Operating System

Operating System

1. The operating system (OS) controls almost all functions on a computer.

2. Multi-user - Two or more users have individual accounts that allow them to work with programs and peripheral devices at the same time. Multitasking - The computer is capable of operating multiple applications at the same time. Multiprocessing - The operating system can support two or more CPUs. Multithreading - A program can be broken into smaller parts that are loaded as needed by the operating system. Multithreading allows different parts of a program to be run at the same time.

3. Hardware Access The OS manages the interaction between applications and the hardware.

   • OS locates and installs the device driver for that component. Assigning system resources and installing drivers are performed with a plug-and-play (PnP) process. The OS then configures the device and updates the registry, which is a database that contains all the information about the computer.

4. File and Folder Management The OS creates a file structure on the hard disk drive to store data. A file is a block of related data that is given a single name and treated as a single unit.

   • Directories can be kept inside other directories. These nested directories are referred to as subdirectories. Directories are called folders in Windows operating systems, and subdirectories are

5. User Interface The OS enables the user to interact with the software and hardware. Operating systems include two types of user interfaces: Command-line interface (CLI) - The user types commands at a prompt, as shown in Figure 1. Graphical user interface (GUI) - The user interacts with menus and icons, as shown in Figure 2.

6. Application Management The OS locates an application and loads it into the RAM of the computer. Applications are software programs, such as word processors, databases, spreadsheets, and games. The OS allocates available system resources to running applications.

   • To ensure that a new application is compatible with an OS, programmers follow a set of guidelines known as an Application Programming Interface (API

7. The way that a CPU handles information can affect the performance of the OS. Two common architectures used to process data are:

   • x86 - A 32-bit architecture that processes multiple instructions using a 32-bit address space.
     • x64 - This 64-bit architecture adds additional registers specifically for instructions that use a 64-bit address space.

8. A desktop OS has the following characteristics: Supports a single user Runs single-user applications Shares files and folders on a small network with limited security

9. A NOS contains additional features to increase functionality and manageability in a networked environment. A NOS has the following characteristics: Supports multiple users Runs multi-user applications Provides increased security compared to desktop operating systems

   • A NOS provides network resources to computers, including: Server applications, such as shared databases Centralized data storage Centralized repository of user accounts and resources on the network Network print queue Redundant storage systems, such as RAID and backups
     • The following are examples of network operating systems: Windows Server Red Hat Linux Mac OS X Server

10. An OS must be upgraded periodically to remain compatible with the latest hardware and software. It is also necessary to upgrade an OS when a manufacturer stops supporting it. Upgrading an OS can increase performance. New hardware products often require that the latest OS version be installed to operate correctly. While upgrading an OS may be expensive, you can gain enhanced functionality through new features and support for newer hardware.

11. Partitioning A hard drive is divided into specific areas called partitions. Each partition is a logical storage unit that can be formatted to store information, such as data files and applications. During the installation process, most operating systems automatically partition and format available hard drive space.

    • Primary partition - This primary partition containing the operating system files is usually the first partition.
      • Active partition - The OS uses the active partition to boot the computer. Only one primary partition per disk can be marked active.
        • Extended partition - The extended partition normally uses the remaining free space on a hard drive or takes the place of a primary partition.