1. What is the value of requiring the OS to provide status information? 2. What is the difference between a true layered structure and the way that MS-DOS used layering? 3. Why is an operating system thought to be a \"mandatory middleman\"? § be able to explain the services and value of this 4. What is a virtual machine and why is it necessary? § How does it work (i.e., be able to discuss and/or draw a VM structure in a computer system) 5. Why is debugging a concern for an OS? § How can it be accomplished? 6. Why is a bootstrap loader needed? Solution Ans 1. In context switching among process before a process switched we have to store PCB(Process control Block) by the Operating System.It consists of Process State,Program Counter,Values of Registers,CPU Sheduling Information,Memeory Management Information,Accounting Information and IO Status Information. Value of Status Information is such as How much devices are allocated /occupied,Open File Tables information etc. Ans.2 In MS-DOS Application Program -> Resident system Program->MS-DOS Device Drivers- >ROM-BIOS Device Drivers This architecture is applied. There is no well-structured architecture is defined. There is no CPU Execution Mode (Kernel and User) So if there is error whole system is crashed. In case of Layered approach it follows modular approach. OS is broken into the layer Bottom Layer which is hardware and Top Layer is User. Its main advantage is simplicity of construction and debugging. If error is found at any layer it remains same on that layer system does not crash. Ans 3. Operating system work as a middleman between a user and computer hardware.Its main objective to make system convenient to use and utilitze computer hardware in efficient manner.Variuos types of OS are there such as-INIX,MS-DOS,Windows-98/XP/Vista,Windows- NT/2000,OS/2 and Mac OS. It provides its service to user as well as Programs too: To Program it provide environment to exceute . To user provide platform to execute the program. These are following services provided by OS:- 6.) Error Detection- Ans 4: Virtual Machine- It is based on computer architecture, it is an emulation of a computer system.It also provides the functionality of physical computer Too. It is of following type like:- Advantage Of Virtual Machine:- Architecture:- Guest Operating System and Application | Virtual Machine | Virtual Server 2005 | Windows Server 2003(Host OS) | Physical Computer Ans.5 Debugging is a concern for an OS.As it made up of multi layered architecture so it is easier to find at which layer error is prone .There is two mode for debugging User Mode and Kernal Mode.Kernal mode debugging is very hard. Because we can not rely on crashing machine to communicate that what happened. There are four methods of debugging an operating system:- Sanity Checks Debugger Deterministic Reply Moving Everything to User Space Ans 6.)Bootstrap Loader:- It is a program that is required to loads an operating system after completion on power-on .

1. 1. What is the value of requiring the OS to provide status information?
2. What is the difference between a true layered structure and the way that MS-DOS
used layering?
3. Why is an operating system thought to be a "mandatory middleman"?
§ be able to explain the services and value of this
4. What is a virtual machine and why is it necessary?
§ How does it work (i.e., be able to discuss and/or draw a VM structure in a
computer system)
5. Why is debugging a concern for an OS?
§ How can it be accomplished?
6. Why is a bootstrap loader needed?
Solution
Ans 1. In context switching among process before a process switched we have to store
PCB(Process control Block) by the Operating System.It consists of Process State,Program
Counter,Values of Registers,CPU Sheduling Information,Memeory Management
Information,Accounting Information and IO Status Information.
Value of Status Information is such as How much devices are allocated /occupied,Open File
Tables information etc.
Ans.2
In MS-DOS
Application Program -> Resident system Program->MS-DOS Device Drivers-
>ROM-BIOS Device Drivers
This architecture is applied. There is no well-structured architecture is defined. There is no
CPU Execution Mode (Kernel and User) So if there is error whole system is crashed.
In case of Layered approach it follows modular approach. OS is broken into the layer Bottom
Layer which is hardware and Top Layer is User. Its main advantage is simplicity of construction
and debugging. If error is found at any layer it remains same on that layer system does not crash.
Ans 3.
Operating system work as a middleman between a user and computer hardware.Its main
objective to make system convenient to use and utilitze computer hardware in efficient
manner.Variuos types of OS are there such as-INIX,MS-DOS,Windows-98/XP/Vista,Windows-

2. NT/2000,OS/2 and Mac OS.
It provides its service to user as well as Programs too:
To Program it provide environment to exceute .
To user provide platform to execute the program.
These are following services provided by OS:-
6.) Error Detection-
Ans 4:
Virtual Machine- It is based on computer architecture, it is an emulation of a computer system.It
also provides the functionality of physical computer Too.
It is of following type like:-
Advantage Of Virtual Machine:-
Architecture:-
Guest Operating System and Application
|
Virtual Machine
|
Virtual Server 2005
|
Windows Server 2003(Host OS)
|
Physical Computer
Ans.5
Debugging is a concern for an OS.As it made up of multi layered architecture so it is easier to
find at which layer error is prone .There is two mode for debugging User Mode and Kernal
Mode.Kernal mode debugging is very hard. Because we can not rely on crashing machine to
communicate that what happened.
There are four methods of debugging an operating system:-
Sanity Checks
Debugger
Deterministic Reply
Moving Everything to User Space
Ans 6.)Bootstrap Loader:- It is a program that is required to loads an operating system after
completion on power-on self tests. It is a loader that complete the self test and after completion
load the software and run also. It is loaded into the main memory from the EPROM. It executes
automatically whenever the computer is turning on. It reads the Hard drives boot sector to

3. continue the process of loading the computer ‘s OS. Bootstrap Meaning is –“Pull yourself up by
your bootstrap”. It is stored into the Master boot record(MBR) on computer’s hard drive.When
we restart the computer, it starts its tasks it perform power on self test called as POST.If POST is
successful no issue found then bootstrap load OS from computer to memory .