The SHB Express™ specification upgrades the original PICMG 1.0 PCI-ISA specification, adding PCI Express slots for commercially available peripheral boards. Direct ISA interfaces are not supported on the SHB Express system host boards. Like PICMG 1.0, PICMG 1.3 is designed to move all of the active components that would normally be placed on a PC motherboard to a single plug-in board, or single board computer, called the System Host Board.
With PICMG 1.3, the backplane, sometimes referred to as the system motherboard, may contain only connectors, which makes for much more reliable systems with low MTTR and extremely simple performance upgrades as new SHB’s with new chip sets become available.
SHB Express provides a common set of electrical and mechanical characteristics for the hardware designer. The architecture generally follows the PCI Express and PCI(-X) Local Bus specifications.
The system host board (SHB), or PICMG 1.3 single board computer (SBC), is designed to interface with PCI Express peripherals on a compatible PICMG 1.3 backplane. The PCI Express interconnects with the backplane can operate at x1, x4, x8, x16, and others depending on the capabilities of both the SHB and the backplane.
The optional PCI(-X) portion of the SHB interconnect with the backplane allows for 32- bit operation. The clock rate between the SHB and the backplane can be 33MHz, 66MHz, 100MHz, and 133MHz, depending on how the backplane and SHB are designed. There is also a pin used to enable PCI-X operation if both the SHB and the backplane are capable of operating in this mode.
The SHB Express specification maximizes system design flexibility in a wide variety of military, industrial, medical and telecommunication applications by drawing from the standard slot-card economies of scale with commercial off the shelf (COTS) PCI(-X) and PCI Express plug-in peripheral cards.
