2-bit Full Adder / Subtractor (Chained)

This project demonstrates a 2-bit binary adder/subtractor built from first principles—chaining two full adders. It includes implementations in Assembly (x86-64) and JavaScript.

What it does

• Adds or subtracts two 2-bit numbers (a and b).
• Uses a control flag sub (1 for subtraction, 0 for addition).
• Outputs the 2-bit result and the final carry/borrow.
• Mimics gate‑level logic: XOR for sum, AND/OR for carry, and inversion for subtraction.

Files

• 2adder.asm – NASM assembly implementation (prints result and carry to stdout).
• 2adderSubtraction.js – The addition and subtraction version.
• 2adder.js – The older addition version.
• index.html – To run the script (maybe pretty later).
• .gitignore – To ignore other files.

How to run

Assembly

nasm -f elf64 2adder.asm -o 2adder.o
ld 2adder.o -o 2adder
./2adder

JavaScript

• Download one of the 2 Js files and the index.html
• Put them in the same folder and open the index.html
• Open the browser console to see the results