The "computer" ECU everyone thinks the OP is referring to is married to the car after ~40 starts through DAS....I think. Keeps someone from swapping thier computer into your car and starting it with their key in very simplistic terms.

If it goes bad you get a new one and it gets programmed to the car using SDS.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)