picmg 1.0
picmg 1.3
picmg 1.3 Passive

picmg 1.0: 
  This standard moves components typically located on the motherboard (i.e. memory, CPUs and chipset components) to a single plug-in card. picmg 1.0 CPU Cards look much like standard ISA cards with extra gold finger connections for the ISA bus and the root PCI bus. The "motherboard" is replaced with a simple "passive backplane" that has only PCI and ISA connectors attached to it. These backplane connections include a dedicated system slot of the picmg 1.0 CPU and various connections for standard ISA and PCI peripheral cards. This backplane is simple and robust, with a very low likelihood of failure, given its passive nature. This allows a much lower Mean Time to Repair than classic computer motherboard approaches, as electronics associated with CPUs can be replaced without having to remove peripheral devices.

picmg 1.3 
   picmg 1.3 is the latest in the original picmg 1.x series that adapts the popular desktop PC format to passive backplane implementations popular in more demanding environments such as industrial automation, military, medical and telecom. is a picmg specification which is commonly referred to as SHB Express. SHB Express is a modernization of picmg 1.0 single board computer specification. SHB Express, or System Host Board – Express, uses the same physical form factor as picmg 1.0 boards. The board-to-backplane interfaces are PCI Express instead of PCI and ISA, although the use of PCI remains as an option.
picmg 1.3 Passive: 

picmg 1.3 adds support for high-speed PCI Express (PCIe) slots in place of older ISA slots. Industrial PC systems with passive backplanes can support the latest high-speed graphics and data acquisition cards alongside standard PCI cards. The PIGMG 1.3 bus carries all the signals for up to 16 traditional PCI cards and five more PCIe cards -- far beyond what motherboard-based systems can provide. Design powerful systems with up to 19 expansion card slots. picmg 1.3 handles more power. Traditional picmg 1.0 full-length cards could safely pull up to 227W from the backplane. picmg 1.3 cards can draw up to 500W without damage. This not only makes them more robust, but also provides support for modern dual-processor systems and high-speed CPUs.