computer_basics:operating_system_fundamentals
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Operating System Fundamentals
Adapted from:
LaBerta, Catherine. “System Software.” In Computers Are Your Future. 11th ed. Boston: Prentice Hall., 2010
Mithat Konar
Sept. 25, 2012
The Operating System
- The operating system (OS) is a set of programs that coordinates:
- Hardware functions
- Interaction between application software and computer hardware
The Operating System
- Five basic OS functions:
- Starting the computer
- Managing applications
- Managing memory
- Handling input and output device messages
- Providing a user interface for communication
OS Function 1: Starting the computer
- The OS's first job is to loads itself into RAM
- Called booting
- Booting involves six steps
Booting process
OS Function 1: Starting the computer
- Booting Step 1: Load BIOS (Basic Input/Output System) instructions into memory
- Allows computer to
- Accept keyboard input
- Show information on the monitor
OS Function 1: Starting the computer
- Booting Step 2: Conduct the power-on self-test (POST)
- Confirms that both the computer and its peripheral devices are working properly.
OS Function 1: Starting the computer
- Booting Step 3: Load the operating system
- BIOS loads into memory the kernel, the central part of the OS
- The OS then loads remainder of what's needed
OS Function 1: Starting the computer
- Booting Step 4: Check the system configuration
- The OS checks the system configuration for device drivers—utility programs containing instructions for the proper functioning of peripheral devices
- The OS installs and loads needed drivers
OS Function 1: Starting the computer
- Booting Step 5: Load system utilities
- Antivirus software
- Speaker volume control
- Etc.
OS Function 1: Starting the computer
- Booting Step 6: Authenticate users
- If necessary, facilitate authentication/login, a user name and password
OS Function 2: Managing applications
- Multitasking operating systems permit more than one application to run at the same time.
- The foreground application is the active one.
- The background applications appear inactive.
OS Function 3: Managing memory
- The OS gives each program a portion of RAM memory and keeps them from interfering with each other.
- OS processes often involve using a buffer
- An area that holds data temporarily to make programs run faster
- RAM memory functions as the buffer
OS Function 3: Managing memory
- RAM is organized into pages: units of large fixed size containing program instructions and data.
- Virtual memory uses a portion of the hard disk to extend RAM.
- When RAM is full, copies of pages are temporarily stored in a swap file, a special hard disk file.
- Transferring files between RAM and the hard disk is called paging.
Virtual memory
OS Function 3: Managing memory
- Adding more RAM is often the best way to improve computer performance because:
- Paging slows the computer
- Accessing data from the hard disk is slower than accessing it from RAM
OS Function 4: Handling input and output
- Applications access input and output devices via the OS.
- Device drivers enable communication between the OS and input and output (and other) devices.
OS Function 5: Providing the user interface
- The user interface allows the user to:
- Start application programs
- Manage storage devices
- Safely shut down the computer
- Perform other interactions
User interfaces
OS Function 5: Providing a user interface
- Types:
- graphical user interface (GUI) uses icons and other visual metaphors.
- menu-driven interface:
- Provides text-based menus
- Displays available user options
- **command-line interface:
- Requires the user to type commands to instruct the OS to perform the desired actions
computer_basics/operating_system_fundamentals.1348633441.txt.gz · Last modified: 2012/09/26 04:24 by mithat