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Mainframe computers can process several million-program instructions per second. Large organizations rely on this room-size system to handle large program with huge volume of data. Mainframes are mainly used by Banks, Insurance companies, Finance companies, Airline and Railways reservation system and so on.

Mainframes have even more access to storage space and to input/output device. To work with these extra device mainframes also have more powerful PROCESSORS. This power is useful and required by large corporations who have large amounts of data to process. For example, large international banks who have millions of customer accounts to update regular will need very powerful machine to process and maintain the data.

FEATURES OF MAINFRAME OPERATING SYATEM :

1. Virtual Storage :

Virtual storage is a technique that lets a processor an amount of main storage that is larger than the actual amount of real storage. Virtual storage operating system transfer data between real storage and disk storage as they are needed.

2. Multiprogramming

Multiprogramming means computer can execute more that one Job(program) at a same time. Multiprogramming simply reclaims the CPU during the idle periods and allow another job to execute.

3. Spooling

Spooling manages the output device for application by intercepting output device and directing it to a disk device instead. Then, when program complete executing, the operating system collects its spooled print output and direct it to output device like printer. And another advantage is the execution speed, it is faster.

4. Batch processing

Batch processing means work is processed in a unit of work called Job. Job may have one or more programs to execute in sequencially.

5. Time-sharing

Time sharing is also called as Interactive processing, because it allow user to interact directly to the computer.