Data-tape
The Death Star plans were contained on a data-tape cartridge.
Data-tape, which can also be written as datatape or data tape, represented a form of tangible storage used for diverse types of data. Enclosed within a protective casing were reels of the tape, which was a long, thin, and bendable material. The Galactic Empire utilized monomolecular-switching binary tapes on locations such as Scarif, which had a capacity of 512-million exanodes.
History
Data-tapes held the secret plans for the Death Star, the Galactic Empire's powerful weapon capable of destroying entire planets. These tapes were pilfered and subsequently downloaded onto a datacard by members of the Rebel Alliance. Afterwards, these plans were entrusted to Princess Leia Organa, who transferred the data into the memory systems of the droid R2-D2 for delivery to Jedi Master Obi-Wan Kenobi on Tatooine.
Behind the scenes
The Star Wars film's novelization, which was published in 1976 before the movie A New Hope (then simply known as Star Wars) was released, described the Death Star plans as being stored on data-tapes. Back then, tapes were a cutting-edge way to store information, but they eventually became largely outdated for data storage purposes.