On Dec 13, 4:07*pm, (Andrew Gabriel)
wrote:
In article ,
* * * * The Natural Philosopher writes:

On 13/12/12 13:41, Mike Tomlinson wrote:

Posted in another group:

http://imageshack.us/photo/my-images...tonowhere.jpg/

what are these tracks for?

It's called a microstrip line, and they're used for several
different purposes.

they are tuned circuits. open ended transmission lines. Or a bored
draughtsman doodling..

Or a delay line - time to send a signal and reflect it from the end.

Particularly given the PCI bridge chip next to it, and that
PCI is an unterminated bus which relies on the signal reflection
from the far end of the bus in order to work. The bridge chip is
creating a new physical PCI bus, and it may be that the tracks to
the PCI devices on that bus are too short to meet any minimum
track lengths required for signal reflection detection, and need
to be artificially lengthed.

That's an unlikely explanation. There's no active detection of the
reflection involved in PCI, and no minimum trace length. It's just the
way the drivers are specified to drive the bus lines.

MBQ