The diminutive PC104 board has been around since 1987 and is still popular with embedded engineers. The unique stacking system supports a rugged design and the flexibility of adding a range of expansion modules to the stack to build in all the required functionality. Unfortunately a PC104 stack assembly can be a difficult footprint to work with and potentially involve a rats nest of peripheral cabling.

Many of our PC104 customer base are finding a COM based design is a great alternative to the PC104 route. A COM design shares many of the plus sides of a PC104 development - the ability to easily bring in additional functionality to your core board and a neat footprint whilst eliminating the downsides. Think of a COM as an off-the-shelf building block with all of the functionality if a typical single board computer - CPU, main chipsets, RAM etc but without the usual IO connectors, eg: PS2, D-type etc. Instead the COM plugs into a custom host board using defined interface connections. 

The host board footprint, connector layout, GPIO and any application specific electronics are all tailored to your target application. This means that you can take all the I/O functionality from your PC104 stack and bring it into your customer host board, so you eliminate the cabling and end up with a board footprint specifically tailored to your needs. Measuring 114mm x 95mm, an ETX COM is only marginally larger than the PC104 board and the 84mm x 55mm Nano COM board is even smaller. The connectors that marry the COM and host board are 220-pin board to board connectors and defined mounting hole positions provide further protection from shock and vibration.