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The SD Association (SDA) has announced the SD Express 8.0 (SD8.0) specification, promising up to transfer speed of up to 4GB/s (2GB/s per lane up to two lanes). The SD8.0 spec is built on the PCIe 4.0 standard and uses NVM Express (NVMe) technology.
It builds on the previous 7.0 specification that used PCIe 3.0, which powers the rival CFexpress format. The newest format can either deliver up to 2GB/s transfers with the PCIe 4.0 standard over a single lane using the familiar SD card format with two rows of pins (a combination denoted as PCIe G4L1 in the diagram below), or using PCIe 3.0 across two lanes (PCIe G3L2) which will add a third row of connection pins. The 4GB/s transfer speeds will be delivered by PCIe G4L2 cards using PCIe 4.0 transfer across two lanes (and three rows of pins).
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| SD Express speed comparison chart. Click to enlarge. Image credit: SD Association |
The SDA, which is celebrating its 20th anniversary this year, believes the new SD Express standard will create additional variety in the market and allows manufacturers to make the most of the increased speeds of SD Express to produce more storage choices for consumers. Additionally, the SDA states that SD 8.0 ‘may open even more opportunities for extra high-performance solutions using removable memory cards.’ Importantly, as with all SDA advancements, the SD 8.0 specification maintains backward compatibility across previous generations.
SD8.0 is arriving nearly two years after the SD 7.0 (SD7.0) spec was released in July 2018. The SD7.0 specification introduced PCIe 3.1 and NVMe architecture to SD cards. In February 2019, the SDA introduced the microSD Express 7.1 specification.
Camera and card makers haven’t yet made use of the UHS-III format set out in the older SD6.0 specification
Notably, camera and card makers haven’t yet made use of the UHS-III format set out in the older SD6.0 specification. Memory card manufacturer Sandisk has already shown mockups of SD Express (SD7.0) cards, which raises the possibility that the industry will skip the UHS-III specification entirely.
An alternative memory card format, the CFexpress standard, has been increasing in adoption due to its impressive speeds and performance. CFexpress cards can utilize up to four lanes and currently can deliver 1GB/s speeds per lane. However, the current CFexpress 2.0 standard, announced in February 2019, promised comparable speeds using four PCIe 3.0 lanes to the ones that SD 8.0 will get from two v4.0 lanes
It will be interesting to see when CFExpress standards adopt a PCIe 4.0 interface, as the SDA and CFA continue to be in a memory card arms race. If history has proven anything, it’s that it will take some time before the new standards, and the accompanying performance increases, are commonplace in consumer products. However, the new SD8.0 spec lays impressive groundwork technology for faster cameras and improved workflows for photographers and videographers.
For additional information on SD8.0, the SDA has launched a ‘virtual trade show.’ You can explore it by clicking here.
Articles: Digital Photography Review (dpreview.com)