BY TONY JIA2010.02.19

Mother Board and Buses

What is a Mother Board?

The motherboard is the largest piece of internal hardware. All of the other internal components are attached to or integrated into the motherboard, such as the modem card, video card, and network card are mounted, the Central Processing Unit (CPU) and memory are also directly attached to the motherboard. In order to understand the flow of information from one component to another within the computer, it is first necessary to identify the motherboard and understand how all of the components attached to it operate and interrelate.

Motherboards have come a long way in the last twenty years. The first motherboards held very few actual components. The first IBM PC motherboard had only a processor and card slots. Users plugged components like floppy drive controllers and memory into the slots. Today, motherboards typically boast a wide variety of built-in features, and they directly affect a computer's capabilities and potential for upgrades.

A typical desktop computer has its CPU, main memory, and other essential components on the motherboard. Other components such as external storage, controllers for video display and sound, and peripheral devices may be attached to the motherboard as plug-in cards or via cables, although in modern computers it is increasingly common to integrate some of these peripherals into the motherboard itself.

An important component of a motherboard is the microprocessor's supporting chipset, which provides the supporting interfaces between the CPU and the various buses and external components. This chipset determines, to an extent, the features and capabilities of the motherboard.

Motherboards are also used in many other electronics devices such as mobile phones, stop-watches, clocks, and other small electronic devices.

How Does it Work?

The motherboard is like a big city with many streets and highways that connect all of the buildings together. Instead of streets and highways, the motherboard uses tiny electrical paths to connect each component of the computer together.

These paths are called "buses."

A bus is simply a circuit that connects one part of the motherboard to another. The more data a bus can handle at one time, the faster it allows information to travel. The speed of the bus, measured in megahertz (MHz), refers to how much data can move across the bus simultaneously.

The more buses that connect to a component, the faster it can operate. Buses work just like highways. Wider highways and highways with more lanes are able to carry more traffic than smaller highways and highways with less lanes. The width of the bus determines the number of bits that can be sent simultaneously. In other words, the wider the bus, the faster the computer. A one-byte bus is composed of eight lines. This means that eight bits can travel down the line at one time. A thirty-two bit bus can send four bytes at a time.

Many cities have a freeway. A freeway is designed so that large amounts of traffic can move quickly from one place to another. The motherboard also has a "freeway." It is called the "front side bus," (or FSB). It is the most important bus on the motherboard, because it connects the processor to the main memory and the Northbridge chipset. The faster the FSB is, the faster the computer can operate, since the processor is constantly using the main memory to store and retrieve information. Sometimes the FSB is also called the "system bus.“

FSB speeds can range from 66 MHz to over 800 MHz. Since the CPU reaches the memory controller though the Northbridge, FSB speed can dramatically affect a computer's performance.

Here are some of the other busses found on a motherboard:

The back side bus connects the CPU with the level 2 (L2) cache, also known as secondary or external cache. The processor determines the speed of the back side bus.

The memory bus connects the Northbridge to the memory. The IDE or ATA bus connects the Southbridge to the disk drives. The AGP bus connects the video card to the memory and the CPU.

The speed of the AGP bus is usually 66 MHz. The PCI bus connects PCI slots to the Southbridge. On most

systems, the speed of the PCI bus is 33 MHz. Also compatible with PCI is PCI Express, which is much faster than PCI but is still compatible with current software and operating systems. PCI Express is likely to replace both PCI and AGP busses.

The faster a computer's bus speed, the faster it will operate -- to a point. A fast bus speed cannot make up for a slow processor or chipset.

The Chipset, (2 chips on this motherboard) is like a traffic police, manages and directs the flow of data between each of the components. The BIOS is where the computer's settings are stored and changed. In this picture, you can see most of the connecting slots, ports, and connectors.

http://www.techiwarehouse.com/i/Motherboard/Motherboard1.jpg http://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/

Computer_buses.svg/800px-Computer_buses.svg.png http://stephenrees.files.wordpress.com/2007/12/tindo-bus-2.jpg http://en.wikipedia.org/wiki/Motherboard http://computer.howstuffworks.com/motherboard1.htm