OS Paper 2012

RGPV OS : Solved Question: 2012 Paper

Q1. What is means by operating system? Explain various types of operating system in detail. Ans. OPERATING SYTEM: ·         operating system is the set of programs that controls a computer. ·         It provide a pleasant and effective  interface between the user and the hardware ·         Makes the computer more convenient to use SOME EXAMPLES OF OS: (i)            Windows XP (ii)           MS DOS (iii)          Linux etc   DIFFERENT TYPES OF OS: (i)            Batch Operating system (ii)           Single user operating system (iii)          Multi user operating system (iv)         Multi tasking operating system (v)          Multi programming operating system   (i)           BATCH OPERATING SYSTEM  One or more programs (together with any data needed) are submitted to the computer as a 'job' and put in a queue to await processing. There is no interaction between user and computer. Processing can be done at off-peak times such as overnight, as no interaction is needed Examples : a)            A payroll run for a company. b)            Gas and Electricity bills are produced using a batch processing system   (ii)          SINGLE USER OPERATING SYSTEM A system which is used by a single person at any one time, i.e. the entire information on the hard disk used by only one person is called single user system. This system is not connected to a network so cannot communicate to other users.   (iii)         MULTIUSER OPERATING SYSTEM A number of individual users are connected to a central computer and appear to have control. This is not the same as a network. The processor gives a time slice to each terminal and, during that time allocation, processing that is needed is carried out. By rotating around the terminals on the system and processing in short bursts, each user has the impression that they are the sole users of the system.   (iv) MULTITASKING OPERATING SYTEM Multiple applications are able to be run at the same time by the processor. Usually refers to a PC. A number of tasks are loaded and processed in turn for short time-slices until completed. It appears that the computer is running several applications at the same time..   (V) MULTIPROGRAMING OPERATING SYTEM A multiprogramming system is one where more than one job is held in computer’s main memory at the same time and can be processed by the computer’s CPU at (apparently) the same time. Multiprogramming is used to ensure the most efficient use of the CPU and prevent it from being idle while waiting for a slower peripheral.

Q2. Compare the following: (i)                 Spooling and Buffering Ans.   SPOOLING   BUFFERING 1 SPOOL full form is (Simultaneous Peripheral Operations On-line), spooling refers to as a process of putting jobs in a buffer.   Buffer is a temporary storage area where SPOOL puts its jobs. 2 Spooling is useful because devices access data at different rates.   The buffer provides a waiting station where data can rest for slower devices. 3 The most common spooling application is print spooling, In print spooling, documents are loaded into a buffer.   printer pulls documents off the buffer at its own rate.  4 Spooler are used for long term.   Buffers are used for short term. 5 Spooler are large in capacity to store data as compare to buffer.   Buffer is small and limited in capacity. 6 Spool may be either online or offline. Buffer is necessary to be online i.e., it is direct communication with the computer.

(i)         Hard-Real time systems and Soft-Real time system Ans. REAL TIME OPERATING SYSTEM: In Real time operating system response time is already fixed. Means time to display the result after processing is fixed. Real Time System is used at those Places in which we Requires higher and Timely Response. These Types of Systems are used in Bomb and Reservation. There are two Types of Real Time System     HARD REAL TIME SYSTEM   SOFT REAL TIME SYSTEM 1 Hard Real-Time System guarantees that critical tasks complete on time. Soft Real Time System where a critical real-time task gets priority over other tasks and retains that priority until it completes.   2 Strict about each task and its deadline.   The task and its deadline is manageable. 3 The delay period it can handle must be less (in range of micro second)   The delay period it can handle can be more (around mili second) 4 Example-Rocket Launching   Example- camera and washing machine etc. 5 If result obtain after deadline the result will become invalid   Even if result obtain after deadline the result will be valid. 6 Example: Web browser- We request for certain URL, it takes some time in loading the page. If the system takes more than expected time to provide us with the page, the page obtained is not considered as invalid.     Example: In case of a robot doing some job like line tracing, etc. If a hindrance comes on its path, and the robot doesn't process this information within some programmed deadline (almost instant!), the robot is said to have failed in its task (the robot system may also get completely destroyed!).

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