LEA Instruction
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the Input character can be stored in the data segment
like this:
.DATA
MSG1 DB ‘ENTER A
LOWERCASE LETTER: $’
MSG2 DB 'IN UPPER CASE
IT IS: '
CHAR DB ?,’$’
LEA DX,MSG2
MOV AH,9
INT 21h
Because MSG2 does not end with ‘$’, INT 21h goes on
and displays the character- stored In CHAR.
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Home work solution
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Case Conversion
Exercise :
Write a program begins by prompting the user
to enter a lowercase letter, and on the next line
displays another message with the letter In
uppercase.
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Solution
.MODEL SMALL
.STACK 100H
.DATA
MSG1 DB ‘ENTER A LOWER CASE LETTER: $’
MSG2 DB 0DH,0AH,‘IN UPPER CASE IT IS: ’
CHAR DB ?,’$’
.CODE
MAIN PROC
MOV AX,@DATA
MOV DS,AX
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; print user prompt
LEA DX,MSG1
MOV AH,9
INT 21H
;input a character and convert to upper case
MOV AH,1
INT 21H
SUB AL,20H
MOV CHAR,AL
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;display on the next line
LEA DX,MSG2
MOV AH,9
INT 21H
;DOS exit
MOV AH,4CH
INT 21H
MAIN ENDP
END MAIN
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.MOEDL SMALL
.STACK 100K
.DATA
.CODE
MAIN PRO
MOV AX,@DATA
MOV DS,AX
MOV AH,4CH
INT 21H
MAIN ENDP
END MAIN
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Programming Exercise (1)
Write a program to (a) prompt the user, (b) read
first, middle, and last initials of a person's name,
and (c) display them down the left margin.
Sample execution:
ENTER THREE INITIALS: JFK
J
F
K
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Programming Exercise (2)
Write a program to display a 10 x 10 solid box of
asterisks.
Hint: declare a string in the data segment that
specifies the box, and display it
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Programming Exercise (3)
Write a program to translate the following high
level language assignment statements into
assembly language
• A=B-A
• A = - (A+ 1)
• C=A+B
• A=B-A-1
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