Ex airline engineering IT
Not at all out of the ordinary for particular aircraft variants - even specific _airframes_ - to have specific software for those craft alone. Common culprits are stuff like engine diagnostic downlink, stuff like that. I can definitely name specific bits of kits / parts of IT infrastructure being knocked out leading to certain airframes not flying the next day.
Alas, standardisation = $$$ in airplane world.
Biting the hand that feeds IT
