Why call the PICMG 1.3 specification SHB Express and not SBC Express?
SHB means System Host Board and the technical subcommittee that wrote the specification felt that SHB provided a good way to avoid confusion with PICMG 1.0 and PICMG 1.2 SBCs that support the PCI/ISA or PCI-X/PCI parallel bus interfaces. An SHB performs the same function as an SBC, but an SHB by virtue of the multiple PCI Express serial links along the board’s edge connectors supports multiple communication pathways into the SHB unlike the common parallel bus used in PICMG 1.0 SBCs. PICMG 1.3 SHBs therefore can handle greater data traffic into and out of the board as compared to PICMG 1.0 SBCs. We use the term SHB Express to define a system host board that uses PCI Express as the primary interface to the backplane. The terms “SHB Express” and “PICMG 1.3” are used interchangeably. Additionally, PICMG 1.3 SHBs must always be used with PICMG 1.3 backplanes.
