The Speed of X

2006.04.10

After benchmarking some new flash memory and updating Neocamera's Memory Performance feature, I noticed that it is quite clear how meaningless the X-rating has become. From the days of CD-ROM, an X is supposed to mean a transfer speed of 150 K/s.

The new memory today came as a 2 GB Kingmax SD card rated at 150X and a 256 MB MicroSD (aka Transflash) from ATP rated at 80X. Since the 512 MB Kingmax SD rated at 66X originally turned in an impressive performance, my expectations for the 150X 2GB version were high. On the other hand, a MicroSD card from ATP, who is more of a no-name brand, inspired little anticipation.

Notice how DVD-Burners are sold with a different X-rating for every type of media? Flash memory, on the other hand, mostly come with one X-rating. Since reading is usually faster than writing, guess which one is normally printed in the box? Ironically, it is the write-speed that is most important to digital cameras. Since reading and writing speeds can be quite different, the advertised X-rating of most memory is of little relevance.

Another dent in the usefulness of X-ratings is that most memory card formats are memory devices without any memory controlers. Except for Compact Flash, which includes a controller, this leave a large part of the performance equation missing. This is why all tests in the Memory Performance feature are done using the same multi-card reader. With other card-readers, the results could be different, and they will differ between cameras, but at least the measurements are done on equal footing.

So how did the cards perform? Surprisingly! The Kingmax 150X beat the Kingmax rated at 66X by 35% at writing, which is very good for digital cameras but far from rating difference of 227%. At reading, the 150X rated card did not even perform as well as the 66X card, missing the mark by 12%. The 80X MicroSD card from ATP showed the highest writing speed we ever measured, besting the Lexar CF Pro 80X by 7% and the 150X Kingmax by nearly 50%! The ATP MicroSD card also showed exceptional reading performance.

The benchmarks show that even a single manufacturer does not label its memory-cards consistently. Between manufacturers the numbers are even more inconsistent. Now, before everyone rushes to by ATP MicroSD cards, remember that speed-benchmarks say nothing about reliability. It would be therefore advisable to check out user-experiences with those cards first. After these results, it is diffucult to know what to expect from the 2 GB Kingston 100X CF which will be arriving shortly.

• Technology