TRW2000 is a good 16-bit debugger from the saintly days of yore. It is a lot like ollydbg. I used it quite a few times with older applications. I do not quite remember if it works on XP. I think I may have used it on XP, but I don't fully recall how or if it worked.
Download:
Code:
https://exelab.ru/download.php?action=get&n=MzQw