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Batch Processing Operating stystem, Lecture notes of Operating Systems

Biju Patnaik University of TechnologyOperating Systems

Batch Operating system, Multiprogramming Operating system,Time-sharing Operating system, Multi processing operating system by somya sir

Typology: Lecture notes

2021/2022

Available from 01/13/2022

amrit-patra
amrit-patra ๐Ÿ‡ฎ๐Ÿ‡ณ

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Lecture #3
Evolution of OS:
1. Batch Processing Operating System:
๏ƒœ This type of OS accepts more than one jobs and these jobs are batched/ grouped together according to their similar
requirements. This is done by computer operator. Whenever the computer becomes available, the batched jobs are
sent for execution and gradually the output is sent back to the user.
๏ƒœ It allowed only one program at a time.
๏ƒœ This OS is responsible for scheduling the jobs according to priority and the resource required.
2. Multiprogramming Operating System:
๏ƒœ This type of OS is used to execute more than one jobs simultaneously by a single processor. it increases CPU
utilization by organizing jobs so that the CPU always has one job to execute.
๏ƒœ The concept of multiprogramming is described as follows:
๏ƒœ All the jobs that enter the system are stored in the job pool( in disc). The operating system loads a set of jobs from
job pool into main memory and begins to execute.
๏ƒœ During execution, the job may have to wait for some task, such as an I/O operation, to complete. In a
multiprogramming system, the operating system simply switches to another job and executes. When that job needs to
wait, the CPU is switched to another job, and so on.
๏ƒœ When the first job finishes waiting and it gets the CPU back.
๏ƒœ As long as at least one job needs to execute, the CPU is never idle.
Multiprogramming operating systems use the mechanism of job scheduling and CPU scheduling.
3. Time-Sharing/multitasking Operating Systems
Time sharing (or multitasking) OS is a logical extension of multiprogramming. It provides extra facilities such as:
๏ƒœ Faster switching between multiple jobs to make processing faster.
๏ƒœ Allows multiple users to share computer system simultaneously.
๏ƒœ The users can interact with each job while it is running.
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Lecture

Evolution of OS:

1. Batch Processing Operating System:

๏ƒœ This type of OS accepts more than one jobs and these jobs are batched/ grouped together according to their similar requirements. This is done by computer operator. Whenever the computer becomes available, the batched jobs are sent for execution and gradually the output is sent back to the user. ๏ƒœ It allowed only one program at a time.

๏ƒœ This OS is responsible for scheduling the jobs according to priority and the resource required.

2. Multiprogramming Operating System:

๏ƒœ This type of OS is used to execute more than one jobs simultaneously by a single processor. it increases CPU utilization by organizing jobs so that the CPU always has one job to execute. ๏ƒœ The concept of multiprogramming is described as follows: ๏ƒœ All the jobs that enter the system are stored in the job pool( in disc). The operating system loads a set of jobs from job pool into main memory and begins to execute. ๏ƒœ During execution, the job may have to wait for some task, such as an I/O operation, to complete. In a multiprogramming system, the operating system simply switches to another job and executes. When that job needs to wait, the CPU is switched to another job, and so on. ๏ƒœ When the first job finishes waiting and it gets the CPU back. ๏ƒœ As long as at least one job needs to execute, the CPU is never idle. Multiprogramming operating systems use the mechanism of job scheduling and CPU scheduling.

3. Time-Sharing/multitasking Operating Systems

Time sharing (or multitasking) OS is a logical extension of multiprogramming. It provides extra facilities such as: ๏ƒœ Faster switching between multiple jobs to make processing faster. ๏ƒœ Allows multiple users to share computer system simultaneously. ๏ƒœ The users can interact with each job while it is running.

These systems use a concept of virtual memory for effective utilization of memory space. Hence, in this OS, no jobs are discarded. Each one is executed using virtual memory concept. It uses CPU scheduling, memory management, disc management and security management. Examples: CTSS, MULTICS, CAL, UNIX etc.

4. Multiprocessor Operating Systems

Multiprocessor operating systems are also known as parallel OS or tightly coupled OS. Such operating systems have more than one processor in close communication that sharing the computer bus, the clock and sometimes memory and peripheral devices. It executes multiple jobs at same time and makes the processing faster. Multiprocessor systems have three main advantages: ๏ƒœ Increased throughput: By increasing the number of processors, the system performs more work in less time. The speed-up ratio with N processors is less than N. ๏ƒœ Economy of scale: Multiprocessor systems can save more money than multiple single-processor systems, because they can share peripherals, mass storage, and power supplies. ๏ƒœ Increased reliability: If one processor fails to done its task, then each of the remaining processors must pick up a share of the work of the failed processor. The failure of one processor will not halt the system, only slow it down. The multiprocessor operating systems are classified into two categories:

  1. Symmetric multiprocessing system
  2. Asymmetric multiprocessing system ๏ƒœ In symmetric multiprocessing system, each processor runs an identical copy of the operating system, and these copies communicate with one another as needed. ๏ƒœ In asymmetric multiprocessing system, a processor is called master processor that controls other processors called slave processor. Thus, it establishes master-slave relationship. The master processor schedules the jobs and manages the memory for entire system.

5. Distributed Operating Systems

๏ƒœ In distributed system, the different machines are connected in a network and each machine has its own processor and own local memory. ๏ƒœ In this system, the operating systems on all the machines work together to manage the collective network resource.