Direct-Mapped Cache Memory Design

Overview

This project implements a direct-mapped cache memory using Verilog to demonstrate how cache memory reduces main memory access latency. The design models basic cache behavior including address breakdown, hit/miss detection, and read/write operations, providing a clear understanding of memory hierarchy concepts.

Background

Modern processors operate much faster than main memory, creating a performance gap known as the memory wall. Cache memory bridges this gap by storing frequently accessed data closer to the CPU. A direct-mapped cache offers a simple and fast caching technique where each memory block maps to exactly one cache line.

Cache Architecture

• Fixed mapping of memory blocks to cache lines
• Address divided into Tag, Index, and Offset fields
• Each cache line stores:
  • Data
  • Tag
  • Valid bit
  • Dirty bit

Supported Operations

Read Operation

• Cache Hit: Data is returned directly from the cache
• Cache Miss: Data is fetched from main memory and placed into the cache

Write Operation

• Supports Write-Through and Write-Back policies
• Handles both hit and miss scenarios appropriately

Implementation Details

• Written in Verilog HDL
• Includes comparator logic for tag matching
• FSM-based control logic manages cache access and memory operations
• Main memory module simulates cache fills and evictions

Verification

• Functionality verified using timing diagrams
• Waveform analysis confirms correct behavior for hit, miss, read, and write cases

Key Concepts Covered

• Memory hierarchy
• Cache mapping techniques
• Hit and miss handling
• Verilog-based hardware design
• Timing and waveform analysis

Future Improvements

• Set-associative cache implementation
• Performance comparison with fully associative cache
• Parameterized cache size and block size