The Protostar disappeared in the Delta Quadrant "years" before 2383, along with knowledge of its existence there. Some time later, the Diviner became aware of its location in the Tars Lamora prison colony and began mining operations to look for the ship. It was later accidentally discovered by Dal R'El and Rok-Tahk buried in the Northwest Crevasse within the prison colony.
It was equipped with a holographic training advisor known as Hologram Janeway, modeled after Captain Kathryn Janeway, and holographic projectors in multiple areas of the ship. (PRO: "Lost and Found", "Starstruck")