Many years ago I worked with Data General minis running AOS/VS. We asked one of DG's gurus if there was a way to undelete a file, and he said that the best bet was to crash the system at once, and see whether FIXUP brought it back.
Break on old sub machines is something I totally forgot about. I remember it used to halt when you plugged in the keyboard, which was super annoying when you had to use one.
