give the exact definition of operating system is it necessary to load OS in every system to run any program if so, why?

MY system is showing "BOOT FAILURE:SYSTEM HALTED" after restarting the system please give me the solution for this problem thanking you...........

ITC Infotech,

what kind of operating(s)systems would be needed (and explain why) in an environment where there exist various cluster of networks which are all interconnected in different geographical areas with strong emphasis on online applicating process.

Can I install the Operating System in USB Poratable Drive in 250 or 120GB?

IBM,

Q1. What is an interrupt? How are multiple interrupts dealt with? Q2. Explain the difference between a MONOLITHIC KERNAL and a MICROKERNAL? Q3. List reasons why a Mode switch between threads may be cheaper than a Mode switch between processes. Q4. What is the difference among deadlock avoidance, detection and prevention? Q5. What items of information about a task might be useful in real time scheduling? Q6. Discuss some of the reasons for implementing process migration ? How is the process address space handled during process migration?

Assume that passwords are selected from four-character combinations of 26 alphabetic characters. Assume that an adversary is able to attempt passwords at a rate of one per second. a) Assuming no feedback to the adversary until each attempt has been completed, what is the expected time to discover the correct password?

FCI,

Assuming feedback to the adversary flugging an error as each incorrect character is entered, what is the expected time to discover the correct password?

Assuming one link of the Trojan horse copy-and-observe-later chain is broken. There are two other possible angles of attack by Alice: Alice logging on and attempting to read the string directly, and alice assigning a security level of sensitive to the back-pocket file. Does the reference monitor prevent these attacks?

The flushing policy is described in the subsection on process migration strategies: a) From the perspective of the source, which other strategy does flushing resembles? b) From the perspective of the target, which other strategy does flushing resemble?

Directories can be implemented either as "special files" that can only be accessed in limited ways, or as ordinary data files. What are the advantages and disadvantages of each approach?

Some operating system have a tree structured file system but limits the depth of the tree to some small number of levels. what effect does this limit have on users? How does this simplify file system (if it does)?

In the token-passing mutual exclusion algorithm, is the timestamping used to reset clocks and correct drifts, as in the distributed queue algorithms? if not, what is the function of the timestamping?

HCL,

how does virtual memory work?

iam free downloading the KK Dictionery to my system but that is not installed yet. can anybody tell be why this happen and what the system have to install the software.

DEFINE YOURSELF AT THE TIME OF INTERVIEW IN TELECOM SECTOR?

Airtel,