Do you know how this all works? I do. Its an interest of mine. 2 nukes detonated in high altitude , one and west coast and one in the east coast, that would be enough to cover the whole usa and most of southern canada in an emp blast that would fry everything that isnt hardened.
As for broken windows or ground detonations , the military powers have moved to geometric detonation because the over pressure waves can be just as effective as the tsar bomba with less fall out i.e. less nuclear winter side effects.
Its a more human world wide genocide and gives humanity as a species a better chance of bouncing back after N-day.
I would not be surprised if every nuclear owning government had installed all their electronic equipment underground inside reinforced concrete bunkers...The Germans were very clever at building them during World War 2, without any threat of an EMP being around in those days..