The SD Association has released the name and official specifications for SD Express, the latest Secure Digital (SD) memory card format, as part of its SD 7.0 specification. Created as a successor to UHS-III cards, SD Express is next-next-gen technology that will work alongside a new SDUC card to provide fast, high-capacity memory cards in a familiar package.
As the name suggests, SD Express cards are going to be fast. The SD Express format uses third-gen PCIe and NVMe transfer protocols on top of the dual-level pin layout interface to achieve a maximum transfer speed of 985MB per second—almost a gigabyte per second and roughly 1.5 times faster than UHS-III cards, which still haven’t hit the market yet.
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In order to achieve the maximum transfer speed of SD Express cards, you’ll need a camera or device that supports the new format as well. If you end up sticking your brand new SD Express card inside your 5D Mark III, it’ll simply default back to the speed of UHS-I cards.
SD Express cards will be available in SDHC (High Capacity) and SDXC (Extended Capacity), as well as an all-new SDUC (Ultra Capacity) format. The new SDUC cards will have a maximum storage capacity of 128TB, a large leap from the maximum 2TB capacity of SDXC cards.
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| Infographic provided by the SD Association that details the various specs and classifications of different SD cards. |
It also appears as though it’ll be possible for memory card manufacturers to make SDUC cards for slower SD bus interfaces. So, according to the above graphic, you could theoretically have a 128TB High Speed SD card. With a little back-of-the-napkin math, that means it would take 1,481 days to transfer all 128TB of the card based on the 25MB per second speeds of High Speed SD cards.
To find out more and read more details about the SD Express and SDUC formats, be sure to check out the SD Association’s press release. The SD Association has also released a white paper detailing the new capabilities and features found in the SD 7.0 specifications if you’re interested in really digging deep.
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