Multi User Operating Systems.

Principle Features

The Multi User Operating System is an operating system that can support two or more simultaneous users. Most common operating systems found such as Windows are not actually Multi-User but Single-User operating systems. Single user will allow one user to do one task at a time in Single Task mode or in Multi Task mode they will allow a user to have a number of programs or tasks running at the same time such as printing, downloading and word processing. Multi tasking is when the operating system seems to be performing two or more tasks at the same time, however these tasks is not actually running simultaneously as the processor is actually switching between tasks at a very high speed, therefore each user sees their own task as having priority. One disadvantage can be that the more programs that are run by the user, the more memory that is required.

Multi Tasking can be split into two categories, co-operative and pre-emptive.

Co-operative is when the process currently controlling the CPU must offer a balanced share of the CPU to all other processes, hence Co-operative, as all processes must co-operate for it to work properly. Subsequently an MUOS will allow two or more users a share of the system resources at the same time. The use of the resources must be spread evenly between the requirements of the users so that a problem with one user does not become a problem between all users. Examples of co-operative multi tasking would be Windows 3x and Macintosh.

Pre-emptive is when the applications are forced to share the CPU whether they want to or not and examples of this are Windows 95, NT and UNIX.

Hardware that is necessary to operate a MUOS includes processors, terminals, I/O devices, storage devices and memory.