System on module

A system on a module (SOM) is a Board level circuit that integrates a system function in a single module. This is analogous to a system as referred to in the life sciences as in the human body - digestive-system, and nervous system that go to form functional humans or organisms. The organism being an equivalent of a computer, robot, automotive etc. It may integrate digital and analog functions on a single board. A typical application is in the area of embedded systems. Unlike a Single Board computer, SOM serves a special function like a SoC. The device integrated on the SOM typically requires a high level of interconnection for reasons such as speed, timing, bus-width etc., in a highly integrated module. There are benefits in building an SOM, as for SoC, one notable result is to reduce the cost of the base board or the main PCB. A major advantage of SOM is design-reuse and that it can be integrated into many embedded computer applications.

This acronym SOM has its roots in the Blade based modules. In the mid 80's, when VME blades used daughter/Mezzanine modules, these were commonly referred to as System On a Module (SOM). These SOM's performed specific functions such as Compute functions and Data acquisition functions. SOM's were and still are extensively used by SUN Microsystems, Motorola, Xerox, DEC, and IBM in their Blade computers.

SOM's are not complete embedded computers built on a single circuit board. Like an SOC, the SOM requires a baseboard to complete its design as a functional computer system.

A typical SOM consists of:

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