Mike Dimmick wrote: Did OS/2 use stack-based exception handlers, or is this just an oddity of the original NT implementation? As far as I recall (and bear in mind that all my experience was on Microsoft OS/2 which stopped at version 1.3 or thereabouts (released in early 1991?)) there was was no concept of application level exception handlers at all. If there were I certainly didn't run across them but then again, I was writing kernel mode device drivers at the time and not doing PM programming. Mike Dimmick wrote: A major reason that Win32 ignores the segment registers is simply that no other processor architecture has them, and NT was originally designed to be portable to different architectures You make a good point and one that we're apt to forget these days. Yes there was once a time when NT would run on hardware other than x86 based, and it was planned that successor operating systems would also run on such hardware. Reading that line back it sounds sarcastic but I didn't mean it that way. The market spoke. Rob Manderson http://www.mindprobes.net "I killed him dead cuz he was stepping on my turf, cutting me out of my bling the same way my ho cuts cookies, officer" "Alright then, move along" - Ian Darling, The Lounge, Oct 10 2003