1. What are the reasons for process termination?
☛ Normal completion
☛ Time limit exceeded
☛ Memory unavailable
☛ Bounds violation
☛ Protection error
☛ Arithmetic error
☛ Time overrun
☛ I/O failure
☛ Invalid instruction
☛ Privileged instruction
☛ Data misuse
☛ Operator or OS intervention
☛ Parent termination.
2. List the sub-components of I/O manager in Windows NT?
☛ Network re-director/ Server
☛ Cache manager.
☛ File systems
☛ Network driver
☛ Device driver
3. Tell me What is executive in Windows NT?
In Windows NT, executive refers to the operating system code that runs in kernel mode.
DDks are device driver kits, which are equivalent to SDKs for writing device drivers. Windows NT includes DDks.
5. On what level of security does Windows NT meets?
C2 level security.
6. Tell me What are the rings in Windows NT?
Windows NT uses protection mechanism called rings provides by the process to implement separation between the user mode and kernel mode.
It does not have the features like:
☛ Ability to support multiple processors
☛ Virtual storage
☛ Source level debugging
8. List the possible threads a thread can have?
☛ Ready
☛ Standby
☛ Running
☛ Waiting
☛ Transition
☛ Terminated
9. Explain FtDisk in Operating System (OS)?
It is a fault tolerance disk driver for Windows NT.
The special thread a dispatcher will execute when no ready thread is found.
11. Explain mutant in Operating System (OS)?
In Windows NT a mutant provides kernel mode or user mode mutual exclusion with the notion of ownership.
12. Explain migration process?
It is the transfer of sufficient amount of the state of process from one machine to the target machine.
13. Explain the reasons for process suspension?
☛ Swapping
☛ Interactive user request
☛ Timing
☛ Parent process request
When the OS at the explicit request of another process creates a process, this action is called process spawning.
15. Tell me is Windows NT a full blown object oriented operating system? Give reasons?
No Windows NT is not so, because its not implemented in object oriented language and the data structures reside within one executive component and are not represented as objects and it does not support object oriented capabilities.
16. Explain the key object oriented concepts used by Windows NT?
Encapsulation, Object class and instance.
To achieve maximum efficiency and reliability a mode of operation known as symmetric multiprocessing is used. In essence, with SMP any process or threads can be assigned to any processor.
18. What are the four layers that windows NT have in order to achieve independence?
☛ Hardware abstraction layer
☛ Kernel
☛ Subsystems
☛ System Services.
19. Tell me what has triggered the need for multitasking in PCs?
☛ Increased speed and memory capacity of microprocessors together with the support fir virtual memory
☛ Growth of client server computing
20. Explain page cannibalizing?
Page swapping or page replacements are called page cannibalizing.
21. Can you please explain the difference between demand-paging and pre-paging?
With demand paging, a page is brought into memory only when a location on that page is actually referenced during execution. With pre-paging, pages other than the one demanded by a page fault are brought in. The selection of such pages is done based on common access patterns, especially for secondary memory devices.
For load-time dynamic linking: Load module to be loaded is read into memory. Any reference to a target external module causes that module to be loaded and the references are updated to a relative address from the start base address of the application module.
With run-time dynamic loading: Some of the linking is postponed until actual reference during execution. Then the correct module is loaded and linked.
23. What are placement and replacement algorithms In the context of memory management?
Placement algorithms determine where in available real-memory to load a program. Common methods are first-fit, next-fit, best-fit. Replacement algorithms are used when memory is full, and one process (or part of a process) needs to be swapped out to accommodate a new program. The replacement algorithm determines which are the partitions to be swapped out.
If a process in a monitor signal and no task is waiting on the condition variable, the signal is lost. So this allows easier program design. Whereas in semaphores, every operation affects the value of the semaphore, so the wait and signal operations should be perfectly balanced in the program.
It is a technique proposed by Lam-port, used to order events in a distributed system without the use of clocks. This scheme is intended to order events consisting of the transmission of messages. Each system 'i' in the network maintains a counter Ci. Every time a system transmits a message, it increments its counter by 1 and attaches the time-stamp Ti to the message. When a message is received, the receiving system 'j' sets its counter Cj to 1 more than the maximum of its current value and the incoming time-stamp Ti. At each site, the ordering of messages is determined by the following rules: For messages x from site i and y from site j, x precedes y if one of the following conditions holds....(a) if Ti<Tj or (b) if Ti=Tj and i<j.
26. What is the Buddy system of memory allocation in Operating System (OS)?
Free memory is maintained in linked lists, each of equal sized blocks. Any such block is of size 2^k. When some memory is required by a process, the block size of next higher order is chosen, and broken into two. Note that the two such pieces differ in address only in their kth bit. Such pieces are called buddies. When any used block is freed, the OS checks to see if its buddy is also free. If so, it is rejoined, and put into the original free-block linked-list.
27. Explain latency, transfer and seek time with respect to disk I/O.?
Seek time is the time required to move the disk arm to the required track. Rotational delay or latency is the time it takes for the beginning of the required sector to reach the head. Sum of seek time (if any) and latency is the access time. Time taken to actually transfer a span of data is transfer time.
28. Explain about local and global page replacements?
Local replacement means that an incoming page is brought in only to the relevant process address space. Global replacement policy allows any page frame from any process to be replaced. The latter is applicable to variable partitions model only.
29. Can you please explain the difference between trap and trapdoor?
Trapdoor is a secret undocumented entry point into a program used to grant access without normal methods of access authentication. A trap is a software interrupt, usually the result of an error condition.
30. Tell me when does the condition 'rendezvous' arise?
In message passing, it is the condition in which, both, the sender and receiver are blocked until the message is delivered.
31. What is dynamic scheduling in Operating System (OS)?
The number of thread in a program can be altered during the course of execution.
32. What is dedicated processor assignment in Operating System (OS)?
Provides implicit scheduling defined by assignment of threads to processors. For the duration of program execution, each program is allocated a set of processors equal in number to the number of threads in the program. Processors are chosen from the available pool.
33. What is gang scheduling in Operating System (OS)?
A set of related threads is scheduled to run on a set of processors at the same time, on a 1-to-1 basis. Closely related threads / processes may be scheduled this way to reduce synchronization blocking, and minimize process switching. Group scheduling predated this strategy.
34. What is load Sharing in Operating System (OS)?
Processes are not assigned to a particular processor. A global queue of threads is maintained. Each processor, when idle, selects a thread from this queue. Note that load balancing refers to a scheme where work is allocated to processors on a more permanent basis.
35. Explain busy waiting in Operating System (OS)?
The repeated execution of a loop of code while waiting for an event to occur is called busy-waiting. The CPU is not engaged in any real productive activity during this period, and the process does not progress toward completion.