The Micro SD Card Explained

In this article I’m going to a look at memory cards.  More accurately, I’ll be examining the version which is known as the Micro SD card, in terms of how it developed and what it is used for, and explain what some of the terms are so that you know what to look for.

Over the last few years, more and more portable electronic devices have been developed.  There are digital camcorders and cameras, MP3 players, GPS units, mobile phones and more, but whatever their purpose is they all have one thing in common – they need to store data.  To provide that ability, and to remove the need to carry around a great big hard drive, the Secure Digital or SD card was developed.

microsd card image

This first incarnation was relatively large, but did the job and allowed storage of up to 2 GB.  It wasn’t long though until that capacity wasn’t enough, and portable devices started getting smaller, so new designs came along.  Firstly the format was changed, to become the SDHC, with the ‘HC’ standing for high capacity and allowing up to 32 GB of storage.  At the same time, the memory card itself was shrunk so that it would fit into the smallest of portable devices without affecting the size or weight.  The mini SD card came first, and then the Micro SD card followed soon after.

The Micro SD card really is tiny.  It’s only about 1mm thick, and 15 mm long by 1mm wide or, if you want something to measure it against, about the size of a postage stamp or an adult thumbnail, which is pretty good when you think that a few years back a computer hard drive with the same storage ability would be bigger than your hand.  Like all the other SD card types, in addition to the data capacity it is also graded by class.  This ‘class’ refers to the speeds with which it can read or write data, and you’ll pay more for the higher class cards than the lower ones.  The right class for you depends on your needs, or more accurately the needs of the device the card is being used in.  Traditionally, higher class cards have been used in devices which need to write a lot of data very quickly, such as camcorders and cameras.  Mobile phones don’t really require that kind of ability, but as they continue to evolve it is likely that sooner or later they too will need a higher class of card.

As mentioned above the Micro SDHC format only allows up to 32GB of storage, but consumers continue to demand more.  The very latest format, SDXC (Extended Capacity) allows the Micro SD card to hold at least 64 GB of data and, once the market demands it, a maximum of 2 TB.  It’s hard to imagine at the moment that we’ll need that kind of storage in a mobile phone, but at the rate we are currently expanding our needs it won’t be too long before these appear.

Biljana is a writer and a blogger exploring the latest development in the specific sector of  the memory card and the Micro SD card.

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