How Secure Digital Memory Cards Work

Challenges in Using SD Hardware
A microSD card can be tricky to handle. Here's one inside a smartphone, carefully tucked under a small metal bracket next to the microSD logo.
A microSD card can be tricky to handle. Here's one inside a smartphone, carefully tucked under a small metal bracket next to the microSD logo.
Stephanie Crawford

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. According to Toshiba, the company that invented the technology, the memory cells in the solid-state SD card can only go through about 10,000 write/erase cycles before the hardware is incapable of retaining or updating its data. 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. [source: Toshiba]

Perhaps more important than data lifespan are the challenges of handling the physical cards. Though each SD card is sturdy, it can fall out of a pocket, slip into tight crevices, get lost in a stack of papers, or be irreparably damaged when stepped on or submerged in a liquid. Sliding the SD card in and out of a card reader can be tricky, too, especially for the mini- and micro-sized cards. If the SD card protrudes from the device you're using it in, be careful when you're moving the device, too. To meet these challenges, always handle the card carefully, stay aware of where it is while you're using it and protect it between uses.

Another challenge with SD cards is making sure you have the right type for your device. Selecting the size you need is easy; usually you can just look at an SD card slot and know which of the three sizes is required. However, you also need to select the capacity and speed that's compatible with your device. This can be tricky when you're looking at a wall of SD cards in a store and trying to select the one that gives you the most for your money. This challenge is best met with knowledge about what SD cards your device can handle, both minimum and recommended, and what the SD logos look like for the standard you need: SD, miniSD, microSD, SDHC, miniSDHC, microSDHC, SDXC and microSDXC.

One last challenge with SD cards is something you can't get away from no matter what technology you use: the tendency for old standards to become obsolete and newer ones to replace them. For an SD card itself, this is less of an issue as newer card readers can read older cards. It's devices that use SD cards that present the bigger challenge. To continue using an older device, you'll need to find cards that conform to older standards. SD hasn't retired any standards yet, though, so look for those older standard cards to be available for a while yet.

With so much going for it, what does the future look like for SD card technology? Let's examine that on the next page.

More to Explore