Many mobile phones nowadays support memory cards (a.k.a. flash memory cards) that allow you to store more files, such as images, music, videos or even documents. What I found interesting is the fact that there are several standards of memory cards out there. Different phone models are likely to support different memory cards.

From the customer point of view, it could be confusing. For example, MMC family, which is used by many Nokia phones, has several variants, i.e. MMC, RS-MMC and DV RS-MMC. I have tried to compile the list of flash memory cards that are used in mobile phones. Just a quick note, flash memory cards for other devices, like digital camera, are not included here.

MMC (MultiMedia Card). The standard of this flash memory card is defined by MultiMedia Card Association. It is used in many Nokia phones although some of newer Nokia phones support SD card too.

  • MMC / MMCplus – 24mm x 32mm x 1.4mm. MMCplus is newer standard with higher transfer rate.
  • RS-MMC (Reduced-Size MMC) – 24mm x 18mm x 1.4mm.
  • DV RS-MMC (Dual-Voltage RS-MMC) / – 24mm x 18mm x 1.4mm – It is the next standard of RS-MMC that supports dual voltages, i.e. 3V and 1.8V. The lower voltage is used to reduce battery consumption. RS DV-MMC can be used in the mobile phones that support RS-MMC, but not vice versa.
  • MMCmicro – The newest standard that is smaller than RS-MMC. It is not available in the market as the writing of this blog.

SD (Secure Digital). The standard of this flash memory card is defined by SD Card Association.

  • SD Card – 24mm x 32mm x 2.1mm. The dimension of SD card is similar to MMC, it is just thicker.
  • miniSD – 20 x 21.5 x 1.4mm.
  • microSD / TransFlash / TFlash – 11mm x 15mm x 1mm. This memory card is getting more and more popular. Some Motorola phones, including ROKR, uses microSD.

Memory Stick. This standard is mainly pushed by Sony and it is used in many of Sony Ericsson phones. Sony is a very big company, that’s why they can push their own standard of flash memory. The specification of Memory Stick is available at Memory Stick Developers’ Site.

  • Memory Stick Duo / Memory Stick Pro Duo – 20mm x 31mm x 1.6mm. It is the smaller version of Memory Stick / Memory Stick Pro, which are used in many Sony devices, such as digital camera. Memory Stick Duo can be used in Memory Stick reader using a special adapter.

Why don’t we have only one standard of memory card? Of course, there are some business reasons behind this. As a customer, I would see one standard only. It will make our life easier. We can exchange our memory card with our friends. We don’t need to buy a new memory card when we buy a new phone.

As a real example, at the moment I have three Nokia phones and each of them needs different memory card! I have Nokia 7710 that uses MMC, Nokia 6680 that uses DV RS-MMC and Nokia N80 that uses miniSD.

Update (5-Jan-06): Corrected SD should stand for Secure Digital. DV RS-MMC does not have to be MMCmobile (I removed MMC mobile from the list). Thanks to Petri for the correction.