The Iron Eliminator is not a chip, its an external device not attached to the machine in any way. It allows a coin for instance to be picked up from among a handful of nails which the machine normally would not pick up....and it does work.
Again as its metal detecting there's no free lunch, there's drawbacks.
First what is it. Looks like a test tube full of aluminum filings. One variety had an iron nail wrapped with copper wire. No batteries.
The way it worked was my fooling the ground balance of the Spectrum or XLT. Air balance as normal then ground balance but to the tube. This would be held above the coil and the angle it was held at to the coil set the amount of iron rejection you would get ie 25% or 50%.
The detector also had to have a custom programme installed. This switched off ground tracking for instance (as the machine had to remain balanced to the content of the test tube).
You could then happily search amongst iron contamination that your detector would not normally deal with.
Problems. Ground balance was set to the tube, not to actual ground conditions so normal depths could not be obtained and machine became incredibly 'liffty' (an old pre motion detector term) if you lifted the coil only slightly as you swept it the machine would sound off fit to wake the dead.
So an idea that works but not that well. Far better to buy an old IB/TR detector running at 100 khz.