What’s the Function of a Motherboard?

The term “Motherboard” really came about with the advent of printed circuit boards and microprocessors. A Motherboard allows additional devices and additional capability to be added to a computer by means of plug-in modules, and the term expansion is normally used when referring to a Motherboard’s capability.


Prior to the invention of microprocessors, most computers were Mainframe Computers which had powerful central processing units normally housed in large cabinets. A backplane consisting of a number of interconnected slots creating a bus was used to easily connect additional peripherals and capability. The term “backplane” is also used with modern personal computers nytuesday.

A Motherboard acts like a backplane by allowing additional components to be added to the overall computer system to add different capabilities.

Dual Inline Memory Modules or DIMMs as they are known provide the main computer memory in the form of DRAM (Dynamic Random Access Memory). Dynamic memory requires frequent charging, so that when power is lost the information is quickly lost. These DIMMs are connected to the Motherboard by means of dedicated slots in the Motherboard itself.

A chipset incorporated in the motherboard provides the communications between the main processor and other external devices such as the memory and graphics controllers as well as some slower speed devices such as Ethernet, Wireless Controllers and USB devices.

A computer system must include a form of Non-Volatile memory in order to store crucial information such as BIOS or Firmware. This type of memory is often in the form of Flash ROM, which for technical reasons, is not really suitable as the main memory system. Another variation of this type of memory is NVRAM (Non-Volatile Random Access Memory) as used with some computer networking devices such as Routers and Data Switches. With Non-Volatile memory, information is retained following a main power outage.

Expansion slots on the Motherboard allow for additional capability that is not possible directly from the main board itself. Such devices as graphics cards, Network cards, SAN (Storage Area Network) cards and Modem cards. A hard disk controller is also needed to provide communication and transfer of data to the connected Hard Disk Drive, so a slot will normally be required for this too. Because manufacturers of computer systems are always trying to produce products with a smaller footprint, low profile cards have been developed in order to take up less space with the computer system chassis.

Each area of the overall system such as the DRAM, CPU, expansion cards and non-volatile memory require power and must be connected to the computer’s power supply via connectors from the Motherboard.

All subsystems and components of the computer system must be synchronized from a common source if they are to function as a single overall system, so they require some form of clocking signal for this purpose. Most low-end systems use a single phase clock from a single clock generator which produces a squarewave signal at a constant frequency. Single phase refers to the fact that the signal is carried on a single copper wire. Some more complex systems will employ a 2 or even 4 phase clocking signal to be able to synchronise multiple subsystems or components.

The Motherboard is an essential component in a modern Personal Computer and is the catalyst to provide connectivity and allow collaboration between a growing number of additional components, subsystems and peripherals. Many manufacturers produce the Motherboards themselves, but ATX is by far the most popular and there are fewer specialist chipset manufacturers, the main ones being AMD, Intel and Nvidia.

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