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What are system buses, How they work ? Where can i get more info abt the same?
What are ISA and PCI buses?


  • MrEdMrEd Member Posts: 180
    : What are ISA and PCI buses?

    OK, Ill have a go at this one.

    A bus is basically a collection of tracks (or wires) that carry data from one place to another. For example buses might come in 8-bit, 16-bit, 64-bit etc "widths" meaning they contain 64 (or whatever) tracks.

    A system bus in a PC just means a bus that is used to connect major components in the system, eg connecting the CPU to external cache memory or something.

    ISA and PCI are just different standards for bus architecture. They both connect peripheral devices (such as a modem or sound card) to the rest of the system.

    ISA (Interconnect Standard Architecture?) was one of the first standard buses in PCs and can come in 8-bit or 16-bit varieties. The bus runs at about 8MHz (i think) meaning that the data moving along the bus sends 8 (or 16) bits of information in one cycle and there are 8 million cycles per second. These days, nothing much uses the ISA bus and new motherboards dont even have them.

    PCI (Peripheral Connect Interface?) is a newer and far superior bus. I think its 32-bit and runs at 33MHz, meaning it can transfer more data at once (32-bits) and faster (33MHz). This bus is still very common in motherboards.

    Other system buses in most PCs include AGP (Advanced Graphics Port?) for a high speed dedicated graphics bus, USB (Universal Serial Bus) which is a serial bus (1-bit wide) used to connect external devices such as scanners, modems etc. There are many many other buses which aren't as public as these though.

    Im sorry, but im not sure where you could find this kind of information. Theres a good hardware site at, or you could try to find the original specs for the ISA or PCI buses which would probably be too detailed. Also, browse through some of those upgrade and repair your PC books in a bookstore somewhere.

    This help?

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