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Key features of the Operating System
User interfaceisone of the significant feature in Operating System. The only way that user can make interaction with a computer. If the computer interface is not user-friendly, the user slowly reduces the computer usage from their normal life. This is the main reason for the key success of GUI (Graphical User Interface) based Operating System. The GUI is a window based system with a pointing device to direct I/O, choose from menus, make selections and a keyboard to enter text.Its vibrant colours attract the user very easily. Beginners are impressed by the help and pop up window message boxes. Icons are playing vital role of the particular application.
Now Linux distribution is also available as GUI based Operating System. The following points are considered when User Interface is designed for an application.
· The user interface should enable the user to retain this expertise for a longer time.
· The user interface should also satisfy the customer based on their needs.
· The user interface should save user’s precious time. Create graphical elements like Menus,Window,Tabs, Icons and reduce typing work will be an added advantage of the Operating System.
· The ultimate aim of any product is to satisfy the customer. The User Interface is also to satisfy the customer.
· The user interface should reduce number of errors committed by the user with a little practice the user should be in a position to avoid errors (Error Log File)
Memory Management is the process of controlling and coordinating computer’s main memory and assigning memory block (space) to various running programs to optimize overall computer performance. The Memory management involves the allocation of specific memory blocks to individual programs based on user demands. At the application level, memory management ensures the availability of adequate memory for each running program at all times.
The objective of Memory Management process is to improve both the utilization of the CPU and the speed of the computer’s response to its users via main memory. For these reasons the computers must keep several programs in main memory that associates with many different Memory Management schemes.
The Operating System is responsible for the following activities in connection with memory management:
• Keeping track of which portion of memory are currently being used and who is using them.
• Determining which processes (or parts of processes) and data to move in and out of memory.
• Allocation and de-allocation of memory blocks as needed by the program in main memory. (Garbage Collection)
Process management is function that includes creating and deleting processes and providing mechanisms for processes to communicate and synchronize with each other.
A process is the unit of work (program) in a computer. A word-processing program being run by an individual user on a computer is a process. A system task, such as sending output to a printer or screen, can also be called as a Process.
A computer consists of a collection of processes, they are classified as two categories:
• Operating System processes which is executed by system code
• User Processes which is execute by user code
All these processes can potentially execute concurrently on a single CPU.
A process needs certain resources including CPU time, memory, files and I/O devices to finish its task.
The Operating System is responsible for the following activities associated with the process management:
• Scheduling processes and threads on the CPUs
• Creating and deleting both user and system processes
• Suspending and resuming processes
• Providing mechanisms for process synchronization
• Providing mechanisms for process communication
The following algorithms are mainly used to allocate the job (process) to the processor.
1. FIFO 2. SJF 3. Round Robin 4. Based on Priority
This algorithm is based on queuing technique. Assume that a student is standing in a queue to get grade sheet from his/her teacher. The other student who stands first in the queue gets his/ her grade sheet first and leaves from the queue. Followed by the next student in the queue gets it collected and so on. This is the basic logic of the FIFO algorithm.
Technically, the process that enters the queue first is executed first by the CPU, followed by the next and so on. The processes are executed in the order of the queue.
This algorithm works based on the size of the job being executed by the CPU.
Consider two jobs A and B.
1) A = 6 kilo bytes 2) B = 9 kilo bytes
First the job “A” will be assigned and then job “B” gets its turn.
The Round Robin (RR) scheduling algorithm is designed especially for time sharing systems. Jobs (processes) are assigned and processor time in a circular method. For example take three jobs A, B, C. First the job A is assigned to CPU then job B and job C and then again A, B and C and so on.
The given job (process) is assigned based on a Priority. The job which has higher priority is more important than other jobs. Take two jobs A and B. Let the priority of A be 5 and priority B be 7.
Job B is assigned to the processor before job A.
The major challenge in computer and software industry is to protect user’s legitimate data from hackers. The Operating System provides three levels of securities to the user end. They are
• File access level
• System level
• Network level
In order to access the files created by other people, you should have the access permission. Permissions can either be granted by the creator of the file or bythe administrator of the system.
System level security is offered by the password in a multi-user environment.
Both windows and Linux offer the password facility.
Network security is an indefinable one. So people from all over the world try to provide such a security.
All the above levels of security features are provided only by the Operating System.
The Operating Systems should be robust. When there is a fault, the Operating System should not crash, instead the Operating System have fault tolerance capabilities and retain the existing state of system.
File management is an important function of OS which handles the data storage techniques. The operating System manages the files, folders and directory systems on a computer. Any type of data in a computer is stored in the form of files and directories/folders through File Allocation Table (FAT). The FAT stores general information about files like filename, type (text or binary), size, starting address and access mode (sequential/indexed / indexed-sequential/ direct/relative). The file manager of the operating system helps to create, edit, copy, allocate memory to the files and also updates the FAT. The OS also takes care of the files that are opened with proper access rights to read or edit them. There are few other file management techniques available like Next Generation File System (NTFS) and ext2(Linux).
This is a one of the features of Operating System. It has two or more processors for a single running process (job). Processing takes place in parallel is known as parallel processing. Each processor works on different parts of the same task or on two or more different tasks. Since the execution takes place in parallel, this feature is used for high speed execution which increases the power of computing.
This is a one of the features of Operating Systems. It allows execution of multiple tasks or processes concurrently. For each task a fixed time is allocated. This division of time is called Time- sharing. The processor switches rapidly between various processes after a time is elapsed or the process is completed.
For example assume that there are three processes called P1, P2, P3 and time allocated for each process 30, 40, 50 minutes respectively. If the process P1 completes within 20 minutes then processor takes the next process P2 for the execution. If the process P2 could not complete within 40 minutes, then the current process P2 will be paused and switch over to the next process P3.
This feature takes care of the data and application that are stored and processed on multiple physical locations across the world over the digital network (internet/intranet). The Distributed Operating System is used to access shared data and files that reside in any machine around the world. The user can handle the data from different locations. The users can access as if it is available on their own computer.
The advantages of distributed Operating System are as follows:
1. A user at one location can make use of all the resources available at another location over the network.
2. Many computer resources can be added easily in the network
3. Improves the interaction with the customers and clients.
4. Reduces the load on the host computer.
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