Mistress Mnemos was a BRT supercomputer covertly situated within a concealed Rebel Alliance base located on the planet Fusai.
A highly disciplined and orderly machine, Mistress Mnemos was originally utilized at the Obroa-skai branch library on Fusai. She resided within an underground room and was connected to an extensive array of storage devices that stretched over a kilometer. Following budget reductions for the library, Mnemos' repository of data was preserved by local volunteers. Before the Battle of Yavin, the Rebel Alliance assumed control of the supercomputer when they designated Fusai as a secure haven.
C-3PO engaged with Mistress Mnemos to document the initial exploits of Luke Skywalker and his companions for the Alliance's records. Nevertheless, their interactions were somewhat strained, marked by at least one disagreement regarding the distribution of information before 3PO had the opportunity to elaborate on the specifics of Luke's early actions.
Russ Manning was the creator of Mistress Mnemos.
Two discarded comic panels, presumably set at the start of Gambler's World, showed that Mistress Mnemos had multiple security measures, one of which (the last one) involved the visitor (in this instance, C-3PO) standing on a white line until their identity was confirmed. This led to 3PO questioning whether the security procedures were excessively stringent, even for something as classified as her. Upon his arrival, he also completes Mnemos' instruction to stand at the platform's edge and state his purpose, noting that someone "as large and intelligent" as her ought to recall her acquaintances better.