Another competing magnet-based data storage system during the 1950s and 1960s was the use of large metal cylinders coated with ferromagnetic material. These drums featured heads that read and wrote data as the drum turned. Typically, the drum was used as secondary data storage for one or several computers. Programs could be loaded onto or off of the drum using punched paper tape or punched cards. Drums as storage became obsolete by the time magnetic-core memory became mainstream.