The PICMG 1.0 PCI-ISA standard was the first PICMG standard that moved all of the 
components normally located on a PC motherboard to a single plug-in card or single board computer. Looking much like a standard ISA or PCI card, a PCI-ISA CPU card or SBC has two edge connectors on it – one for the PCI bus and one for the ISA bus. The “motherboard” is replaced with a simple “passive backplane” that has only connectors soldered to it. This backplane design standard was designed to be simple and robust, with a very low failure rate.
Standard PICMG 1.0 systems have several advantages over previous non-standard systems. First, they are more maintainable than a motherboard system and have a much lower mean time to repair (MTTR). Second, it is easy to upgrade to a newer and faster processor if desired. Third, passive backplane CPU’s are generally manufactured by industrial suppliers who provide configuration control and longer product lifetimes than those typical of the desktop world.
The more recent PICMG 1.3 standard has largely replaced PICMG 1.0 in the industrial computer marketplace.
