Talk:SD card

SD Extension Lead

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.

Can anyone explain the difference betwwn the secure digital card and compact flash card. When to use what? What should check in the digital camera before we buy it?

CompactFlash is more open, and doesn't have any DRM whatsoever. However, it's more expensive and larger. Depends on what you want. 74.101.127.217 00:49, 6 May 2007 (UTC)

Speed Information?

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)

X Speed Ratings

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)

It means that the speed is the same as a 6X CD reader/writer would be. Single-speed CD-ROM is 150KB/s (this is how fast the disc is read when your audio CD player is playing music on a standard CD). The "X ratings" for SD cards follow the same convention, even though it makes little technical sense (6X actually means something with respect to a CD, but as far as I know, the "baseline speed" for a SD card isn't 150KB/sec - i.e. the first SD cards weren't 1X).

In other words, it means six times as fast, just as it says ("six times faster" would be different in that it could be interpreted to mean "seven times as fast"?). 900/150 = 6. From what I've learned in the last week or so, this speed rating refers exclusively to the read speed, and the write speed is generally quite a bit closer. I'm not clear on whether or not there's a fixed relationship between the read and write speeds, or if, for example, some "150X" cards write at "80X" while others only write at "60X." -Erik Harris 12:16, 23 October 2006 (UTC)

X Speed Ratings: SLC vs MLC,?

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

Searching for "slc mlc sd" gives eg. this document: http://www.pamiec.com.pl/pub/Samsung_SLC_NAND_Flash_Advantage.pdf.

Standards or marketing buzzwords within SD cards (what does 'Ultra' mean?)

While looking for a digital camera I stumpled upon some terms that are not explained in this article:

• SD Ultra
• SD Ultra II, or SD Ultra, Model II, Model II plus
• SD, eXtreme II

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)

Those are all names of different SanDisk cards. as is explained in the second paragraph of the article, the speeds are multiples of 150 kB/s. That would make the 80x card 12 MB/s and the other card 23 MB/s. --Niffux 13:13, 21 June 2006 (UTC)

Actually, doing a find doesn't show any 'ultra' in the whole article, and the second paragraph doesn't help clear it up, if you're trying to figure out what speed 'ultra' is. Some of the stuff I'm looking at in advertising gives no multiple speeds, much less ultra or anything else and just says "fast" ... which is marketing lingo for "give us your money, now!" and not a technical reference at all. However, one site did say that any card which doesn't say 'high-speed' or 'ultra' were no more than 2MB/s [1] - which helps only in the negative information sense.

I'm going to order the one card which does give me a multiple speed (2G, x133 ~$35), even though my current camera probably doesn't support such high transfer speeds :\

~ender 2006-11-17 4:02:AM MST

'Ultra II' is a model name or brand for a line of Sandisk cards; it isn't an indication of speed. They also have other models. These are outside of the scope of this document, except perhaps to mention that some brands have a range of different models with different speeds. The appropriate place to look up the speed of a 'Sandisk Ultra II' would be to go to Sandisk, I think. Note that 'speed' is not a single characteristic; read speed and write speed can vary relative to each other, as can the speed of writing to very small blocks and the speed of writing to larger blocks. 136.186.1.186 (talk) 03:48, 1 July 2008 (UTC)

Ultra-II SD card with same reader?

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)

All devices will support these cards. That speed is an estimate of the maximum speed the card will go. A device will wait while the card does its thing; a faster card will cause less wait at the device. Some devices don't particularly need a very fast card so you are unlikely to notice a difference in the higher speeds, but the cards will still work. 136.186.1.185 (talk) 03:58, 1 July 2008 (UTC)

4 and 8GB?:

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)

Where are you located? In the U.S. Newegg (and many other retailers) sells 4GB SD cards for around $85. Lennylim 22:18, 27 June 2006 (UTC)

You can also find various SD cards in 4Gb flavor on Ebay, though I have never seen an 8Gb card. silvarbullet1 22:50, 17 August 2006 (UTC)

I've searched high and low because of this mythical 8GB SD card. I do not think it exists. - 97.113.31.133 (talk) 21:08, 17 January 2009 (UTC)

Indeed not. An 8gb SD card is not possible. Read the article for why :) ǝɹʎℲxoɯ (contrib) 01:13, 18 January 2009 (UTC)

Those are typically SDHC cards, as 8GB is not possible under the SD format. However, SDHC is an extention of SD. —Preceding unsigned comment added by Stuston (talk • contribs) 18:04, 5 February 2009 (UTC)

Minimum sizes

Anyone know the minimum size of a SD Card? I'm guessing 4mb but I could be wrong Towel401

What do you mean? The minimum size available for retail sale? The minimum size in current production runs? The smallest card ever made? Only one of those is not subject to change without notice within a matter of months. --Smack (talk) 03:31, 15 July 2005 (UTC)

I think he would rather mean the smallest possible size, if there is one. --70.104.80.228

uiktler_{Subscript text#REDIRECT [[}

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Target page name--24.235.221.28 (talk) 16:00, 1 August 2009 (UTC)[[Media:[Example.ogg]''Link title'''''''Italic text''''']]]]

Made a few changes:

• Rephrased in a few places.
• Provided reference for SD overtaking CF as most popular format.
• Removed the claim that SD card is an 'official replacement' for CF as it is not. CF has a lot of uses that SD simply does not do currently although some of this is changing with SDIO. CF is also very much the standard on high-end digital cameras and there is no sign that I can see of a shift to SD here.
• Moved the point about possible floppy replacement to memory card as this is not specific to SD.

Blorg 16:39, 11 Nov 2004 (UTC)

Among other things (such as SD having a 4-bit bus and CF a 16-bit bus), SD is not ATA disk compatible, which is the primary reason CF still has a long way to go in its lifetime. Thanks to the ATA compatibility, CF cards can be connected electrically to an embedded or small computer's I/O bus with no extra controller hardware, making CF still rather popular as a spindled-disk replacement. --Todd Vierling 29 June 2005 15:12 (UTC)

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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)

Gives 404 today. --Nikerabbit 08:37, 8 Dec 2004 (UTC)

Fine today. silvarbullet1 22:52, 17 August 2006 (UTC)

Clarification on royalties

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.

Good question. I rewrote that sentence. Better now? Moxfyre (ǝɹʎℲxoɯ | contrib) 18:57, 11 June 2009 (UTC)

Are links to products appropriate?

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)

Good idea, done. Bergsten 12:57, 3 October 2005 (UTC)

More dSLRs using SD in foreseeable future?

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)

Size restrictions of cameras?

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 don't know why, but allow me to speculate: Perhaps they don't want to deal with managing more memory than that, as it takes a certain amount of chutzpah for the software to adapt to increasingly large cluster sizes or number of blocks. A 512 Mb is a million 512 byte sectors, so 16 sector clusters (8 k) is the minimum cluster size for a managing FAT16 structure, which is slightly easier to implement than FAT32. Or maybe it a power requirements or bit addressing size thing? Or maybe they will work just fine, but the manufacturer doesn't want to be on the hook if the larger SD cards don't work. —EncMstr 01:39, 13 July 2006 (UTC)

Yes, It is the memory addressing. Palm handheld computers have the same problem, older handhelds support up to 1Gb, the latest support 2 Gb. The reason seems to be the FAT16/32 filesystem issue. http://kb.palmone.com/SRVS/CGI-BIN/WEBCGI.EXE?New,kb=PalmSupportKB,CASE=obj(34080),ts=Palm_External2001 silvarbullet1 22:58, 17 August 2006 (UTC)

Compatibility section

I think there should be a separate section on compatibility, e.g. between SD and MMC cards, the issue with 2GB and larger SD cards, etc.

Technology

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)

Images

It would be nice if the table comparing different versions of SD cards contained thumbnail images just to show what each format is like. silvarbullet1 23:05, 17 August 2006 (UTC)

SD vs. SDHC

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)

SD uses byte based addressing, whilst SDHC uses sector based (512 byte chunks) addressing. A non-SDHC card is a byte based card with FAT32. Since the address field is 32-bits, you can get 4 GB on the old cards. But the standard also specified FAT16, hence the limit on 2 GB. PierreOssman 07:01, 7 June 2007 (UTC)

Is incompatibility between SD and SDHC a hardware or a firmware issue? The filesystem is a firmware issue, but what about the block vs byte addressing? Could that be worked around by a firmware upgrade or does it require a SD card reader specifically designed to handled it? To get a little less theoretic: The Wii currently only supports SD, but not SDHC, is it fixable without new hardware? -- Grumbel 09:11, 8 November 2007 (UTC)

In theory yes it can be a simple firmware update, several Nokia mobile phones have had SDHC suport enabled by a firmware update Golden Dragoon (talk) 02:34, 5 December 2007 (UTC)

Not necessarily. I believe SD 2.0 has tighter electrical specifications than SD 1.x (such as lower voltage tolerances and higher current tolerances) so a SD 1.x device may, but would not necessarily, qualify as an SD 2.0 device. It would need to be meet the electrical specs of SD 2.0 before it could be able to offically support SDHC and carry the SDHC logo. It is possible that some SD 1.x devices will already meet this spec just because they were designed well from the start, but they would need to be tested to ensure they meet the SD 2.0 electrical spec and also have a firmware upgrade. 136.186.1.185 (talk) 04:08, 1 July 2008 (UTC)

SuperSD

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)

SD locking

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

As details of SD security are not in public domain, one can only speculate that locking is similar to ATA Security Feature Set (commands SECURITY_SET_PASSWORD, SECURITY_UNLOCK, ...). In that case, if a password has been set, after each power-up the hard disk requires a correct password to be sent before it starts accepting commands that access data; the BIOS handles that transparently to the user until the drive is moved to another computer. --saimhe 23:42, 12 April 2007 (UTC)

The locking is actually specified in the simplified specification. But yes, the behaviour is almost identical to how ATA does it. PierreOssman 07:01, 7 June 2007 (UTC)

Optional write protect tab

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)

Max supoorted size clarification

(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)

Good question. :) There are "SD" cards in excess of 2GB (I've only seen 4GB SD), but the SD (non-HC) standard doesn't officially support them, and many devices will choke on these 4GB SD cards. Furthermore, many SDHC devices will also choke on these 4GB SD cards, though they'll work on 4GB and 8GB SDHC cards. I believe the current official limit is 8GB, though I'm not positive. I'm pretty sure that the current version of the spec does not support 128GB cards. That appears to be a figure based on the memory addressing methods, which I guess would allow addressing up to 128GB of space. That doesn't mean the standard supports those sizes yet. I agree, clarification is necessary. Unfortunately, I don't have quite a clear enough understanding to make the changes myself. —Erik Harris 16:28, 19 January 2007 (UTC)

Based on the current size of the fields in the CSD, maximum card size is 64 GB. PierreOssman 07:01, 7 June 2007 (UTC)

SD card versus USB flash memory

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)

Not quite. This isn't quite an apples/oranges comparison, but it's not quite apples/apples, either. SD Cards have a variety of applications, primarily for small form-factor storage in portable devices (though it is used in some non-portable devices, and there are readers built into computers). USB storage devices aren't suitable for most of the SD applications. They're more useful for portable storage of files that are brought from computer to computer, without requiring a reader device supporting a specific format (given that USB has become very much a standard I/O port on PCs and Macs in recent years). There are a number of competing forms of memory storage for portable devices (SD, CompactFlash, xD, Memory Stick, etc), but USB storage devices are part of a largely-separate market sector. —Erik Harris 18:51, 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)

Data size

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)

This isn't a lie as much as it's a disagreement on standards. The SI standard specifies that "giga" means one billion, "mega" means one million, and so forth. For years, computer users have used binary approximations of these prefixes, based on "kilo" being 2^10, or 1024, and "close enough" to "kilo" to be usable. In recent years, there's been an effort to switch to a differentiating standard, using the rather ridiculous-sounding (IMO) "kibi," "mebi," etc. Some have insisted that because of this effort that "KiB," "MiB," etc are the "correct" way of doing it. However, this new standard is not officially ratified/recognized/used. The end result is that there's no "right" way. The official SI way says 1GB = 1 billion bytes. The de-facto binary way says 1GB = 2^30 bytes. Manufacturers obviously prefer the SI way because it makes their devices look larger than the binary notation, but their way is also "correct." Neither is a lie. Generally, the 512MB cards "really" have 512MB, but MB is still defined in the SI way, so they contain 512,000,000 bytes (approximately, with allowances for overhead), not 536,870,812 (512*2^20) bytes. So it doesn't follow, as you suggest, that the 1GB cards must contain 1024MB.

It is confusing, and it'd be nice if everyone stuck with one standard, but they don't. But that doesn't mean that using one standard instead of the other is a lie. —Erik Harris 12:30, 20 March 2007 (UTC)

I always thought that these 7.4 % of reserves achieved by "converting" 1 GB to 1 GiB may just be dedicated to spare sectors which, in turn, are silently managed by the SD controller. Aren't they? --saimhe 22:49, 12 April 2007 (UTC)

In fact, the kibi... prefixes are an actual standard (IEC 60027-2), recognized additionally by the CIPM and IEEE. More details at http://physics.nist.gov/cuu/Units/binary.html . Msauve (talk) 11:53, 27 December 2007 (UTC)

Formatting

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

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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

Nokia N800 supporting SDHC?

Is there a reference available for the claim that the N800 supports SDHC? While the Nokia N800 tech specs say it is 'configurable up to 4GB', this is just because it has two SD card slots. The same page also states 'compatible with cards up to 2GB', which says to me that it's not SDHC. I'm going to remove the N800 from the list of SDHC devices unless a reference can be provided. Wibbble 01:10, 8 April 2007 (UTC)

I've removed it. Wibbble 18:34, 13 April 2007 (UTC)

Nokia N800 uses Linux so they'll get SDHC support when they upgrade to a recent kernel. PierreOssman 07:01, 7 June 2007 (UTC)

Article tone

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)

Open Source implementations

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:

• What makes the OLPC implementation more open-source than previous reverse-engineered versions?
• How does the simplified spec version 1.0 (released in 2004) differ from the full spec?
• How does the simplified spec version 2.0 (released in 2007) differ from the full spec?

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)

The OLPC version is not really more open than the previous ones. They just made sure to use an open interface, not one of the many still closed. PierreOssman 07:01, 7 June 2007 (UTC)

If the "simplified spec" is unavailable for microSD, htf can microSD be 'open source compatible'? For that matter, what does that row even MEAN? --moof 01:38, 26 September 2007 (UTC)

Too... many... modes...

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:

• which ones are distinct?
• when did they originate?
• exactly which models of SD/MMC cards support them?

MOXFYRE (contrib) 15:16, 11 May 2007 (UTC)

MMC and SD use the same electrical specification, both in SPI and "native" mode. They use different, incompatible protocols though. Generally, an SD card does not support the MMC protocol and vice-versa. The wider modes use the same protocol, just with more data bits to get the speed up. Also, the high-speed modes differ between SD and MMC so they can't be interchanged either way. PierreOssman 07:01, 7 June 2007 (UTC)

SDIO

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)

Image in infobox

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 vote diagram. Given the current choice of images, I vote for the diagram. It's simply much clearer, brighter, and more informative. There are photos of bona fide SD cards elsewhere in the article, I see no reason why one has to appear first. MOXFYRE (contrib) 14:53, 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)

EyeFi

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)

It is mentioned in the Extra Features section. Artemis3 (talk) 09:03, 25 November 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)

EyeFi uses a wireless access point. It can only function in infrastructure mode, not in an ad-hoc network. It uses the AP to connect to centralized servers, and individual computers can separately connect to those servers. So there's no direct EyeFi-to-PC communication. I'll try to update the article to reflect this. ǝɹʎℲxoɯ (contrib) 21:12, 16 January 2009 (UTC)

DRM

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)

I am as anti DRM as Richard Stallman and the EFF, yet i see those paragraphs as nonsense. The only useful thing i can think of using DRM in a SD or SDHC is if, the labels or movie studios started selling their "products" using these instead of CDs or DVDs. And i have not heard of any players or formats being planned for that, yet. A 1g SD might cost them a couple of dollars while 4g DVDs go for 50cents or so. Not to mention the public reaction in the USA about way smaller and more efficient storage and playing devices that could easily outlast all current methods. Those are big no noes for an aging industry. Anyway yes, i suggest to remove those two paragraphs (2 and 3) from the DRM section. There is a nice DRM article you can always link to. Artemis3 (talk) 08:55, 25 November 2007 (UTC)

speeds of SD vs. SDHC cards

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 HD 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)

Bassi tab?

Where does this term come from? A web search shows this article as the only reference using this term for a sliding write protect tab. Is this possibly a case of vanity vandalism? Msauve (talk) 12:05, 27 December 2007 (UTC)

Market Penetration

This is growing into an open-ended list, which is a bad thing.

Either it should list each and every model of camera/... that supports SD - clearly insane, or a description of the market segments. 'many high end cameras/camcorders'

--Speedevil (talk) 12:13, 26 January 2008 (UTC)

SDHC maximum capacity

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)

Why SDHC is limited to 32 GB and not 2 TB

Page 97:

5.3.3 CSD Register (CSD Version 2.0)

device size, C_SIZE, 22 bits, value 00 xxxxh, Readonly, CSD-slice [69:48]

C_SIZE_MULT is removed.

Page 98:

READ_BL_LEN This field is fixed to 9h, which indicates READ_BL_LEN=512 Byte.

Page 98:

C_SIZE This field is expanded to 22 bits and can indicate up to 2 TBytes (It is the same as the maximum memory space specified by a 32-bit block address.) This parameter is used to calculate the user data area capacity in the SD memory card (not include the protected area). The user data area capacity is calculated from C_SIZE as follows: memory capacity = (C_SIZE+1) * 512K byte As the maximum capacity of the Physical Layer Specification Version 2.00 is 32 GB, the upper 6 bits of this field shall be set to 0.

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)

Why SD-Card v1.01 can handle 4 GB

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:

Table 5.3.2 CSD Register (CSD Version 1.0)

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

"The maximum block length might therefore be in the range 512...2048 bytes"

Page 92

C_SIZE

"This parameter is used to compute the user's data card capacity"

memory capacity = BLOCKNR * BLOCK_LEN

memory capacity = (C_SIZE+1) * MULT

memory capacity = (C_SIZE+1) * 2^(C_SIZE_MULT+2)

memory capacity = (C_SIZE+1) * 2^(C_SIZE_MULT+2) * 2^(READ_BL_LEN)

C_SIZE is 12 bits => 0..4095

C_SIZE_MULT is 3 bits => 0..7

Thus maximum capacity is:

memory capacity = (4095+1) * 2^(7+2) * 2^(11) = 4294967296 = 4 GiB

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)

The same specification states that the speed of SD cards is officially limited to 2 GB (see pages 5 and 14). A 4 GB variant, while it does indeed appear to be possible according to those figures on page 92, is still not to-spec and should not be considered an 'SD card'. 136.186.1.191 (talk) 01:58, 1 July 2008 (UTC)

The speed is not 2GB.. And 4GB cards are defined in the spec. Electron9 (talk) 00:50, 7 July 2008 (UTC)

Another way to look at this is that SD Cards (as opposed to SDHC Cards) and, more importantly, SD Card Hosts support FAT16. FAT16 is limited to 65,536 clusters, but because certain clusters are reserved, it has a practical limit of 65,524. FAT16 has a maximum cluster size of 64KB. (That's 64 * 1,024B, or 65,536 Bytes.) That limits a FAT16 volume to 65,536 Bytes * 65,524 clusters, or 4,294,180,864 Bytes. That's less than the 4GB limit of FAT16 as the operating system counts it (4 * 1,024 * 1,024 * 1,024, or 4,294,967,296), but more that 4GB as the storage device counts it (4 * 1,000 * 1,000 * 1,000, or 4,000,000,000 Bytes). So SD Cards can handle 4GB, but not 4GB. TCav (talk) 14:31, 3 April 2009 (UTC)

Common Problems: Repair a non-formatable SD-card

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)

I want to point out that "low level" disk tools aren't truely low level. I don't think it is even possible for the avarage user to get low level access to modern hard drives. With SD cards, I don't think it's even possible to do anything with the controller that would allow any sort of low level access, let alone trying to do it over a USB card reader. The USB connection makes it even less likely so because of the OS sees any "disk" as a collection of 512 byte blocks, regardless of what the SD card uses internally. The best the avarage person can do is zero fill the drive, and that's what many of these "low level" software packages do. 66.114.93.6 (talk) 18:58, 4 January 2009 (UTC)

If Windows sees that the first sector of an SD card looks like a partition table with no partitions Windows will refuse to reformat the card and will say that it has unknown capacity. Zeroing the first sector fixes this problem though I think windows will still format the card incorrectly after this. 86.13.77.126 (talk) 09:24, 10 January 2009 (UTC)

SD transfer speeds

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)

Simple question, the answer to which I know is contingent on many variables.

Can someone please estimate for me the approximate number of pictures one can get onto a Secure Digital card, in each of the qualities of pictures, and in each of the sizes of cards? Thank you. —Preceding unsigned comment added by Heathbug (talk • contribs) 21:10, 12 April 2008 (UTC)

How long is a string of wire ..?

In what way should we know what motive, pixel frame, compression efficiency, ccd noise etc.. you camera has? Electron9 (talk) 21:23, 20 April 2008 (UTC)

This isn't the right place for such information, but every website that sells Flash will have some kind of chart that estimates the capacity based on the file format. Here's one such example: http://www.kingston.com/flash/sdhc.asp?id=5 --JJLatWiki (talk) 23:50, 1 May 2008 (UTC)

SD-cards can handle 4 GB, SDHC can handle 32 GB. Bad edits BEWARE!

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)

SDXC backwards compatibility

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)

A device that's SDHC compatible, though manufacturer claims not

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.

SD 1.01 cards w/ more than 66x

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)

I removed the sentence about the maximum of 66x, because SD 1.01 card w/ higher speeds exist. If anyone wants to revert this change, he should have a source that SD 1.01 cards w/ >66x speed are faster then allowed by the specification. --MrBurns (talk) 01:32, 20 March 2009 (UTC)

Speed Classes are not exclusive to SDHC Cards

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)

Done. TCav (talk) 23:01, 18 April 2009 (UTC)

help

Can you plug the Wii version into a camera to take pics!?!?4DJONG (talk) 15:43, 17 May 2009 (UTC) What is up with that ! and/or ? habit I am getting mad!!!! —Preceding unsigned comment added by 4DJONG (talk • contribs) 15:11, 17 May 2009 (UTC)

lock switch

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)

I also don't know what this lock is meant to do. I thought it might lock the Micro SD card into the slot at the base of an SD adapter, but it doesn't (unless mine is broken). The article currently fails to mention what the lock is actually for. --Bilge [TC] 15:55, 15 September 2009 (UTC)

Hacked cards, miss clasifications stickers.

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)

There are fraudulently marked and spec'ed electronics products of all kinds, from LCD screens to cables to batteries to flash media... there is nothing particular to SD cards that I am aware of. Do you have any specific information on fraudulently marked SD cards? Moxfyre (ǝɹʎℲxoɯ | contrib) 17:51, 14 August 2009 (UTC)

missing aspects on speed classes

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:

• speed class: does it apply to SDHC only, or equally to SD and SDHC?
• does the "speed class" apply only to the card itself, or also to a host device (i.e. a laptop, a camera etc)?
  • in the latter case: does a host device of a lower class always able to read/write a card of a higher class? What about vice versa?
• overall, is there any incompatibility possible caused purely by classes of a card and a host device?

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)

4 Bit transfer mode optional or not?

The article Secure_Digital_card says that "All memory cards must support all three modes [1 Bit, 4 Bit and SPI], except for microSD where SPI is optional." Though the tables in the miniSD card and microSD articles state that 4 Bit mode is optional for all form factors. Now what? --83.171.186.53 (talk) 10:00, 3 September 2009 (UTC)