Class 10 cards were replaced by U1, U2 and U3. A U1 card offers a minimum write speed of 10MB/s and replaces Class 10. A U2 card offers a minimum write speed of 20MB/s and U3 offers 30MB/s. These, too, are on their way out thanks to the growing data demands placed by the rise of 4K video.

Corum, Chris (14 September 2011). "Arizona students first to trial mobile phones with NFC for door access". CR80 News . Retrieved 28 July 2021. This category is very important. There are two types of SDHC or SDXC cards — UHS-I and UHS-II. UHS-II has a second row of pins and uses Low Voltage Differential Signaling Technology, allowing for read speeds up to 312 MB/s. UHS-I tops out at 104 MB/s. There’s also UHS-III, but nothing on the market uses that specification yet (and it doesn’t seem likely that anyone ever will). Unless you are a pure hobbyist or on a tight budget, we highly recommend getting a UHS-II card. They aren’t significantly more expensive anymore, and you’ll be happy you did, even if just for the decreased transfer-to-computer times. Speed Class SD Part 1, Physical Layer Simplified Specification, Version 4.10" (PDF). Archived from the original (PDF) on 2013-12-02 . Retrieved 2014-01-02. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sourcesin this section. Unsourced material may be challenged and removed.Lexar ships 128 GB Class 10 SDXC card; March 2011". Betanews.com. 2011-03-16 . Retrieved 2014-01-02. Lexar Announces Industry's First 256GB SDXC UHS-I Memory Card". Micron . Retrieved 22 December 2012.

Clark, Sarah (11 November 2009). "DeviceFidelity launches low cost microSD-based NFC solution". nfcw.com . Retrieved 28 July 2021.SDExpress Delivers New Gigabtye Speeds For SDMemory Cards" (PDF). SD card (Press release). SD association. Samsung announced the world's first EVO Plus 256GB microSDXC card in May 2016, [36] and in September 2016 Western Digital (SanDisk) announced that a prototype of the first 1 TB [c] SDXC card would be demonstrated at Photokina. [37] SD Express Cards with Pie and Name Interfaces" (PDF). SD Association: 9. June 2018. Archived from the original (PDF) on 2020-11-12 . Retrieved 2018-06-27.

All SD cards let the host device determine how much information the card can hold, and the specification of each SD family gives the host device a guarantee of the maximum capacity a compliant card reports. In February 2019, Micron and SanDisk unveiled their microSDXC cards of 1 TB capacity. [41] 2019–present: SDUC [ edit ] 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 USB device classes and Bluetooth profiles.) [ citation needed] In February 2014, SanDisk introduced the first 128GB microSDXC card, [33] which was followed by a 200GB microSDXC card in March 2015. [34] September 2014 saw SanDisk announce the first 512 GB SDXC card. [35] The SD card specification defines three physical sizes. The SD and SDHC families are available in all three sizes, but the SDXC and SDUC families are not available in the mini size, and the SDIO family is not available in the micro size. Smaller cards are usable in larger slots through use of a passive adapter.

UHS Speed Class

The format of the Card-Specific Data (CSD) register changed between version 1 (SDSC) and version 2.0 (which defines SDHC and SDXC). Avoid these at all costs. No cameras support the format and mutliple experts that have spoken to PetaPixel don’t believe any ever will. Repeat: no camera on the market in any category supports the SD Express format. Without such support, you get worse performance while paying significantly more than SD UHS-II cards. SD Express looks identical to SD cards, but don’t perform the same. Avoid them. | Photo by Jaron Schneider for PetaPixel 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 below), and the fact that SDHC cards are shipped preformatted with the FAT32 file system.