Talk:SD card

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SD card was nominated as a Engineering and technology good article, but it did not meet the good article criteria at the time (March 27, 2015). There are suggestions on the review page for improving the article. If you can improve it, please do; it may then be renominated.

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Text has been copied to or from this article; see the list below. The source pages now serve to provide attribution for the content in the destination pages and must not be deleted as long as the copies exist. For attribution and to access older versions of the copied text, please see the history links below.

Merged MiniSD (history) → SD card
Merged MicroSD (history) → SD card

X Speed Ratings: SLC vs MLC,?

Probably, a thing related to speed ratings of SD cards is the SLC vs MLC issue. Although it is almost never mentioned by SD cards distributors, it seems the critical factor impacting access times, write and read speed, as well as the media durability. I'm absolutely not any kind of expert here, I just wanted to give a hint, hoping it's usefull for soemone more knowledgable. I can't say what is the link between 60, 133, 150x etc. ratings and the SLC/MLC, but there is something on here it seems. Or are the MLC not present on the market anymore?

Searching for "slc mlc sd" gives eg. this document: The Samsung SLC NAND Flash Advantage.

Compatibility section

I think there should be a separate section on compatibility, e.g. between SD and MMC cards, the issue with 128 GB and larger SD cards, etc.

performance-loss with reformating

In SDUC > exFAT filesystem, it is mentioned twice that one can reformat the card. It is however not mentioned that one needs to know the exact specs (like allocation unit size and erase block size) of an SD-Card to do so, or lose up to 50% performance. Said specs are usually not profided by the vendors, even if asked, you have to guess them with flashbench.

SD 7.0 does not support UHS-II/IIIcards

SD Express cards cannot support UHS-II interface. SD7. 0 and SD7. 1 define full size SD and microSD form factors using two power supplies, a traditional 3.3 volt and 1.8 volt. 112.104.98.124 (talk) 08:33, 9 October 2024 (UTC)[reply]

Removal of "Relationship between bus modes and card speed classes" section

Hi @RickyCourtney. I wanted to discuss your removal of the section I recently added called "Relationship between bus modes and card speed classes" and why you felt "The section seems unnecessary". The text I wrote before the table was a brief version of my thinking of why it was valuable but I can elaborate, although I would like to hear your thinking. Surlyhacker (talk) 21:37, 8 June 2025 (UTC)[reply]

I didn't understand why the section was necessary. Also I wasn't sure what the source was. RickyCourtney (talk) 23:23, 8 June 2025 (UTC)[reply]

Physical Layer Specification References

I updated the Physical Layer Specification references to fix 2 broken references that another editor failed at replacing my references. Right before I posted this comment, I clicked on each of the reference links in the right column of the table, and every reference downloaded a PDF file, except the bottom reference which forces a person to go through extra steps to get the latest PDF. • Sbmeirow • Talk • 11:26, 20 June 2025 (UTC)[reply]

BTW, when I created these references, I archived each PDF at archive.org to ensure we always have a copy available, even if LINK ROT happens. If any of my references stop working, then change the word "live" to "dead", then the reference link will switch over to the archived link. • Sbmeirow • Talk • 11:41, 20 June 2025 (UTC)[reply]

BTW, I already forced references from 2 college websites and an asian webstie to "dead" to ensure a reader always get known good PDF from archive.org, which prevents someone at those websites from replacing the PDF with a bad or hacked PDF at some future date. • Sbmeirow • Talk • 11:47, 20 June 2025 (UTC)[reply]