The term motherboard, mainboard, system board or mainboard refers to a multilayer circuit board on which the central components of a computer, namely the processors, memory units, slots for expansion cards, the interfaces and connections are located. This system-specific board determines system-relevant parameters such as system performance, expandability, connectivity and future-proofing through its design.
Motherboard components and interfaces
The motherboard contains all the components for controlling the connected hardware and peripherals. In detail, the following system components are on the motherboard: The central processing unit( CPU) with the CPU socket and the chipset, the PC bus with the slots for the expansion cards, the slots for the memory latches for Dynamic RAM( DRAM), Synchronous Dynamic RAM( SDRAM) or Extended Data Output DRAM( EDO-DRAM), the Level 2 cache, the real-time clock, the BIOS ROM and the CMAS RAM, the input and output interfaces - the serial interface, the parallel interfaces, USB interfaces, FireWire, the EIDE or SCSI controller, the DMA controller, interrupt controller, drive controller and the keyboard processor. In addition, the motherboard's printed circuit board contains the power distribution network( PDN), which supplies all chips, ASICs, etc., and all active components with the appropriate supply voltage.
Increasing integration density and application requirements mean that, depending on the conceptual orientation of the computer - desktop, notebook, tablet PC - the motherboard also accommodates the sound card and graphics processors, the components for the network connection, for WLAN or Bluetooth
The sizes of motherboards
Due to the different requirements, the multitude of different modules, processors, interfaces and slots, and last but not least the runtime and circuit optimization, motherboards vary in size. In order to have comparison possibilities and to facilitate computer design, their designs and form factors are specified.
The form factors determine the dimensions of the motherboards and where the individual components, slots and connectors are located on the motherboard. It also specifies which power supply and enclosure may be used. There are about 20 form factors for motherboards. The smallest such as PC/104 or the ETX module have module size and are about 100 mm x 100 mm. Somewhat larger are motherboards in the various ITX form factors. Even larger are the various ATX form factors or BTX form factors. They are around 300 mm x 250 mm, and the even larger ones like the WTX form factor 400 mm x 350 mm.