​In this blog post, we’ll explore how to convert a BCD (Binary-Coded Decimal) number into its binary equivalent using an 8086 assembly language program. The following code snippet demonstrates this process:

DATA SEGMENT
NO1 DB "9036"
D2 DB ?
D1 DB 16 DUP(?)
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE, DS:DATA
START:
MOV AX, DATA
MOV DS, AX
LEA SI, NO1
LEA DI, D1
MOV CX, 04H
TOP:
MOV AL, [SI]
MOV DX, 0CH
UP1:
ROL AX,1
DEC DX
JNZ UP1
AND AX, 1111000000000000B
MOV DX, 04H
UP2:
ROL AX, 1
JNC DN
MOV BX, 1
MOV [DI], BX
JMP DN2
DN:
MOV BX, 0
MOV [DI], BX
DN2:
INC DI
DEC DX
JNZ UP2
INC SI
DEC CX
JNZ TOP
INT 3
CODE ENDS
END START

In this blog post, we’ll explore how to reverse an array using an 8086 assembly language program. We will walk through the logic, the step-by-step execution, and provide a working code snippet to illustrate the process.

Overall Process:

1. The program initializes registers and sets up pointers to the source (ARR) and destination (REV_ARR) arrays.
2. It processes each element of the original array, copying it in reverse order to the destination array.
3. After processing all elements, the program terminates, leaving the reversed array in memory.

8086 Assembly Code:

DATA SEGMENT
STR1 DB 01H,02H,05H,03H,04H
STR2 DB 5 DUP(?)
DATA ENDS

CODE SEGMENT
ASSUME CS:CODE, DS:DATA
START:
MOV AX, DATA
MOV DS, AX
LEA SI, STR1
LEA DI, STR2+4
MOV CX, 05H

BACK: CLD
MOV AL, [SI]
MOV [DI], AL
INC SI
DEC DI
DEC CX
JNZ BACK

INT 3
CODE ENDS
END START

A palindrome is a word, phrase, or sequence that reads the same forward and backward. This 8086 assembly program determines whether a given string is a palindrome by reversing the string and comparing it to the original.

The program follows these steps:

1. Initialize the Data Segment: Load the string to be checked.
2. Reverse the String: Store the reversed string in another memory location.
3. Compare the Original and Reversed Strings: Use CMPSB to compare byte-by-byte.
4. Print the Result: Display whether the string is a palindrome or not.

In this blog post, we’ll explore how to perform a block transfer using an 8086 assembly language program. The following code snippet demonstrates this process:

DATA SEGMENT
STRING1 DB 01H,02H,03H,04H,05H
STRING2 DB 4 DUP(0)
DATA ENDS

CODE SEGMENT
ASSUME CS:CODE,DS:DATA
START: MOV AX,DATA
MOV DS,AX
MOV ES,AX
LEA SI,STRING1
LEA DI,STRING2
MOV CX,05H
CLD
REP MOVSB
INT 3
CODE ENDS
END START

Array search is where assembly starts feeling like real programming — you need a pointer, a counter, a comparison, and a conditional branch, all working together. This program searches a five-element byte array for a target value and prints either “FOUND” or “NOT FOUND” using a reusable MACRO that wraps the DOS print call.

DOS interrupt 21h function 09h is the easiest way to print a string in 8086 assembly: point DX at your string, set AH to 09h, call INT 21h, and you’re done. No loop, no character counter, no BX pointer arithmetic. The tradeoff is a minor convention: the string must end with a $ character so DOS knows where to stop. Compare this with the function 02h character loop approach — 09h is cleaner for fixed strings; 02h gives you more control for dynamic output.

INT 10h is the BIOS video interrupt — completely separate from the DOS INT 21h family. Where INT 21h talks to the operating system, INT 10h talks directly to the video BIOS to control the screen: cursor shape, cursor position, character output, screen modes. This short program demonstrates two of those functions: setting the cursor shape and moving it to a specific screen position.