the purpose of a bus in PCB design

purpose of a bus

Hi,

Could you please tell me what is the purpose of a bus in PCB design? I have tried to search this out and as i can see, is it that the tracks in a bus must be kept the same? ie net length, same layer, same via count etc?

Re: purpose of a bus

It's so the wheels go round and round.

A bus is just a term for a collection of alike signals.

In a schematic they will be connected to a single thick line, just as a graphical representation.

I.E. You can have a data bus, all the data signals D0-D7 etc routed together, with same lengths etc.
You can have an address bus, other buses etc.

On the PCB they are all single connections but will be treated as a "collection of alike signals" (or bus - single item carrying lots) by the software when auto routing or manual bus routing depending upon the software's capability.

For instance - you may say that all signals in that bus are to have the same spacing class, layer and track length etc and in Cadstar you can select the bus and apply whatever routing rule to all alike signals on the bus, instead of having to select each individual signal and apply the rules to each one separately.
I am sure it is similar in pother PCB software.