ch.4 Flashcards
System software
Consists of all the programs that enable
the computer and its peripheral devices to
function smoothly
system software divided into two main categories:
- The operating system
- System utilities (utility programs)
System utilities (utility programs)
Provides various maintenance
functions
operating system five basic
functions
o Starts the computer
o Manages applications
o Manages memory
o Handles input and output
device messages
o Provides a user interface
for communication
Starting the computer
o Loading— to transfer something from a
storage device, such as the hard disk , to
memory.
o Booting—loading the OS into RAM
* Cold boot: Starting computer when it
has not yet been turned on
* Warm boot: Restarting a computer that
is already on
WARM Boots are often necessary after installing
new software or after an application crashes or
stops working.
six steps of Booting system
1- BIOS is loaded
2- power on self-test is completed
3- operating system is loaded
4- system configuration is completed
5- system utilities is loaded
6- user is authenticated
Step 1: Activate the BIOS and
Setup Program
o BIOS (Basic Input/Output System) instructions
provide the computer with descriptions of the internal
equipment
* Bios is encoded on ROM (read-only memory)
* Does not control external devices
o Adjustable energy settings
o Setup program
* Includes settings that control computer hardware
* Do not alter—making incorrect changes to a BIOS
device will cause the system not to boot
In the BIOS UI, a user can:
*configure hardware
*set the system clock
*enable or disable system components
*select which devices are eligible to be a potential
boot device
*set various password prompts, such as a password
for securing access to the BIOS UI functions itself
and preventing malicious users from booting the
system from unauthorized peripheral devices.
tep 2: Initiate the PowerOn Self-Test
o Power-on self-test (POST)—to confirm
that both the computer and its peripheral
devices are working properly
o If the POST fails:
* A beep will sound.
* An error message will appear on the
monitor.
* The computer will stop.
Step 3: Load the Operating
System
o BIOS
* Looks for the operating system
* Loads the kernel into memory— the central
part of the operating system that starts
applications, manages devices and memory,
and performs other essential functions.
o The operating system loads the system
configuration information.
Step 4: Configure the System
o Operating system
* Checks the registry
oDatabase that stores information about
software and peripherals choices, for
configuration information
* Checks the configuration for drivers
o Utility programs containing instructions for
the proper functioning of peripheral devices.
* Automatically detects plug-and-play (PnP)
devices
* Checks for conflicts between devices
* Installs and loads needed drivers
Step 5: Load System Utilities
o Antivirus software
o Speaker volume control
o Power management options
Step 6: Authenticate a User
o Verifies authorized users
* Enter an authentication/login user name
and password
o Profile—a record of a specific user’s
preferences for the desktop theme, icons, and
menu styles
o Account—for multiuser computer systems each
user has an account
* Consists of user name, password, and
storage space
* Created by server/computer administrator
Managing applications
o Single-tasking operating systems—run
only one application at a time
o Multitasking operating systems—permit
more than one application to run at the same
time
* The foreground application is the active
one.
* Background applications appear inactive.
o Preemptive multitasking—ensures all
applications have fair access to the CPU
Managing memory
o Buffer
* Area that holds data and instructions
temporarily
* Makes programs run faster
o RAM memory functions as the buffer.
o OS gives each program a portion of RAM
memory and keeps them from interfering
with each other.
o Virtual memory—uses portion of hard disk to
extend RAM
* Pages—units of fixed size, contain program
instructions and data
* 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—paging
o Adding more RAM—best way to improve computer
performance:
* Paging slows computer.
* Accessing data from hard disk is slower than
accessing from RAM.
o Windows Vista and Windows 7 come with Windows
ReadyBoost
* Allows allocation of space on removable memory
devices such as USBs that can be used to increase
the size of RAM
* Better performance than hard disk virtual memory
because accessing files on flash memory is quicker
than accessing the hard drive
Coordinating tasks
o Device drivers—enable communication
between computer and devices
o Interrupts—signals created by input and
output devices
* Notify the OS when actions are taken
Providing the user interface
The part of the OS that you
see and interact with and by which users and
programs communicate with each other.
user interface Allows the user to:
- Start application programs
- Manage storage devices
- Safely shut down the computer
Types of user interfaces
o Graphical user interface (GUI)
o Menu-driven user interface
o Command-line user interface
o Graphical user interface (GUI)
- Uses icons—small images that:
oRepresent computer resources used to
initiate actions
oAppear on the desktop - Work area created after the OS loads into memory
- Sidebar—invisible 1-inch vertical strip on the
right side of the desktop, holds user designated
gadgets - Programs you open will appear in the center of
the desktop.
Menu-driven user interface
Menu-driven user interface
* Provides text-based menus
* Displays available user options
Enables you to avoid memorizing keywords (such as
copy , paste) and syntax (a set of rules for entering
commands)
Command-line user interface
- Requires the user to type commands to instruct
the OS to perform the desired actions - Uses complicated rules of syntax
Three categories of operating
systems
o Stand-alone operating systems—used by single
users
o Server operating systems—used in client/server
network environments
o Embedded operating systems—found on ROM
chips in portable or dedicated devices
Embedded Operating Systems
o Designed for specific applications
o Compact and efficient
o Eliminate many unneeded features of OSs
o Used in PDAs, cell phones, kitchen
appliances, point-of-sale devices, industrial
robots, etc.
