Tapes come in reels and cartridges of many sizes and shapes. Although still used in legacy systems, open reels have been mostly superseded by cartridges with enhanced storage capacities. Locating a specific record on tape requires reading every record in front of it or searching for markers that identify predefined partitions. Although most tapes are used for archiving rather than routine updating, some drives allow rewriting in place if the byte count does not change. Over the years, storage density has increased from 200 to 38,000 bpi.
Tape is more economical than disks for archival data.
However, if tapes are stored for the duration, they must be periodically recopied or the tightly coiled magnetic surfaces may contaminate each other. See helical scan. The semi-permanent or permanent holding place for digital data. Storage means disks and tapes, not memory. Memory, which is made of RAM chips, is a temporary workspace for executing instructions and processing data.