{{short description|Board-level circuit that integrates a system function in a single module}} {{more footnotes needed|date=December 2016}}
right|275px|thumbnail|Typical SoC use in a system on a module circuit board thumbnail|SoM block diagram example
A '''system on a module''' ('''SoM''') is a board-level circuit that integrates a system function in a single module. 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, a SoM serves a special function like a system on a chip (SoC). The devices integrated in the SoM typically require a high level of interconnection for reasons such as speed, timing, bus width, etc. There are benefits in building a SoM, as for SoC; one notable result is to reduce the cost of the base board or the main PCB. Two other major advantages of SoMs are design-reuse and that they can be integrated into many embedded computer applications.{{explain|date=September 2018}}
== History ==
The acronym ''SoM'' has its roots in the blade-based modules. In the mid-1980s, when VMEbus blades used M-Modules,<ref>{{Cite web|url=https://standards.ieee.org/ieee/1386/2076/|title=IEEE 1386-2001 - IEEE Standard for a Common Mezzanine Card Family: CMC|website=IEEE}}</ref> these were commonly referred to as system On a module (SoM).{{citation needed|date=May 2022}} These SoMs performed specific functions such as compute functions and data acquisition functions. SoMs were used extensively by Sun Microsystems, Motorola, Xerox, DEC, and IBM in their blade computers.
== Design ==
A typical SoM consists of:
* at least one microcontroller, microprocessor or digital signal processor (DSP) core **multiprocessor systems-on-chip (MPSoCs) have more than one processor core * memory blocks including a selection of ROM, RAM, EEPROM and/or flash memory * timing sources * industry standard communication interfaces such as USB, FireWire, Ethernet, USART, SPI, I²C * peripherals including counter-timers, real-time timers and power-on reset generators * analog interfaces including analog-to-digital converters and digital-to-analog converters * voltage regulators and power management circuits
== See also == * {{annotated link|CompactPCI}} * {{annotated link|Futurebus}} * {{annotated link|PCI Mezzanine Card}} * {{annotated link|VPX}} * {{annotated link|VXS}}
== References == {{Reflist}} {{refbegin}} * ANSI/IEEE Std 1014-1987 and ANSI/VITA 1–1994 * [https://standards.ieee.org/ieee/1386/2076/ 1386-2001 - IEEE Standard for a Common Mezzanine Card Family: CMC] * Standard ANSI/VITA 46.0-2007 * [http://opensystemsmedia.com/hall-of-fame/vita-technologies/pci-mezzanine-cards VITA Technologies Hall of Fame - PCI Mezzanine Cards] {{refend}}
Category:Microcomputers Category:Embedded systems Category:Computer buses Category:IEEE standards