CDIs and interfaces

Couldn't find much help with google. Can someone give me a short course on
Course Deviation Indicators (CDIs) and their interfaces to the equipment that
drives them?

Looking at a couple of web sites, there appear to be tens of unique models of
the CDIs, a different model for each possible NAV radio or GPS (LORAN, etc) to
be used with it. Is the interface really proprietary and unique to each radio?

Specifically, considering migrating my setup from a KX-155/KX-170B combination
to a GNS530/KX-155 combination and trying to figure out whether my existing CDIs
(King KI-2??) can or should be used with the new setup.

More generally, I'd just like to understand a little more about these interfaces
and what the choices are.

....and what does a "serializer" do?

Thanks!

Dave
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