The SD Association announced the SD8.0 Specification for SD Express memory cards receive seven faster transfer speeds by using the PCIExpress (PCIe)4.0s pecification delivering a maximum of nearly 4gigabytes per second(GB/s) data transfer rate.
These full sized cards continue to use the NVMeExpress(NVMe) upper layer protocol enabling advanced memory access mechanism.
The SD Express memory cards using SD8.0 specification maintain backward compatibility.
SD Express uses the PCIe4.0 specification and the latest NVMe specification (up to version1.4). SD8.0 specification provides two transfer speed options for SD Express memorycard. The two transfer speeds are accomplished by supporting either PCIe3.0x2 or PCIe4.0x1 architectures with upt o~2GB/s and with PCIe4.0x2 technology with up to 4GB/s.
SD Express cards offering PCIe4.0x1 architecture use the same form factor as defined for SD7.0 specification cards with a second row of pins to deliver transfer speeds upto2GB/s.
SD Express cards supporting dual PCIe lanes (PCIe3.0x2 or PCIe4.0x2 technologies) have three rows of pins.
The SD8.0 specification continues giving system developers access to PCIe and NVMe technologies,such as Bus Mastering, Multi Queue (without locking mechanism)and Host Memory Buffer.