Embedded computer modules (SOM, System On Module, or COM, Computer On Module) with the size of a credit card (85.6 × 53 mm), such as COM Express with a mature ecosystem, Qseven built for ultra-compact systems, and SMARC suitable for more powerful multimedia applications, are different from standard motherboards. They transmit I/O signals through the golden finger interface to reduce the size and increase the system design's flexibility. Expansion and upgrades do not need to replace the entire system motherboard.