So I read this book several years ago and now I'm trying to remember the name. I know this is a fairly vague description but I'm hoping it's enough for someone to catch on and help me.
I know this isn't exactly in order and I honestly can't even remember if it was a trilogy or not but here goes.
Set in the future, humans had built an AI controlled space based weapon. Somehow the AI malfunctioned and now destroys anything that flies higher than a few hundred feet over the ground. There are also many human factions, many at war with each other but what I remember best about one is they have human "calculators" who work in a factory with a abacuses. At least two sets of railroads are in use, due to disagreement between two factions. Dolphins are now sentient/telepathic and rule the oceans. At one point, there are prop-plane battles going between 2 factions but I can't remember if this is before or after someone manages to destroy the space weapon.
Thank you again for taking time to read and try to help me remember! If i'm lucky I didn't pass the book along and still have it at home but I'm pretty sure I did.