![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 |
Can someone expand the paragraph on speed in this article? I recently bought a camera that uses SD and SDHC cards, and in my attempt to find out which cards are fastest, I've found a confusing jumble of information. The new SDHC format has Type 2, 4, and 6, corresponding to speeds of 2, 4, and 6MB/sec, but that's clearly not the whole story, because SD and SDHC cards are being advertised as 60X, 120X, 150X (this is the only part defined in the article), and there are considerable differences between read and write speeds that aren't always obvious to shoppers. With manufacturers claiming 23MB/sec, and the newest spec calling for 6MB/sec, there's definitely some important information missing in that gap. I'd start the section myself, but it's clear that I don't have all that much of a clear idea on the SD/SDHC speed situation. - Erik Harris 20:01, 14 October 2006 (UTC)
Why does the page (Dec 1 '08) say "SD cards typically have transfer rates in the range of 10-20 MBytes/s, but this is always changing, particularly in light of recent improvements to the MMC standard.[4]". Strange, most SD cards claim to be nowhere clsoe to that fast! 67.242.12.28 ( talk) 20:39, 1 December 2008 (UTC)
Basic cards transfer data up to 6 times as fast (900 KiB/s) as the standard CD-ROM speed
Six times as fast, does it mean six times faster? Or that it is six times faster than the slowest SD speed, to bring up to the same speed as cdrom? I don't get it JayKeaton 07:05, 21 October 2006 (UTC)
While looking for a digital camera I stumpled upon some terms that are not explained in this article:
A retailer talked about 80 speed (before Ultra "he thought") and 150 speed (with ultra "he thought"). Also he was not able to tell me what measurement unit the 80 and 150 is in.
Velle 10:46, 15 June 2006 (UTC)
I see an ad for a Scandisk Ultra-II 2GB SD card with "a minimum sustained write speed of 9 megabytes (MB) per second and a read speed of 10MB per second." Will these work with all SD reader devices, or do the devices have to be ready for the higher transmission speeds? Thanks, AxelBoldt 03:34, 14 Feb 2005 (UTC)
Anyone know the minimum size of a SD Card? I'm guessing 4mb but I could be wrong Towel401
Blorg 16:39, 11 Nov 2004 (UTC)
The site referred to by the second external link, http://www.handhelds.org/projects/h3800.html, appears to be down. This may be temporary, but does anyone know if that page is still valid? -- LostLeviathan 06:08, 4 Dec 2004 (UTC)
The Technical Explanation section states "Royalties for SD/SDIO licenses are imposed for manufacture and sale of memory cards and host adapters ($1000 per year plus membership at $1500/year) but SDIO cards can be made without royalties and MMC host adapters do not require a royalty." Is it correct that a license and royalty is not required if a host adaptor is implemented in firmware using the lower performance MMC/SPI mode to communicate with an SDIO card, even though a SDCard Association membership is required to obtain the required documentation? If true, is it possible then to sell a product containing an SDIO-only card (not combo) and host adaptor without the need to pay any liscense fee or royalty to the SDCard Association? -- 216.54.240.190 18:02, 13 July 2005 (UTC)
Also, what does this sentence mean: "Overall, SD is less open than CompactFlash or USB flash memory drives, which can be implemented free of charge, but require licensing fees for the associated logos and trademarks." I have no idea whether it's telling me that SD cards do or do not require licensing fees, logos and/or trademarks. It should be broken out into self-contained unambiguous sentences.
Under the guise of "examples", currently there are a couple of links to 3rd party vendors of a product or two right now in the main article page. I suggest these be removed. -- SaulPerdomo 19:52, 18 September 2005 (UTC)
Description and market Penetration section stated that current dSLRs were using CF exclusively (the Nikon's D50 being the only exception). I've added the three Pentax models, which use SD as well (even before D50). I've also just recalled that Canon's flagship models EOS 1D Mark II/IIN and EOS 1Ds Mark II can use SD as storage media as well (in addition to CF).
So, I'm thinking: could we expect deeper SD penetration in this market any soon? If so, it could be proper to change the text in the second paragraph to "Additionally, SD has not yet conquered the Digital SLR market" and/or "where CompactFlash still remains the most popular format" (and then appropriately change the text in parentheses too). I'm not quite sure myself, so I'm not really suggesting it (yet). I'd rather be happy to hear what other people think. -- Bilbo 18:25, 11 January 2006 (UTC)
I think that SDHC will slowly overtake CF in dSLR cameras. Many now offer dual support, and the availability of adapters to use SD/SDHC cards in a CF-equipped camera are commonplace. I have used one for quite awhile and my last few card purchases have been SDHC. The advantages of SD/SDHC over CF are numerous, from the smaller size to the higher durability, and in many cases all else being equivalent, SDHC are often cheaper. For me, the use of SDHC is one of added flexibility as I can use them in my dSLR, my wife's smaller camera and directly into our TV for slide shows. I think the 'most popular format' statement is likely outdated now (May 2010) but have no data to back it up.
-Both CF and SD however, seem to be able to withstand numerous laundry wash/dry cycles....;) Ken ( talk) 20:28, 18 May 2010 (UTC)
I've seen many digital cameras that say they support SD cards "up to 512MB". Does anyone know more about this? —The preceding unsigned comment was added by 131.191.67.168 ( talk • contribs) .
I think it's using some chip with CMOS NAND Flash technology. Maybe 90 nm CMOS process?
With 2TB spec out SD may become a viable alternative to tape backup or Bluray, but how long will the data stay good on an SD card? —Preceding unsigned comment added by Squid57squid ( talk • contribs) 16:07, 15 May 2009 (UTC)
Does anyone have some somewhat-rigorous information on the difference between SD and SDHC? I was under the impression that SDHC simply standardized the acceptance of the FAT32 file system in SD cards, and that there weren't any other really substantive differences between the two formats. That would be enough to explain the compatibility differences, because a device designed to support only FAT16 would not read a FAT32-formatted card. However, most of the 4GB cards on the market today are not SDHC cards, and do not truly conform to the (FAT16-based) SD 1.1 standard, either. As such, they do not work in many devices designed to support SDHC cards. This tells me that there's a more significant difference between SD and SDHC. I'd like to know what those differences are, but I've come up empty in my search for info. - Erik Harris 12:16, 23 October 2006 (UTC)
Some manufactures, such as Pretec are introducing a new kind of cards called SuperSD. These cards are compatible with both SD 1.1 and MMC 4.0, however they have their own standard from the μ Alliance. There are also smaller version of SuperSD cards. I think that these cards should be mentioned here.
http://www.files.e-shop.co.il/iag/sd/SuperSD_DM-back.jpg
194.90.21.74 09:43, 25 October 2006 (UTC)
The SD card can also be locked to a specific device. I do not know if this is simply a part of the DRM properties, or it's a security feature being available for the end-user. If I lock the miniSD card on my phone, I cannot access it elsewhere, and the card is not readable under Windows nor mountable under Linux. Unlocking the card makes it accessible again. Some more explanation of this would be greatly apreciated. —The preceding unsigned comment was added by 195.249.172.62 ( talk) 2006-11-23T01:19:54
I have removed the following uncited text from the article, pending a citation, and simplified paragraph:
There is, however, a less well-known fact: the tab is implemented only as mechanical part (detected by a contact switch inside the SD Card socket) so that the device can write to the write protected SD card if its firmware decides to ignore the tab or if the switch is broken. Many users reported data loss when the switch was worn down or broken especially on early sockets where manufacturing process was not perfected or due to firmware bugs. Some devices also allow users to ignore write protect switch for user's comfort. Kingmax makes its SD cards without a write-protect tab because the company claims that the tabs are too fragile [2].
-- Peter Campbell 22:38, 21 December 2006 (UTC)
(this would be best added into the table) What is the max supported size of SD ? The article says "Capacity limit in all SD/MMC formats appears to be 128 GB ..." But then later "A new SD format, SDHC, allows capacities in excess of 2GB". So is SD limited to 2GB, 128 GB or something else ?
xerces8 , -- 195.3.81.25 10:28, 19 January 2007 (UTC)
The whole GB/GiB thing always confuses. Is the "1GB" cards really 1GB? Is the 512MB cards really 512MiB or 512MB? If the 512MB cards really is 512MB, then isn't the 1GB cards 1,024GB? It's kinda confusing. I highly doubt that the 1GB cards really is 1GB cards. I do NOT think that wikipedia should "lie" about the size just because the cards says something else. —Preceding unsigned comment added by Ran4 ( talk • contribs)
There seems to be some confusion out there about how the SD cards are to be formatted. The SD Card Association has official card formatting software. http://www.sdcard.org/about/downloads/ . The software is free and includes a PDF manual in English and Japanese. The manual notes that "Generally, SD/SCHC Memory Card file systems with generic operating system formatting software do not comply with the SD Memory Card Specification. If you have formatted SD/SDHC Memory Card with generic operating system formatting software, reformat SD/SDHC Memory Card using this software or the appropriate formatting software prepared by the SD hosts provider." 67.169.225.3 05:08, 7 April 2007 (UTC)ddevore
In effect I had troubles using SD 2GB cards formatted with Windows XP (both FAT and FAT32): I experienced very low transfer rates writing files to subfolders. I solved reformatting with the aforementioned software. Updated version can be found here: http://panasonic.jp/support/global/cs/sd/download/sd_formatter.html
Please keep in mind that Wikipedia is an encyclopedia, not a tech tutorial/advice website. Some of the recent changes strayed greatly from an "encyclopedic tone" and turned the article more into a how-to column, with lines like "when purchasing memory cards, do this." Also note that anything contained within <ref></ref> tags does not appear in the main body of the article. One of the reference descriptions was changed in such a way that it made no sense in the proper context, but might have made sense if it were inserted into the article. I've done my best to manually reverse these changes without reverting all of the other changes that have been made recently. — Erik Harris 15:33, 9 April 2007 (UTC)
As of February 2007, the SDCA has released an updated version of the simplified specification. Does anyone know what prompted this update? Also, the OLPC project says it has produced a truly open-source SD implementation. I've added both these things to the article, but I would like more context:
It'd be nice to provide more information on the capabilities and limitations of open-source implementations. MOXFYRE ( contrib) 18:01, 4 May 2007 (UTC)
There seems to be mass confusion about what exactly are the different modes of operation supported by SD cards. Especially it has become clear that the MMC and SPI modes are *not* the same (SPI mode is sort of a limited subset), as Samsung's datasheet clearly distinguishes them. Also, is the one-bit SD mode the *same* as one-bit MMC mode? Part of this article says that they're different because the one-bit SD mode uses separate data and command channels, but below the big comparison table it's implied that they are the same. The 4-bit and 8-bit parallel modes are clearly distinct. I think we really need to sort out the different SD access modes:
MOXFYRE ( contrib) 15:16, 11 May 2007 (UTC)
I believe that the diagram works best in the infobox to show at a glance what an SD card looks like. Rstoplabe14 disagrees however and believes that his image of two SD cards should be used instead. I think we need to establish a consensus on using either one or the other. AlexJ 14:48, 4 September 2007 (UTC)
I am not a Wikipedia writer or editor or any such thing. I am just a web surfer, and I want to share the following story with you. I wanted to find out what the *bottom* of an SD card looks like. So I did some Googling, and after looking at a ton of web pages that only showed the *top* of an SD card, I finally was happy to find this page because it shows exactly what I was looking for: a picture of the *bottom* of an SD card. Thanks for putting that picture here, and I also suggest that you put such a picture on the web page at this URL: http://en.wikipedia.org/wiki/Secure_Digital_card JohnDrefnier 04:30, 10 September 2007 (UTC)
What about the Eye Fi-card? Info about that card isn't as yet included in the article. 81.71.112.102 18:51, 31 October 2007 (UTC)
The article incorrectly states that EyeFi uses a nearby computer, however, I once read an article that said it uses a boradband WiFi to connect to EyeFi servers, and then back to the host computer, which must be running their software. Can anyone confirm this or knows which article I'm talking about? -- stuston ( talk) 20:18, 16 January 2009 (UTC)
The DRM section (mostly the second and subsequent paragraphs) sounds quite full of FUD to me. Nothing is sourced and it sounds like just a rant, slightly paranoid, on DRM. I don't see that it adds much that's useful. - Ethan ( talk) • 2007-11-25 00:55 (UTC)
According to Sd card#Speeds, SD cards come in four different possible speeds - 0.9mb/s, 6mb/s, 10mb/s, and 20mb/s. According to Sd card#SDHC, SDHC cards come in three different possible speeds - 2mb/s, 4mb/s, and 6mb/s. From that, it looks like the fastest SDHC card is slower then the fastest SD card. Is that correct or is there something I'm missing? And if it is correct... why? According to the article, "SDHC uses a different memory addressing method". Is that what's slowing it down? TerraFrost 19:57, 4 December 2007 (UTC)
Reference 10 on the article claims that the current maximum capacity supported by the "Physical Layer Simplified Specifications Version 2.00" for SDHC is 32GB. If I understand correctly a new version of the specification could support more, but it's not clear if a hardware or software update will be required for readers to suport higher capacities than 32GB. I don't want to muddy the waters here by editing the article without being certain. Input anyone? --Anonymous —Preceding unsigned comment added by 221.106.232.1 ( talk) 01:05, 14 February 2008 (UTC)
This site also claims 32GB is maximum. Someone please clear this up. -- Xerces8 ( talk) 09:37, 4 March 2008 (UTC)
Page 97:
Page 98:
Page 98:
Thus the card have bit fields to represent upto and including 2 TByte. BUT the SD Card association have decided that memory cards shall be limited to 32 GByte. However this doesn't prevent any 3rd party to make hardware that will handle this just fine. Electron9 ( talk) 11:00, 16 March 2008 (UTC)
Technical reference as to why SD-Cards v1.01 can handle 4 GB as per the standard document: In the SD Card Associations "Simplified Physical Layer Specification v2.00" it is specified in:
Page 89:
Name | Width | Cell type | CSD-slice |
---|---|---|---|
READ_BL_LEN | 4 | R | [83:80] |
C_SIZE | 12 | R | [73:62] |
C_SIZE_MULT | 3 | R | [49:47] |
Page 91
READ_BL_LEN | Block-length |
---|---|
0-8 | reserved |
9 | 29 = 512 Bytes |
10 | 210 = 1024 Bytes |
11 | 211 = 2048 Bytes |
12-15 | reserved |
Page 92
I hope this clearify the situation on SD-Card v1.01 capacity. However not all devices are implemented in such way to allow for READ_BL_LEN to be set to 10 or 11. Electron9 ( talk) 10:45, 16 March 2008 (UTC)
In the "form factor" section, it states that "SD cards typically have higher data transfer rates, but this is always changing, particularly in light of recent improvements to the MMC standard."
Higher than what? Memory Stick? CF? —Preceding unsigned comment added by 66.131.186.22 ( talk) 01:09, 28 March 2008 (UTC)
It seems some people have fun by changing the max capacity of SD-cards to something which is in contradiction to the specification. Even when the relevant parts are included within the article itself!
The last incident is with Amoiwangjy on 2008-05-20 that only have one contribution and a Comcast Cable/NJ user on 2008-05-30 that then changed the "contradiction" to be an all out consistently wrong information.
A standard SD-card can handle anything from 2048 bytes to 4 GB.
c_size=0, c_size_mult=0, read_bl_len=9
(c_size+1) * 2**(c_size_mult+2) * 2**(read_bl_len) = 2048
A standard SDHC can handle anything from 512 KB to 32 GB (inoffically 2 TB).
c_size=0
(c_size+1) * 512 * 1024 = 512 * 1024
This not saying that they are sold with all possible capacities. Usually 8 MB is the minimum.
Some SD-card reader systems does not correctly process the READ_BL_LEN parameter. And therefore will not correctly recognise some cards (esp 2G and 4G cards in std sd-card readers). But this is NOT the same as saying >1GB - 4GB standard sd-cards doesn't exist or will not work. Electron9 ( talk) 01:46, 13 June 2008 (UTC)
There seems to be substantial overlap between the SDHC and SDXC specs. Are the latter backwards-compatible with SDHC readers? This seems especially pertinent with SDXC cards being announced in the 32GB range, overlapping with currently available SDHC cards. MrZaius talk 11:01, 6 March 2009 (UTC)
There are SD 1.01 cards available w/ read and write speeds more than 66x, i.E. [3]. I own one of this cardws myself (the 133x/30x 2GB version). It only can be read at about 5.4 MB/s (~36x) w/ my card reader using hdtach, but I think the reasopn for this is my old card reader (hama 19 in 1 rev. 1.0, model number 00055114). -- MrBurns ( talk) 08:23, 14 March 2009 (UTC)
This article places the reference to the Speed Classes (6.1 SD Speed Class Ratings) under SDHC (6 SDHC). While both SDHC and the Speed Class came out of the Version 2.00 spec, and SDHC Cards must meet at least Class 2, the Speed Classes can and do apply to SD Cards as well as SDHC Cards. In other words, the specification does not preclude the use of Speed Classes for SD Cards (as opposed to SDHC Cards.)
For instance, the SanDisk Extreme III 2GB SD Card is a Class 6 Card, the SanDisk Ultra II 2GB SD Card is a Class 4 card, and the SanDisk Standard 2GB SD Card is a Class 2 card. SanDisk is not alone in the use of Speed Classes for it's SD Cards. PNY identifies its 2GB Optima Secure Digital as a Class 4 card.
I think the subheading of SD Speed Class Ratings (6.1) should be moved to 3.1, under the heading of Speed. TCav ( talk) 21:22, 2 April 2009 (UTC)
SD cards have a small lock switch (at least the large ones). You can also see this on the photos included in the article. What is this switch good for? Could someone include this information in the article? Thanks! -- 86.135.82.168 ( talk) 11:35, 31 July 2009 (UTC)
There are hacked cards that act like say 16 gig cards but after you put more than a gig on them data starts getting lost. There are also cards with stickers for class 6 but are actually class 2. Some mention to this fraud should be given. —Preceding unsigned comment added by 204.13.130.37 ( talk) 17:24, 14 August 2009 (UTC)
I had a chance to use this article for finding a right card for my situation, and I found that the following aspects are missing or not clear in the article:
I still don't feel an expert in the topic, but hopefully someone can give answers by improving the article itself. Thanks! -- DenisYurkin ( talk) 22:21, 29 August 2009 (UTC)
Please add to the article to explain why is it called "Secure" Digital? Does it have some security features? If so, what are they? What types of problems do they defend against? Or is this just meaningless marketing hype? 68.110.104.80 ( talk) 17:16, 1 November 2009 (UTC)
"Some manufacturers have produced 4 GB SD cards that conform to neither the SD2.0/SDHC spec nor existing SD devices. [1]"
So it doesn't conform to SD (SD v1.xx) nor SDHC (SD v2.00). And no mention of SDXC, so what does it conform to ..?? :-) Electron9 ( talk) 04:40, 10 December 2009 (UTC)
The article lacks technical details on SDXC. For example, is it a type 2 card (like the way SDHC type 1)? Does it siiply use the 6 extra bits (for a total of 22 bits) that are currently unused in the SDHC (which only allows the use of 16 out of the 22)? Has the SD association ever said why they only extended SD to 32GB (from 2GB if you follow their official specs) when it seemed fairly obvious that wasn't going to last very long and it seems that they could have easily supported 1TB at the time (albeit what file system to choose may have been a more difficult choice)... (The obvious answer is money, but may be thay have an offiical answer on why they did this) Nil Einne ( talk) 09:02, 25 January 2010 (UTC)
So how come I keep seeing them on the shelves in random photo and electronics shops? There's still a stock of them knocking around and there must still be enough of a user base occasionally buying fresh cards (why throw out a perfectly servicable 3 or 4 mpixel camera with good optics if it hasn't broken, just because it's >5 years old?) for it to be worth that small square of the establishment's shelf space. Case in point, last time I found a film camera in the cupboard with a near-finished film, took the last couple shots and dropped it off at the local pharmacy for processing (mid january this year (2010)) - a few packets of 128mb smartmedia hanging on their flash card rack, inamongst the SDs, memory sticks, compact flashes and XDs. Price was ludicrous for the capacity (£20?) but it was there and available. Plus Amazon has _loads_ of them. 193.63.174.10 ( talk) 14:35, 15 March 2010 (UTC)
The article says "Standard SD card capacities have a maximum of 2 GB.[1] The capacity range for high-capacity SDHC cards overlap, beginning at 4 GB". So apparently they do not overlap. Where is truth? Goochelaar ( talk) 13:07, 18 March 2010 (UTC)
Hi guys,
Please don't change data rate measurements to bytes per second. it leads to confusion.
InternetMeme ( talk) 15:09, 13 June 2010 (UTC)
The main page of this article lacks information on the maximum heat a typical SD chip can perform in.
Do chips ever fail because of high heat? Does the data transfer at different speeds ever change when the operating temperature reaches a critical point? Dexter Nextnumber ( talk) 02:11, 23 June 2010 (UTC)
I understand one of the "secure" features of SD is a read only, guaranteed unique ID a lot of embedded system software uses for copy protection. Can anyone pitch in on this? Thanks! —Preceding unsigned comment added by 84.1.50.169 ( talk) 20:41, 24 June 2010 (UTC)
I think that UHS specification belongs to Transfer modes rather than to Speeds section. Despite of marketing fuss about it, the specification itself seemingly have nothing to do with minimal speed of transfer. Real cards (like Kingston SD10A/64GB) are still double labeled with Class 10 and UHS-I. It seems that UHS-I label is just a characteristic of interface supported and has no direct connection to the transfer speed. -- Korj.by ( talk) 07:55, 27 June 2010 (UTC)
I cannot find anywhere that sells 4 and 8 gig SD cards. Are they available for purchase, or just in development. If so, maybe it should be noted in the available sizes that you cant buy 4 and 8 gig cards yet. AshTM 00:37, 26 June 2006 (UTC)
These seem to be competing forms of memory storage. Am I correct? What if any significant advantages/disadvantages exist between them? Tmangray 04:01, 12 February 2007 (UTC)
Memory card readers are more and more found embedded in laptops, desktops, printers, etc. This will make them competing soon. —Preceding unsigned comment added by 82.67.63.244 ( talk) 19:01, 10 January 2008 (UTC)
I know there's a table that indicates the ratings, write speed, and class of specific cards, but not a table on specific cards' models or availabilities/discontinuities. The 256MB, 512MB, and 1GB SD cards have been discontinued, and models beyond the 2GB cards are still available. Shouldn't there be a table about the cards' models or availabilities/discontinuities? Just asking.
~~
LDE
JRuff~~(
see what I have contributed) July 20, 2010, 18:06 (EDT) —Preceding
undated comment added 22:06, 20 July 2010 (UTC).
Shouldn't the section "SDHC cards with greater than 32 GB capacity" come *after* the section introducing SDHC cards? Thanks, 71.175.53.166 ( talk) 14:37, 29 December 2010 (UTC)
I propose that we merge MicroSD and MiniSD articles into the Secure Digital article. Basically, the smaller cards are nothing more than a subset of the larger cards. To fill out the articles for the smaller cards would require large amounts of duplicate text. I think it is better to have a one-stop-place for all the information. What are you thoughts? • Sbmeirow • Talk • 22:02, 30 January 2011 (UTC)
![]() | The contents of the MiniSD page were merged into SD card/Archive 1. For the contribution history and old versions of the redirected page, please see its history; for the discussion at that location, see its talk page. |
Can someone expand the SDIO section? How does the electrical interface and protocol compare to CF and PC Card? 132.205.93.63 02:01, 13 June 2007 (UTC)
I think the following information would help many people. I am not sure if it is suitable for Wikipedia. Where could the following be put in order to maybe insert a reference into the SD-Card wikipedia page? Is a different WikiMedia project suitable? If you have an answer I'd be happy if you could copy it to my user page! This is a problem I face quite often. Now the text about SD-cards:
SD cards can become corrupted quite easily when a faulty device deletes its "secure area". It is not possible to revive it with a normal format operation (e. g. the one integrated in Microsoft Windows). Special software can do a low level format. After that and a following high level format the card is usable again. E. g. this free software works: http://hddguru.com/content/en/software/2006.04.12-HDD-Low-Level-Format-Tool/
More info: http://www.internettablettalk.com/forums/showthread.php?t=10014&page=3
HelgeHan ( talk) 14:03, 22 March 2008 (UTC)
Previous to editing this article, I've come across conflicting statements and confusion in multiple engineering blogs and articles. Many people were under the impression that SPI might be optional because of statement in this wikipedia article. Some people said they never found a SD card that didn't work with SPI bus. I decided to download the SD specs and investigate so I could determine the facts, which I then created this electrical interface section and corrected statements in other sections. The only big holes in this section is that I didn't describe the newest 1.8-volt higher speed protocols for SDHC and SDXC families. The most important part that I've done is describe what is common across ALL of the SD families.
I recently emailed the Help Desk at the SD Card Association and asked them to review section Secure_Digital#Electrical_interface. I received an email back from them today, which they said "We have looked over http://en.wikipedia.org/wiki/Secure_Digital#Electrical_interface and the content seems to be correct." Obviously since this is a personal email to me and other people can't validate it, it doesn't prove jack, but I thought I should pass it along.
If you find a technical mistake in the "electrical interface" section, please reply to this comment with the problem and the EXACT section of the SD specification that states otherwise, so we can investigate and determine the correction. Thanks. • Sbmeirow • Talk • 21:08, 24 February 2011 (UTC)
What is the upper limit on the memory size of SD/microSD cards? There has to be a upper limit put down by the laws of physics right (or in other words, theres a limit to how small a transistor can be shrunk)? Can anybody answer this question? 137.132.250.10 ( talk) 10:00, 23 March 2011 (UTC)
This table seems to be wrong -- looks like it should be MB(ytes) not Mbits, but I can't find a decent citation else I'd edit it myself. Anyone? One source here: http://www.toshiba-memory.com/en/sd_speed_classes.html -- but perhaps the official info is buried in the member-only pages of http://www.sdcard.org/.
Class 2: 8 Mbit/s Class 4: 15 Mbit/s Class 6: 20 Mbit/s Class 10: 30 Mbit/s
98.237.205.71 ( talk) 03:25, 11 October 2010 (UTC) —Preceding unsigned comment added by 98.237.205.71 ( talk) 03:21, 11 October 2010 (UTC)
I agree this is confusing and needs to be clarified. Typically I think SD cards are measuered in MegaBytes but I can't verify this.
78.105.181.134 (
talk) 17:43, 30 May 2011 (UTC)
The technical specification linked to by reference 1 explicitly states in multiple places that the maximum capacity is 2GB.
The calculation to show 4GB in this article is I believe based on this from the specification:
• C_SIZE This parameter is used to compute the user’s data card capacity (not include the security protected area). The memory capacity of the card is computed from the entries C_SIZE, C_SIZE_MULT and READ_BL_LEN as follows:
memory capacity = BLOCKNR * BLOCK_LEN
Where
BLOCKNR = (C_SIZE+1) * MULT MULT = 2C_SIZE_MULT+2 (C_SIZE_MULT < 8) BLOCK_LEN = 2READ_BL_LEN, (READ_BL_LEN < 12)
To indicate 2 GByte card, BLOCK_LEN shall be 1024 bytes.
Therefore, the maximal capacity that can be coded is 4096*512*1024 = 2 G bytes.
Example: A 32 Mbyte card with BLOCK_LEN = 512 can be coded by C_SIZE_MULT = 3 and C_SIZE = 2000.
This does not say that the BLOCK_LEN value can be greater than 1024 and as the specification elsewhere says 2GB is maximum capacity why keep pushing the 4GB size? noq ( talk) 13:31, 31 March 2010 (UTC)
Does anybody know if there is an extension lead available that enables an SD card to be inserted into one end - female (i.e. the same connection as is found on a laptop), the other end being a male connection. Any help would be greatly appreciated.
The article currently says this. I added the citation needed tag because it's unsourced. More importantly it sounds rather dubious. The simple fact is the SD 2.0 spec which defined SDHC cards only specified up to 32GB. The fact that larger is possible by simply specifying a larger size doesn't change the fact it's not in the spec therefore a fully compliant SDHC device is not guaranteed to work with a card greater then 32GB. If the SD group had simply defined a SD 3.0 or 2.5 even if they had used FAT32 but allowing greater then 32GB this would likely lead to confusion since you would have SDHC cards greater then 32GB but which may or may not work with older fully SDHC compliant devices. For this reason giving a new name is preferred in many areas, even if it's simply SDHC2. As for the file system, the limitations in certain versions of Microsoft Windows may have been a factor but I haven't seen much evidence it was the sole reason why exFAT was selected over FAT32. As far as I understand it, there are several reasons why exFAT may be preferred for rather large volumes, e.g. 2TB (the maximum SDXC specifies); performance, maximum file size. In other words, perhaps without the Windows limit the SD2.0 would have specified larger cards e.g. 64GB or 128GB as the maximum for SDHC but there's no reason to think we wouldn't still have had SDXC at some stage and probably not using FAT32. So the article is likely misleading to make the unsourced claim the sole reason for SDXC and to use a different file system is due to the limitations in Windows. Nil Einne ( talk) 07:39, 3 July 2011 (UTC)
Is the acronym SDSC something used by official standard bodies, or invented by various forums? Electron9 ( talk) 00:10, 22 May 2011 (UTC)
This article is full of extraneous links. Only the first instance of a link (eg, SDHC) is necessary. Also, many links that used to go to other pages (eg, microSD) simply redirect back to this (article) page. Is there a WP 'bot' that can clean this up? Regards, nagualdesign ( talk) 17:13, 21 July 2011 (UTC)
The lead section says that SDXC cards have an upper limit of 2 TiB, but the section of the article focused on SDXC cards says they have an upper limit of 2 TB. I realize that the difference is functionally moot, given the standard practice of binary prefixing, but since the first instance is the unusual form, I feel that it ought to be changed. Feedback? 69.105.38.18 ( talk) 17:48, 9 July 2010 (UTC)
15, June 2011:
I see in the article, when stating capacities, it is always in MB, GB or TB, not MiB, GiB or TiB. Does, for instance, a 2 "GB" SD card really have 2GB of data storage (like a hard disk), or GiB (Like a memory chip,, 2 to the power of..)?
My 2GB SD card has a capacity of 1.83GiB (after formatting), which leads me to believe that its capacity is 2GB. A 2GiB disk volume would have a capacity of 2GiB after formatting, I think. — Preceding
unsigned comment added by
184.76.47.120 (
talk) 03:54, 16 June 2011 (UTC)
In respect to Secure Digital cards, 1 megabyte = 1 million bytes and 1 gigabyte = 1 billion (U.S. billion) bytes. See the cautionary notes on the packaging; this has been the case from the beginning. Thus, the use of the binary prefixes in this context is incorrect. — Preceding unsigned comment added by 96.251.57.12 ( talk) 00:51, 10 October 2011 (UTC)
"Fragmentation may slow down the effective write speed but the effect is tiny compared with that of fragmentation on hard drives. Defragmentation tools may be used. However, it is unnecessary to use any disk optimization tool because on an SD card the time required to access any block is the same."
So, is the read delay "tiny" or nil? — Preceding unsigned comment added by SomeAvailableName ( talk • contribs) 08:29, 10 March 2011 (UTC)
In the past, what is the Lowest-Capacity that EXISTS for each of these card types? I'm not talking about the standard, but what is the lowest card that ever shipped.
• Sbmeirow • Talk • 10:55, 7 March 2011 (UTC)
I deleted the second paragraph of Section 11.2, on a "homebrew hack" that interfaces an SD card to a popular router, explaining in the Change Summary that there is now a better way of getting an SD card on a router (new products under $100 by several makers that have USB ports). The author reverted me and explained on User talk:Electron9 that one point the paragraph made was the simplicity of the SD interface. I still am not sold on the relevance, but don't feel strongly about it, and leave the issue for possible comments by third parties. Spike-from-NH ( talk) 21:27, 25 October 2011 (UTC)
Last try from new editor (I understand that SOME of you do not want to lose some of US). (Some of this message may need to be moved to one or more topics - though I don't know list of topics.) Go ahead.
I tried to alert you that IMO the article was too technical. I would think that is the kind of feedback that you would want - even if you are sufficiently knowledgeable about the topic to think that the writing is NOT too technical. (My practical suggestions are near end of this message.) I was precise to state the "too technical" at front-end of my comments. Then, I detailed it with enough information (TMI?) that someone could follow my train of logic to understand why I believe it is "too technical." I am fine that article was moved, but the reasoning given to me was that my questions were "buying advice" questions. No, those were the questions that brought me to the site. SD card now bought. Info from this site did not give me info I sought to help me understand basics of purchase-decisions. e.g., My task was "buy SD card." Simple task, if you know what it is. (I already knew I needed MICRO SD card, at least 2 GB, but that was all.) Compare: Sent to grocery to "buy potatoes" or "buy apples" - Unless you know intended use (and cook's proficiency), you have good chance of buying "wrong" potatoes or apples. (i.e., Some potatoes better for baking, mashed, potato salad. Some apples better for pies vs. raw-eating. Don't know: ask someone in Produce Section. Cannot use same logic at store - unless can trust the store.) Seems that issues of SD cards is similar. One basic thing I needed to know was whether SD and SDHC interchangeable for my use. (People who suggested "buy-online" or "wait till Black Friday" missed the point of the details I provided. If this was a purchase that could have waited until I could research it, that would have been fine advice .- which I would have known anyway)
FWIW, someone advised I could "tag" the article as "too technical" - but, without telling me how to do that - Or, telling me in a way that is too technical. Person tell me to do x, but in a way that is too technical for me (at this point) to know how to do x. At this stage, if your suggestions/comments are written in mark-up language, without explanation, I am not going to understand. (I have previously asked if there is a 'Wiki-edit Glossary.') I AM *NEW* here. I will learn more if people tell/show me how to do something, rather than changing it on my OWN page FOR me. ("Give a man a fish..." vs. "Teach a man to fish....") Far better to talk WITH someone than to talk AT them.
My suggestions: Perhaps all articles, but certainly articles of technical content, could have a scale (1-5?) re intended audience, or, pre-requisites. e.g. " Before reading this article, see xyz (with pointer). If you understand everything there, then return here." Similarly, edit box gives option to indicate whether one is highly knowledgeable about something. This is a binary question. Would you not get more useful info if people could rate their knowledge on 3-point or 5-point scale?
Note: if I am not responsive soon, I suggest no over-interpretation. I have much else that also needs attention. I expect to be here episodically, at least for now, rather than "be here usually." -- KnowLimits ( talk) 01:49, 25 November 2011 (UTC)
![]() | This article may be too technical for most readers to understand.(December 2011) |
Accessibility is discussed in the linked article from this banner. Accessibility should be achieved without removing notable technical detail. -- Kvng ( talk) 23:42, 26 November 2011 (UTC)
The rapidity at which vendors complied with an extension of the specification might be notable. A list (in our Section 7.1) of dates on which specific vendors announced that they intended to ship a compliant product, is not notable. Spike-from-NH ( talk) 00:36, 26 November 2011 (UTC)
Because this talk page is getting rather long, and has comments going back to 2005, I propose setting it to automatically archive threads older than 90 days (but leaving a minimum of 5 threads).
If nobody objects, I will add the code to do this in about a week. Chzz ► 10:14, 25 November 2011 (UTC)
Fine, so, I'll make it 1 year - after waiting a few more days. It's easy to adjust the time later anyway. Chzz ► 09:46, 28 November 2011 (UTC)
Done
Continuing with the discussion in "Too technical" and "History" above: I envisage leaving in "Design and implementation" only the features that help a reader decide what SD is all about and what flavors there are--then renaming it "Features". Sections that describe how it works ("File system", "Transfer modes", "Interface", "Power use", and "Storage capacity and incompatibilities") I'd move to a new section "Technical details" to occur afterward, even after the sections that describe the market acceptance and vendor-specific features.
The fact that the ability to plug an SD chip into an SD slot is impeded by several factors seems important to a lot of readers; I also appreciated knowing exactly what goes wrong, and the exact history, but these are also "Technical details". I'll volunteer for the editing, but will instead focus on nits for a few days to await youse's responses. Spike-from-NH ( talk) 14:30, 28 November 2011 (UTC)
Well, the silence was deafening, and it is now done. I've reorganized the article in this order:
Followed by stuff you might not need to know:
Apologies in advance if people are suddenly unable to find anything! Spike-from-NH ( talk) 12:20, 5 December 2011 (UTC)
The article describes Thin SD in two places as "rare" (I think the article used to hedge its bets by saying "rare or nonexistent") but I've never seen one. Similarly, my uneducated guess is that there is no new product design for which miniSD is the best choice, and a quick use of Google only shows sales of off-brand miniSDs, some at "close-out" prices, presumably for owners of existing host devices. If miniSD is a dead end, it is notable and the article ought to say so, but I wouldn't know what to cite as proof of this. Spike-from-NH ( talk) 12:52, 7 December 2011 (UTC)
I've been corrected once after writing "an SD" (which I read "an ess dee" not "an Secure Digital") but the article has it both ways. Is there a decision on this? Spike-from-NH ( talk) 12:52, 7 December 2011 (UTC)
The "Technical details"/"Interfaces"/"SD Card Pin-outs" section needs to include the pin assignments for the micro and mini sizes as well as the standard size as the mapping is not obvious (the cards even have different numbers of contacts). JohnAHind ( talk) 18:23, 21 December 2011 (UTC)
Despite the deafening silence on the above queries in the last two weeks, I have another query. Matthiaspaul has edited the article to assert that the use of the exFAT file system is mandatory for all SDXC cards. The understanding I had, based on the text of this article when I started massaging it, is that depending on the specification version it obeys, SDXC cards could be factory formatted with either FAT32 or exFAT.
Paul also makes a good case that the decision to use exFAT is disastrous, as it requires (at least for universal compatibility) manufacturers to embrace a technology that is proprietary and that "many alternative or older operating systems do not support exFAT for technical or legal reasons" (his wording as I edited it). If true, though, this should be treated as a controversy we document rather than a fact that we report. He also states that FAT32 could have been used for file systems above 32 GB, such as those on SDXC cards, but I see a claim that this wouldn't be supported under Windows, which is a good reason not to do so; at any rate, this veers toward advocacy.
More knowledgeable editors than I should review the text to make sure we are saying the right thing in the right way. Spike-from-NH ( talk) 12:56, 25 December 2011 (UTC)
Please upload YOUR personal photos and drawings to Wikimedia Commons, so we can use them in this article:
After you upload, please leave a comment in this section and remove the request. • Sbmeirow • Talk • 01:41, 26 November 2011 (UTC)
I woonder if they would let us use the image from here ? It does show the evolution to smaller sizes nicely ! -- 195.137.93.171 ( talk) 22:10, 29 February 2012 (UTC)
I've heard that when Bit 13 of the CSD is set an SDHC card becomes permanently read only with no possibility of unsetting the bit. Is this true or BS? Bizzybody ( talk) 09:56, 11 March 2012 (UTC)
The article refers to four types of SD card: SDSC, SDHC, SDXC and SDIO However:
May I suggest that
fwiw LookingGlass ( talk) 21:18, 23 May 2012 (UTC)
From the article:
Following the reference leads to a page which says this:
The article seems to be saying the opposite of the source. However, I got here because of a discussion on a web forum where someone was able to use a SDXC card in a SDHC device, so I don't think this is just a case of misquoting the source. What's going on here? Ken Arromdee ( talk) 20:10, 31 May 2012 (UTC)
The table listing “×” ratings (which, remember, is an old metric) is getting out of hand and I have pared it back. A previous contributor created separate columns for read speed and write speed, though the text makes it clear that various vendors vary in their selection of speeds as a basis of measurement. Today Anon has expanded the table further, to go from "common ratings" apparently to all conceivable ratings. He has also inserted question marks after most of the measurements, which seem to call into question their usefulness and express an opinion of disapproval--but we already knew both things.
The table ought not be to tell the reader how fast their 120× card can perform, because we can't do that, but to give a small, representative list of old-style ratings, and relate them to the newer Speed Class, with the cautionary notes set out in the text.
Anon has also asserted measurement error in the table and the text, which I am not an expert on, and I did not post-edit him there. Spike-from-NH ( talk)
Nowhere in this article could I find the most fundamental information about SD cards: what memory they actually contain. The summary simply says they contain "Non-volatile memory" without any details at all, this seems like a massive omission! — Preceding unsigned comment added by 80.4.146.163 ( talk) 17:24, 28 June 2012 (UTC)
Could someone please explain the meaning of "secure" in the name? Gwideman ( talk) 05:38, 15 April 2012 (UTC)
The article says "Any recent version of the above can format SD cards using the UDF file system." I just tried Windows 7 HP SP1 and it does not offer UDF when formatting an SD card. I guess it is a case of "citation needed" ? -- Xerces8 ( talk) 22:09, 25 October 2012 (UTC)
The GPX MW3836 (with SUFFIX NO: E1 label) MP3 player is able to read/write up to at least 4GB SDHC even though GPX claims is can only use up to 1GB standard SD cards. That gives this cheap $20 player 5GB of storage. :) I've a Lexar 4GB SDHC in mine. It'd be nice to see a site off-Wikipedia with a list of specific devices that support SDHC though they officially don't.
It quite often happens that devices support things that their manufacturers don't claim (including things available at the time). The claim is basically "we have tried this and pretty much guarantee that it works. If you try anything else, great, but don't come whining to us". I have plenty of devices that accept larger SD or Micro SD cards than claimed, larger laptop and desktop computer RAM than claimed, and so on. Lots of Windows XP computers that "don't" support Windows 7, do. Asus motherboards for AMD processors generally support and make use of ECC memory, though memory manufacturers don't list this. Of course, you may run into trouble when 8GB model xyz works and you buy 8GB model zyx, which doesn't. I've found a Google search like <Inspiron 1501 4GB> to be useful. Pol098 ( talk) 15:24, 31 December 2012 (UTC)
I added text:
The speed class rating does not totally characterize card performance. Different cards of the same class may vary considerably while meeting class specifications. In addition, speed may vary markedly between writing a large amount of data to a single file (sequential access, as when a digital camera records large photographs or videos) and writing a large number of small files (a random-access use common in smartphones). One study found that, in this random-access use, some Class 2 cards achieved a write speed of 1.38Mb/sec, while all cards tested of Class 6 or greater, including those from major manufacturers, were over 100 times slower.
Some Original Research: I tested two 8GB Micro SDHC cards, including one from a manufacturer supporting small files well, and another (which had been my preferred choice before checking sources) from a manufacturer with a good reputation. The first card with CrystalDiskMark got a 4kB file writing speed of well over 1MB/s (I didn't write it down unfortunately), the other 0.007MB/s (decimal point, 2 zeros, 7, no typo). While photographs and video recordings are a different matter, for general-purpose mobile phone and similar use, handling small files well is important, particularly if running programs off the card. Pol098 ( talk) 15:36, 31 December 2012 (UTC)
Lots of subtleties here concerning how different SD cards are designed and whether the devices they plug into keep them powered up, let them go to sleep automatically, put them in sleep mode, up pull the plug and shut off the power to the card. for example:
http://harizanov.com/2012/05/tinysensors-sd-card-power-consumption-worries-and-solution/
http://www.motherboardpoint.com/micro-sd-power-consumption-t191597.html
I think that the best we can do is to simply say that power consumption varies widely between different cards and between different devices the cards plug into. Either that or give power consumption of SD cards a separate article and try to cover all the variables. -- Guy Macon ( talk) 22:51, 1 January 2013 (UTC)
To pick a nit on a separate editing issue: "envisage" is the British rendition of "envision". As this article uses American grammar, the latter is appropriate and the recent edits are good. Spike-from-NH ( talk) 14:23, 9 January 2013 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 |
Can someone expand the paragraph on speed in this article? I recently bought a camera that uses SD and SDHC cards, and in my attempt to find out which cards are fastest, I've found a confusing jumble of information. The new SDHC format has Type 2, 4, and 6, corresponding to speeds of 2, 4, and 6MB/sec, but that's clearly not the whole story, because SD and SDHC cards are being advertised as 60X, 120X, 150X (this is the only part defined in the article), and there are considerable differences between read and write speeds that aren't always obvious to shoppers. With manufacturers claiming 23MB/sec, and the newest spec calling for 6MB/sec, there's definitely some important information missing in that gap. I'd start the section myself, but it's clear that I don't have all that much of a clear idea on the SD/SDHC speed situation. - Erik Harris 20:01, 14 October 2006 (UTC)
Why does the page (Dec 1 '08) say "SD cards typically have transfer rates in the range of 10-20 MBytes/s, but this is always changing, particularly in light of recent improvements to the MMC standard.[4]". Strange, most SD cards claim to be nowhere clsoe to that fast! 67.242.12.28 ( talk) 20:39, 1 December 2008 (UTC)
Basic cards transfer data up to 6 times as fast (900 KiB/s) as the standard CD-ROM speed
Six times as fast, does it mean six times faster? Or that it is six times faster than the slowest SD speed, to bring up to the same speed as cdrom? I don't get it JayKeaton 07:05, 21 October 2006 (UTC)
While looking for a digital camera I stumpled upon some terms that are not explained in this article:
A retailer talked about 80 speed (before Ultra "he thought") and 150 speed (with ultra "he thought"). Also he was not able to tell me what measurement unit the 80 and 150 is in.
Velle 10:46, 15 June 2006 (UTC)
I see an ad for a Scandisk Ultra-II 2GB SD card with "a minimum sustained write speed of 9 megabytes (MB) per second and a read speed of 10MB per second." Will these work with all SD reader devices, or do the devices have to be ready for the higher transmission speeds? Thanks, AxelBoldt 03:34, 14 Feb 2005 (UTC)
Anyone know the minimum size of a SD Card? I'm guessing 4mb but I could be wrong Towel401
Blorg 16:39, 11 Nov 2004 (UTC)
The site referred to by the second external link, http://www.handhelds.org/projects/h3800.html, appears to be down. This may be temporary, but does anyone know if that page is still valid? -- LostLeviathan 06:08, 4 Dec 2004 (UTC)
The Technical Explanation section states "Royalties for SD/SDIO licenses are imposed for manufacture and sale of memory cards and host adapters ($1000 per year plus membership at $1500/year) but SDIO cards can be made without royalties and MMC host adapters do not require a royalty." Is it correct that a license and royalty is not required if a host adaptor is implemented in firmware using the lower performance MMC/SPI mode to communicate with an SDIO card, even though a SDCard Association membership is required to obtain the required documentation? If true, is it possible then to sell a product containing an SDIO-only card (not combo) and host adaptor without the need to pay any liscense fee or royalty to the SDCard Association? -- 216.54.240.190 18:02, 13 July 2005 (UTC)
Also, what does this sentence mean: "Overall, SD is less open than CompactFlash or USB flash memory drives, which can be implemented free of charge, but require licensing fees for the associated logos and trademarks." I have no idea whether it's telling me that SD cards do or do not require licensing fees, logos and/or trademarks. It should be broken out into self-contained unambiguous sentences.
Under the guise of "examples", currently there are a couple of links to 3rd party vendors of a product or two right now in the main article page. I suggest these be removed. -- SaulPerdomo 19:52, 18 September 2005 (UTC)
Description and market Penetration section stated that current dSLRs were using CF exclusively (the Nikon's D50 being the only exception). I've added the three Pentax models, which use SD as well (even before D50). I've also just recalled that Canon's flagship models EOS 1D Mark II/IIN and EOS 1Ds Mark II can use SD as storage media as well (in addition to CF).
So, I'm thinking: could we expect deeper SD penetration in this market any soon? If so, it could be proper to change the text in the second paragraph to "Additionally, SD has not yet conquered the Digital SLR market" and/or "where CompactFlash still remains the most popular format" (and then appropriately change the text in parentheses too). I'm not quite sure myself, so I'm not really suggesting it (yet). I'd rather be happy to hear what other people think. -- Bilbo 18:25, 11 January 2006 (UTC)
I think that SDHC will slowly overtake CF in dSLR cameras. Many now offer dual support, and the availability of adapters to use SD/SDHC cards in a CF-equipped camera are commonplace. I have used one for quite awhile and my last few card purchases have been SDHC. The advantages of SD/SDHC over CF are numerous, from the smaller size to the higher durability, and in many cases all else being equivalent, SDHC are often cheaper. For me, the use of SDHC is one of added flexibility as I can use them in my dSLR, my wife's smaller camera and directly into our TV for slide shows. I think the 'most popular format' statement is likely outdated now (May 2010) but have no data to back it up.
-Both CF and SD however, seem to be able to withstand numerous laundry wash/dry cycles....;) Ken ( talk) 20:28, 18 May 2010 (UTC)
I've seen many digital cameras that say they support SD cards "up to 512MB". Does anyone know more about this? —The preceding unsigned comment was added by 131.191.67.168 ( talk • contribs) .
I think it's using some chip with CMOS NAND Flash technology. Maybe 90 nm CMOS process?
With 2TB spec out SD may become a viable alternative to tape backup or Bluray, but how long will the data stay good on an SD card? —Preceding unsigned comment added by Squid57squid ( talk • contribs) 16:07, 15 May 2009 (UTC)
Does anyone have some somewhat-rigorous information on the difference between SD and SDHC? I was under the impression that SDHC simply standardized the acceptance of the FAT32 file system in SD cards, and that there weren't any other really substantive differences between the two formats. That would be enough to explain the compatibility differences, because a device designed to support only FAT16 would not read a FAT32-formatted card. However, most of the 4GB cards on the market today are not SDHC cards, and do not truly conform to the (FAT16-based) SD 1.1 standard, either. As such, they do not work in many devices designed to support SDHC cards. This tells me that there's a more significant difference between SD and SDHC. I'd like to know what those differences are, but I've come up empty in my search for info. - Erik Harris 12:16, 23 October 2006 (UTC)
Some manufactures, such as Pretec are introducing a new kind of cards called SuperSD. These cards are compatible with both SD 1.1 and MMC 4.0, however they have their own standard from the μ Alliance. There are also smaller version of SuperSD cards. I think that these cards should be mentioned here.
http://www.files.e-shop.co.il/iag/sd/SuperSD_DM-back.jpg
194.90.21.74 09:43, 25 October 2006 (UTC)
The SD card can also be locked to a specific device. I do not know if this is simply a part of the DRM properties, or it's a security feature being available for the end-user. If I lock the miniSD card on my phone, I cannot access it elsewhere, and the card is not readable under Windows nor mountable under Linux. Unlocking the card makes it accessible again. Some more explanation of this would be greatly apreciated. —The preceding unsigned comment was added by 195.249.172.62 ( talk) 2006-11-23T01:19:54
I have removed the following uncited text from the article, pending a citation, and simplified paragraph:
There is, however, a less well-known fact: the tab is implemented only as mechanical part (detected by a contact switch inside the SD Card socket) so that the device can write to the write protected SD card if its firmware decides to ignore the tab or if the switch is broken. Many users reported data loss when the switch was worn down or broken especially on early sockets where manufacturing process was not perfected or due to firmware bugs. Some devices also allow users to ignore write protect switch for user's comfort. Kingmax makes its SD cards without a write-protect tab because the company claims that the tabs are too fragile [2].
-- Peter Campbell 22:38, 21 December 2006 (UTC)
(this would be best added into the table) What is the max supported size of SD ? The article says "Capacity limit in all SD/MMC formats appears to be 128 GB ..." But then later "A new SD format, SDHC, allows capacities in excess of 2GB". So is SD limited to 2GB, 128 GB or something else ?
xerces8 , -- 195.3.81.25 10:28, 19 January 2007 (UTC)
The whole GB/GiB thing always confuses. Is the "1GB" cards really 1GB? Is the 512MB cards really 512MiB or 512MB? If the 512MB cards really is 512MB, then isn't the 1GB cards 1,024GB? It's kinda confusing. I highly doubt that the 1GB cards really is 1GB cards. I do NOT think that wikipedia should "lie" about the size just because the cards says something else. —Preceding unsigned comment added by Ran4 ( talk • contribs)
There seems to be some confusion out there about how the SD cards are to be formatted. The SD Card Association has official card formatting software. http://www.sdcard.org/about/downloads/ . The software is free and includes a PDF manual in English and Japanese. The manual notes that "Generally, SD/SCHC Memory Card file systems with generic operating system formatting software do not comply with the SD Memory Card Specification. If you have formatted SD/SDHC Memory Card with generic operating system formatting software, reformat SD/SDHC Memory Card using this software or the appropriate formatting software prepared by the SD hosts provider." 67.169.225.3 05:08, 7 April 2007 (UTC)ddevore
In effect I had troubles using SD 2GB cards formatted with Windows XP (both FAT and FAT32): I experienced very low transfer rates writing files to subfolders. I solved reformatting with the aforementioned software. Updated version can be found here: http://panasonic.jp/support/global/cs/sd/download/sd_formatter.html
Please keep in mind that Wikipedia is an encyclopedia, not a tech tutorial/advice website. Some of the recent changes strayed greatly from an "encyclopedic tone" and turned the article more into a how-to column, with lines like "when purchasing memory cards, do this." Also note that anything contained within <ref></ref> tags does not appear in the main body of the article. One of the reference descriptions was changed in such a way that it made no sense in the proper context, but might have made sense if it were inserted into the article. I've done my best to manually reverse these changes without reverting all of the other changes that have been made recently. — Erik Harris 15:33, 9 April 2007 (UTC)
As of February 2007, the SDCA has released an updated version of the simplified specification. Does anyone know what prompted this update? Also, the OLPC project says it has produced a truly open-source SD implementation. I've added both these things to the article, but I would like more context:
It'd be nice to provide more information on the capabilities and limitations of open-source implementations. MOXFYRE ( contrib) 18:01, 4 May 2007 (UTC)
There seems to be mass confusion about what exactly are the different modes of operation supported by SD cards. Especially it has become clear that the MMC and SPI modes are *not* the same (SPI mode is sort of a limited subset), as Samsung's datasheet clearly distinguishes them. Also, is the one-bit SD mode the *same* as one-bit MMC mode? Part of this article says that they're different because the one-bit SD mode uses separate data and command channels, but below the big comparison table it's implied that they are the same. The 4-bit and 8-bit parallel modes are clearly distinct. I think we really need to sort out the different SD access modes:
MOXFYRE ( contrib) 15:16, 11 May 2007 (UTC)
I believe that the diagram works best in the infobox to show at a glance what an SD card looks like. Rstoplabe14 disagrees however and believes that his image of two SD cards should be used instead. I think we need to establish a consensus on using either one or the other. AlexJ 14:48, 4 September 2007 (UTC)
I am not a Wikipedia writer or editor or any such thing. I am just a web surfer, and I want to share the following story with you. I wanted to find out what the *bottom* of an SD card looks like. So I did some Googling, and after looking at a ton of web pages that only showed the *top* of an SD card, I finally was happy to find this page because it shows exactly what I was looking for: a picture of the *bottom* of an SD card. Thanks for putting that picture here, and I also suggest that you put such a picture on the web page at this URL: http://en.wikipedia.org/wiki/Secure_Digital_card JohnDrefnier 04:30, 10 September 2007 (UTC)
What about the Eye Fi-card? Info about that card isn't as yet included in the article. 81.71.112.102 18:51, 31 October 2007 (UTC)
The article incorrectly states that EyeFi uses a nearby computer, however, I once read an article that said it uses a boradband WiFi to connect to EyeFi servers, and then back to the host computer, which must be running their software. Can anyone confirm this or knows which article I'm talking about? -- stuston ( talk) 20:18, 16 January 2009 (UTC)
The DRM section (mostly the second and subsequent paragraphs) sounds quite full of FUD to me. Nothing is sourced and it sounds like just a rant, slightly paranoid, on DRM. I don't see that it adds much that's useful. - Ethan ( talk) • 2007-11-25 00:55 (UTC)
According to Sd card#Speeds, SD cards come in four different possible speeds - 0.9mb/s, 6mb/s, 10mb/s, and 20mb/s. According to Sd card#SDHC, SDHC cards come in three different possible speeds - 2mb/s, 4mb/s, and 6mb/s. From that, it looks like the fastest SDHC card is slower then the fastest SD card. Is that correct or is there something I'm missing? And if it is correct... why? According to the article, "SDHC uses a different memory addressing method". Is that what's slowing it down? TerraFrost 19:57, 4 December 2007 (UTC)
Reference 10 on the article claims that the current maximum capacity supported by the "Physical Layer Simplified Specifications Version 2.00" for SDHC is 32GB. If I understand correctly a new version of the specification could support more, but it's not clear if a hardware or software update will be required for readers to suport higher capacities than 32GB. I don't want to muddy the waters here by editing the article without being certain. Input anyone? --Anonymous —Preceding unsigned comment added by 221.106.232.1 ( talk) 01:05, 14 February 2008 (UTC)
This site also claims 32GB is maximum. Someone please clear this up. -- Xerces8 ( talk) 09:37, 4 March 2008 (UTC)
Page 97:
Page 98:
Page 98:
Thus the card have bit fields to represent upto and including 2 TByte. BUT the SD Card association have decided that memory cards shall be limited to 32 GByte. However this doesn't prevent any 3rd party to make hardware that will handle this just fine. Electron9 ( talk) 11:00, 16 March 2008 (UTC)
Technical reference as to why SD-Cards v1.01 can handle 4 GB as per the standard document: In the SD Card Associations "Simplified Physical Layer Specification v2.00" it is specified in:
Page 89:
Name | Width | Cell type | CSD-slice |
---|---|---|---|
READ_BL_LEN | 4 | R | [83:80] |
C_SIZE | 12 | R | [73:62] |
C_SIZE_MULT | 3 | R | [49:47] |
Page 91
READ_BL_LEN | Block-length |
---|---|
0-8 | reserved |
9 | 29 = 512 Bytes |
10 | 210 = 1024 Bytes |
11 | 211 = 2048 Bytes |
12-15 | reserved |
Page 92
I hope this clearify the situation on SD-Card v1.01 capacity. However not all devices are implemented in such way to allow for READ_BL_LEN to be set to 10 or 11. Electron9 ( talk) 10:45, 16 March 2008 (UTC)
In the "form factor" section, it states that "SD cards typically have higher data transfer rates, but this is always changing, particularly in light of recent improvements to the MMC standard."
Higher than what? Memory Stick? CF? —Preceding unsigned comment added by 66.131.186.22 ( talk) 01:09, 28 March 2008 (UTC)
It seems some people have fun by changing the max capacity of SD-cards to something which is in contradiction to the specification. Even when the relevant parts are included within the article itself!
The last incident is with Amoiwangjy on 2008-05-20 that only have one contribution and a Comcast Cable/NJ user on 2008-05-30 that then changed the "contradiction" to be an all out consistently wrong information.
A standard SD-card can handle anything from 2048 bytes to 4 GB.
c_size=0, c_size_mult=0, read_bl_len=9
(c_size+1) * 2**(c_size_mult+2) * 2**(read_bl_len) = 2048
A standard SDHC can handle anything from 512 KB to 32 GB (inoffically 2 TB).
c_size=0
(c_size+1) * 512 * 1024 = 512 * 1024
This not saying that they are sold with all possible capacities. Usually 8 MB is the minimum.
Some SD-card reader systems does not correctly process the READ_BL_LEN parameter. And therefore will not correctly recognise some cards (esp 2G and 4G cards in std sd-card readers). But this is NOT the same as saying >1GB - 4GB standard sd-cards doesn't exist or will not work. Electron9 ( talk) 01:46, 13 June 2008 (UTC)
There seems to be substantial overlap between the SDHC and SDXC specs. Are the latter backwards-compatible with SDHC readers? This seems especially pertinent with SDXC cards being announced in the 32GB range, overlapping with currently available SDHC cards. MrZaius talk 11:01, 6 March 2009 (UTC)
There are SD 1.01 cards available w/ read and write speeds more than 66x, i.E. [3]. I own one of this cardws myself (the 133x/30x 2GB version). It only can be read at about 5.4 MB/s (~36x) w/ my card reader using hdtach, but I think the reasopn for this is my old card reader (hama 19 in 1 rev. 1.0, model number 00055114). -- MrBurns ( talk) 08:23, 14 March 2009 (UTC)
This article places the reference to the Speed Classes (6.1 SD Speed Class Ratings) under SDHC (6 SDHC). While both SDHC and the Speed Class came out of the Version 2.00 spec, and SDHC Cards must meet at least Class 2, the Speed Classes can and do apply to SD Cards as well as SDHC Cards. In other words, the specification does not preclude the use of Speed Classes for SD Cards (as opposed to SDHC Cards.)
For instance, the SanDisk Extreme III 2GB SD Card is a Class 6 Card, the SanDisk Ultra II 2GB SD Card is a Class 4 card, and the SanDisk Standard 2GB SD Card is a Class 2 card. SanDisk is not alone in the use of Speed Classes for it's SD Cards. PNY identifies its 2GB Optima Secure Digital as a Class 4 card.
I think the subheading of SD Speed Class Ratings (6.1) should be moved to 3.1, under the heading of Speed. TCav ( talk) 21:22, 2 April 2009 (UTC)
SD cards have a small lock switch (at least the large ones). You can also see this on the photos included in the article. What is this switch good for? Could someone include this information in the article? Thanks! -- 86.135.82.168 ( talk) 11:35, 31 July 2009 (UTC)
There are hacked cards that act like say 16 gig cards but after you put more than a gig on them data starts getting lost. There are also cards with stickers for class 6 but are actually class 2. Some mention to this fraud should be given. —Preceding unsigned comment added by 204.13.130.37 ( talk) 17:24, 14 August 2009 (UTC)
I had a chance to use this article for finding a right card for my situation, and I found that the following aspects are missing or not clear in the article:
I still don't feel an expert in the topic, but hopefully someone can give answers by improving the article itself. Thanks! -- DenisYurkin ( talk) 22:21, 29 August 2009 (UTC)
Please add to the article to explain why is it called "Secure" Digital? Does it have some security features? If so, what are they? What types of problems do they defend against? Or is this just meaningless marketing hype? 68.110.104.80 ( talk) 17:16, 1 November 2009 (UTC)
"Some manufacturers have produced 4 GB SD cards that conform to neither the SD2.0/SDHC spec nor existing SD devices. [1]"
So it doesn't conform to SD (SD v1.xx) nor SDHC (SD v2.00). And no mention of SDXC, so what does it conform to ..?? :-) Electron9 ( talk) 04:40, 10 December 2009 (UTC)
The article lacks technical details on SDXC. For example, is it a type 2 card (like the way SDHC type 1)? Does it siiply use the 6 extra bits (for a total of 22 bits) that are currently unused in the SDHC (which only allows the use of 16 out of the 22)? Has the SD association ever said why they only extended SD to 32GB (from 2GB if you follow their official specs) when it seemed fairly obvious that wasn't going to last very long and it seems that they could have easily supported 1TB at the time (albeit what file system to choose may have been a more difficult choice)... (The obvious answer is money, but may be thay have an offiical answer on why they did this) Nil Einne ( talk) 09:02, 25 January 2010 (UTC)
So how come I keep seeing them on the shelves in random photo and electronics shops? There's still a stock of them knocking around and there must still be enough of a user base occasionally buying fresh cards (why throw out a perfectly servicable 3 or 4 mpixel camera with good optics if it hasn't broken, just because it's >5 years old?) for it to be worth that small square of the establishment's shelf space. Case in point, last time I found a film camera in the cupboard with a near-finished film, took the last couple shots and dropped it off at the local pharmacy for processing (mid january this year (2010)) - a few packets of 128mb smartmedia hanging on their flash card rack, inamongst the SDs, memory sticks, compact flashes and XDs. Price was ludicrous for the capacity (£20?) but it was there and available. Plus Amazon has _loads_ of them. 193.63.174.10 ( talk) 14:35, 15 March 2010 (UTC)
The article says "Standard SD card capacities have a maximum of 2 GB.[1] The capacity range for high-capacity SDHC cards overlap, beginning at 4 GB". So apparently they do not overlap. Where is truth? Goochelaar ( talk) 13:07, 18 March 2010 (UTC)
Hi guys,
Please don't change data rate measurements to bytes per second. it leads to confusion.
InternetMeme ( talk) 15:09, 13 June 2010 (UTC)
The main page of this article lacks information on the maximum heat a typical SD chip can perform in.
Do chips ever fail because of high heat? Does the data transfer at different speeds ever change when the operating temperature reaches a critical point? Dexter Nextnumber ( talk) 02:11, 23 June 2010 (UTC)
I understand one of the "secure" features of SD is a read only, guaranteed unique ID a lot of embedded system software uses for copy protection. Can anyone pitch in on this? Thanks! —Preceding unsigned comment added by 84.1.50.169 ( talk) 20:41, 24 June 2010 (UTC)
I think that UHS specification belongs to Transfer modes rather than to Speeds section. Despite of marketing fuss about it, the specification itself seemingly have nothing to do with minimal speed of transfer. Real cards (like Kingston SD10A/64GB) are still double labeled with Class 10 and UHS-I. It seems that UHS-I label is just a characteristic of interface supported and has no direct connection to the transfer speed. -- Korj.by ( talk) 07:55, 27 June 2010 (UTC)
I cannot find anywhere that sells 4 and 8 gig SD cards. Are they available for purchase, or just in development. If so, maybe it should be noted in the available sizes that you cant buy 4 and 8 gig cards yet. AshTM 00:37, 26 June 2006 (UTC)
These seem to be competing forms of memory storage. Am I correct? What if any significant advantages/disadvantages exist between them? Tmangray 04:01, 12 February 2007 (UTC)
Memory card readers are more and more found embedded in laptops, desktops, printers, etc. This will make them competing soon. —Preceding unsigned comment added by 82.67.63.244 ( talk) 19:01, 10 January 2008 (UTC)
I know there's a table that indicates the ratings, write speed, and class of specific cards, but not a table on specific cards' models or availabilities/discontinuities. The 256MB, 512MB, and 1GB SD cards have been discontinued, and models beyond the 2GB cards are still available. Shouldn't there be a table about the cards' models or availabilities/discontinuities? Just asking.
~~
LDE
JRuff~~(
see what I have contributed) July 20, 2010, 18:06 (EDT) —Preceding
undated comment added 22:06, 20 July 2010 (UTC).
Shouldn't the section "SDHC cards with greater than 32 GB capacity" come *after* the section introducing SDHC cards? Thanks, 71.175.53.166 ( talk) 14:37, 29 December 2010 (UTC)
I propose that we merge MicroSD and MiniSD articles into the Secure Digital article. Basically, the smaller cards are nothing more than a subset of the larger cards. To fill out the articles for the smaller cards would require large amounts of duplicate text. I think it is better to have a one-stop-place for all the information. What are you thoughts? • Sbmeirow • Talk • 22:02, 30 January 2011 (UTC)
![]() | The contents of the MiniSD page were merged into SD card/Archive 1. For the contribution history and old versions of the redirected page, please see its history; for the discussion at that location, see its talk page. |
Can someone expand the SDIO section? How does the electrical interface and protocol compare to CF and PC Card? 132.205.93.63 02:01, 13 June 2007 (UTC)
I think the following information would help many people. I am not sure if it is suitable for Wikipedia. Where could the following be put in order to maybe insert a reference into the SD-Card wikipedia page? Is a different WikiMedia project suitable? If you have an answer I'd be happy if you could copy it to my user page! This is a problem I face quite often. Now the text about SD-cards:
SD cards can become corrupted quite easily when a faulty device deletes its "secure area". It is not possible to revive it with a normal format operation (e. g. the one integrated in Microsoft Windows). Special software can do a low level format. After that and a following high level format the card is usable again. E. g. this free software works: http://hddguru.com/content/en/software/2006.04.12-HDD-Low-Level-Format-Tool/
More info: http://www.internettablettalk.com/forums/showthread.php?t=10014&page=3
HelgeHan ( talk) 14:03, 22 March 2008 (UTC)
Previous to editing this article, I've come across conflicting statements and confusion in multiple engineering blogs and articles. Many people were under the impression that SPI might be optional because of statement in this wikipedia article. Some people said they never found a SD card that didn't work with SPI bus. I decided to download the SD specs and investigate so I could determine the facts, which I then created this electrical interface section and corrected statements in other sections. The only big holes in this section is that I didn't describe the newest 1.8-volt higher speed protocols for SDHC and SDXC families. The most important part that I've done is describe what is common across ALL of the SD families.
I recently emailed the Help Desk at the SD Card Association and asked them to review section Secure_Digital#Electrical_interface. I received an email back from them today, which they said "We have looked over http://en.wikipedia.org/wiki/Secure_Digital#Electrical_interface and the content seems to be correct." Obviously since this is a personal email to me and other people can't validate it, it doesn't prove jack, but I thought I should pass it along.
If you find a technical mistake in the "electrical interface" section, please reply to this comment with the problem and the EXACT section of the SD specification that states otherwise, so we can investigate and determine the correction. Thanks. • Sbmeirow • Talk • 21:08, 24 February 2011 (UTC)
What is the upper limit on the memory size of SD/microSD cards? There has to be a upper limit put down by the laws of physics right (or in other words, theres a limit to how small a transistor can be shrunk)? Can anybody answer this question? 137.132.250.10 ( talk) 10:00, 23 March 2011 (UTC)
This table seems to be wrong -- looks like it should be MB(ytes) not Mbits, but I can't find a decent citation else I'd edit it myself. Anyone? One source here: http://www.toshiba-memory.com/en/sd_speed_classes.html -- but perhaps the official info is buried in the member-only pages of http://www.sdcard.org/.
Class 2: 8 Mbit/s Class 4: 15 Mbit/s Class 6: 20 Mbit/s Class 10: 30 Mbit/s
98.237.205.71 ( talk) 03:25, 11 October 2010 (UTC) —Preceding unsigned comment added by 98.237.205.71 ( talk) 03:21, 11 October 2010 (UTC)
I agree this is confusing and needs to be clarified. Typically I think SD cards are measuered in MegaBytes but I can't verify this.
78.105.181.134 (
talk) 17:43, 30 May 2011 (UTC)
The technical specification linked to by reference 1 explicitly states in multiple places that the maximum capacity is 2GB.
The calculation to show 4GB in this article is I believe based on this from the specification:
• C_SIZE This parameter is used to compute the user’s data card capacity (not include the security protected area). The memory capacity of the card is computed from the entries C_SIZE, C_SIZE_MULT and READ_BL_LEN as follows:
memory capacity = BLOCKNR * BLOCK_LEN
Where
BLOCKNR = (C_SIZE+1) * MULT MULT = 2C_SIZE_MULT+2 (C_SIZE_MULT < 8) BLOCK_LEN = 2READ_BL_LEN, (READ_BL_LEN < 12)
To indicate 2 GByte card, BLOCK_LEN shall be 1024 bytes.
Therefore, the maximal capacity that can be coded is 4096*512*1024 = 2 G bytes.
Example: A 32 Mbyte card with BLOCK_LEN = 512 can be coded by C_SIZE_MULT = 3 and C_SIZE = 2000.
This does not say that the BLOCK_LEN value can be greater than 1024 and as the specification elsewhere says 2GB is maximum capacity why keep pushing the 4GB size? noq ( talk) 13:31, 31 March 2010 (UTC)
Does anybody know if there is an extension lead available that enables an SD card to be inserted into one end - female (i.e. the same connection as is found on a laptop), the other end being a male connection. Any help would be greatly appreciated.
The article currently says this. I added the citation needed tag because it's unsourced. More importantly it sounds rather dubious. The simple fact is the SD 2.0 spec which defined SDHC cards only specified up to 32GB. The fact that larger is possible by simply specifying a larger size doesn't change the fact it's not in the spec therefore a fully compliant SDHC device is not guaranteed to work with a card greater then 32GB. If the SD group had simply defined a SD 3.0 or 2.5 even if they had used FAT32 but allowing greater then 32GB this would likely lead to confusion since you would have SDHC cards greater then 32GB but which may or may not work with older fully SDHC compliant devices. For this reason giving a new name is preferred in many areas, even if it's simply SDHC2. As for the file system, the limitations in certain versions of Microsoft Windows may have been a factor but I haven't seen much evidence it was the sole reason why exFAT was selected over FAT32. As far as I understand it, there are several reasons why exFAT may be preferred for rather large volumes, e.g. 2TB (the maximum SDXC specifies); performance, maximum file size. In other words, perhaps without the Windows limit the SD2.0 would have specified larger cards e.g. 64GB or 128GB as the maximum for SDHC but there's no reason to think we wouldn't still have had SDXC at some stage and probably not using FAT32. So the article is likely misleading to make the unsourced claim the sole reason for SDXC and to use a different file system is due to the limitations in Windows. Nil Einne ( talk) 07:39, 3 July 2011 (UTC)
Is the acronym SDSC something used by official standard bodies, or invented by various forums? Electron9 ( talk) 00:10, 22 May 2011 (UTC)
This article is full of extraneous links. Only the first instance of a link (eg, SDHC) is necessary. Also, many links that used to go to other pages (eg, microSD) simply redirect back to this (article) page. Is there a WP 'bot' that can clean this up? Regards, nagualdesign ( talk) 17:13, 21 July 2011 (UTC)
The lead section says that SDXC cards have an upper limit of 2 TiB, but the section of the article focused on SDXC cards says they have an upper limit of 2 TB. I realize that the difference is functionally moot, given the standard practice of binary prefixing, but since the first instance is the unusual form, I feel that it ought to be changed. Feedback? 69.105.38.18 ( talk) 17:48, 9 July 2010 (UTC)
15, June 2011:
I see in the article, when stating capacities, it is always in MB, GB or TB, not MiB, GiB or TiB. Does, for instance, a 2 "GB" SD card really have 2GB of data storage (like a hard disk), or GiB (Like a memory chip,, 2 to the power of..)?
My 2GB SD card has a capacity of 1.83GiB (after formatting), which leads me to believe that its capacity is 2GB. A 2GiB disk volume would have a capacity of 2GiB after formatting, I think. — Preceding
unsigned comment added by
184.76.47.120 (
talk) 03:54, 16 June 2011 (UTC)
In respect to Secure Digital cards, 1 megabyte = 1 million bytes and 1 gigabyte = 1 billion (U.S. billion) bytes. See the cautionary notes on the packaging; this has been the case from the beginning. Thus, the use of the binary prefixes in this context is incorrect. — Preceding unsigned comment added by 96.251.57.12 ( talk) 00:51, 10 October 2011 (UTC)
"Fragmentation may slow down the effective write speed but the effect is tiny compared with that of fragmentation on hard drives. Defragmentation tools may be used. However, it is unnecessary to use any disk optimization tool because on an SD card the time required to access any block is the same."
So, is the read delay "tiny" or nil? — Preceding unsigned comment added by SomeAvailableName ( talk • contribs) 08:29, 10 March 2011 (UTC)
In the past, what is the Lowest-Capacity that EXISTS for each of these card types? I'm not talking about the standard, but what is the lowest card that ever shipped.
• Sbmeirow • Talk • 10:55, 7 March 2011 (UTC)
I deleted the second paragraph of Section 11.2, on a "homebrew hack" that interfaces an SD card to a popular router, explaining in the Change Summary that there is now a better way of getting an SD card on a router (new products under $100 by several makers that have USB ports). The author reverted me and explained on User talk:Electron9 that one point the paragraph made was the simplicity of the SD interface. I still am not sold on the relevance, but don't feel strongly about it, and leave the issue for possible comments by third parties. Spike-from-NH ( talk) 21:27, 25 October 2011 (UTC)
Last try from new editor (I understand that SOME of you do not want to lose some of US). (Some of this message may need to be moved to one or more topics - though I don't know list of topics.) Go ahead.
I tried to alert you that IMO the article was too technical. I would think that is the kind of feedback that you would want - even if you are sufficiently knowledgeable about the topic to think that the writing is NOT too technical. (My practical suggestions are near end of this message.) I was precise to state the "too technical" at front-end of my comments. Then, I detailed it with enough information (TMI?) that someone could follow my train of logic to understand why I believe it is "too technical." I am fine that article was moved, but the reasoning given to me was that my questions were "buying advice" questions. No, those were the questions that brought me to the site. SD card now bought. Info from this site did not give me info I sought to help me understand basics of purchase-decisions. e.g., My task was "buy SD card." Simple task, if you know what it is. (I already knew I needed MICRO SD card, at least 2 GB, but that was all.) Compare: Sent to grocery to "buy potatoes" or "buy apples" - Unless you know intended use (and cook's proficiency), you have good chance of buying "wrong" potatoes or apples. (i.e., Some potatoes better for baking, mashed, potato salad. Some apples better for pies vs. raw-eating. Don't know: ask someone in Produce Section. Cannot use same logic at store - unless can trust the store.) Seems that issues of SD cards is similar. One basic thing I needed to know was whether SD and SDHC interchangeable for my use. (People who suggested "buy-online" or "wait till Black Friday" missed the point of the details I provided. If this was a purchase that could have waited until I could research it, that would have been fine advice .- which I would have known anyway)
FWIW, someone advised I could "tag" the article as "too technical" - but, without telling me how to do that - Or, telling me in a way that is too technical. Person tell me to do x, but in a way that is too technical for me (at this point) to know how to do x. At this stage, if your suggestions/comments are written in mark-up language, without explanation, I am not going to understand. (I have previously asked if there is a 'Wiki-edit Glossary.') I AM *NEW* here. I will learn more if people tell/show me how to do something, rather than changing it on my OWN page FOR me. ("Give a man a fish..." vs. "Teach a man to fish....") Far better to talk WITH someone than to talk AT them.
My suggestions: Perhaps all articles, but certainly articles of technical content, could have a scale (1-5?) re intended audience, or, pre-requisites. e.g. " Before reading this article, see xyz (with pointer). If you understand everything there, then return here." Similarly, edit box gives option to indicate whether one is highly knowledgeable about something. This is a binary question. Would you not get more useful info if people could rate their knowledge on 3-point or 5-point scale?
Note: if I am not responsive soon, I suggest no over-interpretation. I have much else that also needs attention. I expect to be here episodically, at least for now, rather than "be here usually." -- KnowLimits ( talk) 01:49, 25 November 2011 (UTC)
![]() | This article may be too technical for most readers to understand.(December 2011) |
Accessibility is discussed in the linked article from this banner. Accessibility should be achieved without removing notable technical detail. -- Kvng ( talk) 23:42, 26 November 2011 (UTC)
The rapidity at which vendors complied with an extension of the specification might be notable. A list (in our Section 7.1) of dates on which specific vendors announced that they intended to ship a compliant product, is not notable. Spike-from-NH ( talk) 00:36, 26 November 2011 (UTC)
Because this talk page is getting rather long, and has comments going back to 2005, I propose setting it to automatically archive threads older than 90 days (but leaving a minimum of 5 threads).
If nobody objects, I will add the code to do this in about a week. Chzz ► 10:14, 25 November 2011 (UTC)
Fine, so, I'll make it 1 year - after waiting a few more days. It's easy to adjust the time later anyway. Chzz ► 09:46, 28 November 2011 (UTC)
Done
Continuing with the discussion in "Too technical" and "History" above: I envisage leaving in "Design and implementation" only the features that help a reader decide what SD is all about and what flavors there are--then renaming it "Features". Sections that describe how it works ("File system", "Transfer modes", "Interface", "Power use", and "Storage capacity and incompatibilities") I'd move to a new section "Technical details" to occur afterward, even after the sections that describe the market acceptance and vendor-specific features.
The fact that the ability to plug an SD chip into an SD slot is impeded by several factors seems important to a lot of readers; I also appreciated knowing exactly what goes wrong, and the exact history, but these are also "Technical details". I'll volunteer for the editing, but will instead focus on nits for a few days to await youse's responses. Spike-from-NH ( talk) 14:30, 28 November 2011 (UTC)
Well, the silence was deafening, and it is now done. I've reorganized the article in this order:
Followed by stuff you might not need to know:
Apologies in advance if people are suddenly unable to find anything! Spike-from-NH ( talk) 12:20, 5 December 2011 (UTC)
The article describes Thin SD in two places as "rare" (I think the article used to hedge its bets by saying "rare or nonexistent") but I've never seen one. Similarly, my uneducated guess is that there is no new product design for which miniSD is the best choice, and a quick use of Google only shows sales of off-brand miniSDs, some at "close-out" prices, presumably for owners of existing host devices. If miniSD is a dead end, it is notable and the article ought to say so, but I wouldn't know what to cite as proof of this. Spike-from-NH ( talk) 12:52, 7 December 2011 (UTC)
I've been corrected once after writing "an SD" (which I read "an ess dee" not "an Secure Digital") but the article has it both ways. Is there a decision on this? Spike-from-NH ( talk) 12:52, 7 December 2011 (UTC)
The "Technical details"/"Interfaces"/"SD Card Pin-outs" section needs to include the pin assignments for the micro and mini sizes as well as the standard size as the mapping is not obvious (the cards even have different numbers of contacts). JohnAHind ( talk) 18:23, 21 December 2011 (UTC)
Despite the deafening silence on the above queries in the last two weeks, I have another query. Matthiaspaul has edited the article to assert that the use of the exFAT file system is mandatory for all SDXC cards. The understanding I had, based on the text of this article when I started massaging it, is that depending on the specification version it obeys, SDXC cards could be factory formatted with either FAT32 or exFAT.
Paul also makes a good case that the decision to use exFAT is disastrous, as it requires (at least for universal compatibility) manufacturers to embrace a technology that is proprietary and that "many alternative or older operating systems do not support exFAT for technical or legal reasons" (his wording as I edited it). If true, though, this should be treated as a controversy we document rather than a fact that we report. He also states that FAT32 could have been used for file systems above 32 GB, such as those on SDXC cards, but I see a claim that this wouldn't be supported under Windows, which is a good reason not to do so; at any rate, this veers toward advocacy.
More knowledgeable editors than I should review the text to make sure we are saying the right thing in the right way. Spike-from-NH ( talk) 12:56, 25 December 2011 (UTC)
Please upload YOUR personal photos and drawings to Wikimedia Commons, so we can use them in this article:
After you upload, please leave a comment in this section and remove the request. • Sbmeirow • Talk • 01:41, 26 November 2011 (UTC)
I woonder if they would let us use the image from here ? It does show the evolution to smaller sizes nicely ! -- 195.137.93.171 ( talk) 22:10, 29 February 2012 (UTC)
I've heard that when Bit 13 of the CSD is set an SDHC card becomes permanently read only with no possibility of unsetting the bit. Is this true or BS? Bizzybody ( talk) 09:56, 11 March 2012 (UTC)
The article refers to four types of SD card: SDSC, SDHC, SDXC and SDIO However:
May I suggest that
fwiw LookingGlass ( talk) 21:18, 23 May 2012 (UTC)
From the article:
Following the reference leads to a page which says this:
The article seems to be saying the opposite of the source. However, I got here because of a discussion on a web forum where someone was able to use a SDXC card in a SDHC device, so I don't think this is just a case of misquoting the source. What's going on here? Ken Arromdee ( talk) 20:10, 31 May 2012 (UTC)
The table listing “×” ratings (which, remember, is an old metric) is getting out of hand and I have pared it back. A previous contributor created separate columns for read speed and write speed, though the text makes it clear that various vendors vary in their selection of speeds as a basis of measurement. Today Anon has expanded the table further, to go from "common ratings" apparently to all conceivable ratings. He has also inserted question marks after most of the measurements, which seem to call into question their usefulness and express an opinion of disapproval--but we already knew both things.
The table ought not be to tell the reader how fast their 120× card can perform, because we can't do that, but to give a small, representative list of old-style ratings, and relate them to the newer Speed Class, with the cautionary notes set out in the text.
Anon has also asserted measurement error in the table and the text, which I am not an expert on, and I did not post-edit him there. Spike-from-NH ( talk)
Nowhere in this article could I find the most fundamental information about SD cards: what memory they actually contain. The summary simply says they contain "Non-volatile memory" without any details at all, this seems like a massive omission! — Preceding unsigned comment added by 80.4.146.163 ( talk) 17:24, 28 June 2012 (UTC)
Could someone please explain the meaning of "secure" in the name? Gwideman ( talk) 05:38, 15 April 2012 (UTC)
The article says "Any recent version of the above can format SD cards using the UDF file system." I just tried Windows 7 HP SP1 and it does not offer UDF when formatting an SD card. I guess it is a case of "citation needed" ? -- Xerces8 ( talk) 22:09, 25 October 2012 (UTC)
The GPX MW3836 (with SUFFIX NO: E1 label) MP3 player is able to read/write up to at least 4GB SDHC even though GPX claims is can only use up to 1GB standard SD cards. That gives this cheap $20 player 5GB of storage. :) I've a Lexar 4GB SDHC in mine. It'd be nice to see a site off-Wikipedia with a list of specific devices that support SDHC though they officially don't.
It quite often happens that devices support things that their manufacturers don't claim (including things available at the time). The claim is basically "we have tried this and pretty much guarantee that it works. If you try anything else, great, but don't come whining to us". I have plenty of devices that accept larger SD or Micro SD cards than claimed, larger laptop and desktop computer RAM than claimed, and so on. Lots of Windows XP computers that "don't" support Windows 7, do. Asus motherboards for AMD processors generally support and make use of ECC memory, though memory manufacturers don't list this. Of course, you may run into trouble when 8GB model xyz works and you buy 8GB model zyx, which doesn't. I've found a Google search like <Inspiron 1501 4GB> to be useful. Pol098 ( talk) 15:24, 31 December 2012 (UTC)
I added text:
The speed class rating does not totally characterize card performance. Different cards of the same class may vary considerably while meeting class specifications. In addition, speed may vary markedly between writing a large amount of data to a single file (sequential access, as when a digital camera records large photographs or videos) and writing a large number of small files (a random-access use common in smartphones). One study found that, in this random-access use, some Class 2 cards achieved a write speed of 1.38Mb/sec, while all cards tested of Class 6 or greater, including those from major manufacturers, were over 100 times slower.
Some Original Research: I tested two 8GB Micro SDHC cards, including one from a manufacturer supporting small files well, and another (which had been my preferred choice before checking sources) from a manufacturer with a good reputation. The first card with CrystalDiskMark got a 4kB file writing speed of well over 1MB/s (I didn't write it down unfortunately), the other 0.007MB/s (decimal point, 2 zeros, 7, no typo). While photographs and video recordings are a different matter, for general-purpose mobile phone and similar use, handling small files well is important, particularly if running programs off the card. Pol098 ( talk) 15:36, 31 December 2012 (UTC)
Lots of subtleties here concerning how different SD cards are designed and whether the devices they plug into keep them powered up, let them go to sleep automatically, put them in sleep mode, up pull the plug and shut off the power to the card. for example:
http://harizanov.com/2012/05/tinysensors-sd-card-power-consumption-worries-and-solution/
http://www.motherboardpoint.com/micro-sd-power-consumption-t191597.html
I think that the best we can do is to simply say that power consumption varies widely between different cards and between different devices the cards plug into. Either that or give power consumption of SD cards a separate article and try to cover all the variables. -- Guy Macon ( talk) 22:51, 1 January 2013 (UTC)
To pick a nit on a separate editing issue: "envisage" is the British rendition of "envision". As this article uses American grammar, the latter is appropriate and the recent edits are good. Spike-from-NH ( talk) 14:23, 9 January 2013 (UTC)