Editing SD card (section)

=== {{anchor|Express}} SD Express ===
[[File:SD Express Highest Speed Card Standard.jpg|thumb|Front and back of an SD Express card]]

The SD Express bus was introduced in June 2018 with the SD 7.0 specification. By incorporating a single [[PCI Express 3.0]] (PCIe) lane and supporting the [[NVM Express]] (NVMe) storage protocol, SD Express enables full-duplex transfer speeds of up to 985&nbsp;MB/s. Compatible cards must support both PCIe and NVMe, and may be formatted as SDHC, SDXC, or SDUC. For backward compatibility, they are also required to support the High-Speed and UHS-I buses. The interface reuses the UHS-II pin layout and reserves space for two additional pins for future use.<ref>{{cite web |date=June 27, 2018 |title=SD Express Card Spec Announced – PCIe + NVMe Up To 985 MB/s |url=https://www.anandtech.com/show/12902/sd-express-card-spec-announced-pcie-nvme-up-to-985mbs |website=AnandTech |access-date=12 April 2025 |archive-date=12 April 2025 |archive-url=https://web.archive.org/web/20250412032606/https://www.anandtech.com/show/12902/sd-express-card-spec-announced-pcie-nvme-up-to-985mbs |url-status=live }}</ref> In February 2019, the SD Association announced microSD Express,<ref>{{cite news |last=Gartenberg |first=Chain |date=25 February 2019 |title=Memory cards are about to get much faster with new microSD Express spec |url=https://www.theverge.com/circuitbreaker/2019/2/25/18239558/microsd-express-sd-association-new-format-speed-faster-mwc-2019-data-transfer |url-status=live |archive-url=https://web.archive.org/web/20190315212414/https://www.theverge.com/circuitbreaker/2019/2/25/18239558/microsd-express-sd-association-new-format-speed-faster-mwc-2019-data-transfer |archive-date=15 March 2019 |access-date=18 March 2019 |work=The Verge}}</ref> along with new visual marks to help users identify compatible cards and hosts.<ref>{{cite news |last=Henchman |first=Mark |date=25 February 2019 |title=The microSD Express standard combines PCI Express speeds, microSD convenience |url=https://www.pcworld.com/article/3343067/the-microsd-express-standard-combines-pci-express-speeds-microsd-convenience.html |url-status=live |archive-url=https://web.archive.org/web/20190808085536/https://www.pcworld.com/article/3343067/the-microsd-express-standard-combines-pci-express-speeds-microsd-convenience.html |archive-date=8 August 2019 |access-date=18 March 2019}}</ref>

SD Express cards can perform [[direct memory access]] (DMA), boosting performance but also increasing the host system’s attack surface in the event of a malicious or compromised card.<ref>{{cite web |date=May 19, 2022 |title=When microSD Cards Turn Against You |url=https://research.nccgroup.com/2022/05/19/when-microsd-cards-turn-against-you/ |website=NCC Group}}</ref>

The SD 8.0 specification, announced on 19 May 2020, expanded the bus interface to support [[PCIe 4.0]] on all cards and dual lanes on full-size cards. With dual lane PCIe 4.0, this update raised theoretical maximum transfer speeds to 3,938&nbsp;MB/s using an additional row of contacts.<ref>{{Cite press release |title=SDExpress Delivers New Gigabtye Speeds For SDMemory Cards |publisher=SD association |url=https://www.sdcard.org/press/whatsnew/SDExpressDeliversNewGigabtyeSpeedsForSDMemoryCards.pdf |access-date=2020-05-19 |url-status=live |archive-url=https://web.archive.org/web/20200520193348/https://www.sdcard.org/press/whatsnew/SDExpressDeliversNewGigabtyeSpeedsForSDMemoryCards.pdf |archive-date=2020-05-20 |work=SD card}}</ref> Revisions continued with version 9.0 in February 2022<ref>{{Cite web |title=sd 9.0 |url=https://www.sdcard.org/cms/wp-content/uploads/2022/05/SD-SPECIFICATION-9-%E2%80%93NEW-OPPORTUNITIES-FOR-SD-MEMORY-CARDS_EN.pdf |url-status=live |archive-url=https://web.archive.org/web/20240802052922/https://www.sdcard.org/cms/wp-content/uploads/2022/05/SD-SPECIFICATION-9-%E2%80%93NEW-OPPORTUNITIES-FOR-SD-MEMORY-CARDS_EN.pdf |archive-date=August 2, 2024 |accessdate=July 31, 2024}}</ref> and version 9.1 in October 2023,<ref name="SDver9.1">{{Cite web |date=2023-10-27 |title=New SD Express Specifications Introduce New Speed Classes and Next-Level Performance Features {{!}} SD Association |url=https://www.sdcard.org/press/thoughtleadership/sd-9-1-specification-introduces-new-speed-classes-and-next-level-performance-features-2/ |url-status=live |archive-url=https://web.archive.org/web/20240401075430/https://www.sdcard.org/press/thoughtleadership/sd-9-1-specification-introduces-new-speed-classes-and-next-level-performance-features-2/ |archive-date=2024-04-01 |access-date=2024-04-01 |website=www.sdcard.org |language=en-US}}</ref> further refining the standard.

Adoption has been gradual. In February 2024, [[Samsung]] announced it was sampling its first microSD Express cards,<ref>{{Cite web |last=Cunningham |first=Andrew |date=2024-02-28 |title=Speedy "SD Express" cards have gone nowhere for years, but Samsung could change that |url=https://arstechnica.com/gadgets/2024/02/sd-express-cards-from-samsung-promise-faster-than-sata-speeds-for-microsd-devices/ |access-date=2025-04-09 |website=Ars Technica |language=en-US |archive-date=9 April 2025 |archive-url=https://web.archive.org/web/20250409140340/https://arstechnica.com/gadgets/2024/02/sd-express-cards-from-samsung-promise-faster-than-sata-speeds-for-microsd-devices/ |url-status=live }}</ref> though commercial availability remained limited. Interest increased when Nintendo confirmed in April 2025 that the upcoming [[Nintendo Switch 2|Switch 2]] would only support microSD Express cards, without backwards compatibility for UHS-I cards.<ref>{{Cite web |last=Anderson |first=Robert |date=2025-04-04 |title=You Can Already Buy Switch 2 Compatible MicroSD Express Cards |url=https://www.ign.com/articles/nintendo-switch-2-microsd-express-cards-where-to-buy |access-date=2025-04-09 |website=IGN |language=en}}</ref>