Batch processing

Batch processing is a technique in which an Operating System collects the programs and data together in a batch before processing starts. An operating system does the following activities related to batch processing −

• The OS defines a job which has predefined sequence of commands, programs and data as a single unit.

• The OS keeps a number a jobs in memory and executes them without any manual information.

• Jobs are processed in the order of submission, i.e., first come first served fashion.

• When a job completes its execution, its memory is released and the output for the job gets copied into an output spool for later printing or processing.

Advantages

• Batch processing takes much of the work of the operator to the computer.

• Increased performance as a new job get started as soon as the previous job is finished, without any manual intervention.

Disadvantages

• Difficult to debug program.
• A job could enter an infinite loop.
• Due to lack of protection scheme, one batch job can affect pending jobs.

Multitasking

Multitasking is when multiple jobs are executed by the CPU simultaneously by switching between them. Switches occur so frequently that the users may interact with each program while it is running. An OS does the following activities related to multitasking −

• The user gives instructions to the operating system or to a program directly, and receives an immediate response.

• The OS handles multitasking in the way that it can handle multiple operations/executes multiple programs at a time.

• Multitasking Operating Systems are also known as Time-sharing systems.

• These Operating Systems were developed to provide interactive use of a computer system at a reasonable cost.

• A time-shared operating system uses the concept of CPU scheduling and multiprogramming to provide each user with a small portion of a time-shared CPU.

• Each user has at least one separate program in memory.

• A program that is loaded into memory and is executing is commonly referred to as a process.

• When a process executes, it typically executes for only a very short time before it either finishes or needs to perform I/O.

• Since interactive I/O typically runs at slower speeds, it may take a long time to complete. During this time, a CPU can be utilized by another process.

• The operating system allows the users to share the computer simultaneously. Since each action or command in a time-shared system tends to be short, only a little CPU time is needed for each user.

• As the system switches CPU rapidly from one user/program to the next, each user is given the impression that he/she has his/her own CPU, whereas actually one CPU is being shared among many users.

Multiprogramming

Sharing the processor, when two or more programs reside in memory at the same time, is referred as multiprogramming. Multiprogramming assumes a single shared processor. Multiprogramming increases CPU utilization by organizing jobs so that the CPU always has one to execute.

The following figure shows the memory layout for a multiprogramming system.

An OS does the following activities related to multiprogramming.

• The operating system keeps several jobs in memory at a time.

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• This set of jobs is a subset of the jobs kept in the job pool.

• The operating system picks and begins to execute one of the jobs in the memory.

• Multiprogramming operating systems monitor the state of all active programs and system resources using memory management programs to ensures that the CPU is never idle, unless there are no jobs to process.

Advantages

• High and efficient CPU utilization.
• User feels that many programs are allotted CPU almost simultaneously.

Disadvantages

• CPU scheduling is required.
• To accommodate many jobs in memory, memory management is required.

Interactivity

Interactivity refers to the ability of users to interact with a computer system. An Operating system does the following activities related to interactivity −

• Provides the user an interface to interact with the system.
• Manages input devices to take inputs from the user. For example, keyboard.
• Manages output devices to show outputs to the user. For example, Monitor.

The response time of the OS needs to be short, since the user submits and waits for the result.

Real Time System

Real-time systems are usually dedicated, embedded systems. An operating system does the following activities related to real-time system activity.

• In such systems, Operating Systems typically read from and react to sensor data.
• The Operating system must guarantee response to events within fixed periods of time to ensure correct performance.

Distributed Environment

A distributed environment refers to multiple independent CPUs or processors in a computer system. An operating system does the following activities related to distributed environment −

• The OS distributes computation logics among several physical processors.

• The processors do not share memory or a clock. Instead, each processor has its own local memory.

• The OS manages the communications between the processors. They communicate with each other through various communication lines.

Spooling

Spooling is an acronym for simultaneous peripheral operations on line. Spooling refers to putting data of various I/O jobs in a buffer. This buffer is a special area in memory or hard disk which is accessible to I/O devices.

An operating system does the following activities related to distributed environment −

• Handles I/O device data spooling as devices have different data access rates.

• Maintains the spooling buffer which provides a waiting station where data can rest while the slower device catches up.

• Maintains parallel computation because of spooling process as a computer can perform I/O in parallel fashion. It becomes possible to have the computer read data from a tape, write data to disk and to write out to a tape printer while it is doing its computing task.

Advantages

• The spooling operation uses a disk as a very large buffer.
• Spooling is capable of overlapping I/O operation for one job with processor operations for another job.

A transaction processing system is a computer database system that balances and controls purchases of goods and services within a business network. A common example is a company's online store. The transaction processing system coordinates the warehousing and distribution of the item, the credit and bank transaction from the consumer's payment account and the business's management of inventory, sales, profits and payroll. This complex system has many advantages and disadvantages.

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Handling Operations

In some ways, the main benefit of a transaction processing system can also be a disadvantage: the handling of several thousand operations at once. The transaction processing system must simultaneously coordinate thousands, even millions, of purchases, debit consumers' bank accounts, hold each person's private banking and address information and ship out or process the order to the consumer. This system is helpful for any business that wants to make selling goods and services easier for consumers. However, this complex system can be difficult to handle if the business is not large enough to utilize a transaction processing system.

Security and Hardware Problems

Transaction processing systems are a combination of software and hardware used to handle immense quantities of consumer and business data. Because of this, viral security breaches may occur in this system, especially because consumers' private information is held within the database. Also, any hardware malfunction, such as an electrical outage, could damage a well integrated system that serves millions of consumers. If a business has the resources, the business can invest in high-quality computer security to ensure consumer protection and have hardware to back up data or generators for electricity.

Access to Untapped Markets

A transaction processing system makes it easier for consumers around the world to utilize a business's services through a simple online system. Transaction processing systems allow people from across the world to access a business and buy that business's goods and services. In a globalized market, the potential for growth is enhanced when the processing system is implemented properly.

Too Much Consolidation

Investing in a transaction processing system requires a lot from a firm. It requires technical people to maintain it 24 hours a day, seven days a week. The business will also need flawless integration with other departments, such as shipping, payroll processing, accounting and inventory. The business will need to create new departments, which may include international shipping or an information technology department. All these variables could create fears that too much consolidation and change is taking place. Some businesses are incapable to being the lone provider of every service to consumers.