The motherboard is the main printed circuit board (PCB) found in computers.

Its functions are the following:

1.It holds the crucial electronic components of a system, such as the central processing unit (CPU) and the memory; 

2.It allows communication between the components; 

3.It provides connectors for the other peripherals. 

The CPU socket is the mechanical component that provides electrical connections between the microprocessor and the PCB. 

The larger chips (CPU and Northbridge) are generally air cooled with heat sinks mounted on them.

A motherboard contains significant sub-systems such as the chipsets. Chipsets are sets of specialized chips, which provide the supporting interface between the CPU, the buses (data paths) and the external components. Northbridge and Southbridge are the chipsets that handle communications and sort data traffic on most motherboards. 

The Northbridge handles interaction between the processor, the main memory, the Accelerated Graphics Port (AGP) and the PCI (Peripheral Component Interconnect) bus. These are the components that most benefit from fast communication with the processor. The FSB (Front Side Bus) links the CPU to the Northbridge. 

The Southbridge is connected to the Northbridge by the internal bus. It handles more basic, slower, forms of I/O, such as ports, USB ports, and SATA (the standard electronic interfaces used between the bus and the disk storage devices).

System busses

Computer busses (from Latin “omnibus” = for all) connect different parts of the motherboard to one another make data transfers possible. The most critical connection of any computer system, the system bus, controls the transfers between the CPU, the main memory, and the I/O devices.

The system bus carries three types of information: address, data, and control. 

The address information describes where data is located and where it needs to go during a particular operation. We call data the actual digital pieces of information that need to be read or written.

The control bus carries commands from the CPU and returns status signal from the devices involved in the operation.

 The system bus is like the internal transport system of your computer. 

Consider the following example. You want to listen to some music from your hard disk drive as an MP3 file. The file has to be transferred to the sound card before you can listen to it on your speakers. The address information is the location of the MP3 file on your hard disk and the location of the soundcard. The control information manages how this transfer takes place - which direction and through which components. All of this is managed by the CPU.

Ports available on the rear of the motherboard

On the rear of the motherboard, you can find a set of ports. These ports allow the user to connect peripherals to the computer system.

The most important ports are the following:

-PS/2 port (mouse): it is color coded (green) to match the 6-pin male connector on the mouse cable;

-PS/2 port (keyboard): it is color coded (purple) to match the 6-pin male connector on the keyboard cable;

-USB ports (USB = Universal Serial Bus): the USB industry standard has now widely replaced the other types of connection, and is used for connecting all sorts of devices;

-Serial Port (sending data one bit at a time): it is for 9-pin female connectors. Now replaced by USB ports, it was used to connect a variety of devices (mouse, modem, etc);

-VGA port (VGA = Video Graphics Array): it is for 15-pin male connectors. It is used for video peripherals such as monitors, projectors and TV screens;

-Jack: analog microphone jack to connect a microphone; analog line-out/speaker jack to connect the speaker, analog line-in jack to connect external sources; 

-NIC connector (NIC = Network Interface Controller): it is used for network connections (Ethernet RJ-45 connectors);

-Parallel port (sending data multiple bits at a time): it is for 25-pin male connectors. Now replaced by USB, it was used especially for printers.