4.2 Computer arithmetic and memory system
4.2 COMPUTER ARITHMETIC AND MEMORY OPERATION
ARITHMETIC AND LOGIC OPERATION
What does the bitwise AND operator do in computer arithmetic?
A) Adds two numbers
B) Multiplies two numbers
C) Performs a logical AND operation on corresponding bits of two operands
D) Performs a logical OR operation on corresponding bits of two operands
Answer: C) Performs a logical AND operation on corresponding bits of two operands
Explanation: The bitwise AND operator (&) performs a logical AND operation on each pair of corresponding bits of the operands.
Which operation is performed by the XOR operator in computer logic?
A) Addition
B) Subtraction
C) Logical XOR
D) Logical OR
Answer: C) Logical XOR
Explanation: The XOR (exclusive OR) operator (^) performs a logical XOR operation on corresponding bits of the operands.
What is the result of the expression 5 | 3?
A) 2
B) 3
C) 5
D) 7
Answer: D) 7
Explanation: The bitwise OR operation results in setting any bit to 1 if it is 1 in either or both of the operands.
Which arithmetic operation does the subtraction of two's complement represent?
A) Addition
B) Multiplication
C) Division
D) Subtraction
Answer: D) Subtraction
Explanation: Subtraction of two's complement represents the arithmetic subtraction operation in computer systems.
In binary addition, what does a carry-out indicate?
A) Overflow
B) Underflow
C) Correct result
D) Input error
Answer: A) Overflow
Explanation: A carry-out in binary addition indicates an overflow condition, meaning the result is too large to be represented accurately with the given number of bits.
Which logic gate is used to perform the addition of two binary numbers?
A) AND
B) OR
C) XOR
D) NAND
Answer: C) XOR
Explanation: In binary addition, XOR gates are used to compute the sum bits, while AND gates are used to compute the carry bits.
What does the shift-left logical operation do?
A) Shifts all bits to the left by one position and fills the rightmost bit with 1
B) Shifts all bits to the left by one position and fills the rightmost bit with 0
C) Shifts all bits to the right by one position and fills the leftmost bit with 1
D) Shifts all bits to the right by one position and fills the leftmost bit with 0
Answer: B) Shifts all bits to the left by one position and fills the rightmost bit with 0
Explanation: The shift-left logical operation shifts all bits in a binary number to the left by one position, and fills the rightmost bit with 0.
What is the result of the expression 8 >> 2?
A) 2
B) 4
C) 8
D) 16
Answer: B) 4
Explanation: The right-shift operation (>>) shifts all bits of a binary number to the right by a specified number of positions.
Which operation is performed by the bitwise NOT operator?
A) Bitwise inversion
B) Bitwise AND
C) Bitwise OR
D) Bitwise XOR
Answer: A) Bitwise inversion
Explanation: The bitwise NOT operator (~) performs a bitwise inversion operation, flipping each bit of the operand.
What does the carry flag indicate in arithmetic operations?
A) Overflow
B) Underflow
C) Sign
D) Carry-out
Answer: D) Carry-out
Explanation: The carry flag indicates a carry-out from the most significant bit during arithmetic operations like addition or subtraction, which might be used for multi-precision arithmetic or other purposes.
THE MEMORY HIERARCHY
What is the primary function of the memory hierarchy in computer systems?
A) To reduce the cost of memory
B) To increase the speed of memory access
C) To decrease the power consumption of memory
D) To increase the capacity of memory
Answer: B) To increase the speed of memory access
Explanation: The memory hierarchy is designed to provide faster access to frequently accessed data by storing it in faster and more expensive memory levels.
Which of the following memory types has the fastest access time?
A) Hard disk drive (HDD)
B) Solid-state drive (SSD)
C) Random Access Memory (RAM)
D) Cache memory
Answer: D) Cache memory
Explanation: Cache memory is the fastest memory in the hierarchy, providing quick access to frequently used data and instructions.
What is the role of cache memory in the memory hierarchy?
A) To store data permanently
B) To store frequently accessed data for quick retrieval
C) To provide long-term storage
D) To expand the address space of the processor
Answer: B) To store frequently accessed data for quick retrieval
Explanation: Cache memory holds copies of frequently accessed data and instructions from slower main memory to speed up CPU operations.
Which level of the memory hierarchy typically has the largest capacity?
A) Register
B) Cache
C) Main memory
D) Secondary storage
Answer: D) Secondary storage
Explanation: Secondary storage devices like hard disk drives (HDDs) or solid-state drives (SSDs) typically have larger capacities compared to other levels of the memory hierarchy.
What is the purpose of virtual memory in the memory hierarchy?
A) To increase the physical size of RAM
B) To provide faster access to data
C) To extend the address space beyond the physical memory size
D) To reduce power consumption
Answer: C) To extend the address space beyond the physical memory size
Explanation: Virtual memory allows programs to use more memory than is physically available by temporarily transferring data between RAM and secondary storage.
Which of the following is a characteristic of cache memory?
A) Volatile
B) Slow access time
C) Small capacity
D) Non-expensive
Answer: C) Small capacity
Explanation: Cache memory has a small capacity compared to main memory or secondary storage due to its design for fast access.
What is the typical size range of main memory (RAM) in modern computer systems?
A) Megabytes (MB) to Gigabytes (GB)
B) Kilobytes (KB) to Megabytes (MB)
C) Terabytes (TB) to Petabytes (PB)
D) Bytes (B) to Kilobytes (KB)
Answer: A) Megabytes (MB) to Gigabytes (GB)
Explanation: Main memory sizes in modern computers typically range from several megabytes to multiple gigabytes.
Which memory level is directly accessed by the CPU?
A) Secondary storage
B) Cache memory
C) Main memory
D) Register
Answer: D) Register
Explanation: Registers are the smallest, fastest storage locations in the CPU and are directly accessible by the CPU instructions.
How does the memory hierarchy help in improving performance in computer systems?
A) By reducing the cost of memory
B) By increasing the capacity of memory
C) By providing multiple levels of memory with different speeds and sizes
D) By minimizing power consumption
Answer: C) By providing multiple levels of memory with different speeds and sizes
Explanation: The memory hierarchy allows for faster access to frequently used data while providing larger storage capacities at slower speeds, optimizing performance.
Which memory level retains data even when the power is turned off?
A) Cache memory
B) Main memory
C) Register
D) Secondary storage
Answer: D) Secondary storage
Explanation: Secondary storage devices like hard disk drives (HDDs) or solid-state drives (SSDs) retain data even when the power is turned off, unlike volatile memory like RAM or cache.
INTERNAL AND EXTERNAL MEMORY
What is the primary difference between internal and external memory in computer systems?
A) Access speed
B) Capacity
C) Cost
D) Volatility
Answer: A) Access speed
Explanation: Internal memory (such as RAM) is typically faster than external memory (such as hard disk drives) in terms of access speed.
Which of the following is an example of internal memory?
A) Hard disk drive (HDD)
B) Solid-state drive (SSD)
C) Random Access Memory (RAM)
D) External USB drive
Answer: C) Random Access Memory (RAM)
Explanation: RAM is an example of internal memory that is directly accessible by the CPU for storing data and instructions during program execution.
External memory is also referred to as:
A) Volatile memory
B) Secondary storage
C) Cache memory
D) Registers
Answer: B) Secondary storage
Explanation: External memory, such as hard disk drives or solid-state drives, is often referred to as secondary storage because it provides non-volatile storage for data and programs.
What is the primary purpose of internal memory in a computer system?
A) Long-term storage
B) Temporary storage during program execution
C) Storing data permanently
D) Increasing the capacity of the CPU
Answer: B) Temporary storage during program execution
Explanation: Internal memory, such as RAM, is used to temporarily store data and instructions needed by the CPU during program execution.
Which type of memory is directly connected to the CPU?
A) External memory
B) Cache memory
C) Secondary storage
D) Virtual memory
Answer: B) Cache memory
Explanation: Cache memory is a small, high-speed memory that is directly connected to the CPU, providing fast access to frequently used data and instructions.
What is the typical storage medium used in external memory?
A) Magnetic disks
B) Semiconductor chips
C) Registers
D) Cache memory
Answer: A) Magnetic disks
Explanation: External memory devices such as hard disk drives (HDDs) use magnetic disks to store data persistently.
Which of the following is a characteristic of internal memory?
A) Large capacity
B) Slow access time
C) Volatile nature
D) Low cost per byte
Answer: C) Volatile nature
Explanation: Internal memory, such as RAM, is volatile, meaning it loses its contents when power is turned off.
What is the primary advantage of external memory over internal memory?
A) Faster access time
B) Larger capacity
C) Lower cost per byte
D) Volatility
Answer: B) Larger capacity
Explanation: External memory, such as hard disk drives, typically offers larger storage capacities compared to internal memory like RAM.
Which memory type serves as a bridge between internal and external memory by providing additional storage space?
A) Cache memory
B) Virtual memory
C) Registers
D) ROM (Read-Only Memory)
Answer: B) Virtual memory
Explanation: Virtual memory extends the available memory beyond the physical limits of internal memory by using secondary storage as an extension.
Which memory type is used to store frequently accessed data for quick retrieval by the CPU?
A) Internal memory
B) External memory
C) Cache memory
D) ROM (Read-Only Memory)
Answer: C) Cache memory
Explanation: Cache memory is used to store frequently accessed data and instructions for quick retrieval by the CPU, reducing access times and improving system performance.
CACHE MEMORY PRINCIPLES
What is the primary purpose of cache memory in computer systems?
A) To permanently store data
B) To provide long-term storage
C) To serve as the main memory
D) To temporarily store frequently accessed data for quick access
\Answer: D) To temporarily store frequently accessed data for quick access
Explanation: Cache memory holds copies of frequently accessed data and instructions from slower main memory to speed up CPU operations.
A) Programs tend to access memory locations randomly
B) Programs exhibit spatial and temporal locality
C) Programs access all memory locations with equal frequency
D) Programs do not reuse data or instructions
Answer: B) Programs exhibit spatial and temporal locality
Explanation: Cache memory relies on the principle of locality, where programs tend to access a small set of memory locations frequently (temporal locality) and nearby memory locations (spatial locality).
What is the typical size range of cache memory in modern computer systems?
A) Megabytes (MB) to Gigabytes (GB)
B) Kilobytes (KB) to Megabytes (MB)
C) Terabytes (TB) to Petabytes (PB)
D) Bytes (B) to Kilobytes (KB)
Answer: B) Kilobytes (KB) to Megabytes (MB)
Explanation: Cache memory sizes in modern computers typically range from a few kilobytes to several megabytes, depending on the level of cache (L1, L2, L3).
Which cache replacement policy aims to replace the least recently used cache line when the cache is full?
A) Random replacement
B) Least Recently Used (LRU)
C) First-In, First-Out (FIFO)
D) Least Frequently Used (LFU)
Answer: B) Least Recently Used (LRU)
Explanation: The LRU cache replacement policy replaces the cache line that has not been accessed for the longest time when new data needs to be fetched into a full cache.
What is the purpose of associativity in cache memory?
A) To increase the cache size
B) To reduce the cache access time
C) To increase the number of cache sets
D) To determine the cache replacement policy
Answer: C) To increase the number of cache sets
Explanation: Associativity in cache memory determines the number of cache sets where a particular memory block can be placed, providing flexibility and reducing cache conflicts.
Which cache level is typically the smallest but fastest in terms of access time?
A) L1 cache
B) L2 cache
C) L3 cache
D) L4 cache
Answer: A) L1 cache
Explanation: L1 cache, also known as primary cache, is the smallest but fastest cache level, located closest to the CPU core for quick access.
What is a cache hit in cache memory?
A) When the requested data is found in the cache
B) When the cache is full
C) When the cache is flushed
D) When the cache misses the requested data
Answer: A) When the requested data is found in the cache
Explanation: A cache hit occurs when the CPU requests data or instructions, and the cache contains the requested data, leading to faster access times.
Which cache organization allows any block of main memory to be mapped to any cache line?
A) Direct-mapped cache
B) Fully associative cache
C) Set-associative cache
D) Multi-level cache
Answer: B) Fully associative cache
Explanation: In a fully associative cache, any block of main memory can be mapped to any cache line, providing maximum flexibility but requiring more complex hardware.
What is the main advantage of set-associative cache over direct-mapped cache?
A) Lower access time
B) Simpler hardware implementation
C) Reduced cache conflicts
D) Higher cache capacity
Answer: C) Reduced cache conflicts
Explanation: Set-associative cache reduces cache conflicts compared to direct-mapped cache by allowing multiple main memory blocks to be mapped to each set.
Which cache organization requires the least hardware complexity?
A) Direct-mapped cache
B) Fully associative cache
C) Set-associative cache
D) Multi-level cache
Answer: A) Direct-mapped cache
Explanation: Direct-mapped cache requires the least hardware complexity among the cache organizations, as each main memory block is mapped to a specific cache line using a simple indexing function.
ELEMENT OF CACHE DESIGN -CACHE SIZE
What is the primary determinant of cache size in computer architecture?
A) CPU clock speed
B) Main memory capacity
C) Cache associativity
D) Available chip space and cost constraints
Answer: D) Available chip space and cost constraints
Explanation: The size of the cache is primarily determined by the available chip space and cost constraints in a computer system.
Which statement best describes the relationship between cache size and performance?
A) Larger cache always leads to better performance
B) Smaller cache always leads to better performance
C) Optimal cache size depends on the specific workload and memory access patterns
D) Cache size has no impact on performance
Answer: C) Optimal cache size depends on the specific workload and memory access patterns
Explanation: The optimal cache size depends on the specific characteristics of the workload and memory access patterns. Too small a cache may result in frequent cache misses, while too large a cache may lead to increased access latency and cost.
What is the term used to describe the number of blocks that can be stored in the cache?
A) Cache capacity
B) Cache associativity
C) Cache line size
D) Cache set size
Answer: A) Cache capacity
Explanation: Cache capacity refers to the total number of blocks or bytes that can be stored in the cache.
Which cache design parameter affects the number of cache lines available in a cache?
A) Cache associativity
B) Cache size
C) Cache block size
D) Cache set size
Answer: B) Cache size
Explanation: Cache size directly affects the number of cache lines available in a cache. A larger cache size typically allows for more cache lines.
How does increasing cache size affect the likelihood of cache hits?
A) Increases the likelihood of cache hits
B) Decreases the likelihood of cache hits
C) Has no impact on the likelihood of cache hits
D) Increases the likelihood of cache conflicts
Answer: A) Increases the likelihood of cache hits
Explanation: Increasing cache size generally increases the likelihood of cache hits as more data can be stored in the cache, reducing the frequency of cache misses.
Which of the following cache configurations would have the largest total storage capacity?
A) Direct-mapped cache with 16 cache lines
B) 2-way set-associative cache with 8 sets
C) Fully associative cache with 16 cache lines
D) 4-way set-associative cache with 4 sets
Answer: C) Fully associative cache with 16 cache lines
Explanation: A fully associative cache has the largest total storage capacity as any block can be placed in any cache line, resulting in the maximum flexibility.
What is the trade-off associated with increasing cache size?
A) Increased access time
B) Increased cost and complexity
C) Decreased cache hit rate
D) Decreased CPU performance
Answer: B) Increased cost and complexity
Explanation: Increasing cache size typically results in increased cost and complexity due to the need for additional hardware resources.
How does cache size impact the power consumption of a computer system?
A) Larger cache size reduces power consumption
B) Larger cache size increases power consumption
C) Cache size has no impact on power consumption
D) Cache size indirectly impacts power consumption
Answer: B) Larger cache size increases power consumption
Explanation: Larger cache sizes generally increase power consumption due to the additional circuitry required to implement the larger cache.
Which cache design aspect directly affects the number of cache sets in a set-associative cache?
A) Cache capacity
B) Cache associativity
C) Cache line size
D) Cache block size
Answer: B) Cache associativity
Explanation: Cache associativity determines the number of cache sets in a set-associative cache. Higher associativity results in more cache sets.
How does cache size affect the overall cost of a computer system?
A) Larger cache size reduces overall cost
B) Larger cache size increases overall cost
C) Cache size has no impact on overall cost
D) Cache size indirectly impacts overall cost
Answer: B) Larger cache size increases overall cost
Explanation: Larger cache sizes typically increase the overall cost of a computer system due to the additional hardware resources required to implement the larger cache.
MAPPING FUNCTION
What is the purpose of a mapping function in cache memory design?
A) To determine the cache size
B) To select which cache block holds a particular memory address
C) To determine cache associativity
D) To calculate cache access time
Answer: B) To select which cache block holds a particular memory address
Explanation: The mapping function determines how memory addresses are mapped to specific cache blocks in the cache memory.
Which cache mapping technique maps each block of main memory to a unique cache line?
A) Direct-mapped cache
B) Fully associative cache
C) Set-associative cache
D) Multi-level cache
Answer: A) Direct-mapped cache
Explanation: In direct-mapped cache, each block of main memory is mapped to a unique cache line, making it easy to determine where a particular memory address is stored in the cache.
What is the main disadvantage of direct-mapped cache compared to set-associative cache?
A) Higher access time
B) Higher cost
C) Increased cache conflicts
D) Lower cache capacity
Answer: C) Increased cache conflicts
Explanation: Direct-mapped cache may suffer from cache conflicts, where multiple memory blocks are mapped to the same cache line, leading to potential performance degradation.
In set-associative cache, how many cache lines are there per set?
A) One
B) Two
C) Variable, depending on cache size
D) Equal to the cache size
Answer: C) Variable, depending on cache size
Explanation: Set-associative cache has a fixed number of cache sets, and each set contains a variable number of cache lines depending on the cache size and associativity.
Which cache mapping technique offers the highest flexibility in terms of mapping memory blocks to cache lines?
A) Direct-mapped cache
B) Fully associative cache
C) Set-associative cache
D) Multi-level cache
Answer: B) Fully associative cache
Explanation: Fully associative cache allows any memory block to be placed in any cache line, offering the highest flexibility but requiring more hardware complexity.
How does the associativity of a cache affect the mapping function?
A) Higher associativity results in a simpler mapping function
B) Lower associativity results in a more complex mapping function
C) Associativity does not affect the mapping function
D) Higher associativity results in a more complex mapping function
Answer: D) Higher associativity results in a more complex mapping function
Explanation: Higher associativity requires a more complex mapping function to determine which cache line to place a memory block in, compared to lower associativity.
Which cache mapping technique uses a combination of direct mapping and fully associative mapping?
A) Direct-mapped cache
B) Fully associative cache
C) Set-associative cache
D) Multi-level cache
Answer: C) Set-associative cache
Explanation: Set-associative cache combines elements of direct mapping and fully associative mapping by dividing the cache into sets and allowing multiple cache lines per set.
In a 4-way set-associative cache, how many cache lines are there per set?
A) 1
B) 2
C) 3
D) 4
Answer: D) 4
Explanation: In a 4-way set-associative cache, there are 4 cache lines per set, meaning each set can hold up to 4 memory blocks.
Which cache mapping technique is commonly used in modern processors?
A) Direct-mapped cache
B) Fully associative cache
C) Set-associative cache
D) Multi-level cache
Answer: C) Set-associative cache
Explanation: Set-associative cache strikes a balance between the simplicity of direct-mapped cache and the flexibility of fully associative cache, making it a common choice in modern processors.
What is the advantage of using multi-level cache in computer systems?
A) Lower access time
B) Reduced cache conflicts
C) Lower hardware complexity
D) Increased cache capacity
Answer: B) Reduced cache conflicts
Explanation: Multi-level cache helps reduce cache conflicts by providing multiple cache levels with different access times and capacities, improving overall system performance.
REPLACEMENT ALGORITHM
What is the primary purpose of a replacement algorithm in cache memory design?
A) To determine the cache size
B) To select which cache block to replace when a new block must be brought into the cache
C) To calculate cache access time
D) To determine cache associativity
Answer: B) To select which cache block to replace when a new block must be brought into the cache
Explanation: The replacement algorithm determines which cache block should be replaced when the cache is full and a new block needs to be brought in.
Which replacement algorithm selects the cache block that has been unused for the longest time when a new block must be brought into the cache?
A) Random replacement
B) Least Recently Used (LRU)
C) First-In, First-Out (FIFO)
D) Least Frequently Used (LFU)
Answer: B) Least Recently Used (LRU)
Explanation: The LRU replacement algorithm replaces the cache block that has not been accessed for the longest time, based on the principle that recently used data is more likely to be used again soon.
In which scenario would the FIFO replacement algorithm be preferable?
A) When cache lines have different access frequencies
B) When the cache access time is critical
C) When the cache workload exhibits strong temporal locality
D) When simplicity is preferred over optimization
Answer: D) When simplicity is preferred over optimization
Explanation: The FIFO replacement algorithm is simple to implement but may not always provide optimal cache performance compared to more complex algorithms like LRU.
What is the primary drawback of the FIFO replacement algorithm?
A) It requires complex hardware implementation
B) It may result in poor cache performance for certain access patterns
C) It has a higher cache access time
D) It leads to increased cache conflicts
Answer: B) It may result in poor cache performance for certain access patterns
Explanation: FIFO replacement may result in poor cache performance, especially if the accessed blocks have different access frequencies or exhibit temporal locality.
Which replacement algorithm considers both the frequency and recency of cache block accesses?
A) Random replacement
B) Least Recently Used (LRU)
C) First-In, First-Out (FIFO)
D) Least Frequently Used (LFU)
Answer: D) Least Frequently Used (LFU)
Explanation: The LFU replacement algorithm selects the cache block with the least frequent accesses for replacement, taking into account both the frequency and recency of accesses.
How does the LFU replacement algorithm handle ties (i.e., when multiple cache blocks have the same access frequency)?
A) It selects the cache block that has been unused for the longest time
B) It selects the cache block that was most recently accessed
C) It selects any tied cache block randomly
D) It selects the cache block based on their physical addresses
Answer: A) It selects the cache block that has been unused for the longest time
Explanation: In case of ties in LFU, the algorithm typically selects the cache block that has been unused for the longest time to break the tie.
Which replacement algorithm is considered the simplest to implement?
A) Random replacement
B) Least Recently Used (LRU)
C) First-In, First-Out (FIFO)
D) Least Frequently Used (LFU)
Answer: C) First-In, First-Out (FIFO)
Explanation: FIFO replacement is considered the simplest to implement as it only requires keeping track of the order in which cache blocks were brought into the cache.
Which replacement algorithm is most suitable for applications with well-defined access patterns?
A) Random replacement
B) Least Recently Used (LRU)
C) First-In, First-Out (FIFO)
D) Least Frequently Used (LFU)
Answer: B) Least Recently Used (LRU)
Explanation: LRU replacement is suitable for applications with well-defined access patterns as it replaces the cache block that has been least recently accessed.
What is the main advantage of the random replacement algorithm?
A) It guarantees optimal cache performance
B) It is simple to implement
C) It avoids cache conflicts
D) It provides fair replacement without bias
Answer: D) It provides fair replacement without bias
Explanation: The random replacement algorithm provides fair replacement without bias, as it selects any cache block for replacement randomly.
Which replacement algorithm tends to perform well in scenarios where the workload exhibits both temporal and spatial locality?
A) Random replacement
B) Least Recently Used (LRU)
C) First-In, First-Out (FIFO)
D) Least Frequently Used (LFU)
Answer: B) Least Recently Used (LRU)
Explanation: LRU replacement algorithm tends to perform well in scenarios where the workload exhibits both temporal and spatial locality, as it prioritizes recently accessed data for retention in the cache.
WRITE POLICY
What is the purpose of a write policy in cache memory design?
A) To determine the cache size
B) To specify how data is written to the cache and main memory
C) To select which cache block to replace when a new block must be brought into the cache
D) To calculate cache access time
Answer: B) To specify how data is written to the cache and main memory
Explanation: The write policy determines when and how data is written to the cache and main memory upon write operations.
Which of the following write policies requires updating both the cache and main memory simultaneously?
A) Write-through
B) Write-back
C) Write-allocate
D) Write-no-allocate
Answer: A) Write-through
Explanation: In write-through policy, data is written to both the cache and main memory simultaneously, ensuring consistency between the two.
What is the primary advantage of the write-through policy?
A) Lower memory bandwidth requirement
B) Faster write operations
C) Reduced cache pollution
D) Simplified cache coherence protocol
Answer: A) Lower memory bandwidth requirement
Explanation: Write-through policy reduces memory bandwidth requirement as data is written to main memory along with the cache, reducing the frequency of main memory accesses.
Which write policy writes data only to the cache upon a write operation and defers updating main memory until the cache block is replaced?
A) Write-through
B) Write-back
C) Write-allocate
D) Write-no-allocate
Answer: B) Write-back
Explanation: In write-back policy, data is only written to the cache upon a write operation, and main memory is updated only when the cache block is replaced.
What is the primary advantage of the write-back policy?
A) Lower memory bandwidth requirement
B) Faster write operations
C) Reduced cache pollution
D) Simplified cache coherence protocol
Answer: B) Faster write operations
Explanation: Write-back policy reduces the frequency of main memory writes, resulting in faster write operations compared to write-through policy.
Which write policy requires fetching a cache block from main memory into the cache before performing a write operation?
A) Write-through
B) Write-back
C) Write-allocate
D) Write-no-allocate
Answer: C) Write-allocate
Explanation: Write-allocate policy fetches a cache block from main memory into the cache upon a write miss before performing the write operation.
What is the primary disadvantage of the write-allocate policy?
A) Higher memory bandwidth requirement
B) Slower write operations
C) Increased cache pollution
D) Complex cache coherence protocol
Answer: C) Increased cache pollution
Explanation: Write-allocate policy may increase cache pollution by fetching unnecessary cache blocks into the cache upon write misses.
Which write policy bypasses the cache entirely for write operations, writing directly to main memory?
A) Write-through
B) Write-back
C) Write-allocate
D) Write-no-allocate
Answer: D) Write-no-allocate
Explanation: Write-no-allocate policy writes data directly to main memory without involving the cache for write operations.
What is the primary advantage of the write-no-allocate policy?
A) Lower cache pollution
B) Simpler cache coherence protocol
C) Reduced memory bandwidth requirement
D) Faster write operations
Answer: C) Reduced memory bandwidth requirement
Explanation: Write-no-allocate policy reduces memory bandwidth requirement as it bypasses the cache for write operations, writing directly to main memory.
Which write policy is commonly used in systems where write operations are frequent and performance is critical?
A) Write-through
B) Write-back
C) Write-allocate
D) Write-no-allocate
Answer: B) Write-back
Explanation: Write-back policy is commonly used in systems where write operations are frequent and performance is critical, as it reduces the frequency of main memory writes and improves performance.
NUMBER OF CACHES
How many levels of cache are typically found in modern computer systems?
A) One
B) Two
C) Three
D) Four
Answer: C) Three
Explanation: Modern computer systems commonly have three levels of cache: L1 (closest to the CPU core), L2, and L3 (furthest from the core).
Which cache level is usually the smallest but fastest in terms of access time?
A) L1 cache
B) L2 cache
C) L3 cache
D) L4 cache
Answer: A) L1 cache
Explanation: L1 cache is typically the smallest but fastest cache level, providing quick access to frequently used data and instructions.
What is the primary purpose of having multiple levels of cache?
A) To increase the overall cache capacity
B) To reduce cache access time
C) To minimize cache conflicts
D) To provide a hierarchy of memory access speeds
Answer: D) To provide a hierarchy of memory access speeds
Explanation: Multiple levels of cache provide a hierarchy of memory access speeds, with faster and smaller caches closer to the CPU.
Which cache level typically has the largest capacity?
A) L1 cache
B) L2 cache
C) L3 cache
D) L4 cache
Answer: C) L3 cache
Explanation: L3 cache usually has the largest capacity among the cache levels but longer access times compared to L1 and L2 caches.
In a multi-level cache system, which cache level is shared among multiple processor cores?
A) L1 cache
B) L2 cache
C) L3 cache
D) L4 cache
Answer: C) L3 cache
Explanation: L3 cache is commonly shared among multiple processor cores in a multi-core system to improve overall cache utilization.
Which cache level is typically integrated into the CPU chip?
A) L1 cache
B) L2 cache
C) L3 cache
D) L4 cache
Answer: A) L1 cache
Explanation: L1 cache is often integrated directly into the CPU chip for the fastest access to data and instructions.
What is the main advantage of having multiple cache levels?
A) Lower cost
B) Increased cache capacity
C) Improved cache hit rate
D) Reduced cache access time
Answer: D) Reduced cache access time
Explanation: Multiple cache levels provide a hierarchy of memory access speeds, reducing cache access time by providing faster access to frequently used data.
Which cache level typically serves as a buffer between the CPU cores and main memory?
A) L1 cache
B) L2 cache
C) L3 cache
D) L4 cache
Answer: C) L3 cache
Explanation: L3 cache acts as a buffer between the CPU cores and main memory, providing a larger but slower cache level to bridge the gap between the fast CPU cores and slower main memory.
Which cache level is often shared across multiple CPU cores in a multi-core processor?
A) L1 cache
B) L2 cache
C) L3 cache
D) L4 cache
Answer: C) L3 cache
Explanation: L3 cache is commonly shared among multiple CPU cores in a multi-core processor to improve cache utilization and reduce access latencies.
How does the presence of multiple cache levels impact the overall system performance?
A) It decreases system performance due to cache conflicts
B) It increases system performance by reducing memory access latencies
C) It has no impact on system performance
D) It decreases system performance due to increased cache size
Answer: B) It increases system performance by reducing memory access latencies
Explanation: Multiple cache levels improve system performance by providing faster access to frequently used data, reducing memory access latencies, and improving overall system efficiency.
MEMORY WRITE ABILITY AND STORAGE PERFORMANCE
Which memory type allows both reading and writing operations and retains data even when power is turned off?
A) Volatile memory
B) Non-volatile memory
C) RAM (Random Access Memory)
D) ROM (Read-Only Memory)
Answer: C) RAM (Random Access Memory)
Explanation: RAM allows both reading and writing operations and retains data as long as power is supplied to the memory module.
Which memory type is primarily used for long-term storage and does not require power to retain data?
A) Volatile memory
B) Non-volatile memory
C) Cache memory
D) Register memory
Answer: B) Non-volatile memory
Explanation: Non-volatile memory, such as ROM and flash memory, is used for long-term storage and retains data even when power is turned off.
Which memory type is typically used as the main memory in a computer system and is volatile in nature?
A) ROM (Read-Only Memory)
B) Flash memory
C) HDD (Hard Disk Drive)
D) RAM (Random Access Memory)
Answer: D) RAM (Random Access Memory)
Explanation: RAM is the main memory in a computer system and is volatile, meaning it loses its contents when power is turned off.
Which memory type is commonly used for firmware and program storage in electronic devices?
A) RAM (Random Access Memory)
B) Cache memory
C) ROM (Read-Only Memory)
D) Virtual memory
Answer: C) ROM (Read-Only Memory)
Explanation: ROM is commonly used for firmware and program storage in electronic devices because it retains data even when power is turned off and cannot be easily modified.
Which memory type is used to temporarily store data and instructions during program execution?
A) Cache memory
B) ROM (Read-Only Memory)
C) RAM (Random Access Memory)
D) Flash memory
Answer: C) RAM (Random Access Memory)
Explanation: RAM is used as the main memory to temporarily store data and instructions needed by the CPU during program execution.
Which memory type is typically used to store the BIOS (Basic Input/Output System) in a computer system?
A) RAM (Random Access Memory)
B) ROM (Read-Only Memory)
C) Cache memory
D) Flash memory
Answer: B) ROM (Read-Only Memory)
Explanation: ROM is commonly used to store the BIOS, which is essential for booting up the computer system and initializing hardware components.
What happens to the data stored in volatile memory when power is turned off?
A) Data is retained
B) Data is erased
C) Data is moved to non-volatile memory
D) Data is corrupted
Answer: B) Data is erased
Explanation: Volatile memory loses its contents when power is turned off, resulting in the erasure of data stored in the memory.
Which memory type is typically used for high-speed storage directly accessible by the CPU?
A) ROM (Read-Only Memory)
B) HDD (Hard Disk Drive)
C) Cache memory
D) Flash memory
Answer: C) Cache memory
Explanation: Cache memory is used for high-speed storage directly accessible by the CPU to reduce access latencies and improve system performance.
What characteristic distinguishes non-volatile memory from volatile memory?
A) Speed of access
B) Capacity
C) Permanence of data storage
D) Volatility
Answer: C) Permanence of data storage
Explanation: Non-volatile memory retains data even when power is turned off, providing permanent storage, whereas volatile memory loses its contents when power is turned off.
Which memory type is commonly used for secondary storage in computer systems?
A) RAM (Random Access Memory)
B) ROM (Read-Only Memory)
C) Cache memory
D) HDD (Hard Disk Drive)
Answer: D) HDD (Hard Disk Drive)
Explanation: HDDs are commonly used for secondary storage in computer systems to provide large-capacity, non-volatile storage for data and programs.
COMPOSING MEMORY
What does the term "composing memory" refer to in computer organization?
A) The process of creating memory modules
B) The combination of multiple memory technologies into a single memory system
C) Memory allocation in programming languages
D) The arrangement of memory cells within a memory module
Answer: B) The combination of multiple memory technologies into a single memory system
Explanation: Composing memory involves integrating different memory technologies, such as DRAM and NAND flash, into a unified memory architecture.
Which of the following memory technologies is commonly used for main memory in modern computer systems?
A) Static RAM (SRAM)
B) Dynamic RAM (DRAM)
C) NAND flash
D) Magnetic disk
Answer: B) Dynamic RAM (DRAM)
Explanation: DRAM is commonly used for main memory in modern computer systems due to its high density and cost-effectiveness.
What advantage does NAND flash memory offer over DRAM?
A) Faster access times
B) Lower power consumption
C) Higher endurance
D) Volatility
Answer: B) Lower power consumption
Explanation: NAND flash memory consumes less power compared to DRAM because it does not require constant refreshing to maintain data integrity.
In a composed memory system, what role does DRAM typically play?
A) Long-term storage
B) Main memory
C) Cache memory
D) Virtual memory
Answer: B) Main memory
Explanation: DRAM is commonly used as main memory in composed memory systems due to its fast access times and relatively low cost.
Which memory technology is often used for non-volatile storage in composed memory systems?
A) DRAM
B) SRAM
C) Magnetic disk
D) Optical disk
Answer: C) Magnetic disk
Explanation: Magnetic disks, such as hard disk drives (HDDs) and solid-state drives (SSDs), are commonly used for non-volatile storage in composed memory systems.
What is one disadvantage of NAND flash memory compared to DRAM?
A) Slower access times
B) Higher power consumption
C) Limited endurance
D) Volatility
Answer: A) Slower access times
Explanation: NAND flash memory typically has slower access times compared to DRAM due to its underlying architecture and operation.
What role does cache memory play in a composed memory system?
A) Long-term storage
B) Main memory
C) Temporary storage for frequently accessed data
D) Backup storage
Answer: C) Temporary storage for frequently accessed data
Explanation: Cache memory in a composed memory system serves as temporary storage for frequently accessed data, helping to improve overall system performance.
Which memory technology offers the fastest access times but is the most expensive per unit of storage?
A) DRAM
B) NAND flash
C) SRAM
D) Magnetic disk
Answer: C) SRAM
Explanation: SRAM offers the fastest access times among common memory technologies but is the most expensive per unit of storage, making it suitable for specialized applications such as cache memory.
What is the primary advantage of composed memory systems?
A) Lower cost
B) Faster access times
C) Higher storage capacity
D) Improved energy efficiency
Answer: D) Improved energy efficiency
Explanation: Composed memory systems can achieve improved energy efficiency by integrating different memory technologies optimized for different performance and power characteristics.
Which memory technology is characterized by its ability to retain data without power and is commonly used for BIOS storage?
A) DRAM
B) SRAM
C) NAND flash
D) ROM
Answer: D) ROM
Explanation: ROM (Read-Only Memory) is characterized by its ability to retain data without power, making it suitable for storing essential system firmware like the BIOS.