I've read the through the first bootsector's code, and everything looks good with objdump: _second_stage_start label is supposed to be at ram 0x7e00 and the code calls it, but I'm trying to make my own second stage and don't understand just how the second stage is placed after the first one. I've tried assembling a program with nasm -f bin and just cat appending to the original file, but that doesn't seem to work, even if the new code is at offset 0x7e00. Am I missing something?