What single change turns a simple alternating current generator into a direct current generator?

1. Both machines have the same coil turning in the same magnetic field. 2. In the coil itself the current reverses every half turn in both machines. 3. An alternating current generator uses two slip rings, so that reversal reaches the outside circuit. 4. A direct current generator uses one ring split into two pieces, called a commutator. 5. The split ring swaps contacts at the same instant the current reverses, so the outside circuit always receives current in one direction, which is why removing the brushes cannot be the answer. _Source: Siyavula Physical Sciences Grade 12 (Everything Science, CC BY 4.0), Chapter 11: Electrodynamics_