8086-ASSEMBLY-LANGUAGE-PROGRAMS/Source Code/Introduction/display_string_direct.asm at main · Amey-Thakur/8086-ASSEMBLY-LANGUAGE-PROGRAMS · GitHub

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; =============================================================================
; TITLE: Display String Direct
; DESCRIPTION: Direct string output demonstration using the DOS 09H service
;              with a standard segment layout.
; AUTHOR: Amey Thakur (https://github.com/Amey-Thakur)
; REPOSITORY: https://github.com/Amey-Thakur/8086-ASSEMBLY-LANGUAGE-PROGRAMS
; LICENSE: MIT License
; =============================================================================

; -----------------------------------------------------------------------------
; DATA SEGMENT - Constant storage
; -----------------------------------------------------------------------------
DATA SEGMENT
    MESSAGE DB "Hello World - This is a direct string test!$"
DATA ENDS

; -----------------------------------------------------------------------------
; CODE SEGMENT - Implementation
; -----------------------------------------------------------------------------
CODE SEGMENT
    ASSUME CS:CODE, DS:DATA

START:
    ; Point data segment register to our data area
    MOV AX, DATA
    MOV DS, AX

    ; Setup Display String function
    MOV AH, 09H                     ; Function 09h: Print string at DS:DX
    LEA DX, MESSAGE                 ; Pointer to the string
    INT 21H                         ; Call DOS kernel

    ; Exit safely
    MOV AX, 4C00H
    INT 21H

CODE ENDS

END START

; =============================================================================
; TECHNICAL NOTES
; =============================================================================
; 1. STRING NOTES:
;    - The string must exist in a segment pointed to by DS.
;    - LEA (Load Effective Address) is a highly efficient way to get the
;      offset of a memory label.
; = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =