boot.asm

[org 0x7c00]      ; Set origin to 0x7C00 (where BIOS loads the bootloader)

mov ah, 0x0e      ; BIOS teletype output function
mov bx, hello_msg ; Memory address of our string

print_string:
    mov al, [bx]  ; Load the character at the address in BX into AL
    cmp al, 0     ; Check if it's the null terminator
    je end        ; If it is, we're done printing
    int 0x10      ; Otherwise, call BIOS interrupt to print the character
    inc bx        ; Move to the next character
    jmp print_string

end:
    jmp $         ; Infinite loop to hang the system

hello_msg db 'Welcome to your Custom OS!', 0

; Bootloader signature
times 510-($-$$) db 0 ; Pad the rest of the 512 bytes with zeros
dw 0xaa55             ; The standard PC boot signature