Conditioned Reflex by Lester del Rey

In a post-apocalyptic world where survival is a daily struggle, Paul Ehrlich and his father, Justin, have carved out a fragile existence on a remote farm. While Paul toils to keep their small community afloat, Justin is obsessed with his past inventions and the promise of a better future. Tensions flare as Justin's eccentricities disrupt their harsh routine, but a surprising discovery of an advanced machine from a bygone era reignites hope.

As the machine begins to show signs of intelligence, Paul and Justin must reconcile their differences to harness its potential, or risk losing everything to the chaos of their new world.