MindShare’s UCIe Fundamentals course provides a solid foundation to understanding die-to-die architecture and use of UCIe retimers to extend connectivity beyond the package. The course describes port architecture details including protocol layer, die-to-die adapter layer, logical physical layer and electrical physical layer. We describe single and multi-module configurations. In addition, the course describes the sideband architecture details. Sideband interface is used for back-channel Link training, access to registers, Link management packets and parameter exchanges with remote Link partner. UCIe register architecture and the mechanism by which UCIe-aware SW discovers UCIe capability is described. An optional section describes a Raw Die-to-Die Interface (RDI) and Flit-aware Die-to-Die Interface (FDI) between the die-to-die adapter layer and physical layer.