16 bit assembly bootstrapped loader

boot.asm

bits 16 ; 16-bit Real Mode
org 0x7c00 ; BIOS boot origin 

jmp main ;jump to MAIN function

;Print-Variables 
Message db "MY OWN BOOTLOADER...", 0x0 
MessageB db "Written in x86 assembly language...", 0x0
AnyKey db "Press (ctrl+c) key to reboot...", 0x0 

;Function to print characters to the screen 
Println:
    lodsb ;Load string 
    or al, al
    jz complete
    mov ah, 0x0e 	
    int 0x10 ;BIOS Interrupt 0x10 - Used to print characters on the screen via Video Memory 
    jmp Println ;Loop   	
complete:
    call PrintNwL

;Function to print new lines like '\n' in C/C++ 	
PrintNwL: 
    mov al, 0	; null terminator '\0'
    stosb       ; Store string 
    ;Adds a newline break '\n'
    mov ah, 0x0E
    mov al, 0x0D
    int 0x10
    mov al, 0x0A 
    int 0x10
	ret

;Function to reboot the Machine 
Reboot: 
    ;Sends us to the end of the memory
    ;causing reboot 
    db 0x0ea 
    dw 0x0000 
    dw 0xffff 

;Function which gets the pressed key from the keyboard 
GetPressedKey:
    mov ah, 0
    int 0x16  ;BIOS Keyboard Service
    ret    
   
;Bootloader entry-code | MAIN FUNCTION
main:
    cli ;Clear interrupts 
    ;Setup stack segments 
    mov ax,cs              
    mov ds,ax   
    mov es,ax               
    mov ss,ax                
    sti ;Enable interrupts 
    call PrintNwL
    call PrintNwL
    call PrintNwL
    call PrintNwL
    call PrintNwL
    ;Print the first characters  
    mov si, Message 
    call Println 
    mov si, MessageB
    call Println 
    mov si, AnyKey
    call Println
    label:  call GetPressedKey
            cmp al,03h
            jnz label
    call Reboot 


times 510 - ($-$$) db 0 ;Fill the rest of the bootloader with zeros 
dw 0xAA55 ;Boot signature

CustomBootloader

1. compile the above code using nasm using the command :
      nasm -f bin boot.asm -o boot.img
2. make a bootable usb of the image file created above.