ABSTRACT

Developments in software engineering have also resulted in operating systems that are more maintainable, reliable and understandable. Hence, simple operating systems called job-to-job monitors were devised to control the I/O devices and manage several user programs stored in memory, thereby alleviating some of the work of the operator. Batch operating systems nowadays are only found on small computers with few input devices and no time sharing. In an attempt to satisfy these requirements and increase the efficiency of computer operation, multi-programmed operating systems were introduced. Users of time shared operating systems are provided with distributed terminals linked by transmission lines to the central processor. A tape operating system stores the main part of the program on tape, while a disk operating system (DOS) stores the bulk of its commands on a magnetic disk. There are a number of popular DOS including CP/M, MS-DOS, OS/2 and UNIX.