Part- 2: Understanding the RISC-V Core: The 5-Stage Pipeline Explained

RISC-V core follows a classic 5-stage pipeline design. This approach processes instructions efficiently by breaking them down into smaller, manageable steps. Each stage handles a specific part of instruction execution, allowing multiple instructions to be processed simultaneously, boosting overall performance.

Fig: Pipelined processor with hazard handling




Let’s dive into these five stages:


1️⃣ Instruction Fetch (IF) Stage

Objective: Fetch instructions from memory.

Key Components:

  • Program Counter (PC)
  • Instruction Memory

Tasks:

  • Increment the PC.
  • Fetch the instruction from memory using the current PC.

2️⃣ Instruction Decode (ID) Stage

Objective: Decode the fetched instruction and read register values.

Key Components:

  • Register File (holds general-purpose registers)
  • Control Unit (generates control signals)

Tasks:

  • Decode the opcode and control signals.
  • Read source registers from the register file.

3️⃣ Execute (EX) Stage

Objective: Perform ALU operations, compute addresses for memory operations, and evaluate branch conditions.

Key Components:

  • ALU (Arithmetic Logic Unit)
  • Branch Target Address Generator (for branches and jumps)

Tasks:

  • Execute arithmetic or logical operations.
  • Compute branch target addresses.

4️⃣ Memory Access (MEM) Stage

Objective: Access memory for load/store operations.

Key Components:

  • Data Memory (used for load/store instructions)

Tasks:

  • Read or write data to/from memory for load/store instructions.

5️⃣ Write Back (WB) Stage

Objective: Write the result back to the destination register.

Tasks:

  • Write the result to the register file from the ALU or memory.

⚠️ Hazard Unit

Objective: Detect and handle pipeline hazards (data, structural, control).

Key Components:

  • Forwarding Unit (resolves data hazards)
  • Stall Control Unit (handles pipeline stalls)
  • Branch Prediction Logic (optional for control hazards)

Tasks:

  • Detect hazards in the pipeline.
  • Apply forwarding or stalling as needed to ensure smooth pipeline execution.

This breakdown helps you understand the fundamental components and tasks at each stage in the 5-stage RISC-V pipeline. Stay tuned for more insights into how each stage works in detail with real examples in the next sections!

Comments

  1. My Man is some quality Content.😊

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  2. Sir Could you please share the programming files regarding Risc v

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    1. Thank you for your interest! I’m unable to share the RISC-V files directly, but feel free to check out my About page to reach out for guidance or further questions.

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