Important interview questions on OS (Operating Systems)

OS Concepts
o What do the system calls fork(), vfork(), exec(), wait(), waitpid() do?
Whats a Zombie process? Whats the difference between fork() and
vfork()?
o How does freopen() work? *
o What are threads? What is a lightweight process? What is a heavyweight
process? How different is a thread from a process? *
o How are signals handled? *
o What is a deadlock? *
o What are semaphores? *
o What is meant by context switching in an OS?*
o What is Belady's anomaly?
o What is thrashing?*
o What are short-, long- and medium-term scheduling?
o What are turnaround time and response time?
o What is the Translation Lookaside Buffer (TLB)?
o What is cycle stealing?
o What is a reentrant program?
o When is a system in safe state?
o What is busy waiting?
o What is pages replacement? What are local and global page
replacements?*
o What is meant by latency, transfer and seek time with respect to disk I/O?
o What are monitors? How are they different from semaphores?*
o In the context of memory management, what are placement and
replacement algorithms?
o What is paging? What are demand- and pre-paging?*
o What is mounting?
o What do you mean by dispatch latency?
o What is multi-processing? What is multi-tasking? What is multithreading?
What is multi-programming?*
o What is compaction?
o What is memory-mapped I/O? How is it different frim I/O mapped I/O?
o List out some reasons for process termination.

Hard Disk Drive (HDD) not working on windows 7 after formatting it on Ubuntu ?

I formatted my Western Digital 500 Gb hard disk on Ubuntu 10.4 and now I want to use it on Windows 7 but it cannot detect it. I formatted it with FAT(applicable to all) option. I tried to Google this problem a bit and as suggested by one of the site i tried to format this drive with NTFS. Still windows cannot detect it. Drives in windows 7 is not a problem because I tried a different usb drive on it and it works. I can see the led of the drive glow when I connect it and I can also see remove drive safely option in lower right corner, but i cannot see any option in "my computer" to access the hard disk. Solution: I tried to format my HDD using "diskpart" utility available on widows7. It is working now. Just run "diskpart" on command-promt on diskpart select your HDD and run following commands: CLEAN CREATE PARTITION PRIMARY SELECT PARTITION 1 ACTIVE FORMAT FS=FAT32 QUICK ASSIGN EXIT