SanDisk WORM SD Cards Set to Move Forensic Evidence Into the Future
As with many aspects of Japanese society and life, Japan's police force has just taken a step ahead of the rest of the world. It will come as little surprise, too, that it is in the field of technology.
SanDisk has just announced that Japanese law enforcement has placed a bulk order for their WORM SD Cards, for use in forensic evidence recording and storage. What's so special about these SD cards, you might be wondering?
WORM is actually an acronym that stands for "Write Once, Read Many." The name is meant to describe the tamper-proof nature of the SD cards. Using special technology, the cards automatically lock data that has been written to them immediately after capture, so that it cannot be overwritten, deleted, or tampered with in any way.
Of course, the cards can still be read (for up to 100 years, according to SanDisk's boasts), which is much longer than what is currently used to store evidence. Photographic evidence is still predominantly recorded on 35 mm film, which holds nowhere near the fidelity of digital media like SD cards.
Check out the explanatory video in the source link below. It's pretty quiet, so you may want to put this on in the background while you watch.
Source: Engadget
Flash Memory and Classes/Speeds
Two Class 4 SD cards and a 4 GB Compact Flash card
Today I'd like to address some of the questions we've been receiving regarding the speed of the flash memory we carry here at ShopXtreme. So what exactly is all this 2x, 4x, 6x, 8x business about? Let's take a look.
When in reference to flash memory cards, speed refers to how fast a card can access the data written on it (read speed) and how fast it can store that data on itself (write speed). As you can probably guess, write speed is important when you are doing things like recording video or taking photos, and the data is being written to the card. Read speed, on the other hand, is important when you are trying to access that data (whether it's to access the data on the device itself, or if you are trying to import it to a computer). Just like it would take longer to write an essay than to read one, a card's write speed is often slower than its read speed.
The two types or brands of flash memory that are most common are Secure Digital and Compact Flash. Secure Digital products operate at the same speeds as Compact Flash products, but they differentiate their cards by giving them an "SD Class" rating system. The following table shows the common universal speed designations and proprietary "SD Class" designations that Secure Digital gives its cards:
| Rating | Speed (MByte/s) | SD Class |
|---|---|---|
| 6x | 0.9 | n/a |
| 10x | 1.5 | n/a |
| 13x | 2.0 | 2 |
| 26x | 4.0 | 4 |
| 32x | 4.8 | 4 |
| 40x | 6.0 | 6 |
| 66x | 10.0 | 10 |
| 100x | 15.0 | 15 |
| 133x | 20.0 | 20 |
| 150x | 22.5 | 22 |
| 200x | 30.0 | 30 |
| 266x | 40.0 | 40 |
| 300x | 45.0 | 45 |
Compact Flash does not employ a proprietary class system, but rather sticks to the #x format. Here are the different speeds of Compact Flash memory cards:
| Rating | Speed (MB/s) |
|---|---|
| 6x | 0.9 |
| 32x | 4.8 |
| 40x | 6.0 |
| 66x | 10.0 |
| 100x | 15.0 |
| 133x | 20.0 |
| 150x | 22.5 |
| 200x | 30.0 |
| 266x | 40.0 |
| 280x | 42.0 |
| 300x | 45.0 |
| 333x | 50.0 |
| 400x | 60.0 |
| 433x | 65.0 |
| 600x | 90.0 |
| 666x | 100.0 |
A very important thing to remember is that regardless of the speed or class rating of the card you have, you will be limited by the speed of the device you are using it in, and vice versa. So, for instance, if you have a 600x Compact Flash card, but the digital camcorder you are using it with can only read or write at 200x, then 200x will be your maximum possible speed. Similarly, a camera capable of writing at 32x will not be able to transfer data any faster if it is using a 64x SD card.
Sources: SD, CF