what is the system board of a pc?
A more recent motherboard specification, ATX, improves on the AT design. In both the AT and ATX designs, the computer components included in the motherboard are: 1  The microprocessor. ( 2 Optionally) coprocessors. 3  Memory. 4  basic input/output system (BIOS). 5  Expansion slot. 6  Interconnecting circuitry.