Editing Backplane (section)

==Active vis-à-vis passive backplanes==
[[Image:ISA-Backplane.jpg|thumb|right|300px|ISA Passive Backplane showing connectors and parallel signal traces on back side. Only components are connectors, capacitors, resistors and voltage indicator LEDs.]]
Backplanes have grown in complexity from the simple [[Industry Standard Architecture]] (ISA) (used in the original [[IBM PC]]) or [[S-100 bus|S-100]] style where all the connectors were connected to a common bus. Due to limitations inherent in the [[Peripheral Component Interconnect]] (PCI) specification for driving slots, backplanes are now offered as '''passive''' and '''active'''.

True passive backplanes offer no active bus driving circuitry. Any desired arbitration logic is placed on the daughter cards. Active backplanes include chips which [[Buffer (computer science)|buffer]] the various signals to the slots.

The distinction between the two isn't always clear, but may become an important issue if a whole system is expected to not have a [[single point of failure]] (SPOF) . Common myth around passive backplane, even if it ''is'' single, is not usually considered a SPOF. Active back-planes are even more complicated and thus have a non-zero risk of malfunction. However one situation that can cause disruption both in the case of Active and Passive Back-planes is while performing maintenance activities i.e. while swapping boards there is always a possibility of damaging the Pins/Connectors on the Back-plane, this may cause full outage for the system as all boards mounted on the back-plane should be removed in order to fix the system. Therefore, we are seeing newer architectures where systems use high speed redundant connectivity to interconnect system boards point to point with No Single Point of Failure anywhere in the system.