Before you get started, here's a tool disk to help you create and pack stuff for your programming.
DOWNLOAD HERE

CONTENTS

Chapter 1: INTRODUCTION, AND ABOUT ASSEMBLERS

Chapter 2: ASSEMBLY COMMANDS

Chapter 3: SCREEN PROGRAMMING

Chapter 4: RASTER SPLITS AND INTERRUPTS

Chapter 5: SPRITES, GRAPHICS AND PROGRAMMING YOUR OWN GAMES

Chapter 6: SPLITTING BITMAP PICTURE DATA, MULTIPLE INTERRUPTS, It's DEMO MAKING TIME

For more code, it is recommended that you also try out the the Codebase Wiki web site.