Tic-Tac-Toe in x86 Assembly Language

A classic two-player Tic-Tac-Toe game implemented entirely in x86 Assembly language. This project is designed to run in a DOS environment and provides a simple, text-based interface for gameplay.

🌟 Features

• Two-Player Gameplay: Play against a friend, with Player 0 using 'X' and Player 1 using 'O'.
• Text-Based Interface: A clean and simple command-line interface.
• Dynamic Game Board: The 3x3 board is displayed and updated after each move.
• Win Detection: The game automatically checks for win conditions across all rows, columns, and diagonals.
• Draw Detection: Recognizes when the board is full and no player has won, resulting in a draw.
• Clear Game Status: Displays whose turn it is and announces the winner or a draw at the end of the game.

🛠️ How to Run

To run this game, you will need an x86 assembler (like MASM or TASM) and a DOS emulator (like DOSBox).

Prerequisites

• Assembler: MASM or TASM.
• DOS Emulator: DOSBox is recommended for modern operating systems.

Steps

1. Setup DOSBox:

   • Install and run DOSBox.
   • Mount the directory containing the .asm file as your C: drive. For example, if your project is in C:\dev\assembly, you would type:

     mount c C:\dev\assembly
     c:
     

2. Assemble the Code:

   • Use your assembler to create the object file (.obj). The filename in the example is Tic Tac Toe (Assembly Language Project).asm. You may want to rename it to something simpler like tictac.asm.
   • Using MASM:

     masm "Tic Tac Toe (Assembly Language Project).asm";
     

   • Using TASM:

     tasm "Tic Tac Toe (Assembly Language Project).asm"
     

3. Link the Object File:

   • Create the executable file (.exe) from the object file.
   • Using MASM's Linker:

     link "Tic Tac Toe (Assembly Language Project).obj";
     

   • Using TASM's Linker:

     tlink "Tic Tac Toe (Assembly Language Project).obj"
     

4. Run the Game:

   • Execute the newly created program.

     "Tic Tac Toe (Assembly Language Project).exe"
     

🎮 How to Play

1. The game starts with Player 0.

2. When prompted, enter a number from 1 to 9 to place your mark on the board. The positions correspond to the board as follows:

   1 | 2 | 3
   --+---+--
   4 | 5 | 6
   --+---+--
   7 | 8 | 9
   

3. Player 0 places an 'X' and Player 1 places an 'O'.

4. Players take turns until one player gets three of their marks in a row, column, or diagonal.

5. If all nine squares are filled and no player has won, the game ends in a draw.

📂 Code Structure

The code is organized into data and code segments with clear procedures for each part of the game's logic.

• DATA SEGMENT:

  • Defines all the necessary variables, including the GAME_BOARD, player turn tracker (PLAYER), win/draw flags, and all the text strings displayed to the user.

• CODE SEGMENT:

  • START: The main entry point of the program. It initializes the game and enters the main loop.
  • MAIN_LOOP: The core of the game. It clears the screen, displays the board and player info, waits for input, updates the board, and checks for a win or draw condition.
  • CHANGE_PLAYER: Toggles the current player between '0' and '1'.
  • UPDATE_DRAW: Places the current player's mark ('X' or 'O') on the board at the selected position.
  • CHECK_LINE, CHECK_COLUMN, CHECK_DIAGONAL: A set of procedures that iterate through the board to check for a winning combination.
  • CHECK_DRAW: Scans the board to see if it's full, indicating a draw.
  • GAMEOVER / DRAW: Displays the final game result on the screen.
  • Helper Procedures: Includes functions for PRINT (displaying strings), CLEAR_SCREEN, and READ_KEYBOARD (getting user input).

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This project serves as a great example of game development and system-level programming using Assembly language.

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👤 Author

Muhammad Zeeshan Islam

Co-Founder – Unicodrex | Technical Lead – Skill Sprint | Trainee Game Developer – CEGA | Prompt Engineer