There are several OS development related tutorials on this wiki. This page is an overview of tutorials that are around, sorted by subject area and difficulty. Try these first. It may be a good idea to do some easier stuff first.
Assembly Nasm Bootloader x86 - Code Review Stack Exchange
Follow the installation instructions. On the next screen you will be prompted to select your device. Make sure you select exactly the one you are using. After selecting your device the code editor appears.
Join Stack Overflow to learn, share knowledge, and build your career. Connect and share knowledge within a single location that is structured and easy to search. Have you tried int 21h service 2? DL is the character to print. To print the integer value, you'll have to write a loop to decompose the integer to individual characters.
AmigaOS is a family of proprietary native operating systems of the Amiga and AmigaOne personal computers. It was developed first by Commodore International and introduced with the launch of the first Amiga, the Amiga , in Early versions of AmigaOS required the Motorola series of bit and bit microprocessors.