This document outlines a mini-project to practice addition, subtraction, and converting between ASCII and hexadecimal formats. It provides algorithms for converting 2-digit hexadecimal numbers to ASCII and vice versa. The project instructions are to create I/O functions, input 2 numbers as ASCII, convert to hexadecimal, calculate and display the sum and difference, and allow the user to repeat. An example output is given demonstrating handling of positive and negative results.

1. Project # 3 Page 1 of 1
Mini-Project #3
Name: Date Performed:
Objectives:
• Addition/Subtraction
• ASCII to Hex (for 3 digits)
• Hex to ASCII
***Review***
• Hex-to-ASCII
Before a number could be displayed, it has to be converted to ASCII format. Given a 2-
digit number, the algorithm to convert hex to ASCII is as follows:
o Place the 2-digit number in register AL.
o Use AAM (ASCII Adjust for Multiplication) instruction. This instruction will
separate the 2 digit number to AH (ten) and AL (unit).
o Add 3030H to register AX.
* You could apply AAM twice if the number is greater than 100 but less than 255.
• ASCII-to-Hex
If the number to be manipulated is in ASCII format (i.e., via keyboard input), it has to be
converted to hex before it could be processed. Given a 2-digit number in ASCII format,
the algorithm to convert ASCII to HEX is as follows:
o Place the 2-digit number (ASCII format) in register AX.
o Use AAD (ASCII Adjust for Division) instruction. This instruction will combine
the number into register AL.
Instructions:
• Clear Screen.
• Place all basic I/O routines as functions in your main program: Clear Screen, Read String,
Write String, Read character w/o echo, Skip line (i.e. “n”), HEX-to-ASCII, ASCII-to-
HEX.
• Clear Screen.
• Input #1: First number (2 digits)
• Check for null input. If exists issue an error message and input again.
• Input #2: Second Number (2 digits)
• Check for null input. If exists issue an error message and input again.
• Convert ASCII input to HEX so that you could manipulate it properly.
• Display the SUM and DIFFERENCE of the two numbers. Note that if the result is
negative, you should place a negative sign in front of the number.
• Prompt the user whether the program will be executed again.
• See the example below for the output.

2. Project # 3 Page 2 of 2
First Number: 5
Second Number: 2
SUM = 7
DIFFERENCE = 3
Do you want to continue (Y/N)? Y
First Number: 0
Second Number: 99
SUM = 99
DIFFERENCE = -99
Do you want to continue (Y/N)? Y
First Number: 99
Second Number: 99
SUM = 198
DIFFERENCE = 0
Do you want to continue (Y/N)? N