Next, let's look at what activities require higher SD card speeds and how the SD Association classifies cards by speed. Another measurement you'll see on an SD card is its speed. Speed isn't very important if you're just storing files or taking still photographs.
However, speed is very important when it comes to shooting and playing back video, particularly in high-definition HD. When you have a higher speed SD card, you can capture better quality video with smoother playback. These two standards are not compatible, so be sure to use the standard appropriate for your recording device.
Let's take a closer look at each class and how to determine what speeds an SD card is capable of. Speed Class applies to all SD cards.
The following are the Speed Classes defined by the SD Association and the cards, as well as the video recording and playback qualities usually associated with those classes:. That means the SD card has circuitry designed to read and write to memory at speeds up to MB per second.
Now that you're up to speed on SD card speeds and capacities, let's see what makes Secure Digital cards "secure. What makes a Secure Digital memory card secure? All SD cards have copyright protection for SD standard data types. This enables commercial distributors to put music or other media on the device so that it's protected from illegal copying.
The lock is a tiny slider along one side of the SD card. In unlocked position, you can read and write to the SD card as you would with a USB drive or any other read-write storage device. In the locked position, the SD card will not allow any changes to its file system, making it a read-only device. You might use this feature if you're concerned about accidentally overwriting data from a camera, for example, while reading the SD card on your laptop or desktop computer.
Until now we've focused on the capacity, speed and security associated with SD cards. On the next page, we're popping off the plastic cover and taking a look at the technology inside.
An SD card is a solid-state device. This means it has no moving parts in order to function. This is a big improvement over older portable storage devices. Floppy disks , for example, had flimsy discs inside which spun at high speeds and were subject to data loss when placed near magnetic fields. CDs and DVDs are larger and less durable, and their storage capability degrades quickly with lots of rewrites. An SD card's components are part of its circuitry, and its packaging is small and durable compared to these predecessors.
Speaking of durable, we cracked open an SD card for the picture on this page. It wasn't easy, which is a testament to the aforementioned durability.
The mini and micro sizes are more delicate, though, and you still don't want to store an SD card where it could possibly bend, chip or break. Inside the SD card is circuitry that includes flash memory. In our article How Flash Memory Works , we cover how that circuitry controls the flow of electricity when writing or erasing data on the flash memory chip. In compliance with standards, each SD card comes formatted with a File Allocation Table FAT file system, which is compatible with just about every operating system that might want to access the files in that system.
Occasionally, you might need to reformat an SD card, either to "zero out" the data for a thorough wipe of all data, or to recover the file system after a corruption, which could happen when removing the card during critical read-write operations. So far, we've examined the SD card hardware and the technical side of how it works.
Next, let's discover some of the challenges involved when using SD cards and card readers. SD cards have a lot going for them.
They're small, durable and can be used in any of thousands of devices. They do have some challenges and drawbacks, though. One drawback involves the known limitations of flash-memory technology.
Though this is a proven limitation, it may rarely be a major problem for you since it's equivalent to completely writing and erasing the entire card's contents once a day, every day for 27 years. Perhaps more important than data lifespan are the challenges of handling the physical cards.
Knowing what type of memory card is right for you and your particular devices is becoming vitally important, and this is where we can help. Memory cards are small devices some no bigger than your thumbnail that are used to store electronic data. This can be anything depending on the device from photos, music, movies, games, documents, programs and more. While cards come in a variety of shapes and sizes and are available for a variety of products, all memory cards do essentially the same thing — store data.
Memory cards, also referred to as flash memory, are essentially chips that allow users to write and rewrite data multiple times. Some of the key features of flash memory cards include their small size and the ability to retain data without a power supply. This allows them to fit into a variety of portable consumer devices. Devices like the Nintendo Wii use SD cards. Wii console SD card image by Evan Amos, public domain. Memory cards first took off as the storage medium of choice in photography, with cameras dispensing with film rolls to instead rely on the much smaller and cost-effective memory cards.
As well as digital cameras, memory cards are commonly used in mobile phones to store information like photos and music, as well as in camcorders to store video. Memory cards are also used in other consumer electronic devices such as televisions, portable game devices, printers, DVD recorders and more. Many TVs come with card slots which allow users to see any stored photos on a big screen, while some printers allow you to print directly from images stored on a card.
While you can easily swap cards from one product to another, it's important to remember that different devices take different types of memory cards.
If you already have a device that takes a memory card and want to buy more gear, make sure your intended purchase can take the same type of card. Over the past few years the number of different types of memory cards has reduced drastically, due to standardisation. Secure Digital SD is the most widespread format, and come in various different capacities and speeds. Memory Stick is a proprietary format developed by Sony and as a result is found mainly in Sony devices.
CompactFlash is a standard specifically developed for digital cameras and is now most commonly used in higher-end SLRs. Devices will usually only take one variety of memory card, although some cameras and camcorders have a single slot that accepts two different varieties of cards, such as Sony cameras, which generally take SD and Memory Stick.
Many formats also have sub-variants. While the underlying technology is the same, the size and form factor is vastly different in these variants.
Even though the packaging suggests it's used for cameras, you can still use this SD card on other compatible devices. Credit: Lexar. The simple answer is yes, but with some caveats. As long as your different devices take the same type of card, you should be able to freely use the same memory unit in those different devices. If, for example, your mobile phone and laptop all take SD cards, then you'll be able to use the same SD card to store data, take pictures or transfer information.
You may not be able to access or use your stored data from one device to another, however. Individual devices may use a specific file structure when recording information onto a memory card, or they may use specific file format types. If a device is unable to browse a memory card's directory or cannot read a specific type of file format, then it won't be able to display or utilise something stored using a different device.
Songs stored as MP3 files on a card, for example, can't be played on a device that doesn't have MP3 support. Memory cards are much more shockproof than other storage mediums. Since there are no moving parts in a memory card, they're much less prone to damage from movement, which can occur in a normal hard drive. The case of a memory card can easily take a scratch or two, while scratches on the underside of a CD or DVD will most often result in data loss or an unreadable disk.
Since memory cards are physically so small, perhaps the greatest risk of data loss lies with losing the entire card itself, rather than by some other accident. Most portable devices come with cables to link directly to a PC or laptop, allowing you to transfer any images or data stored on your memory card.
If you don't have your device or cable with you, however, there are other alternatives. The majority of new PCs and laptops are now being sold with built-in card readers. These allow you to slide your card directly into the computer, from which you can access any data stored on the card. There are also stand-alone card readers you can purchase. These card readers can usually read more than one type of card, which is handy if you've got several devices with different memory units.
SD cards all have the same form factor, but different labels depending on its type. The postage-stamp-size SD card is the most popular type of memory card on the market.
Its small size, large capacity and robust design has made it common in everything from cameras to MP3 players. To differentiate between them, the SD Association assigned classes to these speeds of 2, 4, 6 and Each class represents the minimum write speed of the card in megabytes per second. These classes matter most for those wishing to record and save real-time video.
Due to their small size and high storage capacity, SD cards are used in many portable electronic devices. Game systems, digital cameras and video recorders often require a full-size SD card. Smaller devices, like mobile phones and MP3 players most often use a microSD card. Some SD cards have a physical switch on the left side to turn on "write protection. This protects data from accidental loss.
Host devices can designate a password for SD cards or command that they be read-only for extra protection.
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