4-Digit-Decimal-Calculator

A complete and professional digital logic design of a 4-Digit Decimal Calculator, built and simulated in Logisim / Logisim Evolution.
The calculator accepts two 4-digit decimal operands (each digit encoded in 4-bit BCD), performs addition or subtraction, and displays the final result on a four-digit seven-segment display system.

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📌 Overview

This project demonstrates the full design workflow of a multi-digit digital arithmetic system.
The calculator operates on two 4-digit decimal numbers and supports:

• ➕ Addition
• ➖ Subtraction (via two’s complement arithmetic)

The project highlights correct bus routing, splitter usage, control logic, and structured datapath design.

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🎯 Features

• ✔ Supports two 4-digit decimal numbers (each digit = 4-bit BCD)
• ✔ Addition & Subtraction modes
  • 0 → Addition
  • 1 → Subtraction (two’s complement)
• ✔ Seven-segment display output (BCD decoded)
• ✔ Ideal for Digital Logic Design (DLD) courses and demonstrations

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▶️ How to Run This Project in Logisim

✔ Requirements

• Java Runtime Environment (JRE)
• Logisim

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✔ Steps to Run

1. Download or extract the project folder.

   • JRE
   • Logisim
   • The CalculatorCircuit.circ file

2. Open Logisim and Load the circuit file:

   • Go to File → Open
   • Select:

     CalculatorCircuit.circ
     

3. View the Top-Level Circuit
   You will see all main components:

   • Input DIP switches
   • Operation selector
   • Register datapath
   • Seven-segment display modules

4. Enter Input Values

   • Use DIP switches to set each 4-bit BCD digit

5. Choose the Operation

   • Set the selector switch to:
     • 0 → Addition
     • 1 → Subtraction

6. Observe Output

   • The result is displayed across four seven-segment displays

7. Reset

   • Use the reset pin/button to clear all registers and flags

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👤 Contributors

Name
Partho Kumar Mondal
Shahriar Hossain Thesun
Md. Irfan Iqbal

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