ISRO CSE 2014 PYQ

A 16-bit file number permits $2^16$ = 65,536 distinct files. If each user’s access record stores two independent permission bits per file (one read bit and one write bit), the storage per user is 65,536$\times 2 = 131,072 bits = 16,384 bytes = 16 KiB$. Thus 16 KB is correct under the stated two-bit-per-file representation. If the system uses a different ACL encoding, the result could differ.

The function performs one recursive call with n-1 until it reaches $n=1$. Each call does constant work besides the recursive call, so the recurrence is T(n)=T(n-1)+O(1), with T(1)=O(1). Expanding gives O(n) total time and O(n) recursion-stack space.

For three processes with maximum resource demands 3, 4, and 5, a sufficient minimum total number of identical resources that guarantees no deadlock is $\Sigma (Max_i-1)+1$. This is (3-1)+(4-1)+(5-1)+1 = 2+3+4+1 = 10. With 10 resources, at least one process can obtain its maximum and finish; it then releases resources so the others can complete. This is the standard single-resource-type bound.

The spiral model is iterative and risk-driven. Each loop performs planning, risk analysis, engineering, and customer evaluation. It continues through successive refinements and releases; there is no fixed number of loops. The project lifecycle ends when the product is retired or the project is otherwise terminated, so “when the software product is retired” is the intended option.

A dirty bit (modified bit) records whether a page or cache block has been written to since it was brought into memory/cache. If the dirty bit is 1, the contents must be written back to the backing store before the frame/block is reused; if it is 0, no write-back is needed. It does not indicate a page fault or corruption.