Learn Computer Organization & Operating System “Identifying Functionalities of Operating System ” Lesson 6

Identifying Functionalities of Operating System

An operating system is responsible for performing wide variety of tasks. Some of the most important tasks are:

1. User interface
2. File management
3. Device management
4. Memory management
5. Process management
6. Networking
7. Security

An important task of an operating system is to act as a mediator between the computer hardware and the computer user. It interacts with the computer hardware on behalf of the user. However to do so the OS needs to take input from the user.

The OS displays an interface on the computer monitor that it uses to communicate with a computer user. The user communicates with the computer through this user interface by typing in few simple commands without the need of remembering complicated control methods.

Today, the GUIs are the most widely used user interface making use of mouse, keyboard, drop-down menus, toolbars, etc. Because of ease of working with a GUI, today GUI-based OS like Windows XP are most widely used amongst computer users.

File Management
A file is a collection of information stored on a disk. You make a file when you create information (such as text or graphics) using some application, give the file a name and save it on a disk. However, it is actually the OS that physically creates the file and store it on a storage media. But apart from creating and saving a file, an OS is also responsible to retrieve the content of the file or to remove the file from the storage media, when the user gives the necessary commands.

Device Management
The OS is also responsible for managing various input and output devices attached to the computer. It is responsible for controlling the working of hard disk drive, displaying output on monitor, or communicating with peripherals like printers.
However, to communicate with various input/output devices, the OS requires special software called the driver. This is because the OS is written in a high-level programming language (which humans can understand) whereas the input and the output devices attached to the computer can understand electrical signals only. It is the responsibility of the driver to translate the OS commands into electrical signals (bits and bytes for most devices) or a series of laser pulses in a printer.

Memory Management
An important task of an OS is memory management. Computer memory is one of the most crucial components of the computer system. The computer memory consists of registers, cache, random access memory, etc. It is the responsibility of the OS to determine which memory component is free and which can be allocated or deallocated to a resource. This resource can be a hardware device like printer etc. or a software application like Word etc.

An OS is also responsible for managing the virtual addresses. If multiple resources are accessing the computer memory simultaneously, then it is the responsibility of the OS to prevent the resources from interfering with each other’s memory. This is achieved by assigning separate address spaces for each of the resources which are in the memory. Each resource can access only that part of the memory that is uniquely assigned to it.

The OS can also write inactive memory pages to secondary storage. This process is called paging or swapping.

Process Management
Every program running on a computer, be it a service or an application, is a process. And most of today’s processor support multitasking, executing several processes at a time. But despite of this fact, only one process can be executed by a CPU at any given time. It is the responsibility of the OS to determine how to allocate the CPU to any given process. This is called process management.

All the processes that are seeking for CPU usage are added to a process queue. Most OS allocate certain priority level to a process that is seeking for the CPU usage. The OS also allots a certain CPU time to each of the process. This is called time slicing.
When a process currently in CPU exceeds the time assigned to it, it is removed from the CPU and is placed at the end of the process queue. The next process that is to allot the CPU is the one that is having the highest priority. Therefore, using time slicing and priority level, an OS can schedule the CPU resource amongst different processes that are vying for the CPU resource.

Networking
Most current OS has a built-in support for TCP/IP networking protocols. This means that computers running dissimilar operating systems can participate in a common network for sharing resources such as computing, files, printers, and scanners using either wired or wireless connections.

Security
Most of today’s OS provide some or other form of security level. They provide mechanism to protect your computer as well as the data stored in the computer. They provide password protection to keep unauthorized users from accessing your system. Some operating systems also maintain activity logs and accounting of the user’s time for billing purposes. An OS also provide backup and recovery utilities to use to recover the system in case of system failures.