specification, a 64GB module expected to ship next spring. Prices have not been announced, but the new card capacities typically ship at prices slightly higher per unit capacity than existing cards, so it’s reasonable to speculate that a cost of about $100-$150 is likely. Panasonic and PreTec had previously SDXC announced cards with unknown launch dates.

The original SD spec was limited to 4GB card sizes (and 2GB and 4GB cards had compatibility problems with older readers), so in 2006 an extension was introduced, boosting maximum capacity to 32GB with a switch from FAT16 to the FAT32 file system and certain other minor tweaks. The SDHC spec could be sized up to 2TB without causing address size issues, but is limited by the spec to 32GB, a capacity first achieved last year.

Reading the new cards will require SDXC-compatible readers, which are likely to be available cheaply in USB interfaces and ship in lots of laptops at about the time cards appear. While this card boasts read speeds of 60MBps and write speeds of 35MBps, SDXC cards will eventually support read speeds as high as 300MB/s, we’re told, which is within the bandwidth capability of USB 3.0. Capacities will range up to 2TB, so the spec may last up to ten years before another replacement is needed.  A 2TB card would take about two hours to empty or fill at 300MBps, so it’s possible that further enhancements in read speeds are due.

The new spec also brings a new file system to SD, exFAT, an extension of the FAT32 system with longer addresses, support for larger files and more granular logging, and other novel features. ExFAT, like FAT16 and FAT32, is owned by Microsoft and is more suited for memory cards than heavier-overhead file systems like HFS+ and NTFS. At present, exFAT is supported by Windows CE, Windows Vista, Windows 7. A patch is available to enable exFAT support on Windows XP, and an exFAT-supporting Linux kernel is under development. It’s unknown when, if ever, OS X will support exFAT, but presumably it will happen eventually. If not, mac users would be unable to use SDXC cards.