Northbridge question

Luke1294

n00b
Joined
Aug 18, 2004
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55
I am currently on the BIOS/CMOS section of an A+ certification book, and I have a fewww quick questions. Well, actually, they might not be so quick, but whatever.

Can someone give me a good description of the Northbridge, Southbridge, Address Bus, and External Data Bus? Somewhere along the line, I got pretty confused.

Thus far, my understanding is this-

The Northbridge is the memory controlling chip. The EDB allows the CPU to communicate with the RAM. The CPU sends a request for data from RAM to the Northbridge via the address bus, then the requested data is then put on the External Data Bus to go to the CPU..

^^Maybe thats where my confusion lies, but who knows.

When i got REALLY confused is when the Southbridge and other devices are put in. "The Northbridge extends the EDB to the Southbridge, which in turn extends it to everything else" is a paraphrased quote from the book. Okay, so now everything is communication with the CPU, via the External Data Bus. But the Address bus is also extended, allowing the the devices to access RAM.

Is that a correct summation of everything? Please correct me if not, I dont want to go any further with a jenked understanding of the basics.
 
CPU talks to NB, which talks to RAM and SB, which talks to PCI, PATA/SATA, etc.

address bus is where the CPU (or whatever) says "give me this address"
data bus is where data itself is transmitted
 
I just looked this info up myself 2 days ago... Found good data on How stuff works. It may seem stupid in the first pages, but it gets interresting from the Chipset page and on. :)

It should clear (some of) the "what does what" confusion.
 
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