It has strayed but good none the less, I now work Ge90 but have spend a small amount of time on cfm including engine test, your right about the id plug, it is literally just a multi pin plug like a harness connector that just screws onto the EEC, it's got s little wire tether that attaches it to the fanframe and keeps it with the engine itself and doesn't get lost if they swap out an EEC, I believe it's programmed by breaking certain connections, in the circuit, so one the plug is created you can't modify it

well the EEC is connected to the auto throttle computer and the FMC, so while the FMC may do the calculations and so fourth, I would have assumed it still takes the data from the ID plug for its calculations? it is the only place that the specific redline RPM and correct trim settings for all configurations of thrust settings are stored for that specific engine, i cant see how the EICAS would be able to show the redline N1 and so fourth? Interestingly the N1 modifier adjustments are effective up to an altitude of 15500ft or mach .45,

I hate to perpetuate the diversion more but engine red line limits in EICAS aren't specific to a particular engine. The same limits apply to all engines of a given type and rating. There will be a plug which configures the display to show the limits for the installed engine type. Some of the variable limits may come from the EEC, dependent on phase of operation.