I have a Zephyr and a DT400 throttle.
My locos have chips of various manufacture.
Is there a method, without dismantling the loco of reading which chip is fitted in it?
Well, we can't speak for other manufacturers, but if you take a look at the Digitrax decoder index, you will note that many Digitrax decoders have a Manufacturer's ID of "129".
This is found by reading the value of CV#8.
Some other manufacturers also use Manufacturer's IDs, and you will need to consult their documentation for this information.
Note: CV08 is also used to reset Digitrax Series 3 decoders and later to Factory Specifications.
This task is accomplished by writing to CV08 the data value of 8.