Technolocus: Calculating the average of 3 given numbers

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This program will find the average of three numbers given by the user. If the sum of these numbers are not divisible by 3 then approximate average will be shown i.e. the nearest integer will be displayed. Detailed explanation of the code is given as comment. The program is done in Emu8086.



data SEGMENT
    msg1 DB 'Enter 1st number: $'        ;Initializes the strings 
    msg2 DB 0dh,0ah,'Enter 2nd number: $';to be printed to assist 

    msg3 DB 0dh,0ah,'Enter 3rd number: $';user to enter 3 numbers 
    msg4 DB 0dh,0ah,'The average is: $'  ;and print the average. 

    n1 DB ?    ;Defines variables, a '?' means  
    n2 DB ?    ;no value is entered,values will 
    avg DB ?   ;stored at the time of execution. 

    ten DB 10   

ENDS 

code SEGMENT
start: 

    MOV AX, data ;Initializes data segment 
    MOV DS, AX 

    print MACRO msg       ;Define a macro "print". 
        MOV AH,09h        ;Prints the string 'msg' 
        MOV DX,OFFSET msg ;whose starting offset is 
        INT 21h           ;stored in DX. 
    ENDM 

    print msg1  ;Prints the first message 
    MOV AH,01h  ;Asks user for an input 

    INT 21h     ;stores the ASCII value in AL 
    SUB AL,'0'  ;Calculates true binary value 
    MOV n1,AL   ;Stores the value in 'n1' 

    print msg2  ;Prints the second message 
    MOV AH,01h  ;Asks user for second input 
    INT 21h     ;and stores the ASCII in AL 

    SUB AL,'0'  ;Calculates true binary value 
    MOV n2,AL   ;Stores the value in 'n2' 

    print msg3  ;Prints the third message 
    MOV AH,01h  ;Asks user for third input 
    INT 21h     ;and stores the ASCII value in AL 

    SUB AL,'0'  ;Calculates the true binary value 

    ADD AL,n1   ;Add 'n1'to the content of AL 
    ADD AL,n2   ;Add 'n2' to the sum in AL 

    MOV AH,00h  ;Clears AH 
    MOV BL,3    ;Moves the divisor 3 into BL 
    DIV BL      ;Divide AX by 3 and get average 

    MOV avg,AL  ;Stores result in 'avg' 

    print msg4
    MOV AL,avg     ;Brings result in AL 
    MOV AH,0       ;Clears AH 

    DIV ten        ;If the result is not valid BCD 
    MOV DL,AL      ;divide the result by 10 to get  
    MOV CL,AL      ;the first digit and stores it in DL and CL 

    ADD DL,'0'     ;Get the ASCII code 
    MOV AH,02h
    INT 21h        ;Prints the first digit 

    MOV AL,CL      ;Mov the first digit to AL 
    MUL ten        ;Multiply it by 10 
    SUB avg,AL     ;get the second digit  

    XCHG DL,avg    ;stores second digit in DL 
    ADD DL,'0'     ;Get the ASCII value 
    MOV AH,02h
    INT 21h        ;Print the second digit..Voila!

    MOV AX, 4c00h ;Exit to operating system. 
    INT 21h
ENDS 

END start