Topic 2 System software

(a) Describe the purpose of operating systems

- Operating systems provide a software platform on top of which other programs, called application programs, can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run.

Examples of operating systems are DOS, OS/2,Windows and Linux.


(b) Describe the characteristics of different types of operating systems and their uses: batch, real-time, single-user, multi-user, multi-tasking and network systems

Batch
Performing a particular operation automatically on a group of files all at once rather than manually opening, editing and saving one file at a time.

For example, graphics software that converts a selection of images from one format to another would be a batch processing utility.

Real Time
As fast as required. A real-time system must respond to a signal, event or request fast enough to satisfy some requirement. Real time often refers to process control and embedded systems.

For example,
1.space flight computers must respond to changing conditions in order to keep the rocket ship on course.
2.Industrial robots must respond quickly in order to keep the assembly line moving at full speed. 3.Anti-lock brakes and other driving assist systems must respond to changing road conditions immediately in order to benefit the driver and vehicle

Single-User
Single user mode is a mode in which a multiuser computer operating system boots into a single superuser. It is mainly used for maintenance of multi-user environments such as network servers.

Some tasks may require exclusive access to shared resources, for example running fsck on a network share.

Note: The system utility fsck (for "file system check") is a tool for checking the consistency of a file system in Unix and Unix-like operating systems such as Linux.

Multi-User
Multi-user is a term that defines an operating system or application software that allows concurrent access by multiple users of a computer. Time-sharing systems are multi-user systems. Most batch processing systems for mainframe computers may also be considered "multi-user", to avoid leaving the CPU idle while it waits for I/O operations to complete.

Multitasking
Multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU.Multitasking allows many more tasks to be run than there are CPUs.

(c) Identify a range of applications requiring batch processing and a range of applications in which a real time response is required.

1.Batch
ProcessingData processing
A typical batch processing procedure is End of day-reporting (EOD), especially on mainframes. Historically systems were designed to have a batch window where online subsystems were turned off and system capacity was used to run jobs common to all data (accounts, users or customers) on a system. In a bank, for example, EOD jobs include interest calculation, generation of reports and data sets to other systems, print (statements) and payment processing.

2.Printing
This normally involves the operator selecting the documents they need printed and indicating to the batch printing software when, where they should be output and priority of the print job. Then the job is sent to the print queue from where printing daemon sends them to the printer.

3.Databases Batch processing is also used for efficient bulk database updates and automated transaction processing, as contrasted to interactive online transaction processing (OLTP) applications.

4.Images Batch processing is often used to perform various operations with digital images. There exist computer programs that let one resize, convert, watermark, or otherwise edit image files.

5.Converting Batch processing is also used for converting a number of computer files from one format to another. This is to make files portable and versatile especially for proprietary and legacy files where viewers are not easy to come by.Real-time Response