The PCI Express M.2 Specification Revision 4.0 Version 1.0 remains a foundational document for any professional involved in high-performance hardware design or system integration.

Revision 4.0 V1.0 mandates that the electrical idle and detect mechanisms must be robust enough to handle the 16 GT/s eye diagram, which is significantly narrower than Gen3.

Revision 4.0 supports the deep command queues necessary for heavy multitasking and workstation loads. Why Version 1.0 Matters for Developers