Flash memory cards are used in Notebook computers, Digital cameras, Music players, PDAs and Car Stereos. Since these flash memories are cheap and the storage capacity ranges from 8MB to 1GB many people are buying these cards.

There are many types of flash memory cards. There are also USB drives and external hard disks in the market. So before you buy any cards you should first find out whether it is suitable for your notebook or computer. In this article we shall discuss about flash memory cards.

Difference between normal memory and flash memory

In an ordinary memory chip there are many cells. Each cell has either 0 or 1 state. When this cell is charged, its state will change. Which means if it was 1 then it will change to 0 and if it was 0 it will change to 1.

Remove the charge from the memory chip and the cells in the chip will forget their states. It will no longer retain its state.

But a flash memory is different. Even if the power is disconnected from the flash memory chip the cells in flash memory will still remember and retain its last state. This is the speciality of the Flash memory.

Thats why flash memory is better than the normal memory. But even flash memory has its disadvantages. The speed of a flash memory is too slow. Generally the speed of flash memory is 1Mbps. But flash memory with double or triple this speed are also available. The price of flash memory is more expensive than normal memory.

Types of flash memory

1. Smart Media
   
   Smart Media cards were first introduced at 2.7" size and at a thickness of a playing card. Since it could be easily bent the possibility of getting spoiled is high. Smart Media cards can be used in digital cameras and music players. If you want to use this in your computer you need to buy a PC card adapter. The smart media card with 1.8" length, 1.5" breadth and 0.06" thickness are not widely in use.
   
2. Compact Flash
   
   Compact Flash cards are used in Digital cameras, notebooks, PDAs, Music players and car stereos. Compact Flash cards are available with 4GB storage capacity and 1.4" length, 1.7" breadth and 0.2" thickness. Research is being done to increase the storage capacity of compact flash cards to 16GB.
   
3. Memory stick
   
   Many companies are now manufacturing memory sticks. There are many types of memory sticks which are used in digital cameras, notebooks, PDAs, music players and car stereos. Some even get confused between Memory stick, Memory stick duo, Memory stick & select, Memory stick pro. The size of each of these types of memory sticks are different. The storage capacity also differs 128MB, 256MB, 1GB, 2GB and 4GB.
   
4. Secure digital
   
   As though the confusion in memory stick is not enough secure digital type of flash memory are also available. Secure digital flash memory cards can also be used in digital camera, notebooks, PDAs, Music players and car stereos. All popular brands manufacture secure digital cards. Computer experts predict that secure digital cards have very good future. The secure digital cards are very small in size. The size of usual Secure Digital cards (SD card) is 1.2x0.9x0.07.
   
   More recently MiniSD cards are available which are even smaller in size (0.8x0.8x0.5). The storage size is 256MB or 512MB.
   
5. XDPicture cards
   
   Fuji and Olympus cameras use XDPicture cards in their digital cameras. The size of XDPicture cards is 1.0x0.8x0.5. The storage capacity of XDPicture cards are 512MB or 1GB.