While a single board computer is an all-in-one device, some of the do have expansion slots on them that allow additional components to be added to increase their functionalities. These expansion slots include common designs such as

• ISA
• PCA
• PCI/ISA
• MicroSD
• Many others

Expansion slots largely dictate how useful a computer will remain in the future. Simpler, smaller single board computers seldom have these and are intended as simple devices that provide limited functions. More complex single board computer may have several expansion slots, however, that make it possible to keep upgrading them well into the future.