Unidirectional vs. simultaneous bidirectional source synchronous signaling

This paper describes a case study of electrical design optimization methodology for a high-speed point-to-point source-synchronous differential simultaneous bidirectional (SiBiDi) and unidirectional interface. Strengths and weaknesses of each signaling approach are explored and tradeoffs to optimize both are described. These physical links are typically used to interconnect multiple processor subsystems to build symmetric multi-processor (SMP) systems, as well as to connect input/output (I/O) subsystems across relative long distance.