Computer Science Previous Year Questions (page 31)

Explanation

1715 ÷ 12 = 142 remainder 11 (B); 142 ÷ 12 = 11 remainder 10 (A); 11 = B. Reading the remainders upward gives (BAB)₁₂. Check: 11×144 + 10×12 + 11 = 1715.

Explanation

Software evolution covers changes in software architecture (structure and design of systems over time) as well as in programming languages and paradigms used to build them, so both are aspects of evolution.

Explanation

An operating system manages processes (creation, scheduling), memory (allocation, paging) and security/protection of resources, so all three are OS functions.

Explanation

Indices i, i+1, ..., j contain j − i + 1 elements. For example, indices 0 to 9 give 10 elements.

Explanation

Binary search keeps narrowing Beg..End; when Beg passes End (End < Beg) the search range is empty, so the element is not present.

Explanation

A C identifier may contain letters, digits and underscores, and may begin with a letter or an underscore (but not a digit). Both statements are true.

Explanation

A wide-character literal is written with the prefix L, for example L'a', and has type wchar_t.

Explanation

Average cases: binary search O(log n) < linear search O(n) < quick sort O(n log n) < selection sort O(n²).

Explanation

In C the result of % takes the sign of the dividend: 7 % −3 = 1 and −7 % 3 = −1. The two printf calls print 1 and −1.

Explanation

The preprocessor stage replaces #include lines with the file contents and expands macros; the key also counts handling of escape sequences in this preprocessing step, so all three are taken as correct.

Explanation

Scanning left to right: M N O + * gives M*(N+O); then P / gives (M*(N+O))/P; Q R S T / + * gives Q*(R+S/T); the final − joins them: ((M*(N+O))/P) − (Q*(R+(S/T))).

Explanation

71 is the root; 56 and 48 go left; 96 goes right; 76 becomes the left child of 96; 82 goes right of 76 (level 4); 98 is the right child of 96. So 82 is at the deepest level.

Explanation

I: 4×343 + 0×49 + 5×7 + 2 = 1372 + 35 + 2 = 1409. II: 1715 = 11×144 + 10×12 + 11 = (BAB)₁₂. Both are correct.

Explanation

ANSI X12 is the standard for electronic data interchange (EDI) of business documents. X.75 links packet networks, and XON is a flow-control character.

Explanation

EBCDIC is the Extended Binary Coded Decimal Interchange Code, an 8-bit character code used on IBM mainframes.

Explanation

E = 69 = 1000101, X = 88 = 1011000, A = 65 = 1000001, M = 77 = 1001101. Joining the four 7-bit codes gives 1000101 1011000 1000001 1001101, which is option B.

Explanation

A compiler translates the whole source program into object (machine) code. A linker combines object files, and a loader places the program in memory.

Explanation

Complementary subtraction does subtraction by adding the complement (1's, 2's, 9's or 10's) of the subtrahend, so subtraction becomes addition.

Explanation

In series the resistances add: 3 + 3 + 3 = 9 ohm. The keyed value is this equivalent resistance.

Explanation

The output is 1 only when both inputs are 1, which is the AND function.

Explanation

E(E + F) = E, and E absorbs DE. D(E + F) = DE + DF, and DE is again absorbed by E. What remains is E + DF.

Explanation

A half subtractor computes A − B: difference = A ⊕ B and borrow = A'B, since a borrow is needed only when A = 0 and B = 1.

Explanation

A monostable multivibrator has one stable state and one quasi-stable state: a trigger moves it to the quasi-stable state for a fixed time, after which it returns.

Explanation

A demultiplexer with m select lines routes the input to one of 2^m outputs, so n = 2^m (e.g. 1-to-8 DEMUX has 3 select lines).

Explanation

B ⊕ B = 0, because XOR gives 1 only when its inputs differ, and here both inputs are always equal.

Explanation

ISAM is Indexed Sequential Access Method: records are stored sequentially by key and an index allows direct access.

Explanation

Note from the source book: a primary index on a sequentially ordered file is in fact a sparse index (option d), but the official key (as per the Board) is (b) Clustering index.

Explanation

A deductive database model derives new facts from stored facts using rules (logical inference), so it is also called the inference model.

Explanation

The data catalog (data dictionary) is a system database holding metadata, i.e. the description of tables, columns, constraints and other database objects.

Explanation

A 2NF relation must be in 1NF (I is correct). Statement II says non-key attributes are "independent" of the primary key, but 2NF requires them to be fully functionally dependent on it, so II is wrong.

Explanation

By De Morgan's law the complement of a sum of products is a product of sums with each literal complemented: (AB)' = A' + B', (C'D)' = C + D', (B'D)' = B + D'. So F' = (A' + B')(C + D')(B + D').

Explanation

With columns CD = 00, 01, 11, 10: row AB=00 holds m0, m1, m3, m2 → 1 1 _ 1; row 01 holds m4, m5, m7, m6 → only m6; row 11 is empty; row 10 holds m8, m9, m11, m10 → 1 1 _ 1. This matches option A.

Explanation

A flip-flop is a bistable circuit with two stable states, so it stores exactly one bit (0 or 1).

Explanation

In Chrome on Windows, Ctrl + Shift + I (or F12) opens Developer Tools.

Explanation

The journal records transactions in date order (book of original entry, chronological), while the ledger classifies them account-wise (analytical record). Both statements are correct.

Explanation

Depreciation can be charged by the straight line method (fixed amount each year) or the written down value method (fixed rate on the reducing balance). Both are standard methods.

Explanation

Equivalence partitioning divides input data into valid and invalid classes and tests one value from each, using only the specification, so it is a black box technique.

Explanation

A DFD is also called a bubble chart because processes are drawn as circles (bubbles).

Explanation

In the spiral model (Boehm), software is developed in a series of evolutionary or incremental releases, one per loop of the spiral, with risk analysis in each cycle.

Explanation

CASE stands for Computer Aided Software Engineering: software tools that support analysis, design, coding and testing.

Explanation

Boehm's definitions: verification asks "Are we building the product right?" (conforms to specification) and validation asks "Are we building the right product?" (meets user needs).

Explanation

A feasibility study checks whether a project is worth doing, including financial (economic) feasibility and technical feasibility, along with operational and schedule aspects.

Explanation

McCabe's cyclomatic complexity for a connected control flow graph is V(G) = E − N + 2 (or number of decisions + 1).

Explanation

An applet is a small Java program embedded in an HTML page and run by a Java-enabled browser.

Explanation

After break the control leaves the switch, and no case label precedes a4 = 10000;, so that statement can never be reached. a1, a2 and a3 run for cases 1 and 2 (case 1 falls through).

Explanation

Spooling (Simultaneous Peripheral Operations On-Line) stores output on disk and sends it to the slow printer later, so the CPU need not wait for the printer.

Explanation

Disabling (masking) an interrupt means setting a mask bit so the CPU ignores that interrupt until it is unmasked.

Explanation

Faults for 4, 7, 6 (3). Page 1: evict 4 (never used again), fault 4. 7, 6, 1 hit. Page 2: evict 6 or 1 (never used again), fault 5. 7 and 2 hit. Total 5 page faults.

Explanation

The kernel is the core of the OS that stays resident in main memory and directly manages CPU, memory and devices.

Explanation

Privileged instructions (I/O, changing the timer, disabling interrupts, etc.) can run only in kernel mode; attempting them in user mode causes a trap.