Semper Flash devices with Quad, Octal and HyperBus interfaces are JESD251 compliant.
The new eXpanded Serial Peripheral Interface (xSPI) JESD251 standard, ratified by JEDEC in June 2017, defines a high-data throughput, serial interface for nonvolatile memory devices. The xSPI standard defines a minimum set of requirements for compatibility with high-performance serial NOR flash interfaces. JESD251 standardizes 1S-1S-1S and 8D-8D-8D protocols where 8D-8D-8D protocol can be supported with 32-bit and 45-bit addressing schemes. Therefore, JESD251 defines Profile 1.0 and Profile 2.0 for 8D-8D-8D protocols. Profile 1.0 supports 1S-1S-1S and 32-bit addressing 8D-8D-8D protocol, while Profile 2.0 supports 1S-1S-1S and 45-bit addressing 8D-8D-8D protocol. Semper Flash with Octal interface is Profile 1.0 compliant and Semper Flash with HyperBus interface is Profile 2.0 compliant.
JEDEC has added a section in JESD251 in October 2018. The purpose of the addendum (JESD251-1) is to add 4-bit bus width (x4) to JESD251, xSPI standard and Semper Flash with QSPI devices are compliant to JESD251-1.