SD memory card register decoder

This is a utility for decoding SD card registers. On Linux if you have a MMC type card reader (not USB) then you can get the register values with a command similar to:

cat /sys/block/mmcblkX/device/cid
cat /sys/block/mmcblkX/device/csd

Replace X with the number of your device (use lsblk). That will return the CID and CSD respectively. The CID contains identification information and the CSD contains the card interface specifications.

This decoder is based on the official specifications located here. No information is sent to this site about your CID or CSD. It is all decoded locally in your browser.

Other people have done work in this area like Dr Lui. See pages here and here. I hope to collaborate and build a bigger database.

The “Scrub CID” removes the serial number from a CID.

Enter hex:

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