1. Gene Perkins, Lassen High School Networking Academy
Chapter 4
Operating Systems
Gene Perkins, Lassen High School Networking Academy

2. Need for Operating Systems
It serves as a interface between you and the computer hardware
Necessary to manage applications

3. Parts of an Operating System
3 major parts:
User Interface
Kernel
File Management

4. Functions of an Operating System
The OS provides a way for the user to control applications
Works with the BIOS and device drivers to fetch and store data
Contains utilities to optimize the hardware

5. Operating System Types
Multitasking – more than one application running at the same time
Multiuser – more than one user sharing applications or hardware at the same time
Multiprocessing – more than one processor working at the same time
Multithreading – a program that is broken down into smaller parts and run at the same time

6. Common Types of OS’s Windows Linux UNIX Mac OS X (based on UNIX) 3.x
9.x (includes ME)
2000 (includes NT) XP
Linux
UNIX
Mac OS X (based on UNIX)

7. DOS Is a CLI (Command Line Interface) Made up of 3 boot files:
IO.SYS
MSDOS.SYS
Command.com
Contains file system utilities
Has file management commands

8. Command Line Screen

9. DOS Properties
DOS is not user-friendly. The best way to learn about DOS is to use it.
DOS can only run one program at a time.
DOS can only run small programs and has memory limitations (640 Kb max).
DOS is an essential tool for IT professionals and is used extensively for troubleshooting.

10. File Structure All files start at the root directory
All other directories branch off of the root directory
Must know the path to find files in DOS
Paths are typed in either relatively or absolute
C:\myfiles\mypicts\nba.gif
\mypicts\nba.gif

12. Types of DOS Files
Hidden File – The user will not see hidden files when using a normal file search
Read Only – The user can open and read this type of file but cannot modify the file in any way.
Archive – The archive contains a backup copy of files.
System File – The DOS operating system must have these files for a successful boot up.

13. DOS Commands DIR – Displays the content of a folder
CD – Change the working directory
MD – Make a new folder (directory)
RD – Removes a folder
DEL – Deletes a file
REN – Renames a files
COPY – Copies a file from one place to another

14. DOS Commands SET – Sets a path for programs to work from or to
MEM – Displays the system memory
TYPE – Shows the contents of a file
FDISK – Sets partitions on a hard drive
TIME – Sets system time
DATE – Sets system date
CHKDSK – Checks a drive for errors

15. DOS Commands DISKCOPY – Copies a floppy disk to another
EDIT – Opens a file for editing
FORMAT – Prepares the disk to receive data
PRINT – Prints contents of screen or file
ATTRIB – Changes attributes of a file (hidden, read-only, archive)
* - Wildcard that represents everything

16. Internal & External Commands
Some commands are within the command.com file
Copy
Dir
Some commands are separate files
Xcopy
Format
External commands need to be copied onto a floppy when performing diagnostics procedures

17. Switches
Most DOS commands can be modified by using a switch behind them
Attrib can be modified to hide or unhide files using the + or – key
Dir /w – Wide format
Dir /a – displays all files
Dir /h – displays hidden files
Each command has special switches it can use (See 4.2.3)

18. Creating a Boot Disk
Three files are absolutely needed to make a boot disk:
Io.sys
Msdos.sys
Command.com
Other files are also needed to work with the hard drive
Fdisk.exe
Format.com

19. Creating a Boot Disk Insert floppy into the drive
Type in the following commands:
format A: /s
Copy C:\format.com A:\format.com
These commands will transfer the system files and other external files needed
The other way is to select from the Start>Settings>Control Panel>Add Progams and select the create boot disk tab

20. Boot Sequence BIOS searches for the MBR
The bootstrap loader moves the MBR into RAM
The MBR locates and loads the boot files into memory
Io.sys loads msdos.sys
Msdos.sys runs config.sys
msdos.sys runs command.com
Command.com runs autoexec.bat

21. Config.sys Used to modify system parameters
Configures system to run added hardware devices
Installs TSR programs
Redirects program paths
Pressing the F5 or left SHIFT key bypasses config.sys and autoexec.bat
Pressing F8 enters the option screen which allows you to modify bootup

22. Autoexec.bat Batch file that can perform any DOS command
Common autoexec.bat commands:
Prompt $P$G – Displays working directory
Set temp=c:\temp – Sets an area to hold data temporarily
Path=C:\;C:\DOS – Sets search path(s) when looking for data
Smartdrive.exe – Sets 1Mb of memory cache for DOS and 2Mb for Windows

23. Editing System Configuration Files
Type in edit and file name at dos prompt
Edit autoexec.bat
Type in sysedit in the command prompt box
Edit files in Notepad

24. DOS Memory First 640 Kb reserved for running programs
640 to 1024 Kb used to run older DOS programs and BIOS applications
1024 to 1088 used for DOS command files
1088 Kb to 4Gb used for Windows applications

26. Memory Management In the config.sys file to disable expanded memory
Device=C: \Windows\Emm386.exe NOEMS
To load DOS into upper memory
DOS=UMB
To allow DOS to use high memory
DOS=HIGH, UMB

27. Memory Management To allow DOS programs access to expanded memory
Device=C: \Windows\Emm386.exe RAM
To allow device drivers to load into high memory
DEVICEHIGH=C: \DOS\MOUSE.SYS
This allows Windows 3.x and 9x to work
DEVICE=C: \DOS\HIMEM.SYS

28. Virtual Memory
When a section of the hard drive is set aside to be used as the system RAM
The slowest memory available
Usually set to automatically adjust as needed
If there is inadequate virtual memory, your system will freeze
Stored in WIN386.SWP (Win9x) or PAGEFILE.SYS (Win2000)

29. RAM Drive In some cases, RAM can be setup to act as a hard drive
Configured in config.sys using this command:
DEVICE=C:\DOS\ RAMDRIVE.SYS 4096
When data is stored in this manner, it can be lost when powered off

30. General Protection Faults
When windows crashes (blue screens), there is a problem with 2 programs trying to share the same spot in memory
Can also be caused by bad drivers or trying to directly gain access to windows programs
GPF’s can also cause the program to lock

32. Real vs Protected Mode Real mode is used with DOS
System crash will bring down the whole system
Protected mode used with Windows
Allows a program to crash without affecting the system

33. Perform Practice Test