Operating Systems

Definition: Operating Systems

The operating system software (OS) is the most important part of system software. Without the operating system software the computer would be useless. All computers need an operating system to tell them how to work.

The operating system software is the very first program or set of programs loaded when the computer is switched on. The operating system software controls and monitors the operation of the computer system and how the hardware connected to the CPU is used.

 

Operating Systems in Action?

 

Common features of Operating Systems

All operating systems have certain standard functions. These standard functions can be found in all operating system software. These include:

1. Managing memory - The operating system controls how blocks of the computer’s memory are given to programs and data.
   
   
2. Managing input and output. The operating system checks input devices like the mouse and keyboard to see if data has been input to the computer system.

The operating system controls the sending of data to output devices like the VDU and the printer.

3. Managing backing storage
   
The access to all types of backing storage devices is controlled by a special part of the operating system called the filing system. Whenever data is saved or loaded the filing system controls what happens.


Whenever data is saved the operating takes care of how the data is written to the backing store.

So, if you are using a piece of application software and wish to save your data to the backing store, you would use the SAVE command in the application software which would then pass the data to be saved to the operating system which would then write the data to the computer hardware.

4. Error reporting
   The Operating System also generates error messages whenever something goes wrong, for example the Printer runs out of paper. These try and give an indication of what the problem might be e.g 'Paper Out' message.

 

Security

In some operating systems, especially ones that run on computer networks, the access to the computer system is controlled by the operating systems through passwords.

User interface

The operating system provides user interface. This is the means of communicating with the computer system. Features such as icons, commands, etc. are all provided by the operating system.

 

Interactive Systems

Modern computers operate using an interactive system in that the user and the computer interact or communicate with one another.

The user can enter data which is processed immediately or enter commands like 'Save' or 'Print'. The computer responds through dialog boxes asking the user where they would like to save the file or how they would liike the file to be printed. This is similar to a 'conversation'

Increasingly users are interacting with their computers through the user of touch screen technologies.

 

 

Real time Systems

These systems are where data and instructions are processed at the same time it is generated. For example:-

• Booking a flight seat. Delays can lead to double bookings.
• Flying planes or controlling missiles. Delays in processing instructions can lead to accidents!
• Playing games.

The difference between real time and interactive systems is that in real time systems is that speed of response in real time systems is critical

 

 

Interactive Systems and Background Jobs

Modern computers are able to do more than one job at the same time. For example

Burn or record music to a CD. Print a document Listen for new E-mails. Run a word-processing program. The job the user is working on is known as the foreground job. The others, that go on in the background while the user is working are called background jobs.

 

Device Drivers

Device drivers are add on programs to the Operating System that allow the computer to 'speak' or communicate with other hardware devices. For example Printers, Cameras, Scanners, MP3 players etc.

 

 

 

 

What you should be able to do!

1. Explain the purpose of the Operating System..

2. Provide a list of at least 4 jobs controlled by the operating system.

3. Explain the difference between Interactive and Real time Systems.

4. Provide examples of background jobs.

5. Explain the role or purpose of Device Drivers .