this post was submitted on 09 Nov 2023
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Is it possible to buy RAW SD cards? I mean without a master boot record or partition table. I have been using WinHex to write zeros to all the memory addresses thereby wiping out the partition tables, but this is time consuming. Can I just buy them "blank"? Does anyone have a source?

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[–] [email protected] 1 points 1 year ago

I'm sure if you had a big enough order you could buy them from a company with those specifications.

But if you just overwrite the disks anyway and assume they are blank it will be the same. For example.lets say you buy 10 SD cards that are fat32 formatted. If you need to write an image to them then just write over the entire disk with something like dd or a similar tool on windows. You only need to destroy the first few MB of space to nuke the MBR. Gpt is a bit more complex as it stores a backup table at the end of the drive. But it doesn't really matter if you overwrite it.

[–] [email protected] 1 points 1 year ago

You don't need a raw SD card, you can do what you need to do within Windows:

  • Attach the SD card to the system/put it into the SD card reader
  • Open up Command Prompt
  • Type in: Diskpart
  • Type in: List Disk
  • Locate the number corresponding to the disk
  • Where X is the number you found, type in: Select Disk X
  • Type in: Clean

That's it! Now, be very, VERY careful. If you put in the wrong number, YOU WILL PERMANENTLY WIPE THE CONTENTS OF THE DRIVE YOU SELECTED. It's on you, if you make a mistake.

"Exit" exits out of Diskpart. I don't remember if you have to exit out of diskpart and reenter for it to see a change when you remove and insert a new SD card.

I'm sure there's other ways to do this, but this is built into Windows, at zero cost.

[–] [email protected] 1 points 1 year ago (1 children)

Curious to ask what you're using this for.

Regarding buying raw cards, you'd want to buy from an industrial-facing outlet. Going closer to source is your best bet, so, buying from a reseller on Aliexpress or the like. You'll probably need to buy in volume though. The easier solution is probably just to use Diskpart to clean the disk, which takes seconds.

[–] [email protected] 1 points 1 year ago

Tactical dot.

If i know stuff a little, a MBR and a basic partition table is the very minimum requirement to operate a storage device.

[–] [email protected] 1 points 1 year ago

Unless you're doing something at huge scale it sounds like far more aggro than finding a better way to format them how you want. You don't need to overwrite the whole card to get rid of the partition tables.

[–] [email protected] 1 points 1 year ago

To clarify: I have written my own "disk operating system" for an MCU. I simply reads and writes for the first 2Gb of an SD card. I need to write my target image to be loaded on to the MCU at 0x000 and I find that the MBR resides there. I have to load the image from a desk-top PC and the MDB and GPT put me way further into memory (0x01FF).