Boot-code tracing was a highly effective method for cracking copy protection schemes on the Apple II. In it, you would load the first sector of your target disk into RAM at hex address $800, and then replace the routine's normal out point with a break. Executing the modified routine would initiate the boot process, but then immediately return control to you. By repeating these steps at each stage of the process, you could trace the entire bootstrapping process, until you identified and disabled the copy protection routines.