batch processing using sequential files-automated procedures
in the last section, we noted that order taking, credit checking, warehousing, and shipping are manual operation.data processing is the automated operation, and an example of legacy system that employs the sequential file structure for its accounting records. both tapes and disk can be used as the physical storage medium for such systems. however, the use of tapes has declined considerably in recent years for day-to-day operations, tapes are inefficient because they must be physically mounted on a tape drive and then dismounted when the job ends. this approach is labor intensive and expensive. the constant decline in the cost of disk storage in recent years has eliminated the economic advantage once associated with tapes. most organization that still use sequential files store them on disk that are permanently connect(online) to the computer system and require no human intervention. the operational feature of sequential files described earlier are the same of both tape and disk media. today, tapes are primarily as backup device and for storing archive data. for these purposes, they provide an efficient and effective storage medium for a large system.