Backplane

A backplane is generally differentiated from a motherboard by the lack of on-board processing and storage elements.

For example, DIN 41612 connectors (used in the VMEbus system) have three durability grades built to withstand (respectively) 50, 400 and 500 insertions and removals, or "mating cycles".

Backplanes have grown in complexity from the simple Industry Standard Architecture (ISA) (used in the original IBM PC) or 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.

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) .

In addition, as technology progresses, the availability and number of a particular slot type may be limited in terms of what is currently offered by motherboard manufacturers.

There are some limitations to what can be constructed, in that the SBC chip set and processor have to provide the capability of supporting the slot types.

For example, an SBC with the latest i7 processor could interface with a backplane providing up to 19 ISA slots to drive legacy I/O cards.

[5] Some people use the term "midplane" to describe a board that sits between and connects a hard drive hot-swap backplane and redundant power supplies.