TCARS was an acronym for the Temporal Computer Access and Retrieval System (citation needed • edit) used aboard 29th century timeships. It was the successor to the Federation's starship LCARS. Its control interface could be operated by touch or by simply moving one's hand over a control surface.
The TCARS computer system was used aboard Wells-class timeships, such as the USS Relativity. On the Relativity, it could be used to locate past problems in a timeline along with performing normal starship computer routines. (VOY: "Relativity")