A computer-on-module (COM) or System on Module (SOM) is a type of single-board computer (SBC), a subtype of an embedded computer system. An extension of the concept of system on chip (SoC) and system in package (SiP), COM lies between a full-up computer and a microcontroller in nature. Today’s COM modules are complete embedded computers built on a single circuit board.
The design is centered on a microprocessor with RAM, input/output controllers and all other features needed to be a functional computer on the one board. However, unlike a single-board computer, the COM will usually lack the standard connectors for any input/output peripherals to be attached directly to the board.
The module will usually need to be mounted on a carrier board (or “baseboard”) which breaks the bus out to standard peripheral connectors. Some COMs also include peripheral connectors and/or can be used without a carrier.