Parallel Processing Unit

Build a simple parallel processor with multiple ALUs working simultaneously—the fundamental concept behind GPU computing.

Overview

GPUs are powerful because they do many simple operations at once instead of one complex operation at a time. This project demonstrates parallel processing by building four identical ALU channels that all perform the same operation simultaneously on different data. You'll input four values, and all four get processed in a single clock cycle—this is SIMD (Single Instruction, Multiple Data) in action!

Components Needed

  • 4x SN74LS181 IC (ALU)
  • 2x SN74HC374 IC (Register)
  • 16x LED
  • 2x DIP switch (8-position)
  • manyx Wires

Instructions

  1. Build Four Identical ALU Channels

    Set up four 74LS181 ALUs on your breadboards. Connect all their function select lines (S0-S3, M) together—they will all perform the same operation. Each ALU gets its own independent data inputs.

  2. Connect Shared Control Bus

    Wire the function select switches to all four ALUs in parallel. When you change the operation, all ALUs change together. This is the "Single Instruction" part of SIMD.

  3. Wire Independent Data Inputs

    Each ALU channel gets its own 4-bit input via DIP switches or registers. This is the "Multiple Data" part—each ALU processes different values.

  4. Add Output Display

    Connect 4 LEDs to each ALU output (16 total). When you clock the system, all four results appear simultaneously.

  5. Demonstrate Parallel Speedup

    Set all ALUs to ADD mode. Input four different values. In one clock cycle, you get four addition results. A single ALU would need four cycles for the same work!

Challenges

  • Expand to 8 parallel channels
  • Add input registers with parallel load from a data bus
  • Implement a simple shader-like operation across all channels
  • Build a parallel comparator for searching data