MIPS Assembly Project — Computer Architecture

Author: Mostafa Tarek Khalil

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📌 Overview

This project is a MIPS Assembly program that demonstrates fundamental concepts of computer architecture including:

• String/character manipulation using ASCII values
• Integer arithmetic (addition & subtraction)
• Conditional branching (user-driven operation selection)
• MIPS syscall interface for I/O
• Direct memory addressing in the data segment

The project was built alongside an equivalent C++ implementation to validate correctness and illustrate the mapping between high-level and low-level code.

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📁 Project Structure

├── Arch_Project.asm        # MIPS Assembly source code
├── Arch_Project.cpp        # Equivalent C++ source code
└── Arch_Project_Executable_File.pdf     # Compiled executable breakdown (text + data segments)

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⚙️ What the Program Does

1. Display Name Characters with ASCII Values

Prints the first character of each word in the name "Mostafa Tarek Khalil" along with its ASCII integer value:

Character	Index in String	ASCII	Output
M	0	77	M : 77
T	8	84	T : 84
K	14	75	K : 75

2. Display Section Number

Prints Section : 24

3. Read Three Integers from User

Prompts the user to enter three numbers: N1, N2, N3.

4. User-Driven Operation Selection

Asks: "Enter 1 if you want sum or 2 if you want sub"
Uses MIPS branch instructions (beq/bne) to jump to the correct label.

Choice	Operation	Formula
1	Sum	N1 + N2 + N3
2	Subtraction	N1 - N2 - N3

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🖥️ Sample Output

Test Case 1 — Sum (N1=30, N2=20, N3=5):

M : 77
T : 84
K : 75
Section : 24
Enter The First Number : 30
Enter The Second Number : 20
Enter The Third Number : 5
Enter 1 if you want sum or 2 if you want sub: 1
sum (N1+N2+N3) = 55

Test Case 2 — Subtraction (N1=100, N2=30, N3=15):

M : 77
T : 84
K : 75
Section : 24
Enter The First Number : 100
Enter The Second Number : 30
Enter The Third Number : 15
Enter 1 if you want sum or 2 if you want sub: 2
sub (N1-N2-N3) = 55

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🔧 MIPS Assembly — Key Concepts Used

Registers

Register	Usage
$t0	Base address of name string / section number (reused)
$t1–$t3	Stores N1, N2, N3 (user input)
$t4–$t5	Intermediate and final sum
$t6–$t7	Intermediate and final subtraction
$s2	User choice (1=sum, 2=sub)
$a0	Argument for syscall (print/read)
$v0	Syscall code selector

Syscall Codes

Code	Operation
1	Print integer
4	Print string
5	Read integer
10	Exit program
11	Print character (ASCII)

Data Segment Layout

Label	Address	Content
name	0x10010000	"Mostafa Tarek Khalil"
section	0x10010018	24 (word)
sec	0x1001001c	"Section"
colon	0x10010024	" : "
num1	0x10010028	Prompt string
num2	0x10010042	Prompt string
num3	0x1001005d	Prompt string
res1	0x10010077	"sum (N1+N2+N3)="
res2	0x10010089	"sub (N1-N2-N3)="

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📦 Executable File Details

Property	Value
Total Header Size	0x1A0 (416 bytes)
Text Segment Size	0x9D (157 bytes)
Text Segment Start	0x00400000
Data Segment Start	0x10010000
Total Instructions	41 instructions

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💻 C++ Equivalent

#include <iostream>
using namespace std;

int main() {
    string name = "Mostafa Tarek Khalil";
    int sec = 24;

    cout << name[0]  << " : " << (int)name[0]  << "\n";  // M : 77
    cout << name[8]  << " : " << (int)name[8]  << "\n";  // T : 84
    cout << name[14] << " : " << (int)name[14] << "\n";  // K : 75

    cout << "Section : " << sec << "\n";

    int num1, num2, num3, choice;
    cout << "Enter The First Number : ";  cin >> num1;
    cout << "Enter The Second Number : "; cin >> num2;
    cout << "Enter The Third Number : ";  cin >> num3;
    cout << "Enter 1 if you want sum or 2 if you want sub: "; cin >> choice;

    if (choice == 1)
        cout << "sum (N1+N2+N3) = " << num1 + num2 + num3 << '\n';
    else
        cout << "sub (N1-N2-N3) = " << num1 - num2 - num3;

    return 0;
}

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🚀 How to Run

MIPS Assembly (using MARS Simulator)

1. Download MARS MIPS Simulator
2. Open Project_Arch.asm
3. Press Assemble (F3) then Run (F5)
4. Enter the three numbers when prompted, then choose 1 for sum or 2 for subtraction

C++ Version

g++ -o project Project_Arch.cpp
./project

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📚 Concepts Covered

• MIPS data and text segment organization
• Load byte (lb) and load word (lw) instructions
• Arithmetic instructions: add, sub
• Conditional branching: beq, bne for user-driven flow
• Syscall interface for console I/O
• Register conventions and usage
• Relationship between C++ high-level code and MIPS assembly

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Computer Architecture Project — Faculty of Computers & Artificial intelligence - Benha University