Modern Personal Computer Boot up Process The boot up process is necessary for Windows as the hardware does not know where the Operating system is stored. There has to be a simple yet powerful program which loads the kernel in the main memory and executes it. This program in Windows is known as the Bootstrap Loader. The Windows boot up process comprises of the following procedures: · The Power-On Self-Test Phase: Firstly a self-test is performed by the power supply to ensure that the volume and current levels are correct before the Power Good signal is sent to the processor. As soon as this stage is cleared, the microprocessor triggers the BIOS to perform a series of operations. · BIOS ROM Phase: BIOS first carry out the P.O.S.T that performs and verifies all initial hardware checks. After this, the hardware' firmware will individually carry out its own diagnostic test such as S.M.A.R.T. The system will now attempt to determine the sequence of devices to load based on the settings stored in the BIOS to start the operating system. It will start by reading from the first boot up device which usually is the Floppy disk. If the floppy drive does not contain a diskette, it bypasses the first boot up device and detects the second device, which is usually the hard disk. It'll then start by reading the boot code instructions located in the master boot record and copies all execution into the memory when the instructions are validated and no errors are found. · Boot Loader Phase Control is then passed on to the partition loader code which accesses the partition table to identify the primary partition, extended partitions and active partition which is needed to determine the file system and locate the operating system loader file which will call upon the boot.ini file which is located at the root directory to determine the location and entries of the operating system boot partition. At this point in time, the boot up menu is displayed on the screen to allow you to select an operating system to start. NTLDR will pass all information from the Windows registry and Boot.ini file into the next phase. · Operating System Configuration Phase Next step is to load the kernel, hardware abstraction layer and registry information. After this is completed, the control is passed over to the DOS based program which collects and configures all installed hardware devices such as the video adapters and communication ports. It searches for hardware profiles information and load the essential software drivers to control the hardware devices. · Security & Logon Phase Lastly, Ntoskrnl.exe will start up Winlogon.exe which triggers the Lsass.exe or Local Security Administration which is the logon dialog interface that prompts you to select your user profile and verifies your necessary credentials before you are transferred to the Windows desktop. Scheduling Strategies: · Windows has 6 process classes with 7 priorities within each class · Process Classes included: 1. Idle 2. ...

1. Modern Personal Computer
Boot up Process
The boot up process is necessary for Windows as the hardware
does not know where the Operating system is stored. There has
to be a simple yet powerful program which loads the kernel in
the main memory and executes it. This program in Windows is
known as the Bootstrap Loader.
The Windows boot up process comprises of the following
procedures:
· The Power-On Self-Test Phase:
Firstly a self-test is performed by the power supply to ensure
that the volume and current levels are correct before the Power
Good signal is sent to the processor. As soon as this stage is
cleared, the microprocessor triggers the BIOS to perform a
series of operations.
· BIOS ROM Phase:
BIOS first carry out the P.O.S.T that performs and verifies all
initial hardware checks. After this, the hardware' firmware will
individually carry out its own diagnostic test such as
S.M.A.R.T.
The system will now attempt to determine the sequence of
devices to load based on the settings stored in the BIOS to start
the operating system. It will start by reading from the first boot
up device which usually is the Floppy disk. If the floppy drive
does not contain a diskette, it bypasses the first boot up device
and detects the second device, which is usually the hard disk.
It'll then start by reading the boot code instructions located in
the master boot record and copies all execution into the memory
when the instructions are validated and no errors are found.
· Boot Loader Phase
Control is then passed on to the partition loader code which
accesses the partition table to identify the primary partition,
extended partitions and active partition which is needed to

2. determine the file system and locate the operating system loader
file which will call upon the boot.ini file which is located at the
root directory to determine the location and entries of the
operating system boot partition. At this point in time, the boot
up menu is displayed on the screen to allow you to select an
operating system to start.
NTLDR will pass all information from the Windows registry
and Boot.ini file into the next phase.
· Operating System Configuration Phase
Next step is to load the kernel, hardware abstraction layer and
registry information.
After this is completed, the control is passed over to the DOS
based program which collects and configures all installed
hardware devices such as the video adapters and communication
ports.
It searches for hardware profiles information and load the
essential software drivers to control the hardware devices.
· Security & Logon Phase
Lastly, Ntoskrnl.exe will start up Winlogon.exe which triggers
the Lsass.exe or Local Security Administration which is the
logon dialog interface that prompts you to select your user
profile and verifies your necessary credentials before you are
transferred to the Windows desktop.
Scheduling Strategies:
· Windows has 6 process classes with 7 priorities within each
class
· Process Classes included:
1. Idle
2. Below Normal
3. Normal
4. Above Normal
5. High
6. Real time
· Below - High:
· Within a class, processes time-share relative to priority

3. · Lower classes are not run unless higher classes are not
runnable (or there are other idle CPUs)
Idle - only runs if no other process is runnable
Real-time - always run when runnable, will not be interrupted
until the process makes a system call or goes to sleep.
(Process/Thread Scheduling)
Windows uses a round-robin technique with a multi-level
feedback queue for priority scheduling ever since NT, Though
in Vista there were some smart heuristic improvements to
ensure that some processes, such as the disk defragmenter, are
at a lower priority in order to not interfere with foreground
processes.
There are many ways a user can override the inbuilt policies in
windows.
Windows Firewall is a very good example of overriding the
built in security features against internet threats.
Simplicity vs. ease of use
When applied correctly, simplicity results in ease of use. When
users can perform a task successfully on their own without
difficulty or confusion within a suitable amount of time then
they are really happy and that is when we call it “Ease of Use”.
Simplicity is just a method to achieve user satisfaction and ease
of use.
Simplicity is a very effective way to incorporate” ease of use”
factor in your project. Complex, hard-to-use features never
works. By contrast, simple, elegant designs that perform their
function well are a joy to use.
The wireless networking support in Microsoft Windows XP
could have added a wizard to walk users through the
configuration process. This approach would have resulted in
ease of use but not simplicity, because an unessential feature
(the wizard) would have been added. Instead, Microsoft
designed wireless networking to configure itself automatically.
Users ultimately don't care about the configuration details, so
long as it "just works" reliably and securely. This combination

4. of power and simplicity in wireless networking technology has
led to its popularity and rapid adoption.
In developing Windows, Microsoft listened closely to customer
feedback. The company strengthened fundamentals around
performance, reliability, and security.
Microsoft also made it easy to use, with improved navigation,
better wireless networking, and easier access to media and
entertainment.
The operating system is very efficient and fast and uses all the
hardware resources up to its optimum levels.
References:
Process/Thread Scheduling. (n.d.). Retrieved from Operating
Systems Lecture: http://joekaylor.net/osdi-
lectures/scheduling.html