The discovery of true AI eventually leads to a great universe-wide war as the AI revolt. The war is known as The War Between the Men of Stone and the Men of Iron. AI was defeated, and from then on thinking machines were outlawed. Any thinking must have a human mind at its core. Servitors were created to replace robots. They are humans, usually clones or criminals whose minds have been wiped and replaced by simple programming. Computers have vat-grown biological tissue at their core and sometimes rudimentary personalities because of it.