Buying flash memory from poorly reputed places, such as Chinese computer markets, and online auction sites is an often known way to collect BAD flash memory cards that fall short on performance, longevity and data security. SD cards, along with their “counterparts” mini and microSD cards, all contain manufacturer defined information in a set of registers. One is known as the CID, short for Card Identification Register. There is also another called the CSD or Card Specific Data Register. These can only be accessed directly via hardware and not via most card readers. I am aware that it was possible to do this via the SD Card Shield and Arduino, but since I have a Chromebook, things got really easy. Under the Chromebook, the SD reader slot on the side is directly connected to the SD bus of the ARM CPU and is not a USB based reader. By running Chrubuntu, getting the CID or CSD data from a card is as simple as: Garmin g1000 pc trainer for cessna nav iii download.

Et voila! You will be rewarded with a hexadecimal string with the data in it. By comparing some cards that you own with the known signatures, you can have some reassurance whether your cards are similar, or genuine. Unfortunately, I haven’t seen a large CID database online, nor have I seen a CID decoder that will decode the hex string into the component parts (some BCD, some ASCII, others Unsigned Int or best as Hex), so I went on a journey to code one up for CID. I used this reference by Sandisk for the data field lengths and types. The CIDs for the cards I have in my possession that are in reach are as follows:

Please note, while the code below works using the Javascript of your browser, I have no prior Javascript coding until today, with much help from Google searches and W3schools. I won’t warrant the below decoder as being bug free, but it’s free so give it a whirl! If you want a full-screen one, so you can use it side-by-side and compare two separate CIDs, try this “framed” wrapper here. Hope you find this useful! Maybe I’ll get around to coding one for the CSD in the future.