Microprocessor & Interfacing — 8086 Assembly Mini Projects

A comprehensive collection of 8086 Assembly Language mini-projects developed for the Microprocessors & Interfacing (MP&I) course in the Computer Science & Engineering (CSE) program using EMU8086.

Repository Structure

├── Interactive Menu-Driven Calculator/
│   ├── Menu_Driven_Calculator.asm
│   └── README_Menu_Driven_Calculator.md
│
├── Password Verification System/
│   ├── Password_Verification_System.asm
│   └── README_Password_Verification_System.md
│
├── Shopping & Billing System/
│   ├── Shopping_Billing_System.asm
│   └── README_Shopping_Billing_System.md
│
├── Student Result Calculator/
│   ├── Student_Result_Calculator.asm
│   └── README_Student_Result_Calculator.md
│
└── README.md

Projects Overview

#	Project Name	Key Mechanics
1	Student Result Calculator	16-bit arithmetic operations (ADD, DIV), conditional grading branches, stack-based dynamic integer printing using PRINT_NUM.
2	Interactive Menu-Driven Calculator	Infinite execution loop, user menu selection using DOS interrupt (INT 21H, AH=01H), arithmetic processing logic.
3	Shopping & Billing System	POS-style state tracking, dynamic variable updates in .DATA, itemized checkout calculation, and bill generation.
4	Password Verification System	Keyboard input buffering, multi-byte string validation using CMPSB, and attempt counter-based security lockout.

Technical Highlights & Assembly Concepts

All projects are developed using standard 16-bit x86 Real Mode Assembly Language principles and follow the academic requirements of the Microprocessor & Interfacing course.

Memory Addressing & Data Alignment

Concepts implemented:

• 16-bit word storage using DW
• Byte arrays and strings using DB
• Memory pointer operations using:
  • SI
  • DI
• Stack segment allocation:

.STACK 100H

Register Arithmetic & Logic

Arithmetic operations are performed using 8086 registers:

Register	Purpose
AX	Primary accumulator for arithmetic operations
BX	Secondary operand storage
CX	Loop counter and string operation length
DX	Data storage and DOS interrupt communication

Implemented instructions:

ADD
SUB
MUL
DIV
INC
DEC

Control Flow & Branching

Programs use conditional comparisons and jump instructions for decision-making:

Comparison:

CMP

Conditional jumps:

JE
JNE
JGE

These instructions control:

• Menu selection
• Grade calculation
• Password verification
• Input validation

DOS Interrupt Services (INT 21H)

The projects use DOS interrupt services for user interaction.

AH Value	Function
01H	Read a single keyboard character with echo
02H	Display a single ASCII character
09H	Display a string ending with $ delimiter
4CH	Safely terminate program execution

Example:

MOV AH, 09H
INT 21H

String Processing

The Password Verification System demonstrates 8086 string manipulation:

Instructions used:

CLD
REPE CMPSB

Concepts covered:

• Direction flag handling
• Memory block comparison
• SI/DI pointer-based string processing

How to Compile & Run

1. Download & Install Emulator

Install EMU8086 on Windows.

2. Open Assembly Source Code

1. Launch EMU8086.
2. Click Open.
3. Select any .ASM file from the project directories.

Example:

Student_Result_Calculator.asm

3. Emulate & Execute

1. Click Emulate or press: F5

2. In the emulator window, click Run.

3. Interact with the application through the terminal.

Academic Information

Category	Details
Course	Microprocessors & Interfacing (MP&I)
Architecture	Intel 8086 / 8088 Microprocessor
Development Tool	EMU8086 v4.08+

Learning Outcomes

Through these mini-projects, the following 8086 Assembly concepts are demonstrated:

• Memory organization and addressing
• Register-level arithmetic operations
• DOS interrupt-based input/output
• Conditional branching and loops
• Stack operations
• String comparison instructions
• Real-mode x86 programming fundamentals
• Basic application development using Assembly Language