All You Wanted To Know About SD Cards

Secure Digital (SD) Cards are flash memory cards.  Back in 1999, three companies called Matsushita (Panasonic), SanDisk, and Toshiba teamed up to create the SD Card.  With gadgets getting smaller, they saw a need to create smaller non-volatile memory format.  SD Cards come in many different “sizes.”  What I mean is: the cards all measure 24mm x 32mm x 2.1mm, but they come in 8 MB, 16 MB, 32 MB, 64 MB, 128 MB, 256 MB, 512 MB, 1 GB, 2 GB, 4 GB, 6 GB, 8 GB, and 16 GB memory “sizes.”  There have been talks about creating a 32 GB card.  Whew!  My first computer only had 2.1 GB for the WHOLE THING!  Different forms of memory all together, but still a wide span in capacity
 
The SD Card has been very popular.  As a matter of fact, my PDA uses SD cards and I can store extra stuff like photo albums and MP3s.  I had been using a 512mb card for the longest time.  However, after the 2 GB cards became more affordable, I purchased on of those for my PDA.  This is when I discovered the existing compatibility issues between older devices and the newer, larger cards and the SDHC (high capacity) format.  So, I did some research and found that a 1 GB card is okay.

Compatibility Issues

There are many SD card compatibility issues.  My suggestion is to compare you electronic device with the era of SD cards that were available when you purchased it.  If when you purchased you Digital Camera or MP3 player the biggest SD card available was the 1 GB card, you will need to research before you purchase a 2 GB or a 4 GB card.

So, were did the “Secure” come from when the tri-companies named the Secure Digital Card?  Well, Toshiba added encryption hardware to the MMC or MultiMedia Card.   This was done to unruffled the entertainment trade’s apprehension that these MMCs would raise havoc on the legal trade of music. This “encryption” provides some security for rights management on digital music.  With the problems that followed after 1999 with the trade of pirated music over the Internet, the encryption is seldom used in SD Cards.  So, when you see that a card is SDMI-compliant, it means it is compliant with the Secure Digital Music Initiative.

Naming The SD Card

It’s funny how things get their names.  Toshiba was working on a project called the “Super Density Disk” for DVD players.  This never panned out, so the “SD” signature was used for the SD Card.  Have you ever wondered why the “D” looks like half of a round disk or DVD?  It’s kind of like the signature for DVD created by Sony.
 
Now, only three companies created the SD card in response to the Memory Stick by Sony that came out the year before.  How did so many devices end up being SD Card Compatible and not Memory Stick compatible? Think about it!  Nikon, RCA, Palm, Cell

How Did The SD Card Get So Popular?

Phones and a bunch of other manufacturers created their devices to take the SD Card.  How did this come about? 

Hey!  That is a good question and I am glad you asked it.  Back in 2000, at the CES trade show Matsushita, SanDisk and Toshiba Corporations announced that a new industry-wide association would be created to set industry standards for their proprietary SD (Secure Digital) Memory Card.  This was to promote its acceptance in a full spectrum of digital applications. This new organization was named the SD Association (SDA).  Located in California, the SDA’s membership included an impressive 30 world-leading high-tech companies and major content companies.

The card was initially manufactured in 32 mb and 64 mb capacities.  Now they are talking MEGA GIGs for these things.  I remember my Commodore 64.  I told daddy to get me a Commodore 128.  He said, “Son, that is a marketing ploy, the world will never need more than 64 mb for anything except flying space ships.”  No joke!  That was his words.  I should have known better; after all, he was a furniture salesman (an honorable occupation, but not known for being tech-savvy).

In April 2006, the SDA released a detailed specification for some changes to the encryption portion of the SD Card and the release of Micro SD Cards.

When looking at the card from the top there is one required notch on the right side.

On the left side there is usually a Bassi tab. This is the write-protect tab.

SD Card Speeds

Now we are getting into some info that you may be interested in.  This may be a little difficult to understand, but we will give it a go any way.

The CD-Rom will be our baseline comparison.  The CD-Rom write speed is 150kB/s or Kilobytes per Second.  That means that ever second, 1000 bytes of information is written to the CD-Rom surface.  The CD-Rom therefore is a write speed of 1x.  Now, we know that the CD-Rom has different speeds and all, but in comparison to SD Cards, let’s just say it is a 1x.

The bottom, basic SD card writes information up to six times as fast as a CD-Rom.  Okay, that would make it a 6x.  Looking at the math:

900 kB/s vs. 150 kB/s

Okay, when considering high-speed SD cards are made with higher data write rate of 66x.  The terminology may have to change, because many high-end cards have speeds of 150x.

Pat me on the back; I just bought my first 300x card!!  So what!!  Right?

“Right” is the answer.  Who really needs this speed?  If your equipment doesn’t have the ability to transfer data that fast, then the SD Card technology is more advanced than your electronic device.  So, why spend the extra money on speed?

Well, considering the million (plus) read / write capabilities of the card, you may be future-proofing you SD card collection.  Or, you may just want the latest – greatest. 

SD Speed Class Ratings are defined by the SD Association. The SD Speed Class Ratings specify a minimum continuous write speed on an empty SD card.  To fall into a Class 2, the write speed must be 2 MB per second.  A Class 4 card will write at 4 MB per second.  Guess what a Class 6 card must write at.  Yep!  You guessed it: 6 MB per second.

It is my understanding that if you have a 133x card, it should work in any of today’s technology without any hiccups.  I may suggest more speed if you are using an SD Card in a video camera.  But for everything else, you should be okay with a 133x.  Me?  I went on ahead and bought the 300x, but that doesn’t mean my 133x will end up on eBay anytime soon.  I still use them too.

What brand of SD Card should you buy? 

Hum…this would seem hard with all the manufacturers out there, but for me, the choice is 1st: Lexar, 2nd Crucial, 3rd SanDisk and 4th Verbatim.  If you are happy with another brand, I hope I did not hurt your feelings.  Drop me a line and I will update this guide with your “plug.”

Non-Volatile Memory

Well, how about one more bit of info.  SD Cards use what is called Non-Volatile Memory.  This is different that RAM memory like the stuff in your computer (not the hard drive).  When the power is off on your computer, you loose the information.  However, for non-volatile memory, you can turn the power off and the information stays.  Pretty neat considering that SD cards don’t use magnetic memory technology like a hard drive.

I hope this guide was helpful and that you have a better understanding of Secure Digital or SD cards.  If it was helpful, let me know by clicking the “YES” down below.  If you would like to provide your input, I will be happy to add the information to this guide.

Show The World Your World; Share A Photograph.  TM

SULAE--