IMPORTANT: READ before you buy Flash Memory (SD,mini sd, MMC, Compact Flash etc.)

thetargetarcher

Sorry if this has already been covered somewhere. It is very important if you are buying memory for your mobile phone, pda etc.

Tonight I searched the Internet for the meaning of the different card speeds. I came across the following Windows Mobile Team Blog website which explains that: there is no standard to the speed of the cards! The website is:

http://blogs.msdn.com/windowsmobile/comments/1456951.aspx

The important paragraph from the above website reads:

"How about speed?

SD cards have all sorts of marketing names--Ultra, 133x, High Speed, etc. There's no standard for what these terms mean, so I can't tell you if an "Ultra" card is faster or slower than a "133x" one. But I can tell you that there are huge speed differences in different SD cards. A few years ago I did a simple test where I plugged an SD card into a desktop SD reader, copied 30M of files to it, timed the copy with a stopwatch, and then repeated the procedure with different cards. I literally found some cards that finished in 30 seconds while others took 80."

The above was posted on Friday, January 12, 2007 11:07. So it is an up-to-date message.

See http://www.valuemedia.co.uk and view the different products. The site gives performance test results. The Sandisk and Sandisk Ultra II mini sd cards have the same av. read speeds! Only the av. write speeds are different!!

Also see MobyMemory:

It is advertising its own 2GB 150x minisd as having a read speed of 12MB/s and write as 5MB. The same item also states HIGH SPEED Read - Up to 22mb per sec, Write - 7mb per sec transfers [SecureDigital v1.1 specification] The other figures must be the average read and write speeds.

As you can see from viewing the above websites the performance of cards considerably varies. Basically do not believe the hype of the advertising e.g. 133x , 150x, Ultra etc. Investigate what the performance of the card is- the average and the minimum and maximum read and write speeds.

The new SDHC has a new category scheme:

http://www.sdcard.com/europe/TextPage.asp?Page=3

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New addition (14/02/2007):

The memory cards can only operate at the speed that the device you are using them in can handle.

If you use a 80x and a 150x memory card in a device that can handle a maximum speed of 80x then both cards will run at 80x.

Sometimes the firmware (software) of devices is updated to enable the device to handle larger storage and faster memory cards.

The results of the performance tests are usually carried out when the card is brand new and with no data on it. This can be a little misleading with the day to day performance of a card.

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nelly_2

Ive had high and low speed cards for a video camera I used to have, and never really noticed any worthwhile difference.

Challis_2

The SD card standard specifies transfer speed to be in multiples of 150KB/s, the same as CD Drives. A standard SD card should be 6x so approx 900KB/s.

I don't know about the other cards though.

Adam.