8-Bit Pipelined Processor – ELC3030 Project

Overview

This project implements a simple 8-bit pipelined processor using Verilog HDL, designed as part of the Advanced Processor Architecture (ELC 3030) course at the Faculty of Engineering, Cairo University.

The processor follows a RISC-like Instruction Set Architecture (ISA) and supports five pipeline stages with hazard detection and data forwarding.
The complete design flow and verification steps are documented in the accompanying design report, while functional requirements follow the project specification document.

Project Objectives

• Design and implement an 8-bit pipelined processor
• Support Von Neumann architecture
• Apply FSM-based control logic
• Implement data forwarding and hazard handling
• Verify correctness using directed testbenches and waveform analysis

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Processor Specifications

• Architecture: 5-stage pipelined RISC processor
• Data Width: 8 bits
• Registers:
  • 4 General Purpose Registers (R0–R3)
  • R3 functions as a Stack Pointer (SP), initialized to 255
• Memory:
  • 256 bytes, byte-addressable
  • Von Neumann architecture (shared instruction and data memory)
• Reset: Asynchronous, active-high
• Interrupt: Non-maskable external interrupt

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Pipeline Stages

The processor consists of the following pipeline stages:

1. Instruction Fetch (IF)

   • Fetches the instruction from memory using the Program Counter (PC)

2. Instruction Decode (ID)

   • Decodes the instruction and reads operands from the register file

3. Execute (EX)

   • Performs ALU operations and evaluates branch conditions

4. Memory Access (MEM)

   • Handles load/store instructions and stack operations

5. Write Back (WB)

   • Writes execution results back to the register file

Each stage is implemented as a separate Verilog module.

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Instruction Set Architecture (ISA)

The processor supports multiple instruction formats, including:

• Arithmetic & Logical Operations
  • ADD, SUB, AND, OR, NOT, INC, DEC
• Data Transfer
  • MOV, LDM, LDD, STD, LDI, STI
• Control Flow
  • JMP, JZ, JN, JC, JV, LOOP
• Stack Operations
  • PUSH, POP, CALL, RET, RTI
• Input/Output
  • IN, OUT

Instruction encoding and behavior are defined in the project specification.

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Hazard Detection and Data Forwarding

To ensure correct pipelined execution, the design includes a Hazard Detection and Handling Unit.

Supported Hazards

• Data hazards
• Structural hazards
• Load-use hazards

Techniques Used

• Memory → Execute forwarding
• Write Back → Execute forwarding
• Write Back → Decode forwarding
• Pipeline stalling when forwarding is not sufficient

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Verification and Testing

• Each major module has an independent testbench
• Directed test cases verify:
  • Functional correctness
  • Reset behavior
  • Pipeline flow
  • Hazard handling
• Simulation waveforms are analyzed to confirm correct operation

All verification steps and results are documented in the design report.

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Synthesis

The design was synthesized and analyzed for:

• Logic utilization
• Timing constraints
• Maximum operating frequency
• Post-synthesis schematic

Synthesis results are included in the project report.

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