Top 30 Most Common coa viva question You Should Prepare For
Preparing for a coa viva question interview can feel daunting, but with the right preparation, you can significantly increase your chances of success. Mastering common coa viva question can boost your confidence, sharpen your understanding, and allow you to articulate your knowledge effectively. This guide provides you with 30 of the most frequently asked coa viva question, along with detailed strategies and example answers to help you excel.
What are coa viva question?
Coa viva question are interview questions specifically focused on Computer Organization and Architecture. They delve into the fundamental principles behind how computers are designed, how their components interact, and how instructions are executed. These questions cover topics such as CPU architecture, memory management, instruction sets, and input/output systems. Understanding coa viva question is crucial for roles requiring a deep understanding of computer hardware and its underlying principles.
Why do interviewers ask coa viva question?
Interviewers ask coa viva question to assess a candidate's foundational knowledge of computer systems. They want to evaluate your understanding of how hardware and software interact, your problem-solving abilities in the context of system design, and your practical experience in applying these concepts. By posing coa viva question, they can gauge your ability to analyze complex systems, optimize performance, and troubleshoot issues related to computer architecture. They're looking to determine if you possess the core competencies needed for roles involving system architecture, embedded systems, or performance optimization.
List Preview: Top 30 coa viva question
Here's a preview of the 30 coa viva question we'll cover:
What is Computer Organization and Architecture?
Explain the Instruction Cycle.
What are Flip-Flops?
Explain a Common Bus System for Four Registers.
What is Memory Transfer?
Explain Bus Transfer.
What is a Micro-Operation?
Explain Three-State Bus Buffer.
List Memory Reference Instructions.
Explain Instruction Format.
Explain AND and BSA Instructions.
What is the MESI Protocol?
Explain Different Hazards in Pipelining.
What is Pipelining?
Explain Cache Memory.
What is Snooping Protocol?
Explain Types of Interrupts.
Explain Virtual Memory.
What is Assembly Language?
Explain RAID Systems.
What are the Main Components of a Microprocessor?
Explain DMA (Direct Memory Access).
What is Horizontal Microcode?
Explain Direct Mapping.
Explain Associative Mapping.
What is a Wait State?
Explain Non-Restoring Division.
What are the Types of Micro-Operations?
Explain Stack Organization of CPU.
Explain RISC and CISC Architectures.
## 1. What is Computer Organization and Architecture?
Why you might get asked this:
This question is a foundational coa viva question. Interviewers use it to assess your basic understanding of the field and your ability to differentiate between the two concepts. It helps them understand the scope of your knowledge in computer systems.
How to answer:
Clearly define both Computer Organization and Computer Architecture. Explain that Computer Organization deals with the physical components and their interconnections, focusing on how things work. Computer Architecture focuses on the conceptual structure and functional behavior as seen by the programmer. Give examples of each.
Example answer:
"Computer Organization refers to the physical and structural aspects of a computer system, like the signals, interfaces, and memory technology. It's how the different components are interconnected and contribute to realizing the architectural specifications. Computer Architecture, on the other hand, deals with the high-level design, focusing on what the system should do, including instruction sets, addressing modes, and memory management strategies. For instance, the choice of a particular cache memory system is an organizational issue, while the design of the cache coherence protocol is an architectural one. Showing that I understand the distinction between what something does and how it does it helps demonstrate my understanding of coa viva question."
## 2. Explain the Instruction Cycle.
Why you might get asked this:
The instruction cycle is fundamental to CPU operation. This coa viva question checks your understanding of how a CPU executes instructions, a crucial concept in computer architecture.
How to answer:
Explain the four basic stages: Fetch, Decode, Execute, and Store. Describe what happens in each stage and how they contribute to the overall instruction execution process.
Example answer:
"The instruction cycle, also known as the fetch-decode-execute cycle, is the basic operational process of a CPU. First, during the Fetch stage, the CPU retrieves the instruction from memory. Next, in the Decode stage, the instruction is interpreted to determine what operation needs to be performed. Then, the Execute stage carries out the operation. Finally, the Store stage writes the results back to memory or registers. For example, if we're adding two numbers, the fetch stage gets the addition instruction, the decode stage identifies the operands and the operation, the execute stage performs the addition, and the store stage saves the sum back to a register. Understanding this cycle is essential for anyone working with coa viva question as it forms the base of computer operations."
## 3. What are Flip-Flops?
Why you might get asked this:
Flip-flops are fundamental building blocks in digital logic. This coa viva question evaluates your understanding of basic digital components and their role in memory and sequential logic circuits.
How to answer:
Define flip-flops as basic storage elements that can hold a single bit of data. Explain that they are bistable circuits with two stable states. Mention different types like SR, D, JK, and T flip-flops.
Example answer:
"Flip-flops are fundamental digital storage elements. Each flip-flop can store one bit of information, and they're the building blocks for registers and memory units. They operate as bistable circuits, meaning they have two stable states representing 0 and 1. Different types, like SR, D, JK, and T flip-flops, have different triggering mechanisms and functionalities. For example, a D flip-flop simply copies its input to its output on the rising or falling edge of a clock signal. Being able to explain these basic components is foundational to tackling more complex coa viva question."
## 4. Explain a Common Bus System for Four Registers.
Why you might get asked this:
This question tests your understanding of how data is transferred between different components within a computer system, specifically using a bus system. This is a common aspect of coa viva question.
How to answer:
Describe a bus system as a set of shared wires used for data transfer. Explain how multiplexers or tri-state buffers can be used to select which register sends data onto the bus. Show how control signals manage the data flow.
Example answer:
"A common bus system allows multiple registers to share a single pathway for data transfer. Imagine four registers, each connected to the bus via tri-state buffers. Only one set of tri-state buffers is enabled at any given time, allowing only one register to write data onto the bus. For example, if we want to transfer data from register A to register C, we enable the tri-state buffers for register A to place its data onto the bus, and simultaneously enable the loading mechanism for register C to receive that data from the bus. Control signals ensure that only the correct register's buffers are enabled, preventing data collisions. Understanding how the bus system works is key to the discussion of coa viva question."
## 5. What is Memory Transfer?
Why you might get asked this:
Memory transfer is a core operation in computer systems. This coa viva question checks your understanding of how data moves between different memory locations or between memory and other components.
How to answer:
Define memory transfer as the process of moving data from one memory location to another or between memory and registers. Explain the basic operations involved, such as reading from a source location and writing to a destination location.
Example answer:
"Memory transfer is simply the process of moving data between different memory locations or between memory and CPU registers. It involves reading data from a source address in memory and then writing that data to a destination address. For example, a common scenario is moving data from a variable stored in RAM to a register in the CPU for processing. The CPU initiates the read operation with the address of the variable. The data is then placed on the data bus, and the CPU loads it into the register. Being fluent in how the data is moved between components is crucial in coa viva question discussions."
## 6. Explain Bus Transfer.
Why you might get asked this:
This question assesses your understanding of how data is transferred between different components of a computer system using a bus. This is closely tied to understanding coa viva question.
How to answer:
Explain that bus transfer involves transferring data between different devices connected to the bus, like CPU, memory, and I/O devices. Describe the roles of the address bus, data bus, and control bus in the transfer process.
Example answer:
"Bus transfer is the process of moving data between various components connected to the system bus, such as the CPU, memory, and peripheral devices. The bus consists of three main parts: the address bus, which specifies the memory location or I/O device being accessed; the data bus, which carries the actual data being transferred; and the control bus, which carries control signals to coordinate the transfer. For example, when the CPU wants to read data from memory, it places the memory address on the address bus, asserts the read control signal on the control bus, and then the memory places the requested data on the data bus, which the CPU then reads. Understanding the different buses at play helps in the greater understanding of coa viva question."
## 7. What is a Micro-Operation?
Why you might get asked this:
Micro-operations are the fundamental operations performed by the CPU. This coa viva question tests your knowledge of the lowest level of CPU operation.
How to answer:
Define micro-operations as elementary operations performed during one clock cycle. Give examples like loading data, storing data, shifting, and adding. Explain that they form the building blocks of instruction execution.
Example answer:
"A micro-operation is the most basic, elementary operation that a CPU can perform during a single clock cycle. It's like a primitive instruction. Examples include loading data from a register to the ALU, storing data from the ALU back to a register, shifting bits within a register, or incrementing a counter. For example, adding two numbers within the CPU involves a series of micro-operations: loading the numbers into registers, activating the ALU's addition circuit, and storing the result. Understanding these operations is critical for grasping the internal working of a CPU, which is central to coa viva question."
## 8. Explain Three-State Bus Buffer.
Why you might get asked this:
Three-state buffers are crucial for allowing multiple devices to share a common bus. This coa viva question assesses your knowledge of how to manage data flow on a shared bus.
How to answer:
Explain that a three-state buffer has three states: 0, 1, and high impedance (disconnected). Describe how the enable signal controls whether the buffer passes the input signal or disconnects the output from the bus.
Example answer:
"A three-state buffer is a type of electronic switch that has three possible states: logic 0, logic 1, and high impedance, which effectively disconnects the output from the circuit. The buffer either passes the input signal directly to the output (when enabled) or presents a high impedance state, preventing any signal from passing through (when disabled). For example, in a bus system, multiple devices are connected to the same data lines. Three-state buffers are used to ensure that only one device drives the bus at a time. When a device needs to transmit data, its corresponding buffer is enabled, and all other buffers are disabled. This prevents signal contention and ensures clean data transfer. This is a common example of a situation presented in coa viva question."
## 9. List Memory Reference Instructions.
Why you might get asked this:
This coa viva question assesses your understanding of the different types of instructions that interact with memory, a critical aspect of programming and computer architecture.
How to answer:
List common memory reference instructions such as LOAD (read from memory), STORE (write to memory), and potentially other instructions like MOVE (transfer data between memory locations), PUSH (place data on the stack), and POP (retrieve data from the stack).
Example answer:
"Memory reference instructions are instructions that access memory locations to either read data from or write data to memory. The most common examples are LOAD, which reads data from a specified memory address into a register, and STORE, which writes data from a register into a specified memory address. Other memory reference instructions include MOVE, used to transfer blocks of data within memory, PUSH, which places data onto a stack in memory, and POP, which retrieves data from a stack in memory. Different instruction sets have their own specific memory reference instructions, but these are the most fundamental. Knowing the common memory reference instructions is important to understanding coa viva question."
## 10. Explain Instruction Format.
Why you might get asked this:
Understanding instruction formats is crucial for understanding how instructions are structured and how the CPU interprets them. This is a key topic for coa viva question.
How to answer:
Explain that the instruction format defines the layout of an instruction, including fields like opcode, operand(s), and addressing mode. Describe different types of instruction formats (e.g., zero-address, one-address, two-address, three-address).
Example answer:
"The instruction format defines the structure and organization of an instruction. It specifies how the different parts of the instruction, like the operation to be performed (opcode) and the data or memory addresses to be used (operands), are arranged. Different architectures support different instruction formats. For example, a two-address instruction format might have an opcode and two operand fields, where each operand field specifies a register or a memory location. The instruction format directly impacts the complexity of the CPU design and the efficiency of code execution. This knowledge is a foundation for discussing more complex coa viva question."
## 11. Explain AND and BSA Instructions.
Why you might get asked this:
This coa viva question tests your familiarity with specific assembly language instructions and their functions.
How to answer:
Explain that AND is a bitwise logical AND operation, and BSA (Branch and Save Address) is an instruction that combines branching with saving the return address. Describe their use cases.
Example answer:
"The AND instruction performs a bitwise logical AND operation between two operands. Each bit in the result is 1 only if the corresponding bits in both operands are 1. It's commonly used for masking bits or checking specific bit patterns. The BSA, or Branch and Save Address instruction, is used to call a subroutine. It saves the address of the next instruction in a specific location (often memory location 0) and then jumps to the subroutine's starting address. This allows the subroutine to return to the correct location after it's done executing. These kinds of instructions help to solve practical coding questions related to coa viva question."
## 12. What is the MESI Protocol?
Why you might get asked this:
The MESI protocol is a cache coherence protocol widely used in multiprocessor systems. This coa viva question tests your understanding of cache coherence mechanisms.
How to answer:
Explain that MESI is a cache coherence protocol with four states: Modified, Exclusive, Shared, and Invalid. Describe how these states are used to ensure data consistency across multiple caches.
Example answer:
"MESI is a widely-used cache coherence protocol that ensures data consistency across multiple caches in a multiprocessor system. MESI stands for Modified, Exclusive, Shared, and Invalid, which are the four possible states a cache line can be in. Modified means the cache line is dirty (modified) and only exists in this cache. Exclusive means the cache line is clean and only exists in this cache. Shared means the cache line is clean and may exist in other caches. Invalid means the cache line is invalid and should not be used. The protocol uses snooping to monitor bus transactions and update the cache states accordingly. For example, if one processor modifies a cache line, all other caches that have a copy of that line will invalidate their copies. This protocol helps to maintain cache coherence, which helps to illustrate one's knowledge on coa viva question."
## 13. Explain Different Hazards in Pipelining.
Why you might get asked this:
Hazards can stall or disrupt the smooth flow of instructions in a pipeline. This coa viva question tests your understanding of pipeline limitations and how to address them.
How to answer:
Describe the three main types of hazards: structural hazards (resource conflicts), data hazards (data dependencies), and control hazards (branch instructions). Explain how each type can affect pipeline performance.
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, data, and control. Structural hazards occur when multiple instructions try 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 occur when a branch instruction changes the program's control flow. For example, a data hazard can happen when an instruction tries to read a register before the previous instruction has written to it. To mitigate hazards, techniques like stalling, forwarding, and branch prediction are used. Understanding pipeline hazards is essential for optimizing performance in modern processors, which falls under the topic of coa viva question."
## 14. What is Pipelining?
Why you might get asked this:
Pipelining is a key technique for improving CPU performance. This coa viva question assesses your understanding of this fundamental concept.
How to answer:
Explain that pipelining is a technique that allows multiple instructions to be in different stages of execution simultaneously. Describe how it increases throughput and reduces the average execution time per instruction.
Example answer:
"Pipelining is a technique used in processor design to increase instruction throughput. It works by breaking down the execution of an instruction into multiple stages, such as fetch, decode, execute, and write-back, and allowing multiple instructions to be in different stages of execution concurrently. It's like an assembly line, where different stations work on different parts of the same product simultaneously. For example, while one instruction is being executed, the next instruction can be decoded, and the instruction after that can be fetched. This overlap increases the number of instructions completed per unit of time, which improves the overall performance of the processor. Discussions on pipelining make up a major portion of the coa viva question."
## 15. Explain Cache Memory.
Why you might get asked this:
Cache memory is a crucial component for improving memory access times. This coa viva question tests your understanding of how cache memory works and its importance in computer systems.
How to answer:
Explain that cache memory is a small, fast memory that stores frequently accessed data. Describe its role in reducing the average time to access data from memory. Explain the principles of locality of reference (temporal and spatial).
Example answer:
"Cache memory is a small, fast memory that sits between the CPU and main memory (RAM). Its purpose is to reduce the average time it takes for the CPU to access data. It works based on the principle of locality, which states that data that has been accessed recently (temporal locality) or data that is located near recently accessed data (spatial locality) is likely to be accessed again soon. For example, if a program repeatedly uses the same variable, that variable is stored in the cache, so the CPU can access it quickly without having to wait for the slower main memory. Cache memory dramatically improves system performance, and it’s a critical component discussed in coa viva question."
## 16. What is Snooping Protocol?
Why you might get asked this:
Snooping protocols are used for maintaining cache coherence in multiprocessor systems. This coa viva question assesses your understanding of how multiple caches stay consistent.
How to answer:
Explain that snooping protocols are used to maintain cache coherence by monitoring bus transactions. Describe how caches listen to bus activity to detect when a shared data block has been modified by another cache.
Example answer:
"A snooping protocol is a cache coherence mechanism used in shared-memory multiprocessor systems. Each cache monitors (snoops on) the bus to detect when other caches or main memory perform read or write operations. When a cache detects an operation that affects a copy of a data block it has, it takes appropriate action, such as invalidating its copy or updating it with the new value. For example, if one cache writes to a shared data block, all other caches that have a copy of that block will invalidate their copies to ensure that they don't use stale data. Snooping protocols are essential for ensuring data consistency across multiple caches and are a key element in coa viva question discussions."
## 17. Explain Types of Interrupts.
Why you might get asked this:
Interrupts are a fundamental mechanism for handling events in computer systems. This coa viva question checks your understanding of different interrupt types and their purposes.
How to answer:
Describe the different types of interrupts, including hardware interrupts (generated by hardware devices), software interrupts (generated by software), and masked interrupts (can be disabled). Explain the purpose of each type.
Example answer:
"Interrupts are signals that cause the CPU to temporarily suspend its current activity and execute a special routine called an interrupt handler. There are several types of interrupts: hardware interrupts, which are triggered by external hardware devices like the keyboard or network card; software interrupts, which are triggered by software instructions, often used to request services from the operating system; and masked interrupts, which can be disabled by the CPU, allowing it to ignore less critical events when handling high-priority tasks. Understanding and explaining interrupts is key in answering coa viva question."
## 18. Explain Virtual Memory.
Why you might get asked this:
Virtual memory is a crucial technique for managing memory resources efficiently. This coa viva question assesses your understanding of how virtual memory works and its benefits.
How to answer:
Explain that virtual memory is a memory management technique that uses both RAM and disk space to create a larger address space than physically available. Describe how it allows programs to use more memory than physically present and how it facilitates memory protection.
Example answer:
"Virtual memory is a memory management technique that allows a computer to use more memory than is physically available in RAM. It achieves this by using a portion of the hard disk as an extension of RAM. When the system runs out of physical memory, it moves inactive or less frequently used data from RAM to the hard disk, creating space for new data. When the data on the hard disk is needed again, it's swapped back into RAM. For example, you can run several large programs simultaneously even if their combined memory requirements exceed the physical RAM. Virtual memory also provides memory protection, preventing one program from accessing the memory space of another. Understanding this mechanism contributes to more complex coa viva question solutions."
## 19. What is Assembly Language?
Why you might get asked this:
Assembly language provides a low-level interface to the hardware. This coa viva question tests your understanding of low-level programming concepts.
How to answer:
Explain that assembly language is a low-level programming language that uses symbolic codes (mnemonics) to represent machine instructions. Describe its relationship to machine code and its use in direct hardware control.
Example answer:
"Assembly language is a low-level programming language that uses symbolic codes, or mnemonics, to represent machine instructions. Each assembly language instruction typically corresponds to a single machine code instruction. It provides a more human-readable way to write code that directly controls the hardware. For example, instead of writing binary machine code to add two numbers, you could write ADD AX, BX in assembly language. While higher-level languages are more abstract and easier to use, assembly language provides finer-grained control over the hardware and is often used for tasks like writing device drivers or optimizing performance-critical sections of code. Assembly language and machine code are a key component of coa viva question answers."
## 20. Explain RAID Systems.
Why you might get asked this:
RAID systems are widely used for improving data storage reliability and performance. This coa viva question assesses your knowledge of different RAID levels and their characteristics.
How to answer:
Explain that RAID (Redundant Array of Independent Disks) is a storage technology that combines multiple physical disks into a single logical unit to improve performance, redundancy, or both. Describe different RAID levels like RAID 0, RAID 1, RAID 5, and their respective advantages and disadvantages.
Example answer:
"RAID, which stands for Redundant Array of Independent Disks, is a data storage virtualization technology that combines multiple physical disk drive components into one or more logical units for the purposes of data redundancy, performance improvement, or both. There are several RAID levels, each with its own unique configuration. RAID 0, known as striping, improves performance by spreading data across multiple disks but provides no redundancy. RAID 1, known as mirroring, provides redundancy by duplicating data on two or more disks. RAID 5 uses disk striping with parity to provide both performance and redundancy. For example, a company might use RAID 5 for a database server to ensure that data is protected against disk failures while maintaining good performance. Discussing performance like this often comes up with coa viva question."
## 21. What are the Main Components of a Microprocessor?
Why you might get asked this:
This is a foundational coa viva question that tests your understanding of the basic building blocks of a CPU.
How to answer:
List and describe the main components, including the Control Unit (CU), Arithmetic Logic Unit (ALU), and Registers. Explain the function of each component.
Example answer:
"The main components of a microprocessor are the Control Unit (CU), the Arithmetic Logic Unit (ALU), and Registers. The Control Unit fetches instructions from memory and decodes them to generate control signals that coordinate the other components. The Arithmetic Logic Unit performs arithmetic and logical operations on data. Registers are small, high-speed storage locations used to hold data and addresses that the CPU is actively working with. For example, when adding two numbers, the CU fetches the addition instruction, the ALU performs the addition, and registers hold the operands and the result. Being able to explain these parts helps in resolving complex coa viva question."
## 22. Explain DMA (Direct Memory Access).
Why you might get asked this:
DMA is a technique that allows peripherals to access memory directly without CPU intervention. This coa viva question assesses your understanding of how peripherals interact with memory.
How to answer:
Explain that DMA allows peripherals to transfer data directly to or from memory without involving the CPU. Describe the role of the DMA controller and the benefits of DMA in improving system performance.
Example answer:
"DMA, or Direct Memory Access, is a technique that allows certain hardware subsystems within the computer to access system memory independently of the CPU. Instead of the CPU having to copy data between peripherals and memory, a DMA controller handles the transfer directly. This frees up the CPU to perform other tasks, improving overall system performance. For example, when transferring data from a hard drive to memory, the DMA controller takes control of the system bus, reads the data from the hard drive, and writes it directly into the specified memory location. Once the transfer is complete, the DMA controller notifies the CPU. Understanding DMA is crucial to properly answer coa viva question."
## 23. What is Horizontal Microcode?
Why you might get asked this:
Microcode is a low-level control mechanism used in some CPUs. This coa viva question tests your understanding of different microcode organizations.
How to answer:
Explain that horizontal microcode uses a wide control word where each bit directly controls a specific hardware component. Describe its advantages (flexibility) and disadvantages (large control memory).
Example answer:
"Horizontal microcode is a type of microcode organization where each bit in the microinstruction directly controls a specific hardware component within the CPU. This means that a single microinstruction can control many different operations simultaneously. The advantage of horizontal microcode is its high degree of flexibility and parallelism. However, it requires a wide control word, which means that the control memory can be quite large. For example, a horizontal microcode instruction might have separate bits to control the ALU operation, register selection, and memory access, all within the same instruction. Being able to explain this at an interview will showcase your ability to answer coa viva question."
## 24. Explain Direct Mapping.
Why you might get asked this:
Direct mapping is a simple cache mapping technique. This coa viva question assesses your understanding of cache organization and mapping strategies.
How to answer:
Explain that direct mapping is a cache mapping technique where each memory block has a fixed location in the cache. Describe how the cache address is divided into tag, line, and word fields and how the tag is used to verify the correctness of the cached data.
Example answer:
"Direct mapping is a simple cache mapping technique where each memory block can only be placed in one specific location (cache line) in the cache. The memory address is divided into three parts: the tag, the line index, and the word offset. The line index determines which cache line the memory block will be stored in. The tag is stored along with the data in the cache and is used to verify that the correct memory block is present in the cache. For example, if the CPU tries to access a memory location, the cache checks if the tag for that location matches the tag in the cache line. If it matches (a cache hit), the data is retrieved from the cache; otherwise (a cache miss), the data is fetched from main memory and stored in the cache. This is an important process that is central to coa viva question."
## 25. Explain Associative Mapping.
Why you might get asked this:
Associative mapping is a more flexible cache mapping technique. This coa viva question tests your understanding of different cache organization strategies.
How to answer:
Explain that associative mapping allows a memory block to be placed in any location in the cache. Describe how the entire tag is used for comparison and the advantages (lower miss rate) and disadvantages (complex hardware) of this technique.
Example answer:
"Associative mapping is a cache mapping technique where a memory block can be placed in any available cache line. This provides greater flexibility compared to direct mapping. When the CPU requests data, the cache controller compares the tag of the requested memory address with the tags of all cache lines simultaneously. If a match is found (a cache hit), the data is retrieved. If no match is found (a cache miss), the data is fetched from main memory and placed in any available cache line. Associative mapping reduces the number of conflict misses compared to direct mapping but requires more complex and expensive hardware for the tag comparison. Many questions in coa viva question will revolve around the tradeoffs made during the development."
## 26. What is a Wait State?
Why you might get asked this:
Wait states are used to synchronize the CPU with slower memory or peripherals. This coa viva question assesses your understanding of timing issues in computer systems.
How to answer:
Explain that a wait state is a delay inserted by the CPU to accommodate slower memory or peripheral devices. Describe how it allows the slower device to complete its operation before the CPU continues.
Example answer:
"A wait state is a delay intentionally inserted by the CPU to allow slower memory or I/O devices to catch up. It effectively extends the duration of a memory or I/O cycle. When the CPU tries to access a slow device, the device signals the CPU to insert wait states. During a wait state, the CPU essentially does nothing for one or more clock cycles until the device is ready. This ensures that the CPU doesn't attempt to read data before it's available or write data before the device is ready to accept it. This synchronization helps in the communication between components, which will show your ability to answer coa viva question."
## 27. Explain Non-Restoring Division.
Why you might get asked this:
Non-restoring division is an algorithm used for integer division. This coa viva question tests your understanding of arithmetic algorithms.
How to answer:
Explain that non-restoring division is a division algorithm that avoids restoring the remainder after a subtraction results in a negative value. Describe the steps involved (shift, add/subtract, conditional correction).
Example answer:
"Non-restoring division is a division algorithm that simplifies the division process by avoiding the 'restoring' step required in some other division methods. In this algorithm, if a subtraction results in a negative remainder, you don't restore the original value. Instead, you perform an addition in the next step. The algorithm involves shifting the partial remainder and either adding or subtracting the divisor based on the sign of the previous remainder. After a series of shifts and additions/subtractions, a final correction step is performed to get the correct quotient and remainder. Having the ability to explain mathematical processes like this is crucial to solving coa viva question."
## 28. What are the Types of Micro-Operations?
Why you might get asked this:
Understanding the different types of micro-operations is fundamental to understanding CPU operation. This coa viva question tests your knowledge of the lowest level of CPU activities.
How to answer:
List and describe the different types of micro-operations, including register transfer, arithmetic, logic, and shift micro-operations. Explain the purpose of each type.
Example answer:
"Micro-operations are the fundamental, low-level operations that a CPU performs during each clock cycle. There are several types of micro-operations: Register transfer micro-operations involve moving data between registers. Arithmetic micro-operations perform arithmetic operations like addition, subtraction, multiplication, and division. Logic micro-operations perform logical operations like AND, OR, NOT, and XOR. Shift micro-operations shift the bits in a register left or right. For example, an addition instruction might involve several micro-operations: transferring the operands from memory to registers, performing the addition using the ALU, and storing the result back in a register. Being able to list and explain these operations will greatly increase the success in coa viva question interviews."
## 29. Explain Stack Organization of CPU.
Why you might get asked this:
Stack organization is a fundamental memory management technique. This coa viva question tests your understanding of how stacks are used in CPU operations.
How to answer:
Explain that stack organization uses a stack data structure for storing data and addresses. Describe the push and pop operations and how they are used for subroutine calls and managing temporary data.
Example answer:
"Stack organization in a CPU uses a stack data structure to manage data and addresses. A stack operates on a LIFO (Last-In, First-Out) principle, meaning the last item added to the stack is the first item removed. Two primary operations are used: PUSH, which adds an item to the top of the stack, and POP, which removes the item from the top of the stack. Stacks are commonly used for managing subroutine calls and returns, as well as for storing temporary data. For example, when a subroutine is called, the return address (the address of the instruction after the subroutine call) is pushed onto the stack. When the subroutine is finished, the return address is popped from the stack, allowing the CPU to return to the correct location. Understanding the process of Stacks is a key point to answering coa viva question."
## 30. Explain RISC and CISC Architectures.
Why you might get asked this:
RISC and CISC are two major approaches to CPU design. This coa viva question tests your understanding of the trade-offs between these architectures.
How to answer:
Explain the key differences between RISC (Reduced Instruction Set Computing) and CISC (Complex Instruction Set Computing) architectures. Describe the characteristics of each architecture, including instruction complexity, instruction count, and performance trade-offs.
Example answer:
"RISC (Reduced Instruction Set Computing) and CISC (Complex Instruction Set Computing) are two different approaches to CPU design. RISC architectures use a small set of simple, uniform instructions that can be executed quickly. CISC architectures, on the other hand, use a large set of complex instructions that can perform more complex operations in a single instruction. RISC processors typically require more instructions to perform a given task but can execute each instruction faster. CISC processors require fewer instructions but each instruction takes longer to execute. For example, an Intel x86 processor is a CISC processor, while an ARM processor is a RISC processor. The choice between RISC and CISC depends on the specific application and design goals. These questions of architechture are key to understand coa viva question
