There are several different kinds of memory cards, they all do the same kind of thing, a little like VHS and Betamax did, and like these two formats of video tape some memory cards have succeeded in the market place and some have not and ceased to be manufactured.

Memory Card Losers (the Betamax of memory cards).
  • SmartMedia
  • xD
  • MMC and its versions like MMCPlus and smaller version like RS-MMC and MMC micro
It is not like they were bad, just that in IT, devices get more & more hungry for data. Take cameras for example, they take better quality photos by increasing the mega pixel resolution of the images, more pixels need more space to be stored in, hence cameras require larger memory cards as they get better and better with each new model.
The original designs of some memory cards came up against unforeseen limitations at the time. MMC was never developed past 4GB and xD never got past 2GB, even though they promised 8GB versions, they never transpired, and why should they bother when cards like Compact Flash are being adopted by almost every digital camera manufacturer.

Memory Card Winners (the VHS of the time)
Compact Flash has been able to keep up with the growing storage capacity requirements from capacities from 128MB, 256MB, 1GB, 8GB, 32GB to massive cards of 128GB capacities.

SD less so, it has had to go through 2 redesigns as the original SD was limited to 2GB. The first re-development was SDHC (Secure Digital High Capacity) which went from 4GB to 32GB, but because it was a different design meant  it didn’t work in the older SD only devices. Your camera had to be a new SDHC model, showing the SDHC logo.

SDXC was the 2nd redevelopment breaking through the 32GB barrier of SDHC, SDXC stands for Secure Digital Extended Capacity and promised huge capacities of 2TB, although we’ve only seen 256GB SDXC cards. Again, it is not backwards compatible, so an SDXC card will only work in an SDXC device, it will not function in an older SDHC/SD only or SD only device. You can use your older SD or SDHC cards in a modern SDXC device however.

We said SD only went up to 2GB. There were 4GB versions which were not designed to the SD Association’s specifications, in other words it was a bit of a bodge, and it was pot-luck if it worked in your device or not. Resulting in unhappy customers having just purchased nothing more than a rectangular piece of plastic if it didn’t.

There was a need to reduce the physical size of the SD card, yet keeping it electronically identical, so it would help electronic manufactures when designing small products. This became miniSD. This was reduced even more to become microSD, this resulted in miniSD becoming unpopular, as manufactures simply went to the smallest choice! Hence microSD has kept up to date to become microSDHC and microSDXC, whereas miniSD has not, and we doubt we’ll see a miniSDXC.

Because they are electronically identical, simple adapters can be used meaning you can use your microSD card in devices which have a miniSD slot or an original full sized SD slot.
Memory Stick is Sony’s own design of memory card, but these are starting to die out now because manufacturers either seem to use Compact Flash or SDHC/SDXC for cameras and microSDHC/SDXC for mobile phones. SDHC/SDXC cards are in everything else like SatNavs, tablet computers and MP3 players. Memory Stick will probably not be developed past the Memory Stick Pro DUO version, the largest we have seen is 32GB.

The smaller and electronically identical is the Memory Stick Micro, also known as the M2. The Memory Stick is a brand name Sony created as it did with WalkMan, but people often incorrectly refer to a USB Flash Drive as a Memory Stick, which is something completely different. Sony are now concentrating on their new format, the XQD.

New Memory Cards The XQD is the latest, fastest memory card designed for high speed professional digital SLR cameras, and only a few cameras currently support this type of memory card.

How to choose a memory card.

You may have a device such as a tablet computer, mobile phone, digital camera etc which you’ll want a card to store more photos, videos, music or personal data for work etc. Firstly look at the slot on your device, it should have a logo or name above it (e.g. SHDC), it should also be discussed within the user instructions.

Firstly consider how much you want to spend, and how much capacity you need. If your device has already filled 4GB, then you should maybe think about getting an 8GB card rather than another 4GB. Then make a note of the type of card (e.g. SDHC), and the size (if it applies to that type of card, e.g. miniSD or microSD etc). You should also check the maximum capacity as devices will state the maximum card it will work with. We have seen SDHC devices restricted to a maximum of 8GB, even though SDHC cards go up to 32GB. A 16GB card will therefore not work and appear faulty or may even damage your device!

If you do not have your instructions to hand, the manufacturer’s website should tell you, also related internet forums will also offer help and advice on choosing the right memory card. The memory card manufacturer’s like Kingston, SanDisk and Transcend have compatibility checkers. Simply enter your device, make and model and a list of recommended cards will be displayed (their own make of course).

Look after your memory cards

Memory cards can be very resilient, and a lot of errors are software and not hardware. That means it is the file structure on the card (i.e. how the data is written and organised on the memory card) which becomes corrupted (mixed up), and not an actual physical fault with the card. You may see error messages like “cannot write to card” or photos which cannot be retrieved or just disappear! The manufacturers know this can happen and offer free software on their most expensive models which can rescue images and data from corrupted cards.

Get all the data off the card, and format the card. Fully formatting the card will nearly always fix the problem (if using a PC, use full format and not quick format). It will obviously wipe the memory card of all information so try copy as much off the card as you can.

Memory cards can become corrupted by removing them in the middle of a data write. This is done intentionally by a user, or unintentionally. An example of intentional miss-use of the card is removing it during reading or writing, especially when the card is in a computer. Many people do not realise you should use the Windows ‘eject’ function, because even though Windows says it has finished writing, it may not actually have finished writing data to the card, but assigned it to a background task list. Ejecting a card via the Windows operating system forces any data read/writes to be done there and then. A message will then be displayed stating “It is now safe to remove this device from the computer” or similar.

An example of unintentional miss-use is when a battery dies on a digital camera during filming or taking pictures. Such cards should be re-formatted before using again. Failing to do so may mean subsequent photos are not saved properly, and you may only find out when you come to view or print them later.

For the above reasons it is sensible to have two or more memory cards. So instead of buying one 32GB, get two 16GB ones instead. If you are on holiday, change over the memory cards each day, that way if you lose one, or your camera gets stolen, you’ll still have some memories on the card you left in the hotel.

Common sense also helps to keep memory cards fit and well. We’ve seen memory cards reported as faulty, but they were bent, due to being kept in a wallet, which in turn was kept in a back pocket, and obviously sat on. Also don’t leave them on radiators or on microwaves.