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--- computer_basics:operating_system_fundamentals [2019/12/05 03:48] – mithat
+++ computer_basics:operating_system_fundamentals [2019/12/06 05:11] (current) – [Booting part 1: BIOS and EFI] mithat
@@ Line 25: / Line 25: @@
     * Providing a user interface for communication
-===== OS Function 1: Starting the computer =====
+===== OS function 1: Starting the computer =====
   * OS's first job is to load itself into RAM
-    * Called **booting**
+    * Called **booting**.
-===== OS Function 1: Starting the computer =====
+===== OS function 1: Starting the computer =====
 {{:computer_basics:ch04-booting.jpg?direct&300|}}\\
@@ Line 37: / Line 37: @@
   * Many computers use a **BIOS (Basic Input/Output System)** to begin the booting process.
-  * BIOS allows computer to
+  * The first thing that is loaded into memory and starts running when you turn on.
-    * Accept keyboard input
+  * Manages some core hardware settings.
-    * Show information on the monitor
+  * Handles the very first stages of the booting process.
   * Usually stored in flash memory or CMOS memory chip.
-===== Booting part 1: BIOS and EFI =====
+===== Booting step 1: BIOS and EFI =====
-  * Most newer desktop and laptop systems use **EFI (Extensible Firmware Interface)** instead of a BIOS.
+  * Most newer desktops and laptops use **EFI (Extensible Firmware Interface)** instead of a BIOS.
+    * ** UEFI (Unified Extensible Firmware Interface)** is one example.
   * Like a mini OS.
-    * Does everything BIOS does.
+  * Does everything BIOS does.
-    * Lets user run small utility applications that run on the Extensible Firmware Interface.
+  * Lets user run small utility applications that run on the Extensible Firmware Interface.
-    * Considered more secure than a BIOS.
+  * Considered more secure than traditional BIOS.
 ===== Booting step 2: Test the hardware =====
-   * Many systems perform a **power-on self-test (POST)** or similar test.
+  * Many BIOS/EFIs initiate a **power-on self-test (POST)** or similar test.
-   * Confirms that both the computer and its peripheral devices are working properly.
+  * Confirms that both the computer and its peripheral devices are working properly.
 ===== Booting step 3: Load the operating system =====
   * BIOS or EFI loads an OS's **kernel** into memory.
-     * kernel: the central part of the OS
+    * kernel: the central part of the OS.
-  * The kernel is usually stored on main storage device.
+    * Usually stored on main storage device.
   * The OS then loads remainder of what's needed.
 ===== Booting step 4: Check the system configuration =====
-  * The OS checks the system configuration for **device drivers**
+  * The OS checks the system configuration for **device drivers**.
     * device driver: utility program that enables communication between the OS and a peripheral device.
   * The OS installs and loads the needed drivers.
-===== Booting step 5**: Load system utilities =====
+===== Booting step 5: Load system utilities =====
   * Antivirus software
   * Speaker volume control
   * Etc.
-===== Booting step 6/: Authenticate user =====
+===== Booting step 6: Authenticate user =====
-    * If necessary, facilitate authentication/login, a user name and password
+    * Final part of booting is to facilitate user authentication or login.
+     * Typically a user name and password or fingerprint scan or special code.
-===== OS Function 2: Managing applications =====
+===== 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 =====
+===== OS function 3: Managing memory =====
   * The OS
     * gives each program a portion of RAM memory.
     * 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 =====
+===== OS function 3: Managing memory =====
-  * RAM is organized into **pages**: units of large fixed size containing program instructions and data.
+  * RAM is organized into **pages**: units of large fixed size.
   * **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.
+    * When RAM is full, the contents of the most inactive page or pages are temporarily moved to a **swap file**, a special hard disk file.
+    * When the page is again needed, it is transferred back into RAM.
     * Transferring files between RAM and the hard disk is called **paging**.
@@ Line 95: / Line 95: @@
 {{:computer_basics:ch04-virtualmemory.jpg?direct&600|}}
-===== OS Function 3: Managing memory =====
+===== OS function 3: Managing memory =====
   * Adding more RAM is often a good way to improve computer performance because:
-    * Paging slows the computer
+    * Paging slows the computer.
-    * Accessing data from the hard disk is slower than accessing it from RAM
+    * Accessing data from the hard disk is slower than accessing it from RAM.
-===== OS Function 4: Handling input and output =====
+===== 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: Provide a user interface =====
+===== OS function 5: Provide a user interface =====
   * The **user interface** allows the user to:
     * Start application programs
@@ Line 115: / Line 115: @@
 a) graphical, b) menu-driven, and c) command-line user interfaces
-===== OS Function 5: Provide a user interface =====
+===== OS function 5: Provide a user interface =====
   * Types of user interfaces:
     * **graphical user interface (GUI)** uses **icons** and other visual metaphors.
     * **menu-driven interface**:
-      * Provides text-based menus
+      * Provides text-based menus.
-      * Displays available user options
+      * Displays available user options.
     * **command-line interface**:
-      * Requires the user to type commands to instruct the OS to perform the desired actions
+      * Requires the user to type commands to instruct the OS to perform the desired actions.