Talk:SD card

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.

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.

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 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)

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)

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)

Most of this article is:

"Here's a nice, clean, compact table displaying all the information anyone will ever want to know about SD card version X vs property Y."

"Now here are 27 long unreadable paragraphs duplicating the same information so you'll want to kill yourself by the time you find the next table."

I went through and replaced most of the nbsp and nowrap marked values with... you know, the val template since that's what it was designed for, nuked the incoherent references to jibbibytes that don't even match the standard, added some references, and tried to at least make it slightly easier to edit. This resulted in exposure to the suicide inducing material so I'm going to go do something else like fill out SDS H-Phrases for poorly referenced inorganic chemicals like I usually do, but this was a nice reminder of everything I hate about technology. For all I care it can be reverted and re-uglified or somebody can add more footnotes trying to explain why 1024 is 1000 9 times out of ten but I'm leaving.  :-) A Shortfall Of Gravitas (talk) 06:52, 16 December 2025 (UTC)

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)

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)

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)