Landing a job in computer engineering or related fields often hinges on how well you understand the fundamentals. Mastering computer organisation and architecture viva questions is crucial for demonstrating your expertise during interviews. This guide will equip you with the knowledge and confidence to ace your viva by covering the most frequently asked computer organisation and architecture viva questions. Preparing thoroughly for these computer organisation and architecture viva questions can significantly improve your chances of success.
What are computer organisation and architecture viva questions?
Computer organisation and architecture viva questions are interview questions designed to assess a candidate's understanding of how computers are built, how they function, and how software interacts with hardware. These questions cover a wide range of topics, including instruction set architecture, memory management, pipelining, and cache design. The purpose of these computer organisation and architecture viva questions is to determine if a candidate possesses the core knowledge required to design, analyze, and optimize computer systems. A deep understanding of computer organisation and architecture viva questions is vital for anyone aspiring to work in hardware engineering, embedded systems, or performance optimization.
Why do interviewers ask computer organisation and architecture viva questions?
Interviewers ask computer organisation and architecture viva questions to evaluate a candidate's foundational knowledge and problem-solving abilities. These questions help assess whether the candidate can apply theoretical concepts to practical scenarios. They also reveal the candidate’s ability to think critically about system performance and efficiency. Interviewers look for a clear understanding of the trade-offs involved in different design choices. Furthermore, responses to computer organisation and architecture viva questions can indicate a candidate's ability to learn and adapt to new technologies in the ever-evolving field of computer engineering. Preparing comprehensive answers to computer organisation and architecture viva questions is a strategic step to impress your interviewer.
Here's a preview of the 30 computer organisation and architecture viva questions we'll cover:
What is Computer Architecture?
What is Computer Organization?
What are the three categories of Computer Architecture?
What is the difference between RISC and CISC Architectures?
What are the components of a Microprocessor?
Define Pipelining in Computer Architecture.
What is Cache Memory?
What is Virtual Memory?
What are Interrupts in Microprocessors?
What are Flip-Flops?
What is a DMA (Direct Memory Access)?
What are the different types of Micro-operations?
Explain the MESI Protocol.
What is a Snooping Protocol?
What is the Write-Through and Write-Back Caching?
What is an Instruction Cycle?
What are the fields in an instruction?
What is associativity in Cache?
What are different types of hazards in pipelining?
What is RAID?
What is a Wait State?
What is the DLX Pipeline?
What is Horizontal Microcode?
What are the priority hardware methods?
What is the difference between an Interrupt Service Routine (ISR) and a Subroutine?
What is Addressing Mode?
What is a Bus in Computer Architecture?
What are the types of buses?
Explain the Von Neumann Architecture.
Explain Harvard Architecture.
Now, let's dive into each question with detailed explanations and example answers.
## 1. What is Computer Architecture?
Why you might get asked this: Interviewers ask this to gauge your foundational understanding of the subject. It sets the stage for deeper technical discussions. Assessing knowledge of computer organisation and architecture viva questions begins with this core concept.
How to answer: Define computer architecture as the blueprint of a computer system. Highlight its role in specifying the system's structure, functionality, and implementation. Mention key aspects like instruction sets, memory organization, and I/O systems.
Example answer: "Computer architecture is essentially the conceptual design and fundamental operational structure of a computer system. It outlines what the system does, how it's organized, and how it’s implemented. For instance, when designing a new processor, architects define the instruction set, memory addressing modes, and overall system structure. It’s the first step in bringing a computer system to life, guiding the subsequent design and implementation phases. Showing knowledge about the architectural foundation during these computer organisation and architecture viva questions can set the stage for the rest of the interview."
## 2. What is Computer Organization?
Why you might get asked this: This question differentiates your understanding of architecture versus implementation. It demonstrates your ability to distinguish between abstract design and concrete realization. Being able to discuss computer organisation and architecture viva questions shows you have a robust understanding of computer systems.
How to answer: Explain that computer organization deals with the physical components of a computer system and how they interconnect to implement the architectural specifications. Emphasize hardware details and their interactions.
Example answer: "Computer organization focuses on how the different hardware components of a computer system – like the CPU, memory, and I/O devices – are interconnected and work together to realize the architecture. It’s about the physical implementation details. For example, the choice of specific memory controllers or bus architectures falls under computer organization. It answers how the system works according to the architectural what. Understanding the organisation is vital to answer computer organisation and architecture viva questions. In a project, I had to choose between different bus architectures based on their speed and cost, which was directly related to computer organization principles."
## 3. What are the three categories of Computer Architecture?
Why you might get asked this: This tests your knowledge of the different layers of abstraction in computer architecture. Understanding these categories is essential for designing and analyzing computer systems. This concept is often tested with computer organisation and architecture viva questions.
How to answer: List the three categories: Instruction Set Architecture (ISA), Microarchitecture (or Organization), and System Design. Briefly describe what each category encompasses.
Example answer: "The three main categories of computer architecture are Instruction Set Architecture (ISA), Microarchitecture, and System Design. ISA defines the instructions the processor can execute. Microarchitecture deals with how the ISA is implemented in hardware, including pipelining and caching. System Design covers the overall organization of the system, including memory and I/O subsystems. I remember in my senior design project, we had to make decisions at all three levels to optimize for both performance and power consumption. When answering computer organisation and architecture viva questions, it is important to recall how these concepts are used in real-world applications."
## 4. What is the difference between RISC and CISC Architectures?
Why you might get asked this: This is a classic comparison question that assesses your understanding of different design philosophies in processor architecture. Being able to articulate the tradeoffs between RISC and CISC is key. This contrast is an integral part of computer organisation and architecture viva questions.
How to answer: Explain the core differences: RISC uses a smaller set of simpler instructions executed quickly, while CISC uses a larger set of complex instructions, some requiring multiple clock cycles. Discuss the advantages and disadvantages of each approach.
Example answer: "RISC, or Reduced Instruction Set Computing, uses a small, highly optimized set of instructions that can typically be executed in a single clock cycle. CISC, or Complex Instruction Set Computing, has a much larger instruction set, with some instructions being more complex and taking multiple cycles. RISC aims for simplicity and speed, while CISC aims for versatility. For example, x86 processors are CISC, while ARM processors are RISC. In a project, I chose a RISC processor for its energy efficiency, which was crucial for a mobile application. Understanding the differences is key to solving computer organisation and architecture viva questions. It is an important consideration when designing a system to optimize efficiency."
## 5. What are the components of a Microprocessor?
Why you might get asked this: This question validates your knowledge of the fundamental building blocks of a processor. Knowing these components is essential for understanding how a CPU operates. This is a basic, but important part of computer organisation and architecture viva questions.
How to answer: List and describe key components: Arithmetic Logic Unit (ALU), Control Unit (CU), Registers, Cache memory, System buses, and Interrupt controllers. Explain the function of each.
Example answer: "A microprocessor comprises several key components. The Arithmetic Logic Unit (ALU) performs arithmetic and logical operations. The Control Unit (CU) manages the execution of instructions. Registers are small, fast storage locations used to hold data and addresses. Cache memory is a small, fast memory used to store frequently accessed data. System buses (data, address, control) facilitate communication between components. Interrupt controllers manage interrupt requests. For example, when I was working on optimizing code for an embedded system, understanding how the ALU and registers interacted was crucial. Answering computer organisation and architecture viva questions requires knowing the importance of each component and how they work together."
## 6. Define Pipelining in Computer Architecture.
Why you might get asked this: Pipelining is a core concept for improving processor performance. This question tests your understanding of how it works and its benefits. Pipelining is a central concept covered in computer organisation and architecture viva questions.
How to answer: Explain pipelining as a technique where multiple instruction phases are overlapped. Describe how it divides instruction execution into stages to increase throughput.
Example answer: "Pipelining is a technique used to improve the performance of a processor by overlapping the execution of multiple instructions. It works by dividing the instruction execution process into several stages, such as fetching, decoding, and executing. While one instruction is being executed, the next instruction can be decoded, and so on. This allows multiple instructions to be processed concurrently, increasing throughput. For example, imagine an assembly line in a factory; each station performs a specific task, and multiple products are being worked on simultaneously. Understanding how pipelining works allows you to answer common computer organisation and architecture viva questions correctly. I once used pipelining to significantly speed up a data processing task, reducing the overall execution time by nearly 40%."
## 7. What is Cache Memory?
Why you might get asked this: Cache memory is critical for performance. This question assesses your understanding of its role in reducing memory access time. Cache memory is a common concept in computer organisation and architecture viva questions.
How to answer: Define cache memory as a small, fast memory located close to the CPU, used to store frequently accessed data from main memory. Explain its purpose in reducing average memory access time.
Example answer: "Cache memory is a small, fast memory that sits between the CPU and main memory. Its purpose is to store frequently accessed data so the CPU can access it more quickly than it could from main memory. When the CPU needs data, it first checks the cache. If the data is there (a 'cache hit'), it's retrieved quickly. If not (a 'cache miss'), the data is fetched from main memory and also stored in the cache for future access. For instance, web browsers use cache memory to store frequently visited web pages, so they load faster on subsequent visits. The functionality of cache memory is key for answering computer organisation and architecture viva questions. This concept is vital for understanding how memory access impacts performance."
## 8. What is Virtual Memory?
Why you might get asked this: Virtual memory is an important concept in memory management. This question assesses your understanding of how it provides the illusion of larger memory. Virtual memory is often addressed in computer organisation and architecture viva questions.
How to answer: Define virtual memory as a memory management technique that uses disk storage to extend RAM, providing an illusion of a larger main memory. Explain how it allows programs to execute even if their complete data is not in physical memory.
Example answer: "Virtual memory is a memory management technique that allows a computer to run programs that require more memory than is physically available. It does this by using a portion of the hard drive as an extension of RAM. The operating system moves data between RAM and the hard drive as needed, giving the illusion of having more RAM than is actually installed. This enables programs to execute even if their complete data is not in physical memory. For example, modern operating systems use virtual memory extensively to allow users to run multiple large applications simultaneously. Understanding the benefits of virtual memory is essential for answering computer organisation and architecture viva questions. In a project, I used virtual memory to run simulations that required a very large amount of memory, which exceeded the physical RAM available."
## 9. What are Interrupts in Microprocessors?
Why you might get asked this: Interrupts are essential for handling asynchronous events. This question checks your understanding of how they work and why they are necessary. Interrupt handling is a key topic in computer organisation and architecture viva questions.
How to answer: Explain that interrupts are signals that temporarily halt the CPU’s current activities to service external or internal events. Describe how normal execution resumes after the interrupt is handled.
Example answer: "Interrupts are signals that cause the CPU to temporarily suspend its current execution to handle a higher-priority event. When an interrupt occurs, the CPU saves its current state, jumps to an interrupt handler routine, and executes that routine. Once the interrupt has been handled, the CPU restores its state and resumes its previous execution. For example, when you press a key on your keyboard, an interrupt is generated, causing the CPU to handle the keyboard input. Interrupts are essential for responding to real-time events and handling I/O operations efficiently. Knowing how interrupts are handled is essential to understanding computer organisation and architecture viva questions. I once used interrupts to implement a real-time data acquisition system, ensuring timely responses to incoming data."
## 10. What are Flip-Flops?
Why you might get asked this: This tests your knowledge of basic digital logic elements. Flip-flops are fundamental building blocks in sequential circuits. Basic electronics knowledge is necessary to answer computer organisation and architecture viva questions.
How to answer: Define flip-flops as basic storage elements in sequential circuits that store one bit of data and can change state based on clock signals.
Example answer: "Flip-flops are fundamental building blocks of sequential logic circuits. They are bistable devices, meaning they have two stable states, representing 0 or 1. A flip-flop can store one bit of data, and its state can be changed by applying appropriate signals to its inputs. Flip-flops are typically triggered by a clock signal, ensuring synchronized operation. For example, in a shift register, flip-flops are used to store and shift data bits. Understanding the role of flip-flops is important when responding to computer organisation and architecture viva questions. I remember using flip-flops extensively when designing a digital counter, where their ability to hold state was crucial."
## 11. What is a DMA (Direct Memory Access)?
Why you might get asked this: DMA is a key technique for efficient data transfer. This question assesses your understanding of how it works and its benefits. DMA is a common topic within computer organisation and architecture viva questions.
How to answer: Explain that DMA allows peripherals to directly read/write memory without CPU intervention, improving data transfer efficiency.
Example answer: "Direct Memory Access, or DMA, is a technique that allows peripherals to directly access system memory without involving the CPU. This is particularly useful for high-speed data transfers, such as those involving disk drives or network interfaces. Instead of the CPU handling each byte of data, the DMA controller takes over, freeing up the CPU to perform other tasks. For example, when transferring data from a hard drive to memory, the DMA controller handles the transfer, allowing the CPU to continue executing other instructions. DMA significantly improves system performance by reducing the load on the CPU. Understanding how DMA controllers work can aid in answering computer organisation and architecture viva questions. I used DMA to optimize data transfers in a high-performance storage system, which significantly improved the system's overall throughput."
## 12. What are the different types of Micro-operations?
Why you might get asked this: This tests your understanding of the basic operations performed at the microarchitectural level. It demonstrates your knowledge of how instructions are executed. Micro-operations are frequently discussed in computer organisation and architecture viva questions.
How to answer: List and describe the different types of micro-operations: arithmetic, logic, shift, and transfer operations on registers or memory.
Example answer: "Micro-operations are the basic, low-level operations performed within a CPU during the execution of an instruction. These operations can be broadly categorized into arithmetic, logic, shift, and transfer operations. Arithmetic micro-operations include addition, subtraction, and multiplication. Logic micro-operations include AND, OR, and NOT. Shift micro-operations involve shifting bits left or right. Transfer micro-operations move data between registers or between registers and memory. For example, adding the contents of two registers involves a sequence of micro-operations to fetch the data, perform the addition, and store the result. Understanding micro-operations provides insight into how instructions are executed at the hardware level. Understanding micro-operations is an advanced concept in computer organisation and architecture viva questions. I studied micro-operations to understand the exact sequence of steps a CPU takes to execute code."
## 13. Explain the MESI Protocol.
Why you might get asked this: MESI is a crucial cache coherency protocol in multiprocessor systems. This question assesses your understanding of maintaining consistency across caches. Cache coherency protocols like MESI are crucial topics in computer organisation and architecture viva questions.
How to answer: Explain MESI as a cache coherency protocol with four states: Modified, Exclusive, Shared, and Invalid. Describe how it maintains consistency in multiprocessor cache systems.
Example answer: "MESI is a widely used cache coherency protocol in multiprocessor systems. It ensures that all processors have a consistent view of memory by defining four states for each cache line: Modified, Exclusive, Shared, and Invalid. Modified means the cache line is dirty (has been modified) and is only present in this cache. Exclusive means the cache line is clean and is only present in this cache. Shared means the cache line is clean and may be present in other caches. Invalid means the cache line is not valid and must be fetched from memory or another cache. The MESI protocol uses a snooping mechanism to monitor bus transactions and update cache states accordingly. For example, if one processor modifies a cache line, other processors invalidate their copies to maintain consistency. This protocol is fundamental to the correct operation of shared-memory multiprocessor systems. A complex topic such as this is expected knowledge to answer computer organisation and architecture viva questions. During an internship, I worked on optimizing a parallel application and had to deeply understand the MESI protocol to minimize cache invalidations and improve performance."
## 14. What is a Snooping Protocol?
Why you might get asked this: Snooping protocols are fundamental for cache coherence in shared-memory systems. This question tests your understanding of how they work. Snooping protocols are important for answering computer organisation and architecture viva questions.
How to answer: Explain that snooping protocols are used in cache coherence to monitor (or snoop) the data traffic on a shared bus to maintain consistency among caches.
Example answer: "A snooping protocol is a mechanism used in shared-memory multiprocessor systems to maintain cache coherence. Each cache monitors, or 'snoops,' the shared bus for memory transactions. When a cache sees a transaction that affects a cache line it holds, it takes action to maintain consistency. For example, if one cache writes to a cache line, other caches that hold a copy of that line will invalidate their copies. There are different types of snooping protocols, such as write-invalidate and write-update protocols. Snooping protocols are essential for ensuring that all processors have a consistent view of memory in a shared-memory system. I designed a small snooping cache in a research lab, which helped me to better understand how these protocols work and what some of the tradeoffs are. When discussing multi-processor systems with the interviewer in computer organisation and architecture viva questions, knowing the underlying protocols is important."
## 15. What is the Write-Through and Write-Back Caching?
Why you might get asked this: These are two fundamental cache write policies. This question checks your understanding of the trade-offs between them. Caching techniques like write-through and write-back are often discussed in computer organisation and architecture viva questions.
How to answer: Explain Write-Through as writing data to both cache and main memory simultaneously. Explain Write-Back as writing data only to cache and updating main memory later. Discuss the pros and cons of each.
Example answer: "Write-through and write-back are two common cache write policies. In write-through caching, every write operation updates both the cache and main memory simultaneously. This ensures that main memory always has the most up-to-date data, but it can be slower due to the need to write to main memory on every write. In write-back caching, data is only written to the cache. Main memory is only updated when the cache line is evicted. This is faster, but it introduces the risk of data loss if the cache fails before the data is written to main memory. The choice between write-through and write-back depends on the specific requirements of the system. Write-through is simpler to implement and provides better data consistency, while write-back offers better performance. It is essential to know write policies to answer computer organisation and architecture viva questions. I once worked on a system where we chose write-back caching for its performance benefits, but we had to implement robust error-recovery mechanisms to mitigate the risk of data loss."
## 16. What is an Instruction Cycle?
Why you might get asked this: This is a fundamental concept in computer architecture. This question assesses your understanding of how instructions are processed. This is a basic concept for computer organisation and architecture viva questions.
How to answer: Explain that the instruction cycle includes fetching the instruction, decoding it, executing it, and storing the result if necessary.
Example answer: "The instruction cycle is the sequence of steps that a CPU performs to execute an instruction. It typically consists of four stages: Fetch, Decode, Execute, and Store. During the fetch stage, the instruction is retrieved from memory. During the decode stage, the instruction is decoded to determine the operation to be performed and the operands to be used. During the execute stage, the operation is performed. During the store stage, the result is written back to memory or a register. The instruction cycle is the fundamental process by which a CPU executes programs. Understanding the instruction cycle is very important for improving performance in computer organisation and architecture viva questions. I studied the instruction cycle in detail to understand how pipelining can improve CPU performance by overlapping the execution of multiple instructions."
## 17. What are the fields in an instruction?
Why you might get asked this: Understanding instruction formats is crucial for understanding how programs are executed. This question tests your knowledge of the different parts of an instruction. Instruction format is also a topic in computer organisation and architecture viva questions.
How to answer: Explain that instruction fields typically include the opcode (operation code), source operand(s), destination operand, and sometimes addressing mode.
Example answer: "An instruction typically consists of several fields. The most important field is the opcode, which specifies the operation to be performed (e.g., add, subtract, load). The instruction also includes fields that specify the source operands, which are the data values used as input to the operation. The destination operand specifies where the result of the operation should be stored. Some instructions also include an addressing mode field, which specifies how the operands should be accessed (e.g., direct addressing, indirect addressing). For example, an add instruction might have an opcode for addition, two source operand fields specifying the registers to be added, and a destination operand field specifying the register where the result should be stored. Knowing the arrangement of the instructions helps when discussing computer organisation and architecture viva questions. Understanding instruction formats is crucial for understanding how programs are executed at the machine level."
## 18. What is associativity in Cache?
Why you might get asked this: Associativity is a key parameter in cache design that affects performance. This question tests your understanding of different cache mapping schemes. Cache properties are important to understand for computer organisation and architecture viva questions.
How to answer: Explain that associativity defines how cache blocks are mapped to cache lines. Describe the different types: direct-mapped, fully associative, and set-associative.
Example answer: "Associativity in cache memory refers to the number of cache lines that a given memory block can map to. In a direct-mapped cache, each memory block can only map to one specific cache line. In a fully associative cache, a memory block can map to any cache line. Set-associative caches are a compromise between these two extremes, where the cache is divided into sets, and each memory block can map to any line within a specific set. For example, a 2-way set-associative cache means that each memory block can map to one of two cache lines within its set. Higher associativity reduces the likelihood of cache collisions but increases the complexity and cost of the cache. I simulated the performance of different cache associativity configurations and found that set-associative caches generally provide a good balance between performance and cost. Knowing about associativity is essential for answering computer organisation and architecture viva questions. Therefore, understanding associativity is crucial for optimizing cache performance."
## 19. What are different types of hazards in pipelining?
Why you might get asked this: Hazards can limit the performance of pipelined processors. This question tests your understanding of these limitations and how to mitigate them. Pipeline hazards are a common topic in computer organisation and architecture viva questions.
How to answer: List and describe the different types of hazards: Structural Hazards, Data Hazards, and Control Hazards (branch hazards).
Example answer: "In pipelining, hazards are situations that prevent the next instruction in the instruction stream from executing during its designated clock cycle. There are three main types of hazards: structural hazards, data hazards, and control hazards. Structural hazards occur when multiple instructions need to use the same hardware resource at the same time. Data hazards occur when an instruction depends on the result of a previous instruction that is still in the pipeline. Control hazards, also known as branch hazards, occur when the pipeline needs to make a decision about which instruction to execute next, based on the outcome of a branch instruction. For example, a data hazard occurs when an instruction tries to read a register that is being written to by a previous instruction that is still in the execute stage. Hazard mitigation is key to improving performance and a key talking point in computer organisation and architecture viva questions. These hazards can be mitigated using techniques such as forwarding, stalling, and branch prediction."
## 20. What is RAID?
Why you might get asked this: RAID is an important storage technology for improving reliability and performance. This question assesses your understanding of different RAID levels and their trade-offs. RAID configurations are an important storage concept used in computer organisation and architecture viva questions.
How to answer: Explain that RAID (Redundant Array of Independent Disks) is a data storage technology that combines multiple physical disks into a single logical unit for redundancy or performance improvement.
Example answer: "RAID, or Redundant Array of Independent Disks, is a storage technology that combines multiple physical disk drives into a single logical unit. RAID is used to improve performance, provide redundancy, or both. There are several different RAID levels, each with its own characteristics. For example, RAID 0 stripes data across multiple disks, improving performance but providing no redundancy. RAID 1 mirrors data across two disks, providing redundancy but reducing storage capacity. RAID 5 stripes data and parity information across multiple disks, providing both performance and redundancy. The choice of RAID level depends on the specific requirements of the application. I set up a RAID 5 array for a small business server, which provided a good balance of performance and data protection. Talking about storage systems and performance improvements shows good understanding when answering computer organisation and architecture viva questions. Therefore, understanding RAID is essential for designing reliable and high-performance storage systems."
## 21. What is a Wait State?
Why you might get asked this: Wait states are important for interfacing with slower memory or I/O devices. This question tests your understanding of how processors synchronize with slower components. Understanding synchronization is important for answering computer organisation and architecture viva questions.
How to answer: Explain that a wait state is an extra clock cycle inserted into a processor's operation to allow slower memory or I/O devices time to complete their operations.
Example answer: "A wait state is an extra clock cycle inserted into a processor's timing to accommodate slower memory or I/O devices. When the processor attempts to access a slow device, the device may not be ready to transfer data immediately. In this case, the device asserts a 'wait' signal, which causes the processor to insert one or more wait states into its timing. During a wait state, the processor essentially does nothing, giving the slow device time to complete its operation. For example, when accessing slow external memory, a processor may need to insert several wait states to allow the memory to respond. The number of wait states required depends on the relative speeds of the processor and the device. I analyzed the performance of an embedded system and found that excessive wait states were significantly slowing down the system. Reducing wait states improves performance and an important element in computer organisation and architecture viva questions that you should know."
## 22. What is the DLX Pipeline?
Why you might get asked this: The DLX pipeline is a classic example of a RISC pipeline. This question tests your knowledge of pipeline stages in a simplified processor. Having knowledge of different architectures is important when answering computer organisation and architecture viva questions.
How to answer: Explain that the DLX pipeline has five stages: Instruction Fetch, Instruction Decode, Execute, Memory Access, and Write Back.
Example answer: "The DLX pipeline is a classic example of a RISC pipeline, often used in computer architecture textbooks. It consists of five stages: Instruction Fetch (IF), Instruction Decode (ID), Execute (EX), Memory Access (MEM), and Write Back (WB). In the Instruction Fetch stage, the instruction is fetched from memory. In the Instruction Decode stage, the instruction is decoded, and registers are read. In the Execute stage, the ALU performs the operation. In the Memory Access stage, data is read from or written to memory. In the Write Back stage, the result is written back to a register. The DLX pipeline is a simplified model, but it illustrates the basic principles of pipelining and is useful for understanding pipeline hazards and solutions. Therefore, learning about pipelines such as the DLX, helps with computer organisation and architecture viva questions. I used the DLX pipeline to simulate the performance of different pipelining techniques."
## 23. What is Horizontal Microcode?
Why you might get asked this: This question tests your knowledge of microcode, which is a low-level form of instruction. Understanding microcode can help in understanding how complex instructions are implemented. Microcode is used when discussing control unit implementation in computer organisation and architecture viva questions.
How to answer: Explain that horizontal microcode allows multiple micro-operations to be executed simultaneously by encoding them in wide control words.
Example answer: "Horizontal microcode is a microcode format in which each bit in the microinstruction directly controls a specific hardware resource. This allows multiple micro-operations to be executed simultaneously during a single clock cycle. Horizontal microcode results in wide microinstructions, but it provides a high degree of parallelism and flexibility. For example, a horizontal microinstruction might simultaneously control the ALU operation, register selection, and memory access. Horizontal microcode is often used in high-performance processors where parallelism is crucial. Although more complex to design, it allows for greater control over the hardware, improving efficiency. It’s less common now due to the complexity of managing the wide control words and is a slightly more advanced concept when answering computer organisation and architecture viva questions. I learned about horizontal microcode when studying the implementation of complex instructions in early microprocessors."
## 24. What are the priority hardware methods?
Why you might get asked this: Priority schemes are important for handling multiple interrupt requests. This question tests your knowledge of different hardware-based priority mechanisms. Interrupt handling concepts are frequently used in computer organisation and architecture viva questions.
How to answer: Name two methods: Daisy Chaining and Parallel Priority Encoding, used to decide interrupt servicing order.
Example answer: "When multiple devices request an interrupt simultaneously, a priority scheme is needed to determine which interrupt should be serviced first. Two common hardware methods for implementing priority are daisy chaining and parallel priority encoding. In daisy chaining, the interrupt request signal is passed from device to device in a chain. The device closest to the CPU has the highest priority. In parallel priority encoding, each device has a unique priority level, and a priority encoder selects the highest-priority request. For example, in a system with multiple I/O devices, the device with the most critical real-time requirement might be assigned the highest priority. Parallel priority encoding is faster but requires more hardware than daisy chaining. Understanding the hardware implementation of priority schemes is helpful for addressing computer organisation and architecture viva questions. I once designed an interrupt controller using parallel priority encoding to ensure timely handling of critical events."
## 25. What is the difference between an Interrupt Service Routine (ISR) and a Subroutine?
Why you might get asked this: This question checks your understanding of how interrupts are handled versus normal function calls. It demonstrates your knowledge of asynchronous versus synchronous execution. ISR is a basic part of the curriculum and understanding the concept helps to answer computer organisation and architecture viva questions.
How to answer: Explain that an ISR is a special function that handles interrupts; it is invoked asynchronously and must save and restore the processor state. A subroutine is a normal function called synchronously within a program.
Example answer: "An Interrupt Service Routine (ISR) and a subroutine are both blocks of code that perform specific tasks, but they are invoked in different ways and serve different purposes. An ISR is a special function that is executed in response to an interrupt signal. Interrupts are asynchronous events that can occur at any time, regardless of what the processor is currently doing. When an interrupt occurs, the processor suspends its current execution, saves its state, and jumps to the ISR. The ISR handles the interrupt and then restores the processor's state and resumes the interrupted execution. A subroutine, on the other hand, is a normal function that is called synchronously from within a program. The program explicitly calls the subroutine, and execution transfers to the subroutine until it completes and returns to the calling program. Knowing these differences is important for answering computer organisation and architecture viva questions. Therefore, understanding the differences is important for proper system design."
## 26. What is Addressing Mode?
Why you might get asked this: Addressing modes determine how operands are accessed. This question tests your understanding of different ways to specify memory locations. Addressing modes can change the instruction and that is important to consider when answering computer organisation and architecture viva questions.
How to answer: Explain that addressing mode specifies how the operand of an instruction is chosen; examples include immediate, direct, indirect, and indexed addressing.
Example answer: "Addressing mode specifies how the operand of an instruction is located. Different addressing modes provide different ways to access memory or registers. Common addressing modes include immediate, direct, indirect, and indexed addressing. In immediate addressing, the operand is a constant value included in the instruction itself. In direct addressing, the operand is the address of the memory location where the data is stored. In indirect addressing, the instruction specifies a register that contains the address of the memory location where the data is stored. In indexed addressing, the instruction specifies a base register and an offset, and the operand is located at the address calculated by adding the base register and the offset. The choice of addressing mode affects the flexibility and efficiency of the instruction. When optimizing embedded code the correct addressing mode is essential for efficient use of resources and for answering computer organisation and architecture viva questions to a high level."
## 27. What is a Bus in Computer Architecture?
Why you might get asked this: Buses are fundamental communication pathways in a computer system. This question tests your understanding of their role in connecting different components. Knowing the importance of the BUS is essential for understanding computer organisation and architecture viva questions.
How to answer: Explain that a bus is a communication pathway that transfers data between computer components, typically consisting of data, address, and control lines.
Example answer: "A bus in computer architecture is a communication pathway that transfers data between different components of a computer system. It typically consists of a set of parallel wires that carry data, address, and control signals. The data lines carry the actual data being transferred. The address lines specify the memory location or I/O device being accessed. The control lines coordinate the transfer of data and indicate the type of operation being performed. Buses can be internal to the CPU or external, connecting the CPU to memory and I/O devices. For example, the system bus connects the CPU to main memory and peripherals. The choice of bus architecture affects the performance and scalability of the system. I worked on optimizing bus communication in an embedded system to improve overall system performance. The bus is an important resource and understanding it is important for computer organisation and architecture viva questions."
## 28. What are the types of buses?
Why you might get asked this: Expanding on the previous question, this checks your understanding of the different types of signals carried on a bus. Having knowledge of all the components helps to answer computer organisation and architecture viva questions.
How to answer: List the types of buses: Data bus, Address bus, and Control bus.
Example answer: "There are three main types of buses in a computer system: the data bus, the address bus, and the control bus. The data bus carries the actual data being transferred between components. The address bus specifies the memory location or I/O device being accessed. The control bus carries control signals that coordinate the transfer of data and indicate the type of
