MARINELLE SANTOS 9 - ALPHA PORTFOLIO#6

Northbridge

Alternatively referred to as the PAC (PCI/AGP Controller) and nb, the northbridgeis an integrated

circuit responsible for communications between the CPU interface,AGP, and the memory. Unlike the

Southbridge the Northbridge is directly connected to these components and acts like a "bridge" for the

Southbridge chip to communicate with the CPU, RAM, and graphics controller. Today, the northbridge

is a single-chip that is North of the PCI bus, however, early computers may have had up to three

separate chips that made up the northbridge.

The northbridge typically handles communications among the CPU, in some cases RAM, and PCI

Express (or AGP) video cards, and

thesouthbridge.Some northbridges also contain

integrated video controllers, also known as a

Graphics and Memory Controller Hub (GMCH) in

Intel systems. Northbridge is an Intel chipset that

communicates with the computer processor and

controls interaction with memory, the Peripheral

Component Interconnect (PCI) bus, Level 2cache, and

all Accelerated Graphics Port (AGP) activities.

Northbridge communicates with the processor using

the frontside bus (FSB).

SOUTHBRIDGE

The southbridge is an IC on the motherboard responsible for the hard drivecontroller, I/O controller and

integrated hardware. Integrated hardware can include the sound card and video card if on the

motherboard, USB, PCI, ISA, IDE, BIOS, andEthernet.

A southbridge chipset handles all of a computer's I/O

functions, such as USB, audio, serial, the system BIOS,

the ISA bus, the interrupt controller and the IDE

channels. Different combinations of Southbridge and

Northbridge chips are possible, but these two kinds of

chips must be designed to work together; there is no

industry-wide standard for interoperability between

different core logic chipset designs. Traditionally, the

interface between a northbridge and southbridge was the PCI bus. The main bridging interfaces used

now are DMI (Intel) and UMI (AMD).