Computer Architecture Memory Concepts

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Questions and Answers

What is the primary goal of cache memory?

To keep all processing within the main memory.

To eliminate the use of main memory completely.

To ensure all data is permanently stored.

To provide memory access times similar to the fastest memories. (correct)

Which technique allows the processor to handle I/O while still executing other tasks?

Interrupt-driven I/O (correct)

Polling method

Direct Memory Access (DMA)

Programmed I/O

What does a non-vectored interrupt lack compared to a vectored interrupt?

It cannot be used for high-priority tasks.

It does not specify the address of the interrupt service routine. (correct)

It does not provide multiple interrupt sources.

It cannot hold the current state of the processor.

What is the primary function of the interrupt vector table?

To hold the addresses of service routines for interrupts. Signup and view all the answers

How does the Least Recently Used (LRU) algorithm function in cache management?

It replaces the block that was least recently accessed. Signup and view all the answers

What is the method by which data is transferred directly between an I/O device and memory without processor intervention called?

Direct Memory Access (DMA) Signup and view all the answers

Which of the following best describes the block size in cache memory management?

The unit of data exchanged between the cache and main memory. Signup and view all the answers

Which mechanism is most efficient for memory operations when trying to minimize memory writes?

Write-back policy Signup and view all the answers

What characterizes a vectored interrupt?

The interrupting device sends a unique vector to the CPU. Signup and view all the answers

In a non-vectored interrupt system, how does the CPU identify the interrupting device?

By polling each device to determine which one requested the interrupt. Signup and view all the answers

What is the main function of an interrupt vector table?

It maps interrupt vectors to their corresponding ISR addresses. Signup and view all the answers

What is one drawback of a non-vectored interrupt?

It requires additional time for polling each device. Signup and view all the answers

Which of the following is NOT a tradeoff in memory hierarchy design?

Higher access speed with no increase in cost. Signup and view all the answers

How does a non-vectored interrupt generally signal a device is ready for handling?

By sending a common signal understood by all devices. Signup and view all the answers

What is a primary consideration in the design of memory hierarchy?

Balancing capacity, speed, and cost effectively. Signup and view all the answers

What is one feature of vectored interrupts that distinguishes them from non-vectored ones?

They allow dynamic identification of the ISR based on device input. Signup and view all the answers

What is the primary purpose of a memory hierarchy in computing?

To utilize multiple memory components with varying costs and speeds Signup and view all the answers

What does the Principle of Locality of Reference imply?

Certain memory addresses are accessed more frequently within short periods Signup and view all the answers

Which of the following best describes secondary memory?

It is non-volatile and used for long-term storage of data Signup and view all the answers

What limits the rate at which a processor can execute instructions?

The memory cycle time during read/write operations Signup and view all the answers

How does increasing access time in a memory hierarchy affect overall system performance?

It decreases overall performance by slowing down data access. Signup and view all the answers

What is the role of cache memory in the context of a processor's operation?

To fetch instructions and operands swiftly Signup and view all the answers

Which statement accurately describes the relationship between frequency of access and memory utilization?

Decreased access frequency can indicate effective caching. Signup and view all the answers

What typically happens to memory clusters accessed by a processor over time?

They tend to shift but retain stable usage over short periods. Signup and view all the answers

Study Notes

Memory Hierarchy

A memory hierarchy is used to avoid reliance on a single memory component or technology.
Components in the hierarchy are organized by decreasing cost per bit, increasing capacity, increasing access time, and decreasing access frequency by the processor.
Locality of Reference principle indicates that memory references by the processor tend to cluster, with short-term consistent clusters observed during program execution.

Secondary Memory

Secondary memory, also known as auxiliary or external memory, is non-volatile storage for program and data files.

Cache Memory: Motivation

Processors access memory at least once per instruction cycle, limiting execution speed by memory cycle time.
Cache memory is used to bridge the speed gap between processor and main memory, enhancing instruction execution rates.

Interrupt Processing

Vectored interrupts allow the CPU to know the Interrupt Service Routine (ISR) address in advance, enhancing efficiency.
A device sends a unique vector to the CPU, which then references an interrupt table to execute the appropriate ISR.
Non-vectored interrupts, or polled interrupts, use a common ISR for all requests, requiring the CPU to poll devices to determine the interrupt source.

Memory Design Constraints

Memory design depends on capacity, access time, and cost, generating trade-offs in performance and expense.
Solutions for capacity vs. speed dilemma include using cache memory to exploit locality principles, bridging slow main memory and fast processor speeds.

Cache Memory Principles

Objectives of cache memory include achieving fast memory access timings while supporting larger memory sizes through less costly memory types.
Multi-level caching improves performance through tiered levels of cache.

Cache Size and Management

Cache size directly impacts overall performance, even small caches can yield significant performance gains.
Block size defines the data unit exchanged with main memory, while mapping functions determine block placement in cache.
Replacement algorithms like Least-Recently-Used (LRU) prioritize which blocks to replace based on usage history.

Write Policy in Cache

When a cache block is altered, it must be written back to main memory before replacement.
Write operations can occur continuously or only during block replacement, with aims to minimize redundant writes and maintain efficient cache operation.

I/O Operations

The processor interacts with I/O modules through specific instructions, executing these via commands.
Three techniques for I/O operations include Programmed I/O, Interrupt-driven I/O, and Direct Memory Access (DMA), each offering different performance characteristics.

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Description

This quiz covers key concepts related to memory hierarchy, including cache memory, secondary memory, and interrupt processing. Explore how these components work together to improve processor efficiency and speed during program execution.