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?

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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 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)

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)

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)[reply]

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)[reply]

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)[reply]

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

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)[reply]

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)[reply]

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 / FAT32 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)[reply]

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?

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)[reply]

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)[reply]

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)[reply]

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.