Editing SD card (section)

==Features==
===Card security===

====Commands to disable writes====
The host device can command the SD card to become read-only (to reject subsequent commands to write information to it). There are both reversible and irreversible host commands that achieve this.<ref>{{Cite web |last=By |date=2014-01-19 |title=The Tiniest SD Card Locker |url=https://hackaday.com/2014/01/18/the-tiniest-sd-card-locker/ |access-date=2023-01-20 |website=Hackaday |language=en-US}}</ref><ref>{{cite patent |country=US |number=7827370 |status=patent}}</ref>

====Write-protect notch====
[[File:SD card unlocked and locked.svg|thumb|Diagram showing an orange sliding write-protect switch in both the unlocked and locked positions]]
[[File:Vorderseite Sony Tough SF-M64T SDUHSII011CORRklein.png|thumb|upright|Sony Tough Series SD card, one of the few cards on the market without a sliding tab on the write protect notch]]

Most full-size SD cards have a mechanical write-protect switch, a sliding tab over a notch on the left side (viewed from the top, with the beveled corner on the right), that signals to the device to treat the card as read-only. Sliding the tab up (toward the contacts) sets the card to read/write; sliding it down sets it to read-only. However, the switch position is not detected by the card’s internal circuitry.<ref>{{Cite web|url=https://www.sdcard.org/downloads/pls/index.html|title=Simplified Specifications – SD Association, version 3.10, Part 1, Physical Layer, section 4.3.6" Write Protect Management"|website=sdcard.org|access-date=2019-04-11|archive-date=2019-04-11|archive-url=https://web.archive.org/web/20190411015937/https://www.sdcard.org/downloads/pls/index.html|url-status=live}}</ref> Therefore, some devices ignore it, while others allow overrides.{{citation needed|date=September 2023}}

MiniSD and microSD cards lack a built-in notch but can be used with adapters that include one. Cards without a notch are always writable; cards with preloaded content have a notch but no sliding tab.{{citation needed|date=September 2023}}

====Card password====
{{more citations needed|section=yes|date=September 2023}}
[[File:Sdadaptersandcards.jpg|thumb|MicroSD-to-SD adapter (left), microSD-to-miniSD adapter (middle), microSD card (right)]]

A host device can lock an SD card using a password of up to 16 bytes, typically supplied by the user.{{citation needed|date=September 2023}} A locked card interacts normally with the host device except that it rejects commands to read and write data.{{citation needed|date=September 2023}} A locked card can be unlocked only by providing the same password. The host device can, after supplying the old password, specify a new password or disable locking. Without the password (typically, in the case that the user forgets the password), the host device can command the card to erase all the data on the card for future re-use (except card data under DRM), but there is no way to gain access to the existing data.{{citation needed|date=September 2023}}

[[Windows Phone 7]] devices use SD cards designed for access only by the phone manufacturer or mobile provider. An SD card inserted into the phone underneath the battery compartment becomes locked "to the phone with an automatically generated key" so that "the SD card cannot be read by another phone, device, or PC".<ref>{{Cite web|url=https://support.microsoft.com/en-us/windows/windows-phone-7-3ebc303c-59c0-d367-3995-f258b184fabb|title=Windows Phone 7 – Microsoft Support|website=support.microsoft.com|access-date=2023-01-22|archive-date=2016-05-03|archive-url=https://web.archive.org/web/20160503105252/http://www.windowsphone.com/en-US/how-to/wp7/basics/copy-and-paste|url-status=live}}</ref> [[Symbian OS|Symbian]] devices, however, are some of the few that can perform the necessary low-level format operations on locked SD cards. It is therefore possible to use a device such as the [[Nokia N8]] to reformat the card for subsequent use in other devices.<ref>{{Cite web|url=https://www.engadget.com/2010/11/17/windows-phone-7s-microsd-mess-the-full-story-and-how-nokia-ca/|title=Windows Phone 7's microSD mess: the full story (and how Nokia can help you out of it)|website=Engadget|date=17 November 2010|access-date=13 October 2019|archive-date=8 August 2019|archive-url=https://web.archive.org/web/20190808215308/http://www.engadget.com/2010/11/17/windows-phone-7s-microsd-mess-the-full-story-and-how-nokia-ca/|url-status=live}}</ref>

===smartSD cards===
A smartSD memory card is a microSD card with an internal "[[secure element]]" that allows the transfer of ISO 7816 [[Smart card application protocol data unit|Application Protocol Data Unit]] commands to, for example, [[JavaCard]] applets running on the internal secure element through the SD bus.<ref>{{cite web |url=https://www.sdcard.org/downloads/pls/latest_whitepapers/Activating_New_Mobile_Services_and_Business_Models_With_smartSD_Memory_Cards_Revsied_11-3-2014.pdf |title=Activating New Mobile Services and Business Models with smartSD Memory cards |date=November 2014 |publisher=SD Association |access-date=2017-08-02 |archive-date=2016-12-23 |archive-url=https://web.archive.org/web/20161223213554/https://www.sdcard.org/downloads/pls/latest_whitepapers/Activating_New_Mobile_Services_and_Business_Models_With_smartSD_Memory_Cards_Revsied_11-3-2014.pdf |url-status=dead}}</ref>

Some of the earliest versions of microSD memory cards with secure elements were developed in 2009 by [[DeviceFidelity, Inc.]],<ref>{{cite web |url=https://www.nfcw.com/2009/11/11/32254/devicefidelity-launches-low-cost-microsd-based-nfc-solution/ |title=DeviceFidelity launches low cost microSD-based NFC solution |website=nfcw.com |last=Clark |first=Sarah |date=11 November 2009 |access-date=28 July 2021 |archive-date=4 March 2021 |archive-url=https://web.archive.org/web/20210304175751/https://www.nfcw.com/2009/11/11/32254/devicefidelity-launches-low-cost-microsd-based-nfc-solution/ |url-status=live}}</ref><ref>{{cite web |url=https://www.secureidnews.com/news-item/devicefidelity-rolls-out-microsd-payment-tool/ |title=DeviceFidelity rolls out microSD payment tool |website=SecureIDNews |date=10 November 2009 |access-date=28 July 2021 |archive-date=8 May 2021 |archive-url=https://web.archive.org/web/20210508014458/https://www.secureidnews.com/news-item/devicefidelity-rolls-out-microsd-payment-tool/ |url-status=live}}</ref> a pioneer in [[near-field communication]] (NFC) and [[mobile payments]], with the introduction of In2Pay and CredenSE products, later commercialized and certified for mobile contactless transactions by [[Visa Inc.|Visa]] in 2010.<ref>{{cite web |url=https://investor.visa.com/news/news-details/2010/Visa-and-DeviceFidelity-Collaborate-to-Accelerate-Adoption-of-Mobile-Contactless-Payments/default.aspx |title=Visa and DeviceFidelity Collaborate to Accelerate Adoption of Mobile Contactless Payments |website=visa.com |date=15 February 2010 |access-date=28 July 2021 |archive-date=19 September 2015 |archive-url=https://web.archive.org/web/20150919131031/http://investor.visa.com/news/news-details/2010/Visa-and-DeviceFidelity-Collaborate-to-Accelerate-Adoption-of-Mobile-Contactless-Payments/default.aspx |url-status=live}}</ref> DeviceFidelity also adapted the In2Pay microSD to work with the Apple iPhone using the iCaisse, and pioneered the first NFC transactions and mobile payments on an Apple device in 2010.<ref>{{cite web |url=https://www.engadget.com/2010-05-18-in2pay-is-the-name-of-visa-and-devicefidelitys-money-grubbing-i.html |title=In2Pay is the name of Visa and DeviceFidelity's money-grubbing iPhone case |website=Engadget |date=18 May 2010 |access-date=28 July 2021 |archive-date=26 January 2021 |archive-url=https://web.archive.org/web/20210126201901/https://www.engadget.com/2010-05-18-in2pay-is-the-name-of-visa-and-devicefidelitys-money-grubbing-i.html |url-status=live}}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=trHueSWx0-g |archive-url=https://ghostarchive.org/varchive/youtube/20211029/trHueSWx0-g| archive-date=2021-10-29|title=Device Fidelity's Amitaabh Mohortra Speaks about their micro NFC device for almost any phone |website=youtube.com |date=26 October 2013 |access-date=28 July 2021 |url-status=live}}{{cbignore}}</ref><ref>{{cite web |url=https://www.nfcw.com/2010/09/23/34489/devicefidelity-adds-nfc-microsd-support-for-iphone-4/ |title=DeviceFidelity adds NFC microSD support for iPhone 4 |last=Clark |first=Mike |website=nfcw.com |date=23 September 2010 |access-date=28 July 2021 |archive-date=19 January 2021 |archive-url=https://web.archive.org/web/20210119025901/https://www.nfcw.com/2010/09/23/34489/devicefidelity-adds-nfc-microsd-support-for-iphone-4/ |url-status=live}}</ref>

Various implementations of smartSD cards have been done for payment applications and secured authentication.<ref>{{cite web|url=http://www.sdcard.org/developers/overview/ASSD/smartsd|title=smartSD Memory Cards|publisher=SD Association|access-date=2016-02-23|archive-date=2015-07-08|archive-url=https://web.archive.org/web/20150708041012/http://www.sdcard.org/developers/overview/ASSD/smartsd/|url-status=live}}</ref><ref>{{cite web|url=http://nfctimes.com/news/microsd-vendor-announces-taiwanese-m-payment-trial-using-htc-nfc-phones|title=MicroSD Vendor Announces Taiwanese M-Payment Trial Using HTC NFC Phones|publisher=NFC Times|access-date=2016-02-23|archive-date=2016-04-27|archive-url=https://web.archive.org/web/20160427232346/http://nfctimes.com/news/microsd-vendor-announces-taiwanese-m-payment-trial-using-htc-nfc-phones|url-status=live}}</ref> In 2012 [[Good Technology]] partnered with DeviceFidelity to use microSD cards with secure elements for [[mobile identity]] and [[access control]].<ref>{{cite web |url=https://www.secureidnews.com/news-item/devicefidelitys-good-vault-provides-identity-and-access-solution-for-ios/ |title=DeviceFidelity's Good Vault provides identity and access solution for iOS |website=SecureIDNews |last=Hudson |first=Andrew |date=10 December 2012 |access-date=28 July 2021 |archive-date=23 October 2021 |archive-url=https://web.archive.org/web/20211023195556/https://www.secureidnews.com/news-item/devicefidelitys-good-vault-provides-identity-and-access-solution-for-ios/ |url-status=live}}</ref>

microSD cards with Secure Elements and NFC ([[near-field communication]]) support are used for mobile payments, and have been used in direct-to-consumer mobile wallets and mobile banking solutions, some of which were launched by major banks around the world, including [[Bank of America]], [[US Bank]] and [[Wells Fargo]],<ref>{{cite press release |url=https://www.businesswire.com/news/home/20130114005951/en/Datacard-Group-DeviceFidelity-U.S.-Bank-Announce-New |title=Datacard Group, DeviceFidelity and U.S. Bank Announce New Smart Card and Mobile Payment Program |publisher=Datacard Group |date=14 January 2013 |access-date=28 July 2021 |via=Businesswire |archive-date=20 August 2021 |archive-url=https://web.archive.org/web/20210820214158/https://www.businesswire.com/news/home/20130114005951/en/Datacard-Group-DeviceFidelity-U.S.-Bank-Announce-New |url-status=live}}</ref><ref>{{cite web |url=https://www.nfcw.com/2010/08/19/34339/bank-of-america-to-run-nfc-payments-trial-in-new-york/ |title=Bank of America to run NFC payments trial in New York |website=nfcw.com |last=Clark |first=Sarah |date=19 August 2010 |access-date=28 July 2021 |archive-date=25 January 2021 |archive-url=https://web.archive.org/web/20210125143142/https://www.nfcw.com/2010/08/19/34339/bank-of-america-to-run-nfc-payments-trial-in-new-york/ |url-status=live}}</ref><ref>{{Cite web |url=https://www.businesswire.com/news/home/20101206007176/en/Wells-Fargo-Roll-Mobile-Payments-Pilot-Visa |title=Wells Fargo to Roll Out Mobile Payments Pilot; Visa Demonstrating Capability at CARTES 2010 &#124; Business Wire |access-date=2020-10-14 |archive-date=2020-10-14 |archive-url=https://web.archive.org/web/20201014173430/https://www.businesswire.com/news/home/20101206007176/en/Wells-Fargo-Roll-Mobile-Payments-Pilot-Visa |url-status=dead}}</ref> while others were part of innovative new direct-to-consumer [[neobank]] programs such as [[moneto]], first launched in 2012.<ref>{{cite press release |url=https://www.prweb.com/releases/2012/1/prweb9086910.htm |archive-url=https://web.archive.org/web/20120113083550/http://www.prweb.com/releases/2012/1/prweb9086910.htm |url-status=dead |archive-date=January 13, 2012 |title=DeviceFidelity and SpringCard Launch moneto, the World's First Multi-Platform Mobile Wallet for iPhone and Android at CES |publisher=DeviceFidelity |date=10 January 2012 |access-date=28 July 2021 |via=Cision}}</ref><ref>{{cite web |url=https://www.nfcw.com/2012/09/11/317791/moneto-to-bring-nfc-payments-to-europe/ |title=Moneto to bring NFC payments to Europe |website=nfcw.com |last=Clark |first=Sarah |date=11 September 2012 |access-date=28 July 2021 |archive-date=25 January 2021 |archive-url=https://web.archive.org/web/20210125134752/https://www.nfcw.com/2012/09/11/317791/moneto-to-bring-nfc-payments-to-europe/ |url-status=live}}</ref><ref>{{cite web|url=http://www.rfid-ready.com/201403038507/garanti-bank-deploys-nfc-services-on-microsd.html|title=Garanti Bank deploys NFC services on microSD|publisher=RFID Ready|access-date=2016-02-23|archive-date=2017-02-02|archive-url=https://web.archive.org/web/20170202124458/http://www.rfid-ready.com/201403038507/garanti-bank-deploys-nfc-services-on-microsd.html|url-status=dead}}</ref><ref>{{cite web|url=http://www.nfcworld.com/2012/10/31/320843/devicefidelity-launches-new-range-of-nfc-microsd-devices/|title=DeviceFidelity launches new range of NFC microSD devices|publisher=NFC World+|date=2012-10-31|access-date=2016-02-23|archive-date=2016-04-20|archive-url=https://web.archive.org/web/20160420165354/http://www.nfcworld.com/2012/10/31/320843/devicefidelity-launches-new-range-of-nfc-microsd-devices/|url-status=live}}</ref>

microSD cards with Secure Elements have also been used for secure [[voice encryption]] on mobile devices, which allows for one of the highest levels of security in person-to-person voice communications.<ref>{{cite web |url=https://koolspan.com/iphone_devicefidelity/ |title=iPhone Voice Encryption from KoolSpan and DeviceFidelity |website=koolspan.com |date=11 March 2013 |access-date=28 July 2021 |archive-date=27 January 2021 |archive-url=https://web.archive.org/web/20210127060537/https://koolspan.com/iphone_devicefidelity/ |url-status=dead}}</ref> Such solutions are heavily used in intelligence and security.

In 2011, [[HID Global]] partnered with [[Arizona State University]] to launch campus access solutions for students using microSD with Secure Element and [[MiFare]] technology provided by [[DeviceFidelity, Inc.]]<ref>{{cite web |url=https://www.cr80news.com/news-item/arizona-students-first-to-trial-mobile-phones-with-nfc-for-door-access/ |title=Arizona students first to trial mobile phones with NFC for door access |work=CR80 News |last=Corum |first=Chris |date=14 September 2011 |access-date=28 July 2021 |archive-date=6 November 2021 |archive-url=https://web.archive.org/web/20211106083657/https://www.cr80news.com/news-item/arizona-students-first-to-trial-mobile-phones-with-nfc-for-door-access/ |url-status=live}}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=d4NmYdMAAHU | archive-url=https://ghostarchive.org/varchive/youtube/20211029/d4NmYdMAAHU| archive-date=2021-10-29|title=Case Study: Mobile Access Pilot at Arizona State University |website=youtube.com |date=14 October 2011 |access-date=28 July 2021 |url-status=live}}{{cbignore}}</ref> This was the first time regular mobile phones could be used to open doors without need for electronic access keys.

===<span class="anchor" id="Integrated Wi-Fi"></span> Vendor enhancements===
 {{multiple image
 | SD cards with integrated Wi-Fi
 | perrow      = 2
 | total_width = 390
 | image1      = Eye-Fi Wifi Card.jpg
 | caption1    = Eye-Fi Mobi 16&nbsp;GB
 | image2      = FlashAir 014 (15247275839) (cropped).jpg
 | caption2    = Toshiba FlashAir 16&nbsp;GB
 | image3      = Pqi-air-card 開箱 (8536928274) (cropped).jpg
 | caption3    = PQI air card 4&nbsp;GB
 | image4      = Transcend WiFi SD-Card.jpg
 | caption4    = Transcend Wi-Fi 16&nbsp;GB
 }}
[[File:USB-SD-Cards.jpg|thumb|SD cards with dual interfaces: SD and [[USB]]]]

Vendors have sought to differentiate their products in the market through various vendor-specific features:
* '''Integrated [[Wi-Fi]]''' – Several companies produce SD cards with built-in Wi-Fi transceivers supporting static security (WEP 40/104/128, WPA-PSK and WPA2-PSK). The card lets any digital camera with an SD slot transmit captured images over a wireless network, or store the images on the card's memory until it is in range of a wireless network. Examples include: [[Eye-Fi]] / [[SanDisk Eye-Fi|SanDisk]], [[Transcend Wi-Fi]], [[Toshiba FlashAir]], [[Trek Flucard]], [[PQI Air Card]] and [[LZeal ez Share]].<ref>{{cite web |url=http://www.eye.fi/ |title=Eye-Fi |access-date=2010-08-22 |url-status=dead |archive-url=http://webarchive.loc.gov/all/20100826002041/http%3A//www.eye.fi/ |archive-date=2010-08-26}}</ref> Some models [[Geotagging|geotag]] their pictures.
* '''Pre-loaded content''' – In 2006, SanDisk announced [[Gruvi]], a microSD card with extra digital rights management features, which they intended as a medium for publishing content. SanDisk again announced pre-loaded cards in 2008, under the [[slotMusic]] name, this time not using any of the DRM capabilities of the SD card.<ref>{{cite web |last=Robson |first=Wayde |url=http://www.audioholics.com/news/industry-news/sandisk-slotmusic |title=AudioHolics |date=22 September 2008 |publisher=AudioHolics |access-date=2014-01-02 |archive-date=2013-06-02 |archive-url=https://web.archive.org/web/20130602015817/http://www.audioholics.com/news/industry-news/sandisk-slotmusic |url-status=live}}</ref> In 2011, SanDisk offered various collections of 1000 songs on a single slotMusic card for about $40,<ref>{{cite web|url=http://www.sandisk.com/consumer-products/slotradio|title=slotRadio|publisher=SanDisk|access-date=2011-11-27|archive-date=2011-11-24|archive-url=https://web.archive.org/web/20111124105916/http://www.sandisk.com/consumer-products/slotradio|url-status=live}}</ref> now restricted to compatible devices and without the ability to copy the files.
* '''Integrated USB connector''' – The [[SanDisk]] '''SD Plus''' product can be plugged directly into a [[USB]] port without needing a USB card reader.<ref>{{Citation |url=https://www.theregister.co.uk/2005/07/25/review_sandisk_ultra_ii_sd_plus/ |title=SanDisk Ultra II SD Plus USB/SD card |newspaper=The Register |place=[[United Kingdom|UK]] |date=2005-07-25 |access-date=2024-09-11 |archive-date=2019-08-08 |archive-url=https://web.archive.org/web/20190808091122/https://www.theregister.co.uk/2005/07/25/review_sandisk_ultra_ii_sd_plus/ |url-status=live}}</ref> Other companies introduced comparable products, such as the '''Duo SD''' product of [[OCZ Technology]] and the '''3 Way''' (microSDHC, SDHC and USB) product of [[A-DATA]], which was available in 2008 only.
* '''Different colors''' – SanDisk has used various colors of plastic or adhesive label, including a "gaming" line in translucent plastic colors that indicated the card's capacity. In 2006, the first 256MB microSD to use color-coded cards by Kingmax, which later other brands (e.g., SanDisk, Kioxia) had been implementing to this day.
* '''Integrated display''' – In 2006, ADATA announced a '''Super Info SD''' card with a digital display that provided a two-character label and showed the amount of unused memory on the card.<ref>{{cite web |url=http://www.techpowerup.com/reviews/AData/ADATASuperInfoSD/ |title=A-DATA Super Info SD Card 512MB |publisher=Tech power up |date=2007-02-20 |access-date=2011-12-30 |archive-date=2012-05-18 |archive-url=https://web.archive.org/web/20120518161342/http://www.techpowerup.com/reviews/AData/ADATASuperInfoSD/ |url-status=live}}</ref>

===SDIO cards===
{{more citations needed|section=yes|date=September 2023}}
[[File:SDIO Vector.svg|thumb|upright=0.65|Secure Digital Input Output (SDIO) mark]]
[[File:HP PhotoSmart SDIO Kamera (cropped).jpg|thumb|upright|Camera using the SDIO interface to connect to some HP [[iPAQ]] devices]]

A SDIO (Secure Digital Input Output) card is an extension of the SD specification to cover I/O functions. SDIO cards are only fully functional in host devices designed to support their input-output functions (typically PDAs like the [[Palm Treo]], but occasionally laptops or mobile phones).{{citation needed|date=September 2023}} These devices can use the SD slot to support [[GPS]] receivers, [[modem]]s, [[barcode reader]]s, [[FM radio]] tuners, TV tuners, [[RFID]] readers, [[digital camera]]s and interfaces to [[Wi-Fi]], [[Bluetooth]], [[Ethernet]] and [[IrDA]]. Many other SDIO devices have been proposed, but it is now more common for I/O devices to connect using the USB interface.{{citation needed|date=September 2023}}

SDIO cards support most of the memory commands of SD cards. SDIO cards can be structured as eight logical cards, although currently, the typical way that an SDIO card uses this capability is to structure itself as one I/O card and one memory card.{{citation needed|date=September 2023}}

The SDIO and SD interfaces are mechanically and electrically identical. Host devices built for SDIO cards generally accept SD memory cards without I/O functions. However, the reverse is not true, because host devices need suitable drivers and applications to support the card's I/O functions. For example, an HP SDIO camera usually does not work with PDAs that do not list it as an accessory. Inserting an SDIO card into any SD slot causes no physical damage nor disruption to the host device, but users may be frustrated that the SDIO card does not function fully when inserted into a seemingly compatible slot. (USB and Bluetooth devices exhibit comparable compatibility issues, although to a lesser extent thanks to standardized [[Class driver|USB device classes]] and [[Bluetooth profiles]].){{citation needed|date=September 2023}}

The [[#SDIO|SDIO]] family comprises Low-Speed and Full-Speed cards. Both types of SDIO cards support [[Serial Peripheral Interface]] (SPI) and one-bit SD bus types. Low-Speed SDIO cards are allowed to also support the four-bit SD bus; Full-Speed SDIO cards are required to support the four-bit SD bus. To use an SDIO card as a "combo card" (for both memory and I/O), the host device must first select four-bit SD bus operation. Two other unique features of Low-Speed SDIO are a maximum clock rate of 400&nbsp;kHz for all communications, and the use of Pin 8 as "interrupt" to try to initiate dialogue with the host device.<ref name="SDIOspec">{{cite web |url=https://www.sdcard.org/developers/overview/sdio/sdio_spec/ |title=Simplified Version of SDIO CARD SPEC |publisher=SD Association |access-date=2011-12-09 |archive-date=2015-04-15 |archive-url=https://web.archive.org/web/20150415230526/https://www.sdcard.org/developers/overview/sdio/sdio_spec/ |url-status=dead}}</ref>

===Compatibility===
Host devices that comply with newer versions of the specification provide [[backward compatibility]] and accept older SD cards.<ref name="sdcard.org"/> For example, SDXC host devices accept all previous families of SD memory cards, and SDHC host devices also accept standard SD cards.

Older host devices generally do not support newer card formats, and even when they might support the bus interface used by the card,<ref name=sdcard_using_sdxc/> there are several factors that arise:
* A newer card may offer greater [[#Cpcty|capacity]] than the host device can handle (over 4&nbsp;GB for SDHC, over 32&nbsp;GB for SDXC).
* A newer card may use a [[#Filesys|file system]] the host device cannot navigate ([[FAT32]] for SDHC, [[exFAT]] for SDXC)
* Use of an SDIO card requires the host device be designed for the input/output functions the card provides.
* The hardware interface of the card was changed starting with the version 2.0 (new high-speed bus clocks, redefinition of [[#Storage capacity calculations|storage capacity bits]]) and [[#SDHC|SDHC]] family (ultra-high speed (UHS) bus)
* UHS-II has physically more pins but is backwards compatible to UHS-I and non-UHS for both slot and card.<ref name="sda_bus_speed"/>
* Some vendors produced SDSC cards above 1&nbsp;GB before the SDA had standardized a method of doing so.

{| class="wikitable"
|+ SD compatibility table
! {{Diagonal split header 2|Slot|Card}}
! scope="col" | SDSC
! scope="col" | SDHC
! scope="col" | SDHC<br />UHS
! scope="col" | SDXC
! scope="col" | SDXC<br />UHS
! scope="col" | SDIO
|-
! style="text-align:left;" | SDSC
| {{Partial}}{{Efn|name=sdsccompat|See [[#Storage_capacity_and_compatibilities|discussion about storage capacity and compatibilities]].}} || {{Partial|FAT16, < 4&nbsp;GB}}{{Efn|name=sdsccompat}} || {{Partial|FAT16, < 4&nbsp;GB}}{{Efn|name=sdsccompat}} || {{No}} || {{No}} || {{No}}
|-
! style="text-align:left;" | SDHC
| {{Yes}} || {{Yes}} || {{good|In non-UHS mode}} || {{Partial|FAT32}} || {{Partial|FAT32 in non-UHS mode}} || {{No}}
|-
! style="text-align:left;" | SDHC UHS
| {{good|In non-UHS mode}} || {{good|In non-UHS mode}} || {{Yes|In UHS mode}} || {{Partial|FAT32 in non-UHS mode}} || {{Partial|FAT32 in UHS mode}} || {{No}}
|-
! style="text-align:left;" | SDXC
| {{Yes}} || {{Yes}} || {{good|In non-UHS mode}} || {{Yes}} || {{good|In non-UHS mode}} || {{No}}
|-
! style="text-align:left;" | SDXC UHS
| {{good|In non-UHS mode}} || {{good|In non-UHS mode}} || {{Yes|In UHS mode}} || {{good|In non-UHS mode}}|| {{Yes|In UHS mode}} || {{No}}
|-
! style="text-align:left;" | SDIO
| {{partial|Varies}} || {{partial|Varies}} || {{partial|Varies}} || {{partial|Varies}} || {{partial|Varies}} || {{Yes}}
|}