09

Microprocessors Lab - Experiment 9

Checking Palindrome and Converting BCD to Binary using 8086 Microprocessor

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Aim

• (a) Write an ALP to check whether a string is a palindrome or not.
• (b) Write an ALP to convert a BCD number into binary format.

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Requirements

• Microprocessor: 8086
• Software: MASM (Microsoft Macro Assembler)

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Program Code

(a) Checking if a String is a Palindrome:

DATA SEGMENT
    BLOCK1 DB 'MALAYALAM'    ; String to check
    MSG1 DB "IT IS PALINDROME $"
    MSG2 DB "IT IS NOT PALINDROME $"
    PAL DB 00H
DATA ENDS

PRINT MACRO MSG
    MOV AH,09H
    LEA DX,MSG
    INT 21H
    INT 3H
ENDM

EXTRA SEGMENT
    BLOCK2 DB 9 DUP(?)        ; Adjust the length of BLOCK2 to match the input string
EXTRA ENDS

CODE SEGMENT
ASSUME CS:CODE, DS:DATA, ES:EXTRA
START:
    MOV AX, DATA
    MOV DS, AX
    MOV AX, EXTRA
    MOV ES, AX
    LEA SI, BLOCK1
    LEA DI, BLOCK2 + 8      ; Adjust destination index to end of BLOCK2
    MOV CX, 0009h           ; Adjust loop count to match string length
BACK:
    CLD
    LODSB
    STD
    STOSB
    LOOP BACK
    LEA SI, BLOCK1
    LEA DI, BLOCK2
    MOV CX, 0009h           ; Adjust loop count here as well
    CLD
    REPZ CMPSB
    JNZ SKIP
    PRINT MSG1              ; Print message if palindrome
    JMP END_PRINT
SKIP:
    PRINT MSG2              ; Print message if not a palindrome
END_PRINT:
CODE ENDS
END START

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(b) Converting BCD to Binary:

DATA SEGMENT
    NO DB 32H               ; BCD number (32 in hexadecimal)
DATA ENDS

CODE SEGMENT
ASSUME CS:CODE, DS:DATA
START:
    MOV AX, DATA
    MOV DS, AX
    MOV AX, 0000H
    MOV BL, NO
    MOV AL, NO
    MOV DL, AL
    AND DL, 0FH             ; Extract the lower nibble
    AND AL, 0F0H            ; Extract the higher nibble
    MOV CL, 4
    ROR AL, CL              ; Rotate AL by 4 to shift higher nibble to lower
    MOV DH, 0AH
    MUL DH                   ; Multiply by 10 (decimal)
    ADD AL, DL              ; Add the lower nibble to AL
    MOV CX, AX              ; Store the result in CX
    MOV BL, NO
    INT 3H
    INT 21H
CODE ENDS
END START

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Outputs

(a) Palindrome Check Result:

(b) BCD to Binary Conversion Result:

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Result/Conclusion:

Thus, we successfully wrote an ALP to check if a string is a palindrome and to convert a BCD number into binary format using the 8086 microprocessor and MASM.

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Prepared by:
Name: Jjateen Gundesha
Registration Number: BT22ECI002

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