LC-3 Celsius to Fahrenheit Converter

Author: Will Hall
Course: CS155 — Computer Organization and Assembly Language
Final Project — Spring 2025

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Project Description

This LC-3 assembly program converts a two-digit Celsius temperature (00–99) into Fahrenheit using the formula:

F = (C × 9 / 5) + 32

The program:

• Prompts the user to input two ASCII digits
• Converts those digits into an integer Celsius value
• Applies fixed-point arithmetic using integer instructions only
• Outputs the resulting Fahrenheit value in clean, 3-digit decimal format

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Features Demonstrated

• Subroutine usage with JSR and RET
• Manual ASCII-to-integer conversion
• Fixed-point integer multiplication and loop-based division
• Controlled output formatting using TRAP routines
• Stack pointer initialization (R6)
• Register discipline and clean, modular program structure
• All code written using instructions from the textbook (Patt & Patel)

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How to Run

This program is designed to run using LC3Tools, the modern command-line and GUI LC-3 simulator:

https://github.com/jrincayc/LC3tools

1. Open the LC-3 Simulator
2. Load the file: celsius_to_fahrenheit_final.asm
3. Assemble the program (Assemble → Assemble All)
4. Set PC to x3000 if not already set
5. Run the program (Simulate → Run)
6. Input two digits when prompted (e.g., 3 and 0 for 30°C)
7. The program will output the Fahrenheit result

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Special Requirements

• Must be run in LC3Tools — the modern LC-3 simulator
• Only works with numeric input (00 to 99) — no input validation is provided
• Output is always in 3-digit format (e.g., 032, 086, 111)

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What I Learned

This project involved debugging and understanding:

• How to simulate math operations without floating-point support
• Why register preservation is critical
• How trap routines interact with display formatting
• The LC-3 instruction lifecycle and memory safety
• How to structure a clean, modular assembly program under real constraints

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Final Notes

This project was written and debugged over two months. Every line of logic was hand-built, corrected, and verified through repeated testing. It is stable, accurate, and designed to reflect mastery of the LC-3 as taught in this course.