Question 1

Computer architecture basics — terminology clarification:  Which hardware device, in general terms, is capable of fetching, decoding, and executing a sequence of instructions issued by software?

Accepted Answer

Introduction / Context: In computer architecture, several closely related terms describe parts of the execution engine. Learners often mix up CPU, processor, ALU, and control unit. This question checks whether you can pick the most precise, general term for a hardware device that executes a sequence of instructions. Given Data / Assumptions: The device must be able to fetch, decode, and execute instructions. We are not limiting ourselves to a specific form factor (microprocessor, multi core SoC, or CPU package). Execution implies arithmetic, logic, control flow, and interaction with memory. Concept / Approach: The broadest correct label for any hardware entity that performs the instruction cycle (fetch, decode, execute, write back) is processor. The CPU (central processing unit) is a common subtype of processor. Internal subcomponents such as the ALU (arithmetic logic unit) and CU (control unit) participate but cannot execute full instruction sequences independently in general; they are functional blocks within a processor or CPU. Step-by-Step Solution: Identify the required capabilities: instruction execution end to end.Map capabilities to architectural entities: the processor encompasses fetch/decode/execute.Differentiate subcomponents (ALU, CU) that lack full standalone execution of programs.Select the most general, correct term: Processor. Verification / Alternative check: Architecture texts define a processor as the hardware that executes machine instructions. A CPU is a central processor in a traditional architecture; GPUs and NPUs are also processors because they execute instruction streams, reinforcing that “processor” is the most general fit. Why Other Options Are Wrong: CPU: often correct, but it is a specific class of processor; the question asks for the general term. ALU: performs arithmetic and logic, not full instruction sequencing. CU: coordinates operations but does not by itself execute full instruction sets. None of the above: incorrect because “Processor” fits perfectly. Common Pitfalls: Equating “CPU” with every processor; forgetting that modern systems include multiple specialized processors. Also, confusing subunits (ALU, CU) with the complete execution engine. Final Answer: Processor

Question 2

Software quality workflow — testing vs. debugging:  Which statement correctly distinguishes software testing from debugging in the development lifecycle?

Accepted Answer

Introduction / Context: Two core activities in software quality are testing and debugging. Although related, they serve different purposes. Testing aims to reveal defects; debugging aims to locate and fix their causes. The distinction is fundamental for planning, effort estimation, and tool selection. Given Data / Assumptions: Testing executes code or analyzes artifacts to find failures or nonconformance. Debugging involves diagnosis, isolation, and correction of the underlying faults. Syntax errors are typically caught by compilers or linters before runtime testing. Concept / Approach: Testing (unit, integration, system, acceptance) provides evidence of the presence of defects by observing failures or unmet requirements. Debugging is the engineering activity that follows a failing test: reproduce, instrument, reason about state, identify the faulty code, and apply a fix. They are complementary but not identical. Step-by-Step Solution: Determine which option separates discovery from correction.Recognize that option (a) states: testing finds logical errors; debugging corrects them.Reject the claim that testing is primarily for syntax errors; compilers do that earlier.Conclude that (a) is the accurate distinction. Verification / Alternative check: Industry standards (e.g., IEEE 829/ISO/IEC/IEEE 29119) define testing as evaluation of product quality and debugging as the process of finding and fixing the root cause of failures, aligning with option (a). Why Other Options Are Wrong: (b) Overemphasizes syntax errors; these are compile time issues, not the main focus of testing. (c) Equates testing and debugging; they are distinct phases. (d) “All of the above” cannot be true because (b) and (c) are incorrect. (e) Not applicable because (a) is correct. Common Pitfalls: Assuming tests guarantee absence of defects; tests can show the presence of bugs, not their absence. Confusing static analysis or compilation with dynamic testing. Final Answer: Testing checks for logical errors in the programs, while debugging is a process of correcting those errors in the program

Question 3

Computer organization — addressing modes:  In which addressing mode is the effective address computed by adding a constant displacement to the contents of a register?

Accepted Answer

Introduction / Context: Addressing modes define how the CPU interprets operands within instructions. Understanding each mode is essential for assembly programming, compiler back ends, and performance tuning because it affects how memory addresses are formed and accessed. Given Data / Assumptions: The CPU has registers that can participate in address calculation. A constant displacement (offset) is provided in the instruction encoding. The effective address must be the sum of a register value and a constant. Concept / Approach: Indexed addressing forms the effective address as: EA = R + displacement, where R is a base or index register, and displacement is a constant embedded in the instruction. This is widely used for array access and structure field addressing. Other modes (immediate, absolute, indirect) do not match this computation pattern. Step-by-Step Solution: Identify the calculation: EA must equal register contents plus a constant.Recall standard mode definitions: immediate uses literal data, absolute uses a fixed address, indirect dereferences a pointer from memory.Match the definition to indexed addressing.Select “index mode.” Verification / Alternative check: Instruction set manuals (x86 base+disp, ARM base+imm, RISC-V base+imm) all implement indexed/base-plus-displacement addressing for efficient array and stack access, confirming the choice. Why Other Options Are Wrong: Absolute mode: EA is a constant address, no register addition. Indirect mode: EA is obtained by reading an address from memory via a pointer. Immediate mode: operand is data, not an address. None of the above: not applicable since index mode fits exactly. Common Pitfalls: Confusing indexed with based or relative addressing; many architectures use interchangeable terms but the key property is EA = register + displacement supplied in the instruction. Final Answer: index mode

Question 4

Compiler technology — code generation across machines:  A compiler that runs on one machine but produces executable code for a different target architecture is called a:

Accepted Answer

Introduction / Context: Toolchains often build software for platforms other than the one on which the compiler itself runs—common in embedded systems, mobile development, and operating system ports. Recognizing the term for this capability is fundamental in systems programming. Given Data / Assumptions: The host machine executes the compiler binary. The generated code is intended for a different instruction set architecture (ISA) or ABI. Typical examples include building ARM code on an x86 workstation. Concept / Approach: A cross compiler produces target code for an architecture different from the host. It differs from an optimizing compiler (which focuses on performance transformations), a one pass or multipass compiler (which describe compilation strategy), and native compilers (host and target are the same). Step-by-Step Solution: Identify the host-target mismatch requirement.Match the requirement with the definition of cross compilation.Eliminate options describing unrelated compiler traits (optimization, pass count).Select “cross compiler.” Verification / Alternative check: Widely used toolchains (e.g., GCC, Clang) provide triplets like x86_64-linux-gnu (native) and aarch64-none-elf (cross), reinforcing the terminology. Why Other Options Are Wrong: Optimizing compiler: may be cross or native; concerns transformations. One pass / multipass: describe organization, not host vs. target relation. None of the above: incorrect because cross compiler is the established term. Common Pitfalls: Confusing cross assemblers or linkers with compilers; all can be cross tools, but the question specifically asks about the compiler. Final Answer: cross compiler

Question 5

Loaders and relocation — self-relocating program:  Which option best describes a self-relocating program during program loading and execution?

Accepted Answer

Introduction / Context: Relocation is the process of adjusting address dependent code and data so a program can execute correctly at a memory location different from where it was originally assembled or compiled. Some programs include logic to relocate themselves during load time. Given Data / Assumptions: Address-sensitive portions (such as absolute references) must be corrected if the load base changes. Self-relocation implies code inside the program performs adjustments. Relocation information may be provided by the compiler or assembler. Concept / Approach: A self-relocating program contains relocation routines and tables it uses to adjust its own addresses when loaded. This enables the loader to place the program at varying memory locations. By contrast, absolute programs (option a) cannot relocate. Option b describes a relocatable program generally, not necessarily self-relocating (the loader could do it). Step-by-Step Solution: Identify the property “self” — the program performs relocation itself.Match to the description where the program adjusts its address-sensitive sections.Exclude absolute-only execution and generic relocatable descriptions.Select the option stating the program itself performs relocation. Verification / Alternative check: Classic loaders and OS texts distinguish absolute, relocatable, and self-relocating programs; the latter includes code to walk relocation entries and patch addresses post-load. Why Other Options Are Wrong: (a) Describes an absolute program — the opposite of relocatable. (b) Could describe a relocatable module handled by an external loader, not necessarily self-relocating. (d) Cannot be true because (a) contradicts the definition. (e) Not applicable because (c) is correct. Common Pitfalls: Confusing “relocatable” with “self-relocating.” Many relocations are performed by linkers/loaders; “self” indicates in-program logic. Final Answer: can itself performs the relocation of its address-sensitive portions.

Question 6

Operating systems — compatibility across versions:  Higher versions of an operating system are often designed so that programs built for earlier versions still run without changes. What is this property commonly called in legacy terminology?

Accepted Answer

Introduction / Context: When platforms evolve, preserving the ability to run older applications is critical for users and enterprises. Terminology varies across eras and vendors, but the concept is widely recognized in operating systems, databases, and compilers. Given Data / Assumptions: Newer OS version should run applications built for previous versions unmodified. The question uses legacy phrasing common in older exam banks and vendor literature. We are selecting the best fit among the given choices. Concept / Approach: Modern terminology typically calls this backward compatibility (new system runs old software). In older or vendor specific usage, the same idea was often labeled upward compatibility from the perspective of the application moving upward to a new system version. Among the provided options, “Upward compatibility” best matches the described behavior. Step-by-Step Solution: Interpret the requirement: old programs must run on newer versions.Map this to the compatibility term used in many classic texts and exam banks.Choose “Upward compatibility” as the best available option.Note: in contemporary usage the synonymous term is “backward compatibility.” Verification / Alternative check: Vendor release notes often promise “upward compatible” interfaces, meaning applications written for prior releases continue functioning on the upgrade, aligning with the prompt. Why Other Options Are Wrong: Upgradability: ability to upgrade a system, not compatibility of apps. Upward mobility: not a software term. Universality: too vague; does not denote version-to-version compatibility. None of the above: incorrect because a matching term is provided. Common Pitfalls: Mixing directions: “backward compatibility” vs. “forward compatibility.” Here, the new system supports old apps, which many older sources called “upward compatibility.” Final Answer: Upward compatibility

Question 7

Core responsibilities of an operating system:  Which resources and devices are managed and coordinated by a general-purpose operating system during normal operation?

Accepted Answer

Introduction / Context: An operating system (OS) is the mediator between applications and hardware. It schedules computation, manages storage, and exposes device services. Recognizing the breadth of OS responsibilities is foundational to systems study. Given Data / Assumptions: The OS is general purpose (desktop, server, or mobile class). It provides abstractions like processes, files, and device interfaces. It must ensure protection, fairness, and efficiency. Concept / Approach: An OS manages the processor (CPU scheduling, interrupts), memory (allocation, paging, protection), and I O devices (drivers, disks, networking). File systems, virtual memory, and device stacks are central components. Therefore, the correct answer is that the OS manages all of the listed items. Step-by-Step Solution: Consider CPU: the scheduler and dispatcher allocate CPU time among processes.Consider memory: the OS tracks pages/frames, handles allocation and protection.Consider I O: the OS provides device drivers, buffering, caching, and file systems.Therefore, all listed resources are managed. Verification / Alternative check: Standard OS textbooks and documentation enumerate CPU, memory, and device management as the three pillars of OS responsibilities, confirming the selection. Why Other Options Are Wrong: Any single item (Memory, Processor, or Disks and I O devices) is incomplete. None of the above is incompatible with the OS definition. Common Pitfalls: Overlooking modern extensions (security, power management) and confusing firmware responsibilities with OS responsibilities; nonetheless, the listed three remain core. Final Answer: All of the above

Question 8

Throughput and scheduling — multiprogramming effect:  Which statement best describes a typical advantage of multiprogramming systems compared to single-program systems?

Accepted Answer

Introduction / Context: Multiprogramming allows multiple jobs to reside in memory at once, so the CPU can switch to another job when one blocks for I O. This improves overall throughput and resource utilization compared to running a single job at a time. Given Data / Assumptions: Jobs may be CPU bound or I O bound. Context switching overhead exists but is outweighed by reduced idle time. We compare aggregate performance (throughput), not individual job runtime. Concept / Approach: By overlapping CPU time of one job with I O wait of another, multiprogramming decreases total idle time. This means more jobs complete within a fixed interval. Individual jobs may not finish faster, but the system completes more work overall, increasing throughput. Step-by-Step Solution: Define the goal: improve system utilization and throughput.Recognize that multiprogramming keeps the CPU busy while other jobs wait on I O.Conclude that more jobs finish per unit time.Select the option that states “execute more jobs in the same time period.” Verification / Alternative check: Queueing theory and empirical OS measurements show throughput improvements under multiprogramming, especially with mixed workloads. Why Other Options Are Wrong: Easier to develop: false; multiprogramming is more complex. Execute each job faster: often not true; context switching can slow individual jobs slightly. Only on mainframes: false; all modern systems use multiprogramming. None of the above: incorrect because one option is correct. Common Pitfalls: Confusing response time improvements for short jobs with universal speedups; throughput gains do not guarantee faster completion for every job. Final Answer: execute more jobs in the same time period

Question 9

Language portability — FORTRAN across platforms:  Which statement is NOT true about the FORTRAN programming language and its portability/use?

Accepted Answer

Introduction / Context: High level languages aim to deliver portability across hardware platforms. FORTRAN, one of the oldest high level languages, remains heavily used in scientific and engineering computing. The question probes your understanding of what portability means in practice. Given Data / Assumptions: FORTRAN is standardized (e.g., FORTRAN 77, Fortran 90, and later), enabling cross platform compilers. Platform differences may require minor changes (I O, libraries), but core language constructs are portable. IBM PC and Sun systems have different architectures and operating systems. Concept / Approach: Because FORTRAN is standardized, source code conforming to the standard is largely portable; it is not “totally different” across platforms. Therefore, the statement asserting total difference is not true. The correct choice is the false assertion. The other statements—FORTRAN is high level and widely used in scientific computing—are true. Step-by-Step Solution: Identify the false statement required by the prompt.Evaluate each option against language standards and practice.Confirm that portability exists; therefore “totally different” is wrong.Select option (b) as the NOT true statement. Verification / Alternative check: Real world scientific codes routinely compile across Linux, Windows, and UNIX variants with minimal conditional changes, confirming portability. Why Other Options Are Wrong: (a) True: FORTRAN is a high level language. (c) True: It is heavily used in numerical/scientific computing. (d) All of the above cannot be correct because (a) and (c) are true. (e) None of the above is wrong because one statement is indeed not true. Common Pitfalls: Confusing platform specific I O or compiler pragmas with the core language; such differences do not make programs “totally different.” Final Answer: A FORTRAN program, written for the IBM-PC, is totally different from a FORTRAN program written for execution on the SUN machine

Question 10

CPU datapath registers — identifying the Instruction Register (IR):  Which description correctly matches the role of the Instruction Register (IR) in a processor datapath?

Accepted Answer

Introduction / Context: The Instruction Register (IR) is a key element in the CPU's instruction cycle. It holds the machine instruction currently being decoded and executed. Distinguishing the IR from neighboring registers (PC, MAR, MDR) and functional units (ALU) is essential in computer organization. Given Data / Assumptions: Typical datapath registers include PC (program counter), IR (instruction register), MAR (memory address register), and MDR/MBR (memory data register or buffer). The ALU and control unit carry out operations and sequencing, respectively. Each option describes a specific hardware component's function. Concept / Approach: The IR's role: hold the current instruction's opcode and fields for decode/execute. Compare this to: PC (holds location of next/current instruction), MAR (holds memory addresses for access), MDR/MBR (holds data read from or to be written to memory), and ALU (executes arithmetic/logic). None of the given descriptions states “holds the current instruction,” so “None of the above” is correct. Step-by-Step Solution: Evaluate option (a): describes PC (location of instruction), not IR.Evaluate option (b): describes the ALU or execution hardware, not IR.Evaluate option (c): describes MAR, not IR.Evaluate option (d): describes MDR/MBR, not IR.Conclude that none matches IR's true purpose; select “None of the above.” Verification / Alternative check: Standard datapath diagrams show IR feeding the control unit's decoder and microcontrol logic, while PC, MAR, and MDR perform address fetch and data buffering, confirming our mapping. Why Other Options Are Wrong: (a) Program Counter (PC), not IR. (b) Execution hardware (ALU and control), not IR. (c) Memory Address Register (MAR). (d) Memory Data/Buffer Register (MDR/MBR). Common Pitfalls: Assuming “register that holds instruction location” equals IR; that is the PC's job. IR holds the instruction bits themselves, used for decoding. Final Answer: None of the above

Question 11

Operating systems — page replacement: Which page replacement policy removes a page if it is not in the currently favoured subset (working set) of a process's pages?

Accepted Answer

Introduction / Context: In virtual memory systems, the operating system must decide which page to evict when physical frames are full. Policies like FIFO, LRU, LFU, and working set differ in how they choose a victim page. This question tests understanding of working set–based replacement, which focuses on a process’s current locality of reference. Given Data / Assumptions: The process exhibits locality: a subset of pages is actively used at any time. The “favoured subset” refers to the process’s working set within a window of recent references. When a fault occurs and memory is full, one page must be evicted. Concept / Approach: The working set model tracks the set of pages referenced during the last tau references (or within a time window). Pages outside this set are considered inactive and are the preferred eviction candidates because they are unlikely to be needed soon, reducing the chance of immediate faults. Step-by-Step Solution: Define working set W(t) as pages referenced in the last window.On page fault with no free frames, identify pages not in W(t).Select a victim outside W(t); if all are in W(t), choose the one with weakest evidence of recent use.Thus, the policy evicts a page not in the favoured subset (the working set). Verification / Alternative check: Empirical results and textbook analyses show working set–aware policies reduce thrashing by aligning memory allocation with the process’s active footprint. Why Other Options Are Wrong: FIFO: Evicts the oldest loaded page, ignoring locality. LRU: Prefers the least recently used page, not explicitly the non-working set. LFU: Uses long-term frequency, which can lag phase changes. None of the above: Incorrect because working set matches the description. Common Pitfalls: Confusing LRU with working set; LRU approximates recent use but does not explicitly track a time-window set. Also, ignoring overhead of tracking the working set window is a common oversight. Final Answer: Working set

Question 12

Software engineering — modular design quality: Which of the following best measures how good or bad a module's design is?

Accepted Answer

Introduction / Context: Modular design aims to build software as a set of well-structured, maintainable modules. Two foundational quality measures are cohesion (often called module strength) and coupling (the degree of interdependence). This question asks which measures evaluate modular design quality. Given Data / Assumptions: Cohesion reflects how strongly responsibilities within a module relate to each other. Coupling reflects how much a module depends on other modules. Static analysis is a technique that can help compute or infer metrics, but it is not itself a design quality metric. Concept / Approach: High cohesion and low coupling are widely accepted goals. Measuring cohesion and coupling gives actionable insight: high cohesion suggests focused, understandable modules; low coupling reduces ripple effects of change and eases testing. Combining both yields a balanced picture of design quality. Step-by-Step Solution: Identify recognized metrics: cohesion and coupling.Determine their roles: cohesion internal focus; coupling external dependencies.Conclude that both together assess modular design quality most effectively. Verification / Alternative check: Textbook guidelines (e.g., structured design, object-oriented design) consistently emphasize maximizing cohesion and minimizing coupling as core design principles, validating the combined use of these measures. Why Other Options Are Wrong: Module strength only: Incomplete—ignores coupling effects. Module coupling only: Incomplete—ignores internal focus of cohesion. Static analysis only: A method, not a design quality metric. None of the above: Incorrect because the pair of metrics is correct. Common Pitfalls: Optimizing one metric at the expense of the other; for example, extremely high cohesion with hidden tight coupling through global state. Also, assuming cohesion can be perfectly quantified—often qualitative judgment is required. Final Answer: Both module strength and module coupling

Question 13

Memory management terminology: Information in memory that is no longer valid or no longer wanted is called what?

Accepted Answer

Introduction / Context: Languages with automatic or manual memory management often accumulate unreachable or obsolete data. Recognizing the correct term for such memory helps in understanding garbage collection and resource reclamation strategies. Given Data / Assumptions: Data becomes unreachable when no live references can access it. “No longer wanted” implies the program will not use the data again. Focus is on terminology used in memory management. Concept / Approach: Unreachable or unused memory is called garbage. Garbage collectors traverse the object graph to find reachable objects and reclaim memory from everything else. In manual memory management, developers must free such memory explicitly to avoid leaks. Step-by-Step Solution: Identify the state: data invalid/unwanted.Map to term: unreachable or unreferenced memory.Select the canonical term: garbage. Verification / Alternative check: Standard textbooks and language specifications (Java, .NET, Lisp) define “garbage” as memory eligible for collection because it is not reachable by any thread of control. Why Other Options Are Wrong: Non-volatile/volatile: Electrical persistence properties of memory, not validity of contents. Surplus: Not a standard term in memory management. None of the above: Incorrect because “garbage” is correct. Common Pitfalls: Confusing “invalid” with “dangling pointers,” where memory is freed but references remain; that is the opposite and leads to unsafe access. Garbage implies no references remain. Final Answer: garbage

Question 14

Structured programming principle: Which construct is forbidden by the principles of structured programming?

Accepted Answer

Introduction / Context: Structured programming advocates building programs from a small set of well-defined control structures to improve readability, maintainability, and correctness. Understanding which constructs fit this paradigm is essential. Given Data / Assumptions: Structured constructs include sequence, selection, and iteration. GOTO introduces arbitrary jumps that can create “spaghetti code”. We assume standard imperative languages as context. Concept / Approach: Structured programming replaces unrestrained jumps with structured loops and conditionals. WHILE–DO, DO–WHILE, and IF–THEN–ELSE fit within these constructs. GOTO undermines structure by enabling non-local, unstructured control flow. Step-by-Step Solution: List structured constructs: sequence, IF–THEN–ELSE, WHILE/DO loops.Identify outlier: GOTO provides unconditional jump without block structure.Select GOTO as forbidden by structured programming principles. Verification / Alternative check: Programming methodology literature encourages eliminating GOTO in favor of structured alternatives, allowing easier reasoning and formal verification. Why Other Options Are Wrong: WHILE–DO, DO–WHILE: Structured loops; encouraged. IF–THEN–ELSE: Core selection construct; encouraged. None of the above: Incorrect because GOTO is indeed discouraged/forbidden by the principle. Common Pitfalls: Believing GOTO is never used; in rare low-level scenarios or generated code it appears, but structured design avoids it in source-level logic. Final Answer: GOTO

Question 15

PC file extensions — backups: Which filename extension commonly indicates a backup copy of another file?

Accepted Answer

Introduction / Context: Legacy DOS/Windows conventions use three-letter extensions to signal file types or purposes. Recognizing common extensions helps identify files quickly during troubleshooting and maintenance. Given Data / Assumptions: Many programs create backup copies automatically when saving changes. Conventional backup extension is “.BAK”. Other extensions like .TXT, .COM, .BAS have distinct meanings. Concept / Approach: Users often see pairs like CONFIG.SYS and CONFIG.BAK. The .BAK file holds a prior version, enabling recovery if the new file is faulty. This convention persists across utilities and editors. Step-by-Step Solution: Recall common extensions and their meanings.Match “backup copy” to .BAK.Confirm others: .TXT (text), .COM (command binary), .BAS (BASIC source). Verification / Alternative check: Numerous editors and installers save previous configuration as *.BAK, confirming the convention. Why Other Options Are Wrong: .TXT: Plain text file. .COM: Executable format under DOS. .BAS: BASIC program source. None of the above: Incorrect because .BAK is correct. Common Pitfalls: Assuming all backup files use .BAK; some tools use .OLD or timestamped names, but .BAK remains the most recognized generic backup extension. Final Answer: BAK

Question 16

Programming terminology: A sequence of instructions written in a computer language to achieve a desired result is called what?

Accepted Answer

Introduction / Context: Terms like algorithm and program are related but distinct. Clarity about their definitions helps in software design and documentation. The wording “in a computer language” is the crucial qualifier here. Given Data / Assumptions: “Sequence of instructions” implies stepwise operations. “In a computer language” indicates actual code written for execution. Goal is producing a specific result. Concept / Approach: An algorithm is a language-agnostic procedure or recipe. Once expressed in a programming language so that a computer can execute it, it becomes a program. Decision tables are tabular representations for logic, not necessarily executable code by themselves. Step-by-Step Solution: Interpret the qualifier “in a computer language”.Map to the executable artifact: a program.Exclude algorithm (not necessarily coded) and decision table (a design aid). Verification / Alternative check: Software engineering texts treat algorithms as the abstract logic and programs as their concrete implementations in code. Why Other Options Are Wrong: Algorithm: Abstract method, not necessarily written in code. Decision table: Specification tool, not a code sequence. All of the above: Overbroad; only “program” matches the precise phrasing. None of the above: Incorrect since program fits. Common Pitfalls: Equating “algorithm” with any set of coded instructions; the term is broader and independent of implementation language. Final Answer: Program

Question 17

Assemblers and macros: An instruction in a programming language that is replaced by a sequence of instructions before assembly or compilation is called what?

Accepted Answer

Introduction / Context: Macro facilities allow programmers to define templates that expand into multiple instructions or declarations, improving readability and reducing repetition. Macro processing happens before actual assembly or compilation. Given Data / Assumptions: There exists a pre-assembly/compilation expansion step. The original single directive expands into several low-level instructions. We are distinguishing macros from procedures and other symbols. Concept / Approach: A macro is a named pattern with parameters that the preprocessor or assembler expands inline. Unlike procedures (which are called at runtime), macros generate code at compile time, in place, avoiding call overhead but increasing code size. Step-by-Step Solution: Identify pre-assembly/compile-time expansion behavior.Match to macro definition (textual or syntactic expansion).Exclude runtime constructs (procedures) and non-expanding symbols (labels, literals). Verification / Alternative check: Assembler directives like MACRO/ENDM and C/C++ preprocessor macros (#define) exemplify compile-time expansion into instruction sequences. Why Other Options Are Wrong: Procedure name: Invoked at runtime, not expanded inline by default. Label: A position marker for control flow or data, no expansion. Literal: A constant value embedded in code, no expansion. None of the above: Incorrect because macro is correct. Common Pitfalls: Confusing macros with inline functions; both eliminate call overhead, but macros are textual expansions and lack type checking in many languages. Final Answer: macro

Question 18

Basic definitions: Which statement correctly defines a program?

Accepted Answer

Introduction / Context: Computing terminology distinguishes between hardware (devices), software (programs), and system characteristics (interactive processing). This question focuses on the precise definition of a program. Given Data / Assumptions: A program is software, not a device. Programs consist of instructions executed by a processor. Other options describe hardware or operating modes, not programs. Concept / Approach: The canonical definition is that a program is a finite sequence of instructions intended to perform a task. It may be stored on a device, but it is not the device itself. Interactivity describes processing style, not what a program is. Step-by-Step Solution: Eliminate hardware descriptions (device performing operations, device where information is stored).Eliminate processing mode description (interactive/time-sharing characteristics).Select “a sequence of instructions”. Verification / Alternative check: Introductory CS texts define a program exactly as a sequence of instructions in a programming language intended for execution by a computer. Why Other Options Are Wrong: Option A and B: Define hardware (processor, memory), not software. Option D: Describes time-sharing OS behavior, not a program. None of the above: Incorrect because option C is correct. Common Pitfalls: Equating “computer” with “program”; a program is an abstract artifact that runs on hardware but is not the hardware itself. Final Answer: is a sequence of instructions

Question 19

Deadlocks — classic algorithms: Banker's algorithm for resource allocation is used for which purpose?

Accepted Answer

Introduction / Context: Deadlocks occur when processes wait indefinitely for resources held by each other. Operating systems employ strategies such as prevention, avoidance, detection, and recovery. Banker’s algorithm is a canonical approach; understanding its category is fundamental in OS design. Given Data / Assumptions: Processes declare maximum resource needs. The system can simulate allocations to test for a safe state. A safe sequence exists if every process can finish given available and future releases. Concept / Approach: Banker’s algorithm is a deadlock avoidance technique. Before granting a request, the OS checks whether doing so keeps the system in a safe state. If not safe, the request is deferred. Unlike prevention, it does not structurally constrain resource usage; unlike recovery, it does not roll back after deadlock occurs. Step-by-Step Solution: Collect processes’ maximum claims.Simulate granting the current request.Run the safety check to see if a completion order exists.Grant only if the resulting state is safe, thereby avoiding deadlock. Verification / Alternative check: Algorithm descriptions explicitly categorize it under “avoidance” because it anticipates unsafe allocations and refuses them preemptively. Why Other Options Are Wrong: Prevention: Enforces rules (e.g., ordering resources) to make deadlock impossible; not Banker’s approach. Recovery: Involves detection and rollback/termination after deadlock. Mutual exclusion: A necessary condition for deadlock, not a resolution technique. None of the above: Incorrect because avoidance is correct. Common Pitfalls: Confusing “safe state” (avoidance) with “deadlock-free state” guaranteed by prevention. Also, assuming real systems always know maximum needs; often they do not, limiting practical use. Final Answer: deadlock avoidance

Question 20

Operating systems — purpose: What is the primary purpose of an operating system?

Accepted Answer

Introduction / Context: An operating system (OS) is the core system software that mediates between applications and hardware. While usability is a benefit, the foundational role is resource management to achieve efficiency, fairness, and protection. Given Data / Assumptions: The OS manages CPU, memory, storage, and I/O devices. It schedules processes, allocates memory, and orchestrates device access. The question asks for the primary purpose, emphasizing core responsibility. Concept / Approach: The OS optimizes and arbitrates hardware usage to meet objectives such as throughput, response time, and reliability. It provides abstractions (files, processes, sockets) so applications can run efficiently without handling hardware details. Usability is improved as a consequence of these abstractions, but the fundamental mission is efficient hardware utilization and control. Step-by-Step Solution: Identify OS responsibilities: scheduling, memory management, I/O, storage.Recognize that these functions aim to use hardware resources effectively.Select the option highlighting efficient hardware use as the primary purpose. Verification / Alternative check: Standard OS texts define an OS as a resource manager and control program, prioritizing efficiency and protection. User convenience is a key design goal but flows from these responsibilities. Why Other Options Are Wrong: Make computer easier to use: True but secondary to resource management. Keep system programmers employed: Facetious and incorrect. Allow people to sue the computers: Typographical humor, not relevant. None of the above: Incorrect since efficient hardware use is correct. Common Pitfalls: Equating “primary purpose” with user-facing features only; the OS serves both users and applications by efficiently managing scarce resources. Final Answer: make the most efficient use of the hardware

Operating Systems Concepts Questions