Learning Objectives

North Bridge

• The North Bridge and South Bridge together form the computer's chip set, secondary only to the processor in determining the performance and capabilities of a Pc.
• The North Bridge chip either provides or controls the computer's graphics, RAM, and the front side bus, the main highway for data connecting graphics and memory to the CPU.
• A crucial mechanism in the North Bridge is the memory controller, which constantly renews the memory modules (RAM). Each memory cell with an electrical charge represents a 1 bit. Because the charge begins to dissipate as soon as it's created, the bridge's memory controller endlessly, thousands of times a second, reads each of the millions of cells and writes back the values it read.

North Bridge cont.

• When the CPU needs data from RAM, it sends a request to the North Bridge memory controller. The controller, in turn, sends the request along to memory and tells the CPU how long the processor must wait to read the memory over a speedy connection called the front side bus (FSB).
• The North Bridge is also the liaison with the other component for which speed is crucial: the video card. (Some chip sets have video, sound, or other functions built into them, but on chip video is not as fast as a dedicated expansion card).

South Bridge

• The other half of the PC chip set, the South Bridge is in charge of input/output with the disk drives, audio, networking and universal serial port.
• The South Bridge primarily handles the routing of traffic between the various input/output (I/O) devices on the system for which speed is not vital to the total performance, such as the disk drives, optical drives, PCI-Express devices, the older PCI bus, and the USB, Ethernet, and audio ports.
• It is also responsible for less prominent input/output, such as the real-time clock, interrupt controller, and power management.
• Some South Bridge chips incorporate audio capabilities good enough to support Dolby Digital and THX multimedia audio.