At 10:22 AM 6/18/2003 -0400, you wrote:
>Commonly used to choose between 2 different options,
>for example on an RS232 interface you may want to
>swap TXD and RXD, so you would just install the
>correct resistor to make the paths work out.  Also
>used as a "place holder" where you may, after
>evaluation, want to put in a "real" resistor, say on
>a processor address line, to reduce reflections/EMI.
>Sometimes used on memory parts such that a
>larger part (more pins) could be installed in the
>future and yet have all the signals go to the correct
>pins (typically right justifying the smaller pinned
>part in the socket/board).  This way you don't
>need to re-layout the board, its just a BOM change.
>Finally, its an "oh ****", can't route the signal and
>I need to jumper over some traces.

Handy for single-sided boards, which are still cost effective
in some applications.

>  Resistors are
>auto-insertable, wires are not.

Wires are auto-insertable but they require a special machine
that forms the jumpers from a spool of bare wire and inserts
them. The zero-ohm jumpers can be inserted on the same
equipment. They, like resistors, are dirty cheap- usually
priced the same as the same size of resistor.

Believe it or not, you can also get open-circuit resistors,
and I've specified them. ;-)

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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