Memory Cards Guide

There are a confusing number of memory cards in the marketplace today. So what are they and how do they differ?

Portable memory cards are based on solid state flash  memory technology. Flash memory is non-volatile; this means that  when data is saved to the card it is retained even when the power is  removed. Because the memory is solid state and has no moving parts  it has proven to be very rugged and reliable, making it ideal for  use in portable devices such as digital cameras, PDAs and MP3  players and portable storage devices.

Here we provide a breakdown of the different memory  cards available.

CompactFlash First introduced in 1994 by SanDisk Corporation  CompactFlash memory cards are cheap and reliable and used in a  wide variety of devices. CompactFlash cards use an integrated ATA (Advanced Technology Attachment) controller which makes it  compatible with operating systems and applications that  support industry standard IDE disk drives. The controller  provides power and file management, error correction and I/O  functionality so no special files or drivers are required.

SmartMedia This is the thinnest of all memory cards, sometimes known  as Solid State Floppy Disk Card (SSFDC). It has no on board  controller, and is simply an ‘electrically erasable  programmable read only memory (EEPROM) chip in a thin plastic  card. As it has no controller, the I/O and file management  features have to be handled by the device in which it is used.  This can cause problems with older devices which may not be  compatible with newer high capacity SmartMedia cards.  SmartMedia is an affordable type of memory card, with fast  read and write access.

MultiMediaCard Introduced in 1997 the MultiMediaCard (or MMC card) was a joint development between Siemens and SanDisk.  Initially developed for the mobile phone and pager market it  was quickly adopted for use in other technologies. The size of a postage stamp, the MultiMediaCard  is smaller than CompactFlash and offers easy integration into  various different devices via its seven pad serial interface.  Like CompactFlash, the MMC cards have an on board controller  and, because of their size and low power consumption are  frequently used in small consumer electronic products such as  MP3 players, digital cameras and camcorders.

SD Card Physically the same as an MMC card, the SD  (Secure Digital) Card was developed by Matsushita, SanDisk and  Toshiba. One of the interesting features of SD cards is the  inclusion of built-in copyright protection. They also feature  a write protect switch on the exterior of the card, a high  data transfer rate and high storage capacity. Furthermore new  SD slots are compatible with existing MultiMediaCards. The built-in copyright protection and high  capacity make SD cards popular with manufacturers of MP3 and  audio players.

xD Cards Introduced by Fuji and Olympus, the xD card is  even smaller than the MMC and SD type. Generally more  expensive than SD and SmartMedia cards, they have no on board  controller, but have a high storage capacity.

Memory Stick Memory Stick is Sony's proprietary type of  memory card. It is the size and shape of a stick of chewing  gum, and comes in several varieties with different features.  The standard Memory Stick has a capacity limit of 128MB while  there is a copyright protection version known as MagicGate  Memory Stick, which is used in Sony audio  players.
Other versions are Memory Stick Select, which  features two separate, selectable memory chips with a total  capacity of 256MB. Memory Stick Pro is an advanced version  with a capacity of up to 1GB. Memory Stick Duo and Pro Duo are smaller,  high-speed transfer variants which are compatible with  standard Memory Stick slots when used with a special adaptor. Memory Sticks are used in many different Sony  digital devices such as cameras, audio players, voice  recorders and the Clie range of PDAs.

Card Readers Our USB Card readers provide the convenience  of transferring data to and from flash memory cards, without  connecting the digital device directly to the computer. In  this way, memory cards can be plugged in to the reader and  accessed just like a disk drive! Multi-format card readers allow several  different varieties of memory card to be read by one single  unit. Click here to see our range of multi-format card readers.