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Memory Cards

Thu, 05/03/2007 - 05:32 — Rosalin

Introduction
In today's world, everyday when we deal with enormous amount of data, especially digital data, the storage device play an important role. And the awareness about these storage devices has become especially essential. Be it digital cameras, laptop or palmtop computers, PDA's, Video game consoles, digital music players, USB flash memory drives (pen drives) or cell phones, Memory cards or flash memory devices are the heart of them all.

Flash Memory
Flash memory is type of memory that can be erased and reprogrammed in units of memory called blocks. This works similar to EEPROM (Electrically Erasable Programmable Read Only Memory), only difference being instead of processing the data at the byte level, it processes the data in blocks of memory in a single action or "flash". The data is stored in different blocks, by application of electric charge. And while erasing the data, the electrons pierce through a thin dielectric material, thus removing the electric charge. They retain data even without any power supplied to them.

Types of Memory Cards
We will be mainly dealing with digital camera memory cards. Main type of these being, Compact Flash, Secure Digital, Multi media memory card, Memory Stick and xD.

  • Compact Flash
    Compact Flash is the oldest of types and still is one of the most commonly used memory cards. Most high end digital cameras, especially digital SLR's are Compact Flash compatible. CF comes in two physical sizes; Type I and Type II. Type II being slightly thicker and either of higher capacity or are microdrives. Microdrives were used in earlier type of CF cards. These are small disk drives rather than solid state devices, are more subjected to wear and tear due to moving parts.

    Compact flash are easily available, comparatively cheap (cost per MB of storage space), and are compatible with many digital cameras. And so are the most demanded types. They are available in various ranges; storage capacity from 128 MB up to 8GB.<>

  • Secure Digital (SD)
    Secure Digital cards were initially designed to protect the unauthorized copying of music and security of digital music files, having a mechanical write protect switch to protect data and built-in copyright protection technology. Soon they became popular among small cameras and other digital devices as PDA's, cell phones, MP3 players because of their smaller size and robustness. These also have the advantage of high speed data transfer.
    These are available in various ranges; from 32 MB to 2 GB

    Now MiniSD and MicroSD (TransFlash) cards are also available in market. These are usually smaller in size and thus capacity as suggested by their names. These are mostly used in cell phones.

  • Multimedia Memory Card
    Multimedia Memory cards are similar to SD cards in size and capacity. But they do not have the data security component. Generally these can be used in any device that uses SD cards.
    Available in capacities from 32 MB to 1 GB.

  • Memory Stick
    Memory stick are Sony proprietary memory cards initially designed for Sony CyberShot range of digital cameras. Later they were used for other Sony Electronic devices. Memory stick is available in capacity up to 256MB. But the next generation of this type, Memory Stick Pro are available for capacity up to 1GB and have the feature of data protection (known as MagicGate).

  • eXtereme Digital (xD) Cards
    xD Cards are again proprietary memory cards, designed to be used in digital photography devices, by Olympus and Fujifilm. This is the latest format in memory card genre. These are smaller in size and are designed for minimum power consumption, thereby increasing the battery life.

    They are available in 32 MB to 1 GB capacity.

Which is better? / Which one to buy?When going for a memory card few important points should be taken into consideration.

  1. Speed rating of the memory card is one of the most important aspects after the capacity. Speed rating specifies how fast can data be written into or read from the card. It is specified in speed pre second (10MB per sec, 20 MB per sec etc) or performance multiplier (60X, 80X etc). Higher speed rating means faster rate of data reading or writing.

    But then the device, in which the memory card is placed, plays a major role in speed rating. The device should be able to read/write at similar size to maximize its effect. Another vital point here is the efficiency of interaction among camera software and the cards storage format.

  2. Awareness of compatibility of memory card with the device it would be used, is another significant point to consider. The digital devices do not support all kind of memory cards, though they may support few varieties. i.e. Sony Memory stick and Olympus xD cards.

  3. The capacity of memory card is another important feature to be considered. One should be wise enough to choose the right capacity memory card. Because, more is not always better when it comes to memory cards. It depends upon the usage. Professional photographers or photojournalists would definitely go for higher capacity cards. But for general usage one can go for cards of lower capacity. As more the capacity of the card, more is the cost. But then again one has to decide upon whether to have a card of 4 GB, or 4 cards of 1 GB. One has the advantage of not having to swap between the cards in the middle of documenting some important event. Whereas the other has the advantage of not keeping the all your data in a single card, and getting into misfortune of card getting corrupted (which is pretty rare though) or at the worst case loosing the card.

Conclusion
Memory card market is growing faster and more developed every day, with manufacturers producing smaller cards with higher capacity and less power utilization. The storage capacity of these cards doubles every 15 to 18 months and in the same time price decreasing. So one has to make a choice wisely, which one to buy and which one to avoid, depending upon his/her requirement.