2. Installation, Configuration, and Upgrading,
2.3 Identify the basic system boot sequences and boot methods,
including the steps to create an emergency boot disk with utilities installed
for Windows 9x/Me, Windows NT 4.0 Workstation, Windows 2000 Professional, and
The computer runs the Power On Self Test (POST) which checks BIOS,
CPU, RAM, Video, Keyboard, drives, etc. Once POST is completed, the next
step is to load the Operating System (OS). The minimum information required
on the hard drive is called the Master Boot Program that is needed to locate
the beginning of the OS on the drive. The order in which the files are
required is given below:
POST--> OS -->
MBR--> Partition Table--> DOS Boot Record (IO.SYS)-->
MSDOS.SYS --> COMMAND.COM.
The entire process of DOS boot is described below:
BIOS locates the Master Boot Record
(MBR) on the hard drive.
The partition table find the physical location of the logical boot
drive and turns to the boot record of that logical drive
The boot record (a very short program) loads two hidden files into
memory. These files are IO.SYS and MSDOS.SYS
Once these two files are loaded, the boot record program is longer
needed and turns control over to a file stored on MSDOS.SYS
This program looks on the hard drive for a file named CONFIG.SYS. This file contains
commands that tell DOS how many files it can open at any one time
(FILE=) and how many file buffers (a temporary holding area for a file)
to create (BUFFERS=), etc.
When CONFIG.SYS is done, MSDOS loads COMMAND.COM
AUTOEXEC.BAT (Automatically Executed Batch file) holds a list of DOS commands that are automatically
executed each time DOS loads. Few of these commands are:
a. PROMPT $P$G this instructs DOS to display the current directory name
and the current drive name as part of the prompt.
b. PATH Tells DOS where to look for program files. Example: C:Windows.
c. AUTOEXEC.BAT also loads TSRs (terminate and stay resident programs).
The boot process is completed after AUTOEXEC.BAT has finished
executing. At this point, COMMAND.COM takes control and you have the
command Prompt (C:>).
Windows 95/98 Boot Sequence:
The Windows 95 boot sequence is as follows:
When you power-on the machine, POST (Power-On Self Test) occurs just
as it does for BIOS (Basic Input/Output System) that is not Plug and
The Plug and Play (PnP) BIOS begins by looking at the hardware devices
on the system. The BIOS first enables the devices that are not Plug and
Play, and then tries to make the PnP devices use the remaining
The BIOS looks for devices containing the Operating System (OS) and
loads Windows 95, making information about the current allocation of
resources available to the OS.
Just as with DOS, the Master Boot Record
(MBR) executes the boot
record on the hard drive, which looks for the initial hidden files of
Windows 95, called IO.SYS.
Again, just as with DOS, IO.SYS loads. IO.SYS looks for CONFIG.SYS
file, and, if found, the CONFIG.SYS file executes. The CONFIG.SYS file
is not required for Windows 95. Many of its functions have been
eliminated and incorporated into Windows 95. but you can use the
CONFIG.SYS file to load device drivers, if you want.
After CONFIG.SYS is complete, IO.SYS searches for
MSDOS.SYS. The role
of MSDOS.SYS differs greatly in Windows 95 from that in DOS. In Windows
95, MSDOS.SYS is a hidden file with settings used to customize the boot
The functions of the first few entries in MSDOS.SYS look like the
- WinDir= (Location of the Windows 9x directory)
- WinBootDir= (Location of the Windows 9x startup files)
- HostWinBootDrv= (Drive that is the Windows boot drive)
- BootGUI= (BootGUI=1, automatic graphical startup into
Windows 9x is enabled. BootGUI=0, the system boots to a command prompt)
Next, COMMAND.COM loads just as with DOS. COMMAND.COM is used to
provide a command interface for users and to execute an AUTOEXEC.BAT
file, if it is present.
If AUTOEXEC.BAT is found, it now executes.
Once the OS loads completely, a desktop GUI appears, from which you
can browse, run commands, or applications.
WINDOWS 98 Boot Sequence:
Windows 98 boot process is very similar to Windows 95.
BIOS runs POST
BIOS loads a small DOS core
The DOS core loads Windows 98
To speed up boot process, the 2 second wait cycle of Windows 95 while
"Starting Windows 95" has been replaced with a hold down CTRL key.
You just need to hold down the CTRL key in Windows 98 to go to Startup Menu
Windows XP Boot Sequence:
As with other Windows Operating Systems, when you turn on your PC, it
goes through an elaborate boot up process. It begins when the computer
performs the POST (Power-On Self Test), followed by the POST. The BIOS then
reads the MBR (Master Boot Record) which is in the first sector of the first
hard disk and transfers control to the code in the MBR which was created
during the XP Setup. This is where Windows takes over the startup process.
The MBR reads the boot sector which is the first sector of the active
partition. This sector contains the code that starts Ntldr which is the
boot strap loader for Windows XP. The first role of Ntldr is to allow
full memory addressing, start the file system, read boot.ini and put up
the boot menu. IMPORTANT: Ntldr must be located in root folder of the
active partition along with Ntdetect.com, boot.ini, bootsect.dos (for
dual booting) and Ntbootdd.sys (needed with some SCSI adapters).
Selecting XP from the boot menu (in case of multiple boot options)
causes Ntldr to run Ntdetect.com to get information about installed
hardware. Ntldr then uses the ARC path specified in the boot.ini to find
the boot partition, where Windows XP is installed. Ntldr loads the two
files Ntoskrnl.exe and Hal.dll. These files must be located in the
Ntldr reads the registry files, selects a hardware profile, control
set and loads device drivers, in that order.
Then, Ntoskrnl.exe takes over and starts Winlogon.exe which starts
Lsass.exe (Local Security Administration), This program displays the
Welcome screen and allows the user to log on with his/her user name and
A startup disk is useful in case you have a problem booting up
the computer. You can boot the computer from a startup disk and try to fix
what is actually causing the boot problem. The startup disk is created
during the operating system installation. You can also create it at a later
point, after the installation of the Operating System. Important files that
are needed for booting the computer are stored in the startup disk. The list
of files that are stored in the Startup disk may differ for various Operating Systems
The files copied on to the Windows 95 Startup Disk include the following:
attrib.exe - a file attribute utility
command.com - a Core operating system file
drvspace.bin - disk compression utility
ebd.sys- Utility for the startup disk
edit.com - a text editor
fdisk.exe - disk partition utility
format.com - disk format utility
io.sys - core operating system file
msdos.sys - core operating system file
regedit.exe - real-mode Registry Editor
scandisk.exe - disk status and repair utility
scandisk.ini - disk status utility configuration file
sys.com - system transfer utility
The following files are added to the Windows 98 Startup Disk:
Real-Mode IDE CD-ROM support
Real-Mode SCSI CD-ROM support
Edb.cab file ( These are Cabinet files containing extract utilities)
New extract command: Ext.exe
Utilities contained in the Edb.cab file include the following:
Attrib.exe - file attributes utility
Chkdsk.exe - disk check tool
Debug.exe - debug utility.
Edit.com - a text editor.
Ext.exe - file extract utility.
Format.com - disk format utility, use with care.
Help.txt - Useful for troubleshooting purpose, a help document
Mscdex.exe - CD-ROM file extension for MS-DOS.
Restart.com - restart your computer.
Scandisk.exe - disk scan tool.
Scandisk.ini - disk scan configuration file.
Sys.com - system transfer tool.
Uninstal.exe - tool for removing Windows 98.
A start-up disk may be created during installation of the OS or at a
later stage. To create a Startup disk at a later stage, use Add/Remove
Programs, and select Start Disk stab in Windows 9x.
Insert disk into the floppy disk drive
Insert the Windows 2000 CD-ROM
Browse to bootdisk folder of the CD-ROM drive
makeboot.exe, and follow the instructions on screen.
You can also create an Emergency Repair Disk
(ERD) by clicking Start,
Programs, Accessories, System Tools, and opening Backup. From the Backup
window, click the button for Emergency Repair Disk and the steps.
You will need four blank, formatted, 1.44-MB floppy disks
When formatting a floppy diskette, users have the option of creating a
MS-DOS startup disk, follow the below steps to do this.
1.Place diskette in the computer.
2.Open My Computer, right click the A: drive and click Format.
3.In the Format window, check Create an MS-DOS startup disk.
Safe mode that enables you to enter safely into Windows and correct any
problems that may be preventing them from entering normal mode. Safe mode is
available in Microsoft Windows 95, Windows 98, Windows ME, Windows 2000, and
Windows XP It is not available in Windows 3.x, and Windows NT 4.0. In Safe
mode, the custom config files are skipped, and only required drivers are
loaded. This helps you to correct issues so they can get back into normal
mode. Usually, in Safe mode only mouse keyboard and VGA drivers are loaded.
You can enter the safe mode by pressing the F8 key as soon as the
computer starts up or you see starting Windows 9x message on the screen. You
will see a menu. Enter choice 3 and press enter key.
You can enter the safe mode by pressing the F8 key as soon as the computer
starts up or you see starting windows 2000/XP message on the screen. In the
menu, use the up/down arrow keys to highlight the choice and press enter.
In Windows 2000/XP you will have 3 different choices for Safe Mode:
Safe Mode - Starts Windows 2000 using only required files and drivers (mouse,
monitor; keyboard; mass storage; and no network disabled, if any).
Safe mode with Networking - Starts Windows 2000 using only required files and
drivers, with network enabled.
Safe Mode with Command Prompt - Starts Windows 2000 using only required files
and drivers. After logging on, you will be taken to the command prompt, where
you can do necessary changes, and reboot.
Starts up Windows 2000/XP from the registry information that the Windows
saved at the previous successful shutdown. Use this option only in cases of incorrect
configuration. Last Known Good Configuration does not solve problems caused by
corrupted or missing drivers or files. Also, any changes made since the last
successful startup will be lost.
This feature is not available for Windows 9x operating systems.
Starts Windows with only basic files and drivers. After logging on, the
command prompt is displayed instead of the Windows desktop.
Loads the Command.com and DoubleSpace or DriveSpace files (if present). This
mode is used to run recovery utilities and repair the registry. It also helps to
check the integrity of the file system.
System Restore enables restoring your computer by to its original
configuration or to a configuration point that was set afterwards.
Often a restore is done because of one or more of the following reasons.
a.) Serious data corruption that can not be reversed.
b.) Intend to remove recently installed software and programs and get it
back to how it was when you first purchased it.
c.) You intend to remove all personal data because plan on selling the
computer or plan on giving it away.
Recovery Console can be accessed from Windows 2000/XP setup by booting the
computer with the Windows 2000/XP CDROM. On boot up, you will be presented with
a choice of menu .Select Repair option by pressing R key.
The next screen provides you with two options a. Repair a Windows 2000
installation by using the Recovery Console, or b. Repair using the emergency repair
process. Select Repair by Using Recovery Console and then press C to continue.
You will be requiring administrative privileges to use Recovery Console.
The following tasks may be performed using Recovery console:
ERD (Short for Emergency Repair Disk), creates backups of important
system files and settings. It is useful for troubleshooting problems with
Windows 2000/XP installations. The ERD is required when you go for
Windows repair option. You will be prompted for the diskette when
needed. The ERD is different form boot disk, as the former is used in
conjunction with Windows repair.
The ERD is capable of performing such checks as:
1. Verifying the boot sector is not corrupt.
2. Repairing any startup files.
3. Locate any missing or damaged system files.
Creating Emergency repair Disk for Windows 2000:
1.Click Start >> All Programs >> Accessories >> System
tools >> Backup from the menu.
2.On the tools menu click on create an emergency repair disk and follow the
instructions to complete.
Creating Emergency Repair Disk for Windows NT:
You can create the Emergency repair disk while installing the operating
system. The setup will guide you on how to create the repair disk.
To manually create the Emergency Boot Disk do this:
1.Click on Start the click on Run
2.In the open box type rdisk /s
In the next screen type rdisk in the Open box, and then click Update Repair