Articles: Memory

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How Do You Identify a Flash Card?

Making your choice of the fastest memory card, basing on the results of a test session, is only reasonable if you are absolutely sure that you are purchasing a card from the same series as the one used in the tests. Considering that memory cards of different series, made at different factories and from different parts, differ very slightly (a casual user may not find any difference at all), their manufacturers are free to change everything in the device, including the supplier of the controller or the memory chips. Flash cards are produced in huge batches, so the manufacturers do change their supplier as well as the chip type from time to time, or simply use those parts that they now have at their storehouse. For example, fast and expensive flash cards usually use the so-called SLC (Single Level Cell) memory chips, while their slower and cheaper alternative are MLC chips (Multi Level Cell). As you understand, flash cards on chips of these two types don’t practically differ externally.

However, it is still possible to identify a majority of memory cards. A CompactFlash card usually carries a serial number, which can be displayed at several places, on the card’s butt-end as well as sides (the so-called edge stamp), or on the backside of its cover.


For you to be sure when shopping, I post the identification information about the cards I use in my tests. Each manufacturer has its own identification nomenclature and they are not very willing to share this information with outsiders. So, I give no clues as to deciphering the cards’ IDs – you may find certain regularities by yourself.

Testbed and Methods

So, I’m about to check out the performance of sixteen memory cards of CompactFlash format from different manufacturers. I’ve got samples from “professional” as well as “ordinary” series. Thus, I will see if expensive cards provide a higher performance and to what extent. We will also check out how this performance depends on the camera or the card-reader model.

There were three digital cameras in my tests, two professional and one for “advanced amateurs”, and I used fast serial shooting as the most illustrative mode for determining the card’s performance. I also selected the maximum quality settings (RAW format if possible); the cameras were controlled manually; I used an exposure of less than 1/250s and a white balance preset, appropriate to the lighting. Installing the cameras on a tripod, I was shooting one and the same scene, focusing manually. The lighting didn’t change during the tests, so I got practically same-size files. During the tests, I measured the time interval between my pressing the “shutter release” button and the camera’s reader activity LED stopping to blink.

I also measured the performance of the flash cards with two fastest card-reader models (FireWire and USB 2.0 interfaces), using the same set of benchmarks: the FC Test with “1x400” and “400x1” patterns (i.e. writing and reading a single 400MB file and 400 files, 1MB each) and the Disk Benchmark plug-in from AIDA32. Plugging the card into the reader, I formatted it with the OS’s tools (FAT32, default cluster size).

Unfortunately, I couldn’t get any cards from Lexar Media – this manufacturer is now changing its model series and professional cards are being transferred from the “40X” series to “80X”. I don’t have SanDisk Ultra II and IBM/Hitachi MicroDrive, either. Otherwise, I tried to embrace as many available products as I could.

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