Memory Card Questions

There are so many different types of memory cards and devices that it's not surprising that most people have various Memory Card Questions. This article provides answers to some of the most Frequently Asked Questions (FAQ's) about the different types of memory cards and how they are used. These tiny cards have revolutionised our world, enabling us to store and share countless data such as photos, audio, documents and video. There are thousands of different products and devices that use memory cards which are built to SD standards providing a whole range of storage capacities, speed classes and different physical sizes. The magic of memory cards bring our gadgets to life so it's important to buy the right type of card for your device and your personal needs. Our answers to your memory card questions will help.


Memory Card Questions: What is a Memory Card?
First things first - what exactly is a memory card? Memory cards were developed because many digital products, such as digital cameras, videos and mobile phone, required some form of storage for their data and the ability to transfer files between compatible devices. A special slot or port for inserting a memory card is included on digital devices. Memory cards are small, portable storage devices that use a type of electronic memory called 'flash memory' to store different types of electronic data such as images, video and audio clips and text documents.

Memory Card Questions: How Safe are my Memories?
Memory cards have major advantages over other storage storage devices such as hard disks or DVDs/CDs. Memory cards are less fragile, much more shockproof, less prone to damage from movement and can easily take a couple of scratches without loss of data. Memory Cards are Reliable, Removable and Re-Useable.

Memory Card Questions: How do I Transfer Data from a Memory Card to my Computer?
Most computers are built with multiple slots or ports for transferring data. If your computer is equipped with an SD slot, you can transfer your data by simply inserting your SD memory card. If your computer does not have an SD slot, or is built to an earlier SD standard than your memory card, you can use a USB reader/writer or computer card adapter to easily transfer data from your memory card to your computer.

Memory Card Questions: What is Flash Memory?
Flash memory a type of memory that retains data in the absence of a power supply (non-volatile storage). Flash memory was developed in the late 1900's as solid-state chip technology used for storing digital data and gets its name because the microchip is capable of erasing a section of memory cells "in a flash". Flash Memory Cards have many advantages:

  • Memory Cards are very tough and will not break if dropped - they are both secure and reliable
  • Memory Cards are removable and re-useable
  • Memory Cards are shock resistant, Freeze resistant and X-Ray proof ensuring the safety of your memory card content
  • Memory Cards are extremely compact and can store gigabytes of data in a very small space
  • Memory Cards are very fast and have no moving parts and Flash does not need battery backup
  • Memory Cards allow data to be written and re-written and is not erased when the power is shut off

Memory Card Questions: What is Non-volatile Storage?
Volatile Memory loses its contents when the power is turned off whereas Flash memory provides non-volatile storage (NVS), which means that a power source is not required to retain stored data. Nonvolatile storage means that data stored on your digital device will be stable and is not subject to corruption or loss in the event of a power failure.

Memory Card Questions: Why are there different Shapes and Sizes of Memory Cards?
Memory cards have different storage capacities and transfer speeds. The card dimensions follow one of the many standard shapes in order to fit the devices that they are meant for. All memory cards are compact items, as thin as a credit card that range between the size of a postage stamp to a matchbook size. There are numerous types of Memory Cards for sale, but the SD (Secure Digital) range of cards are the most popular, especially for the 'point and click' cameras followed by the Micro SD cards for mobile phones.

Memory Card Questions: What are the different Capacities of Memory Cards?
Capacity refers to the number of bytes a memory card can hold. Memory cards store gigabytes of data in an extremely small space. In order to accommodate evolving technology and consumer needs, different variations of memory cards have been developed featuring a range of capacities, and generally, the more memory or capacity available on a given card will often mean a higher price tag. 

Memory Card Questions: What are Gigabytes?
A Gigabyte (GB) is a unit of measurement approximately equal to 1024 megabytes. Gigabytes are commonly abbreviated GB in writing and referred to as "gigs" in everyday speech. Computer components process data in bytes or multiples of bytes such megabytes (~1 million bytes), and gigabytes (~ 1 billion bytes). Memory cards indicate storage capacity as 1GB, 2GB, 4GB, 8GB, 16GB, 32GB and 64GB, but as technology marches on capacity will soon be indicated by Terabytes (TB) a thousand billion bytes  - that is, a thousand gigabytes.

Memory Card Questions: SD (Secure Digital) Cards
The most common type of flash memory card is Secure Digital (SD), which include SDHC (Secure Digital High Capacity) or SDXC (Secure Digital ‘Xtra Capacity’) cards. SD also includes the ultra-small MiniSD and MicroSD formats.

Memory Card Questions: The History of SD Memory Cards
The history of SD Cards evolved to meet the needs of consumers and new digital technology

  • 1999: Original SD cards (Secure Digital) were released in 1999 but only went up to 2GB, so SDHC (Secure Digital High Capacity) memory was soon developed
  • 2003: In 2003 Sandisk released the MiniSD as an extension to the SD card standard especially for smaller electronic devices like mobile phones and tablets. MiniSD cards are usually packaged with a MiniSD adapter that provides compatibility with a standard SD memory card slot 
  • 2005: Physically smaller cards, called MicroSD were then developed for storing images up to 2GB on mobile phones. Micro SD cards were released in 2005 and were 80% smaller than standard SD memory cards
  • 2006: SDHC was released in 2006 with a maximum capacity of 32GB that increased to 64GB of storage
  • 2007: Micro SDHC was released in 2007 to provide increased speeds over MicroSD
  • 2009: Higher capacity and faster processing speeds were soon required so the SDXC (Secure Digital ‘Xtra Capacity’) was developed and released in 2009 with a storage capacity from 64GB to 2TB (Terabytes)

SD Memory Cards: SDIO (Secure Digital Input Output) cards
SDIO (Secure Digital Input Output) cards were developed for use with products that needed an input and output function. SDIO cards have the same connections as standard SD cards but will not work correctly with devices not built to the SDIO standard. However, these cards will not cause damage if fitted in error to a device not supporting the SDIO standard.

Memory Card Questions: Ultra High Speed (UHS)
Ultra High Speed (UHS) bus design for SDHC and SDXC cards was added to increase the performance of SDHC and SDXC memory cards. A 'Bus' connects input/output or I/O to Processor and Memory.

Memory Card Questions: CompactFlash (CF) Memory Cards
CompactFlash (CF) cards were initially developed in 1994 for advanced DSLR (Digital Single-Lens Reflex) professional cameras, but were also suitable for high definiton (HD) video cameras, to provide faster processing times with even higher storage capacities with a large 128GB maximum storage capacity. Compact Flash cards are larger than SD cards, can record at a faster rate are extremely tough. CompactFlash (CF) cards may also have a UDMA (Ultra Direct Memory Access) rating. UDMA refers to the technology the card uses to enhance its speed.

Memory Card Questions: MultiMediaCard (MMC)
The MultiMediaCard (MMC) provides a maximum of 4GB of storage. MMC is no longer a supported standard as the last revision of the standard was in 2005 and most cameras do not accept MMC formats.

Memory Card Questions: Reading and Writing Speed
Memory Cards are not just about capacity, they are also about writing and/or reading data to and from a memory card - and how quickly this can be done. The speed of memory card will determine how fast and how many photos or videos can be taken in rapid succession. 'Writing' is the process of transferring data - how fast photos and videos can be saved on to a card (you will need a fast writing speed if you enjoy shooting HD or continuous bursts of action photography). 'Reading' is the process of transferring data from a memory card to a computer and indicates how fast data can be retrieved from a card. Read speed is faster than write speed.

Memory Card Questions: Speed Rating - Class 2, Class 4, Class 6 or Class 10 on SD Cards
If you are using SD cards, the speed of the card is rated as a class rating. The class is the speed rating which measures maximum transfer speed for reading and writing images to and from a memory card, expressed as megabyte (MB) per second. Speed class rating is important when using HD video mode or camcorders when a steady stream of data is being saved. Memory cards specify Class 2 (slowest), Class 4, Class 6 or Class 10 (fastest) on SD Cards.

  • If your product asks for a minimum Class 4 memory card you can use Class 4 or above without any problems
  • If your device requires a Class 6 card you can use a Class 6 or a Class 10 card in most products
  • A device requiring a Class 10 card needs the speed to enjoy the best performance.

Memory Card Questions: What is Backward Compatibility?
As products such as digital cameras, videos, cellphones etc.there are compatibility issues to consider. Devices that only accept the original SD (Secure Digital) card format will not be compatible with SDHC (Secure Digital High Capacity) or SDXC (Secure Digital ‘Xtra Capacity’) memory cards. However, both SDHC and SDXC memory cards are backwards compatible, enabling them to read previous formats. A device is backwards compatible if a product designed for the new standard can receive, read, view or play older formats and standards.

  • SD devices can only use SD memory cards
  • SDHC devices can use both SD memory cards and SDHC memory cards
  • SDXC devices can use SD memory cards, SDHC memory cards and SDXC memory cards

Memory Card Questions: How do I Unlock my Memory Card?
There is a locking switch on the left side of the SD Card which prevents data from being read, written, and deleted from the storage card. Check that the Lock switch is slid up which will place the card into the unlock position.

Memory Card Questions: How Many Memory Cards do I Need?
There are so many devices that now take memory cards - even pet tags use them! A memory card is re-useable and will give many years of service but additional cards will provide you with increased flexibility.

  • Extra memory cards are useful when you're unable download your pictures, e.g. when you're on holiday, or away from home
  • Don't run the risk of running out of storage space - Remember that shooting videos takes up lots of memory
  • Spread the risk of losing a card by using 2 or 3 memory cards with your device

"Memory is like chocolate - you can never get enough of it!"

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