Batch Operating System
  1. In this type of operating system, jobs which are of similar type are grouped together and treated as a batch.
  2. The system will then perform all the required operations in a sequence. So, we consider this as a type of Serial processing.  Eg: Bank Statements

  • Advantages: 
     1. Suppose a job takes a very long time(1 day or so). Then, such processes can be performed even in the absence of humans.
     2. They doesn't require any special hardware and system support to input data.

 

  • Disadvantages:
     1. It is very difficult to debug batch systems.
     2. Lack of interaction between user and operating system.
     3. Suppose an error occurs in one of the jobs of a batch. Then, all the remaining jobs get affected i.e; they have to wait until the error is resolved.

 

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Parallel Computing: Parbegin/Parend Concurrent Statement

A higher level language construct for specifying concurrency is the Parbegin and Parend statement also known as Cobegin and Coend. All statements enclosed between Parbegin and Parend can be executed concurrently.

For given example:

                        

S1 ;

Parbegin

S2 ;

S3 ;

…..

S(n-1) ;

Parend

Sn ;

Precedence graph will be:

 

    42.jpg

 

The advantage of Parbegin and Parend is structured control of statements and semaphores mechanisms. However, this is not powerful to model all possible precedence graph and Fork/Join construct is more powerful.

 

Fork and Join Constructs

The fork L instruction produces execution starts at statement labeled L and continuation of the execution at the statement following the fork instruction. The join instruction provides to recombine two concurrent computations into one and it has parameter (count) to specify the number of computations which are to be joined.

For example:

 

count := 2 ;

S1 ;

FORK L1

S2

…..

GO TO L2 ;

L1: S3 ;

L2: JOIN count; [* count := 2

A4 ;

      

Precedence graph will be:

 

 43.jpg      

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Types of Operating System

We can categories operating systems by their properties:

 

  1. Serial and Batch Operating System: Serial Operating System was fairly simple.  The Operating System was always in memory. Its major task was to transfer control from one job to another. Batch operating System was used programs into batches with similar requirements. The CPU utilization was low. Example: IBM OS/2.
     22.jpg

     

  2. Interactive Operating System: Interactive Operating System allows the to directly interact with Operating System to supply commands and data as application program. Typically, only one one user that has the full control over the system.
    Example:  ATM Machine.
     

  3. Multiprogrammed Operating System: The goal is to reduce CPU idle time. So, they introduced concepts of multiprogramming system by allowing new jobs to take over the CPU whenever the currently running job needed to wait (e.g. for user I/O). However, CPU can execute only one job at a time. Operating System may interrupt the process and give the control one of another ready process. In this way, idle time of CPU can be reduced. In this order Operating System must be able to load multiple program into main memory. Example: Windows and Unix.

    Spooling: Spooling is used in multiprogrammed system. Spooling is an acronym for simultaneous peripheral operations online. Data is sent to and stored in memory until the program for the execution. When data is temporarily held to be used and executed by a program, device or the system, then this process is called Spooling. It overlaps I/O of one job with the computation of other job and uses disk as very large device. It’s a combination of buffering and queueing. Example: IBM DOS/360.

      222.jpg

     

  4. Time sharing Operating System: Time sharing is also known as multitasking system is a logical extension of multiprogramming system. When more than one program can reside into the main memory at a time is known as multiprogramming system and when more than one program can reside into same CPU at a time is known as multitasking system. A time shared Operating System uses CPU scheduling and multiprogramming to provide each user with small portion of time shared system. Time sharing system enables many people. The main objective of multiprogramming system and time sharing system are maximize CPU utilization and minimize response time respectively. Example: Windows.
     

     111.jpg
 

  1. Real time Operating System: Real time Operating System give response within a predefined set period of time. User when there are rigid time requirements of the operating of the processor or flow of data. There are two types of real time operating system:

    (i) Hard real time system: It guarantees that critical tasks completed on time. A kernel is the central of the operating system. Examples: Satellite, Missile System.
    (ii) Soft real time system: It is less restrictive real time operating system. When a critical real time task gets priority over other tasks, and retains the priority until it completes. Example: Banking System.
     

  2. Network and Distributed Operating System: Network Operating System runs on a server and a layer of software is added to the OS connected to the Internet. Each client has its own Operating System. Network OS allows interaction between the machines by having a common communication architecture. Example: a file server, Windows server 2003 and 2008.
    Distributed System are loosely coupled system. It’s not share memory or clock, instead each processor processor has its own local memory. In distributed system common OS shared by a network of systems. Network OS is independent machines accessed by the user and Distributed OS dependent machines accessed by the user to share the resources. There are some advantages of distributed system,e.g. Resource sharing, reliability, communication etc.
     

  3. Parallel Operating System: Parallel operating system are interface between parallel computers and applications. The goal is managing resources of parallel machines.
    This works by dividing sets of calculations into smaller pieces that are done at the same time in different places and by different mechanisms.
     

  4. Clustered and Handheld Operating System: Clustered system has high reliability. It allows two or more systems to share storage. Handheld Operating Systems are used in cellular mobile phones. The limitation of handheld systems are limited memory, slow processor and small display screen. Example: Android.

 

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