Editing SD card (section)

== Capacity ratings ==
Secure Digital includes five card families available in [[#Physical size|three form factors]]. The five families are the original standard capacity (SDSC), high capacity (SDHC), extended capacity ([[#SDXC|SDXC]]), ultra capacity ([[#SDUC|SDUC]]) and [[#SDIO_cards|SDIO]], which combines [[input/output]] functions with data storage.<ref name="sdcard_capacity">{{cite web|title=Capacity|publisher=SD Association|url=http://www.sdcard.org/developers/overview/capacity/|access-date=2011-12-08|archive-date=2020-05-20|archive-url=https://web.archive.org/web/20200520193351/https://www.sdcard.org/developers/overview/capacity/|url-status=live}}</ref><ref name="sdcard_using_sdxc">{{cite web|title=Using SDXC|publisher=SD Association|url=http://www.sdcard.org/consumers/sdxc_capabilities/using_sdxc/|access-date=2011-12-08|archive-date=2014-10-10|archive-url=https://web.archive.org/web/20141010090939/https://www.sdcard.org/consumers/sdxc_capabilities/using_sdxc|url-status=dead}}</ref><ref name="sdcard_sdio">{{cite web|title=SDIO|publisher=SD Association|url=http://www.sdcard.org/developers/overview/sdio/|access-date=2011-12-08|archive-date=2020-05-20|archive-url=https://web.archive.org/web/20200520193351/https://www.sdcard.org/developers/overview/sdio/|url-status=live}}</ref>

{| class="wikitable" style="text-align: center;"
|+ Comparison of capacity standards<ref>{{Cite web |date=2020-12-11 |title=Capacity (SD/SDHC/SDXC/SDUC) {{!}} SD Association |url=https://www.sdcard.org/developers/sd-standard-overview/capacity-sd-sdhc-sdxc-sduc/ |access-date=2025-01-07 |website=www.sdcard.org |language=en-US |archive-date=8 March 2022 |archive-url=https://web.archive.org/web/20220308120216/https://www.sdcard.org/developers/sd-standard-overview/capacity-sd-sdhc-sdxc-sduc/ |url-status=live }}</ref>
!
! scope="col" | SD
! scope="col" | SDHC
! scope="col" | SDXC
! scope="col" | SDUC
|- style="background: white;"
!Mark
| [[File:SD-Logo.svg|frameless|upright=0.25]]
| [[File:SDHC-Logo.svg|frameless|upright=0.25]]
| [[File:SDXC.svg|frameless|upright=0.25]]
| [[File:SDUC.svg|frameless|upright=0.25]]
|-
!Max capacity
| {{Nowrap|2 GB}}
| {{Nowrap|32 GB}}
| {{Nowrap|2 TB}}
| {{Nowrap|128 TB}}
|-
! scope="row" id="Filesys" | File system
| [[FAT12]], [[FAT16]]
| [[FAT32]]
| colspan="2" | [[exFAT]]
|}

=== SD (SDSC) ===
{{More citations needed|section|date=September 2023}}

The original Secure Digital card, also known as Secure Digital Standard Capacity (SDSC), was developed as a second-generation successor to the [[MultiMediaCard]] (MMC) standard. While both formats continued to evolve, they diverged significantly in design and functionality. Secure Digital introduced several key changes to improve usability, durability, and performance:
* Asymmetrical shape of the sides of the SD card prevents inserting it upside down (whereas an MMC goes in most of the way but makes no contact if inverted).{{citation needed|date=September 2023}}
* Most standard size SD cards are {{Convert|2.1|mm|abbr=in}}<ref name="CS">{{Cite web |date=2020-12-11 |title=Capacity (SD/SDHC/SDXC/SDUC) {{!}} SD Association |url=https://www.sdcard.org/developers/sd-standard-overview/capacity-sd-sdhc-sdxc-sduc/ |access-date=2023-05-03 |website=sdcard.org |language=en-US |archive-date=2024-09-11 |archive-url=https://web.archive.org/web/20240911012954/https://www.sdcard.org/developers/sd-standard-overview/capacity-sd-sdhc-sdxc-sduc/ |url-status=live}}</ref> thick, with microSD versions being {{Convert|1.0|mm|abbr=in}}<ref name="CS" /> thick, compared to {{Convert|1.4|mm|abbr=in}} for MMCs. The SD specification defines a card called '''Thin SD''' with a thickness of 1.4&nbsp;mm,<ref name=":0">{{Cite book |url=https://www.sdcard.org/downloads/pls/pdf/?p=Part1_Physical_Layer_Simplified_Specification_Ver9.10.jpg&f=Part1PhysicalLayerSimplifiedSpecificationVer9.10Fin_20231201.pdf&e=EN_SS9_1 |title=SD Specifications Part 1 Physical Layer Simplified Specification |date=December 1, 2023 |publisher=SD Card Association |edition=9.10 |page=5}}</ref> however it was rarely used, as the SDA went on to define even smaller form factors.
* The card's electrical contacts are recessed beneath the surface of the card, protecting them from contact with a user's fingers.
* The SD specification envisioned capacities and transfer rates exceeding those of MMC, and both of these functionalities have grown over time.{{citation needed|date=September 2023}} For a comparison table, see [[#Comparison to other flash memory formats|below]].
* While MMC uses a single pin for data transfers, the SD card added a four-wire bus mode for higher data rates.{{citation needed|date=September 2023}}
* The SD card added [[Content Protection for Recordable Media]] (CPRM) security circuitry for [[digital rights management]] (DRM) content-protection, although it is rarely used and most devices don't support it.<ref>{{Cite web |title=Definition of CPRM |url=https://www.pcmag.com/encyclopedia/term/cprm |access-date=2025-04-29 |website=PCMAG |language=en |archive-date=29 April 2025 |archive-url=https://web.archive.org/web/20250429025631/https://www.pcmag.com/encyclopedia/term/cprm |url-status=live }}</ref><ref>{{Cite web |title=Copyright Protection for Digital Data (CPRM) |url=https://www.sdcard.org/consumers/about-sd-memory-card-choices/copyright-protection-for-digital-data-cprm/ |access-date=2025-04-29 |website=SD Association |language=en-US |archive-date=29 April 2025 |archive-url=https://web.archive.org/web/20250429025631/https://www.sdcard.org/consumers/about-sd-memory-card-choices/copyright-protection-for-digital-data-cprm/ |url-status=live }}</ref>
* Addition of a write-protect notch{{citation needed|date=September 2023}}

The official SDSC specification supports card sizes up to 2 GB and uses a logo to distinguish it from later SD formats.

Due to physical differences, full-size SD cards are incompatible with slimmer MMC slots, and other electrical and protocol-level differences further limit interoperability between the two formats.{{citation needed|date=September 2023}}

===SDHC===
The Secure Digital High Capacity (SDHC) format, announced in January 2006 and defined in version 2.0 of the SD specification, supports cards with capacities up to 32&nbsp;GB.{{efn|name="GiB"}}<ref name="sdcard_capacity"/> The SDHC trademark is licensed to ensure compatibility.<ref name=sandisk-sdhc>[http://www.sandisk.com/Assets/File/pdf/retail/SDHC1.pdf What are SDHC, miniSDHC, and microSDHC?] SanDisk. {{webarchive |url=https://web.archive.org/web/20080916035153/http://www.sandisk.com/Assets/File/pdf/retail/SDHC1.pdf |date=September 16, 2008}}</ref>

SDHC cards are physically and electrically identical to standard-capacity SD cards (SDSC). The major compatibility issues between SDHC and SDSC cards are the redefinition of the Card-Specific Data (CSD) register in version 2.0 (see [[#Storage capacity calculations|below]]), and the fact that SDHC cards are shipped preformatted with the [[FAT32]] file system.

Version 2.0 also introduces a high-speed bus mode for both SDSC and SDHC cards, which doubles the original Standard Speed clock to produce 25&nbsp;[[MB/s]].<ref name=sd-association>[https://www.sdcard.org/developers/overview/bus_speed/ Bus Speed (Default Speed/ High Speed/ UHS)] {{Webarchive|url=https://web.archive.org/web/20161004053633/https://www.sdcard.org/developers/overview/bus_speed/ |date=2016-10-04}} SDcard.</ref>

SDHC host devices are required to accept older SD cards.<ref name="sdcard.org">[https://www.sdcard.org/consumers/compatibility/ About Compatibility with Host Devices] {{webarchive|url=https://web.archive.org/web/20111121065335/https://www.sdcard.org/consumers/compatibility/ |date=2011-11-21}} SD Association.</ref> However, older host devices do not recognize SDHC or SDXC memory cards, although some devices can do so through a firmware upgrade.<ref>[http://www.jetaudio.com/download/cowon_rn_d2.html#241 What's new in Firmware 2.41 Beta (for COWON D2)] {{Webarchive|url=https://web.archive.org/web/20110828092629/http://www.jetaudio.com/download/cowon_rn_d2.html#241 |date=2011-08-28}} JetAudio.</ref>{{Better source needed|date=June 2021}} Older Windows operating systems released before Windows 7 require patches or service packs to support access to SDHC cards.<ref>{{cite web |url= http://support.microsoft.com/kb/934428 |work= Support |title= 934428 – Hotfix for Windows XP that adds support for SDHC cards that have a capacity of more than 4&nbsp;GB |publisher=Microsoft |date=2008-02-15 |access-date= 2010-08-22 |archive-date= 2010-01-03 |archive-url= https://web.archive.org/web/20100103175653/http://support.microsoft.com/kb/934428 |url-status=live}}</ref><ref>{{cite web |url=http://support.microsoft.com/kb/939772 | work=Support |title=939772 – Some Secure Digital (SD) cards may not be recognized in Windows Vista |publisher=Microsoft |date=2008-05-15 |access-date=2010-08-22 |archive-date=2010-02-09 |archive-url=https://web.archive.org/web/20100209062534/http://support.microsoft.com/kb/939772 |url-status=live}}</ref><ref>{{cite web |url=http://support.microsoft.com/kb/949126 |work=Support |title=949126 – A Secure Digital High Capacity (SDHC) card is not recognized on a Windows Vista Service Pack 1-based computer |publisher=Microsoft |date=2008-02-21 |access-date= 2010-08-22 |archive-date=2010-01-09 |archive-url=https://web.archive.org/web/20100109134743/http://support.microsoft.com/kb/949126 |url-status=live}}</ref>

===SDXC===
The Secure Digital eXtended Capacity (SDXC) format, announced in January 2009 and defined in version 3.01 of the SD specification, supports cards up to 2&nbsp;TB,{{efn|name="here, 1&nbsp;TB = 1024"}} compared to a limit of 32&nbsp;GB{{efn|name="GiB"}} for SDHC cards in the SD 2.0 specification. SDXC adopts Microsoft's [[exFAT]] file system as a mandatory feature.<ref>{{Cite web |url=https://www.sdcard.org/developers/overview/capacity/ |title=Capacity (SD/SDHC/SDXC) |website=SD Association |language=en |access-date=2017-03-20 |archive-date=2011-11-21 |archive-url=https://web.archive.org/web/20111121064806/https://www.sdcard.org/developers/overview/capacity/ |url-status=live}}</ref>

Version 3.01 also introduced the Ultra High Speed (UHS) bus for both SDHC and SDXC cards, with interface speeds from 50&nbsp;MB/s to 104&nbsp;MB/s for four-bit UHS-I bus.<ref name="BS">{{cite web |title=Bus Speed (Default Speed/ High Speed/ UHS) |url=https://www.sdcard.org/developers/overview/bus_speed/ |website=SD Association |access-date=20 March 2017 |language=en |archive-date=4 October 2016 |archive-url=https://web.archive.org/web/20161004053633/https://www.sdcard.org/developers/overview/bus_speed/ |url-status=live}}</ref> (this number has since been exceeded with SanDisk proprietary technology for 170&nbsp;MB/s read, which is not proprietary anymore, as Lexar has the 1066x running at 160&nbsp;MB/s read and 120&nbsp;MB/s write via UHS&nbsp;1, and Kingston also has their Canvas Go! Plus, also running at 170&nbsp;MB/s).<ref>{{Cite web |title=Lexar Professional 1066x microSDXC UHS-I Card SILVER Series |url=https://www.lexar.com/portfolio_page/professional-1066x-microsdhcmicrosdxc-uhs-i-cards-silver-series/ |access-date=2021-04-10 |website=Lexar |language=en |archive-url=https://web.archive.org/web/20210410090638/https://www.lexar.com/portfolio_page/professional-1066x-microsdhcmicrosdxc-uhs-i-cards-silver-series/ |archive-date=2021-04-10}}</ref><ref>{{Cite web |title=SanDisk Extreme PRO SDHC And SDXC UHS-I Card |url=https://shop.westerndigital.com/products/memory-cards/sandisk-extreme-pro-uhs-i-sd#SDSDXXY-064G-GN4IN |access-date=2021-04-10 |website=shop.westerndigital.com |archive-date=2021-04-10 |archive-url=https://web.archive.org/web/20210410090637/https://shop.westerndigital.com/products/memory-cards/sandisk-extreme-pro-uhs-i-sd#SDSDXXY-064G-GN4IN |url-status=live}}</ref><ref>{{Cite web |title=Canvas Go! Plus Class 10 SD Cards – UHS-I, U3, V30 – 64&nbsp;GB–512&nbsp;GB |url=https://www.kingston.com/en/memory-cards/canvas-go-plus-sd-card |access-date=2021-04-10 |website=Kingston Technology Company |language=en-US |archive-date=2021-10-11 |archive-url=https://web.archive.org/web/20211011111151/https://www.kingston.com/en/memory-cards/canvas-go-plus-sd-card |url-status=live}}</ref><ref>{{Cite web |title=Canvas Go! Plus Class 10 microSD Cards – V30, A2 – 64&nbsp;GB–512&nbsp;GB |url=https://www.kingston.com/en/memory-cards/canvas-go-plus-microsd-card |access-date=2021-04-10 |website=Kingston Technology Company |language=en-US}}</ref>

Version 4.0, introduced in June 2011, allows speeds of 156&nbsp;MB/s to 312&nbsp;MB/s over the four-lane (two differential lanes) UHS-II bus, which requires an additional row of physical pins.<ref name="BS"/>

Version 5.0 was announced in February 2016 at CP+ 2016, and added "Video Speed Class" ratings for UHS cards to handle higher resolution video formats like [[8K resolution|8K]].<ref name="sda_video_speed">{{cite web | url = https://www.sdcard.org/press/New_SD_Association_Speed_Class_Supports_8K_and_Multi_File_Video_Recording.pdf |date=2016-02-26 |title=NEW SD ASSOCIATION VIDEO SPEED CLASS SUPPORTS 8K AND MULTI-FILE VIDEO RECORDING | publisher = SD Association | access-date = 2016-03-03 | archive-date = 2016-03-07 |archive-url=https://web.archive.org/web/20160307192442/https://www.sdcard.org/press/New_SD_Association_Speed_Class_Supports_8K_and_Multi_File_Video_Recording.pdf |url-status=dead}}</ref><ref>{{cite web |url=http://www.anandtech.com/show/10105/sd-association-announces-50-specification |title=SD Association Announces SD 5.0 Specification: SD Cards For UHD and 360° Video Capture |date=2016-03-01 |first=Anton |last=Shilov |publisher=Anand Tech |access-date=2016-03-03 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303190529/http://www.anandtech.com/show/10105/sd-association-announces-50-specification |url-status=live}}</ref> The new ratings define a minimal write speed of 90&nbsp;MB/s.<ref name="sd50_video_speed">{{cite web |url=https://www.sdcard.org/downloads/pls/latest_whitepapers/Video_Speed_Class-The_new_capture_protocol_of_SD_5.0.pdf |title=Video Speed Class: The new capture protocol of SD 5.0 |publisher=SD Association |date=February 2016 |access-date=2016-03-03 |archive-date=2016-12-23 |archive-url=https://web.archive.org/web/20161223213758/https://www.sdcard.org/downloads/pls/latest_whitepapers/Video_Speed_Class-The_new_capture_protocol_of_SD_5.0.pdf |url-status=dead}}</ref><ref>{{cite web |url=https://www.cinema5d.com/new-video-speed-class-for-sd-cards/ |title=New Video Speed Class for SD Cards |first=Fabian |last=Chaundy |date=2016-02-26 |work=cinema5D |access-date=2016-03-03 |archive-date=2016-03-07 |archive-url=https://web.archive.org/web/20160307015103/https://www.cinema5d.com/new-video-speed-class-for-sd-cards/ |url-status=live}}</ref>

SDXC cards are required to be formatted using [[exFAT]],<ref name="CS" /> but many operating systems will support others.{{citation needed|date=October 2024}}

[[Windows Vista]] (SP1) and later<ref>{{cite web |title=Notable Changes in Windows Vista Service Pack 1 |url=https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-vista/cc709618(v=ws.10) |department=[[Microsoft TechNet|TechNet]] |website=[[Microsoft Docs]] |date=25 July 2008 |access-date=2021-11-07 |archive-date=2021-11-07 |archive-url=https://web.archive.org/web/20211107193722/https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-vista/cc709618(v=ws.10) |url-status=live }}</ref> and [[OS X]] (10.6.5 and later) have native support for exFAT.<ref>{{cite web |url=http://support.apple.com/kb/HT3553 |title=About the SD and SDXC card slots |publisher=Apple Inc. |date=2011-05-03 |access-date=2011-09-05 |archive-date=2011-09-03 |archive-url=https://web.archive.org/web/20110903100124/http://support.apple.com/kb/HT3553 |url-status=live }}</ref><ref>{{cite web |url=http://www.tuxera.com/mac/apple-released-exfat-support-in-os-x-10-6-5-update/ |title=Apple released exFAT support in OS X 10.6.5 update |publisher=Tuxera.com |date=2010-11-22 |access-date=2012-01-04 |archive-date=2012-05-13 |archive-url=https://web.archive.org/web/20120513202527/http://www.tuxera.com/mac/apple-released-exfat-support-in-os-x-10-6-5-update/ |url-status=dead }}</ref> (Windows XP and Server 2003 can support exFAT via an optional update from Microsoft.)<ref>{{cite web|url=https://support.microsoft.com/en-us/kb/955704|title=Description of the exFAT file system driver update package|publisher=Microsoft|date=2011-10-08|access-date=2015-11-27|archive-url=https://web.archive.org/web/20150511025138if_/https://support.microsoft.com/en-us/kb/955704|archive-date=2015-05-11}}</ref>

Most [[Berkeley Software Distribution|BSD]] and [[Linux]] distributions did not have exFAT support for legal reasons, though in Linux kernel 5.4 Microsoft open-sourced the spec and allowed the inclusion of an exFAT driver.<ref>{{cite web |url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.4-exFAT-Is-Coming |title=The Initial exFAT Driver Queued For Introduction With The Linux 5.4 Kernel |publisher=phoronix.com |date=2019-08-30 |access-date=2020-02-05 |archive-date=2019-12-18 |archive-url=https://web.archive.org/web/20191218061425/https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.4-exFAT-Is-Coming |url-status=live }}</ref> Users of older kernels or BSD can manually install third-party implementations of exFAT (as a [[Filesystem in Userspace|FUSE]] module) in order to be able to mount exFAT-formatted volumes.<ref>{{cite web |url=https://code.google.com/p/exfat/ |title=exFAT for BSD and Linux systems from Google Code |access-date=2014-01-02 |archive-date=2014-01-11 |archive-url=https://web.archive.org/web/20140111120127/http://code.google.com/p/exfat/ |url-status=live }}</ref> However, SDXC cards can be reformatted to use any file system (such as [[ext4]], [[Unix File System|UFS]], [[VFAT]] or [[NTFS]]), alleviating the restrictions associated with exFAT availability.

The SD Association provides a formatting utility for Windows and Mac OS X that checks and formats SD, SDHC, SDXC and SDUC cards.<ref>{{cite web |url=https://www.sdcard.org/downloads/formatter_4/ |title=SD Formatter 4.0 for SD/SDHC/SDXC – SD Association |publisher=Sdcard.org |access-date=2014-01-02 |archive-date=2014-02-07 |archive-url=https://web.archive.org/web/20140207233443/https://www.sdcard.org/downloads/formatter_4/ |url-status=live }}</ref>

Except for the change of file system, SDXC cards are mostly backward compatible with SDHC readers, and many SDHC host devices can use SDXC cards if they are first reformatted to the FAT32 file system.<ref>{{cite web |title=Updated: How to upgrade your 3DS SD card, to 64GB and beyond |author=deKay |date=15 January 2015 |website=Lofi-Gaming |url=https://lofi-gaming.org.uk/blog/2013/10/25/updated-how-to-upgrade-your-3ds-sd-card-to-64gb-and-beyond/ |access-date=2018-12-21 |archive-date=2018-12-21 |archive-url=https://web.archive.org/web/20181221134714/https://lofi-gaming.org.uk/blog/2013/10/25/updated-how-to-upgrade-your-3ds-sd-card-to-64gb-and-beyond/ |url-status=live }}</ref><ref>{{cite web |title=Ask Hackaday: How On Earth Can A 2004 MP3 Player Read An SDXC Card? |first=Jenny |last=List |date=29 November 2017 |website=Hackaday |url=https://hackaday.com/2017/11/29/ask-hackaday-how-on-earth-can-a-2004-mp3-player-read-an-sdxc-card/ |access-date=2018-12-21 |archive-date=2018-12-21 |archive-url=https://web.archive.org/web/20181221182601/https://hackaday.com/2017/11/29/ask-hackaday-how-on-earth-can-a-2004-mp3-player-read-an-sdxc-card/ |url-status=live }}</ref><ref>{{cite web |title=High capacity microSD cards and Android – Gary explains |first=Gary |last=Sims |date=9 May 2016 |website=Android Authority |url=https://www.androidauthority.com/high-capacity-microsd-cards-android-gary-explains-690710/ |access-date=2018-12-21 |archive-date=2018-11-22 |archive-url=https://web.archive.org/web/20181122092400/https://www.androidauthority.com/high-capacity-microsd-cards-android-gary-explains-690710/ |url-status=live }}</ref>

===SDUC===
The Secure Digital Ultra Capacity (SDUC) format, described in the SD 7.0 specification, and announced in June 2018, supports cards up to 128&nbsp;TB,{{efn|name="here, 1&nbsp;TB = 1024"}} regardless of form factor, either micro or full size, or interface type including UHS-I, UHS-II, UHS-III or SD Express.<ref>{{cite web |title=SD Express Cards with PCIe and NVMeTM Interfaces |url=https://www.sdcard.org/downloads/pls/latest_whitepapers/SD_Express_Cards_with_PCIe_and_NVMe_Interfaces_White_Paper.pdf |publisher=SD Association |access-date=21 November 2018 |date=June 2018 |archive-url=https://web.archive.org/web/20201112011753/https://www.sdcard.org/downloads/pls/latest_whitepapers/SD_Express_Cards_with_PCIe_and_NVMe_Interfaces_White_Paper.pdf |archive-date=2020-11-12}}</ref>