SD cards—everybody’s got a few, but nobody thinks much about them. That’s a testament to how well they work. But performance always matters, and microSD Express promises to make microSD cards much faster.
What Happened to SD Express?
Announced in February 2019 as part of the SD 7.1 specification by the SD Association, microSD Express follows its larger sibling, SD Express, which landed with a muted thud in mid-2018. SD Express cards didn’t roll out that year despite the standard’s promise of four to five times the performance of current SD cards. Now, however, with microSD Express, it looks like we might finally get blazing fast expansion cards for our laptops, smartphones, and cameras.
It’s not clear why no one got excited about SD Express. Perhaps most companies were waiting for the microSD version to roll out before getting serious. That’s probably the case, as early microSD Express cards are popping up at trade conferences, as well as new card readers, and firmware controllers that cover both versions of SD Express.
There’s nothing available to buy yet, but that should change in the not-too-distant future.
What Is microSD Express?
microSD Express is a smaller version of SD Express. They are new types of SD cards that support a maximum read speed of 985 megabytes per second (MB/s). Current microSD cards, by comparison, don’t even hit 200 MB/s. The Express versions of SD use the PCIe 3.1 interface and NVMe to achieve this. These are the same technologies used by speedy, M.2 “gumstick” solid state drives in PCs. The new Express cards only use one lane of PCIe, however, while M.2 NVMe drives typically use four.
The smaller microSD cards make them an easier fit (literally) for the current way we use SD cards in phones, tablets, and laptops. The only exception is digital cameras, which favor full-size SD and compact flash cards.
What’s Changed?
In 2019, companies have started taking action. Standards associations can make all the new specifications they want, but if companies don’t turn them into real products, they’re just ideas.
For example, PCIe 4.0 was announced in 2017 but only became a reality with new products for PCs in 2019 (just in time for the PCIe 5.0 specification to be announced). SD Express has a similar issue with slow adoption from device makers and SD card manufacturers.
So, what hope does microSD Express have? For one thing, Western Digital (which owns SanDisk) was at Computex 2019 in Taiwan showing a SanDisk microSD Express card. The company didn’t announce a release date for the card, but the fact that it exists is promising.
