HELP understanding Computer Busses ???

Question

Can someone help me understand this better?


Okay. .so this is my understanding ..but it's probably wrong

Expansion Slots can connect to expansion busses (either ISA or PCI or AGP for video cards)
Windows' internet connection communicates with the Modem via a device driver and
tells the modem card to send an IRQ down the ISA bus which is connected directly to a northbridge chip. The northbridge chip then routes the IRQ signal directly to another type of internal bus --the address bus which leads directly to the CPU and contains the hexidecimal I/O Addressing for each device ...but the PCI or ISA slots don't contain the I/O Address resource

IS this at all right ??






thnks

Answer 1

Partially right, about 50-50 I figure:

AGP is NOT a bus, it is a dedicated one line. ISA is a 8 MHz thing that I think goes to the "southbridge" not northbridge.

Sending IRQ about right.

PCI and ISA do contain I/O Address, what you put down is very wrong.

Answer 2

Heres what I know for sure... ISA Bus is either an 8bit or 16 bit depending on its length. if you look at a ISA card thats a 16 bit there will be a notch with more pins the 8 bit card dont have the notch or the extra Pins. and at default clock speed is 8Mhz and its tied to the southbridge chipset. Some card on the ISA is plugNplay and others need jumpers set for an IRQ and IO configuration... PCI Bus is a 32 bit bus that runs at default clock of 33MHz and its a PlugNplay setup and it will assign its own IRQ to whatever is free thats also tied to Southbridge Chipset. The Floppy controller and PS/2 Ports Com ports LPT ports are connected to a multifuction chip which also connects to the southbridge. Back in the old days where a controller card was needed to work the floppy drives and Ps/2 com ports... AGP is its own bus to the North Bridge and its Runs at 66Mhz at its default clockspeed they come in 1x 2x 4x 8x. And have different lengths and features. THE IRQ thing does sound right.