PPT 02 - Mesa Community College

Operating Systems
MCC – CIS105
Describe the functions of an operating system (OS)
Describe the components of a personal computer
operating system
Describe various operating system user interfaces
Describe the OS Management Functions
Describe the differences among multiprocessing,
multiprogramming, and time-sharing
List several functions that are typically performed by
utility programs
CIS 105 – Mesa Community College
Operating Systems for
Personal Computers
Common Operating Systems
CIS 105 – Mesa Community College
Platform is the combination of the operating
system software and computer hardware.
Windows on an Intel-based or AMD-based PC
Wintel is one of the most common
Linux on an Intel-based or AMD-based PC
Mac OS on Intel-based or Freescale-based
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Operating Systems
Roles & Components
System software controls the operations of
computer hardware.
Serves as the interface between the user,
applications, and hardware.
User Interface – how users issue commands to the
Primary components (covered in next few slides):
Kernel – core software
Device Drivers – little programs to operate specific
Utility programs – applications used to manage and
secure a computer
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Utility Programs Examples
File manager
Create, rename, delete, and move files and folders
Backup and Restore
Backup: make copies of files on hard disks to another
storage device
Restore: retrieve files from backup device
Use System Restore under Accessories to backup
system settings before installing new programs.
Control Panel Items
Add and Remove Programs
Date and Time
Virus Protection and Firewalls
Power Options
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Device Drivers
Device drivers are little programs used to operate
a particular device.
The programs are provided by the manufactures.
Device drivers must be installed after installing the
new hardware, or the device will not work.
Some common devices that require drivers are
the mouse, keyboard, video display card, printer,
scanner, and USB ports.
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Main part (core) of the operating system
Loaded from hard drive into memory when
computer is booted
Cold Boot - starting the computer by turning on the
Warm Boot – restarting the computer when it is
already on
Resides in memory after it has been loaded
(resident portion or the core)
Loads other operating system programs from
disk storage as needed (nonresident)
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Boot Process
1. Central Processing Unit (CPU) reads the chip
with the BIOS (Basic Input/Output System)
2. POST – Power On Self Test
Tests memory, buses, cards, etc
Results are compared to CMOS values
3. Load Boot Program from hard drive
4. Boot program loads Kernel from hard drive
5. User’s system configuration is loaded
Reads preference files and registry
Load required device drivers
6. Present User Interface
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User Interfaces
User Interface – how users issue commands
to the system.
Command-Line (see next slide for examples)
Dos, Unix
List of commands presented
Graphical User Interface (GUI)
Interact with icons, menus, buttons, etc.
Windows, Mac OS, Linux
Win CE – handhelds, palmtops
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User Interfaces - examples
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OS Management Functions
Process Management (program or task)
Memory Management
Input/output Management
System Administration
See next few slides for additional information…
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Process or Task Management
The OS determines which instructions the processor (CPU)
will execute.
A processor can only do one thing at-a-time, but
it pretends to do more than one thing by…
Multiprogramming - is running two or more programs
concurrently, but only one is actually being executed at any
one time.
Programs take turns using the CPU
Event-driven – An event tells the operating system when to switch, for example
a button click could suspend a file download in background.
Time-Sharing - programs take turns using the CPU
Time-driven – preset time intervals
Typically used in mainframes with many users
Multiprocessing – is running multiple programs
simultaneously in a system with more than one CPU
Each programs runs on its own processor (dual core)
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Memory Management
The OS allocates memory (RAM) to each application as
it is launched or started.
Foreground – the program that is currently running
Background – lower priority and waiting for idle time
Virtual Memory
Some computers do not have enough real memory (RAM) to
keep all of the programs that are opened loaded in memory.
Portions of programs being executed are stored on disk and are
swapped into memory as needed
Can be implemented by paging
Divide memory into small, fixed-size pages, and pages are
saved out to disk when not in use.
If CPU spends too much time paging, it is call thrashing.
To correct thrashing, fewer programs should be ran concurrently,
or add additional memory.
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Input / Output Management
The OS handles all I/O to and from storage
devices, keyboards, and displays.
Devices installed on each computer may be
different, so the OS uses device drivers.
Plug-and-Play – devices have software encoded
on them (ROM), which allows them to be
recognized by the OS when installed, so the
device driver installation process can begin
Disk and File Management – Format command,
copy, delete, rename, etc. (Windows Explorer)
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I/O Management - Printing
Spooling: program saves output to a disk
file rather than sending directly to a printer
After saving the file, it is placed in a queue
File printed when printer becomes available
Allows program to complete print
command much more quickly, so the user
may continue working on the document.
Writing to disk much quicker than sending
data to printer
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System Administration
System Performance – use system monitoring software
to see which tasks are taking too much time
(Ctrl-Alt-Del – Windows Task Manager)
System Security
create users and passwords
Handles network functions
Establishes connections and manages peer-to-peer networks.
Share documents and resources (hard drives, printers) over
Network Operating System (NOS)
Usually used to referred to the software on a server dedicated to
managing users, services, and security.
Accessibility / Adaptive Technology
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MCC Courses
Learn more about a specific operating
system by taking one of the following…
CIS126DL – Linux Operating System
MST150 – MS Windows Professional
CIS 105 – Mesa Community College
Capron; Computers: Tools for An
Information Age, 8th Ed. 2003
Pfaffenberger: Computers in Your Future 2003
Shelly: Discovering Computers 2008
Microsoft Clipart
CIS 105 – Mesa Community College