1. What Are Operating Systems? What Are Their Functions? Describe the Open Systems Interconnection Reference Model (Osi Model) & Its Seven Layers.

693 Words Aug 31st, 2012 3 Pages
An operating system (OS) is a set of computer program that manages the hardware and software resources of a computer. At the foundation of all system software, the OS performs basic tasks such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating networking, and managing files. The computerized system may be a computer, a workstation, a server, a PC, a notebook, a smartphone, a road navigation device or another system with "intelligence" of its own. It also may provide a graphical user interface for higher level functions. Types of Operating System - DOS (Disk Operating System), UNIX, LINUX, Windows, Windows NT

Operating System Functions
At the simplest level, an
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1. Program creation
2. Program execution
3. Access to Input/Output devices
4. Controlled access to files
5. System access
6. Error detection and response
7. Interpreting the commands
8. Managing peripherals
9. Memory management
10. Processor management
11. Information management
12. Process communication
13. Networking

Various services performed by operating systems are discussed below.
Process management: It deals with running multiple processes. Most operating system allow a process to be assigned a priority which affects its allocation of CPU time. Interactive operating systems also employ some level of feedback in which the task with which the user is working receives higher priority. In many systems there is a background process which runs when no other process is waiting for the CPU.
Memory management: The memory manager in an OS coordinates the memories by tracking which one is available, which is to be allocated or deallocated and how to swap between the main memory and secondary memories. The operating system tracks all memory used by each process so that when a process terminates, all memory used by that process will be available for other processes.
Disk and file systems: Operating systems have a variety of native file systems that controls the creation, deletion, and access of files of data and programs.
Networking: Most current operating systems are capable of using the TCP/IP networking protocols. This means that one

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