FASM syntax (replace use16 with BITS 16 if using NASM)
Simple bootloader made by AshlandGaming! <3

Using INT 16 (for pause), INT 10 (string printing) and 0xffff:0000 (reboot)

To boot on physical hardware (e.g "Acer computers")

use16
org 0x7C00

jmp Start

Start:
mov si, msg
call Print

xor ah, ah
int 16h

jmp word 0xffff:0000 ; Change word to dword if problems happen

Print:
lodsb
cmp al, 0
je Done
mov ah, 0eh
int 10h
jmp Print

Done:
ret

cli
hlt

msg db 'Hello World! Press any key to reboot...', 13, 10, 0

times 510-($-$$) db 0
dw 0xAA55