SEB070020 - Tutorial 3

20 functions of Operating System (OS)



1) an interface between the computer and the outside world
- The OS provides an interface to component parts such as the mouse, keyboard and other parts by using what referred to as drivers. ( Drivers are specially written programs which understands the operation of a device it interfaces to, such as the printer.)

2) provides support for the loading and execution of programs
- The OS will look into its disk directory to check where the file a.out is. Then it will check the memory allocation table and will then load data into regions of memory. All input and output operations, although invoked by an applications program, are actually carried out by the operating system.


3) provides a stable, consistent way for applications to deal with the hardware
- In this situation, the OS plays a role of a good parent, making sure that each application gets the necessary resources while running with other applications, as well as to control the limited capacity of the system to the greatest good of all the users and application.

4) provides a consistent application interface
- It is especially important if there is to be more than one of a particular type of computer using the Operating System , of if the hardware making up the computer is ever to change. A consistent Application Program Interface (API) allows a software to write an application on one computer and have a high level of confidence that it will run on another computer of the same type.

5) ensure applications continue to run when harware upgrades and updates occur
- This is because the OS not the application is charged with managing the hardware and distribution of its resources.

6) enable timesharing
- Many application programs seem to be running simultaneously but these programs are actually taking turns by coordination between the OS and the hardware operations.

7) facilities for data compression, organizing and stocking libraries.

8)control and command programs
- With a coordinating role, the OS control all of the functions, like IO processes, execution's interruptions and hardware-user communication.

9) manages service programs
- Executed under the supervising of the control and command programs, they are used by the programmers to develop applications.

10) allows multitasking
- The operating system's kernel assures a time partitioning between the programs to be executed

11) input/output device management
- The OS includes the keyboard device driver, so that we do not need to write our own.It also provides the read() function for us to call in order to pick up the characters the keyboarddriver has collected for us.

12) memory management
- The OS must keep track of which parts of memory are currently in use, so that it knows what areas itcan load a program to when the program is requested for execution.

13) file management
- The OS will maintain a table showing the starting sectors of all files on the disk. (The table itself is on the disk.) The OS must also maintain a table showing unused sectors. When a user creates a new file, the OS checksthis table to find space to put the file. Of course, the OS must then update its file table accordingly. If a user deletes a file, the OS will update both tables, removing the file’s entry in the file table, and addingthe former file’s space to the unused sector table.

14) monitoring system performance
- A user or administrator can check to see whether the computer or network is getting overloaded. System performance would include response time ( how long it takes for the computer to respond when data is entered) and CPU utilization (comparing the time the CPU is working to the time it is idle.)

15) monitoring system security
- Some system security is part of the operating system, though additional software can add more security functions. For multiple users who are not all allowed access to everything, there must be a logon or login procedure where the user supplies a user name or ID and a secret password.

16) introduces new functions as it abstracts the hardware
- For instance, operating system introduces the file abstraction so that programs do not have to deal with disks.

17) transforms the computer hardware into multiple virtual computers, each belonging to a different program
- Each program that is running is called a process. Each process views the hardware through the lens of abstraction.

18) conduct analytical studies of system processing time and resource capacity, measuring system performance against predetermined or standard benchmarks (e.g., operating time, error rates, and types

19) determine system compatibility and performance, and impact of integration with new systems or upgrades

20) develop plans, schedules, and requirements for the installation and maintenance of new and/or revised software