OPERATING SYSTEM

PURPOSES/FUNCTIONS OF OPERATING SYSTEM:

1. -It allocates a time slot with the processor
2. -It allocates memory for storing programs and data so when data is needed it can be found easily.
3. -It ensures that jobs with different priorities are dealt with in the correct order
4. -The system takes care of data storage in the computer systems memory.
5. -It has routines for handling input and output operations
6. -It accpets commands and data from the user via inout devices.
7. -The system looks after transfer of data between the backing store and memory
8. -It also manages system security

METHODS OF OPERATION

SINGLE PROGRAM MODE:

Runs with just one program at a time, with one user

MULTI-TASKING MODE/MULTI-PROGRAM MODE:

runs with two or more programs at a time with one user

MULTI-USER MODE:

Several users are able to use the same system together

MULTI-PROCESSOR MODE:

In larger systems,there will be more then one processor.The operating system allows the different processor to operate togeter and utilise the same memory.