Path: utzoo!attcan!uunet!cs.utexas.edu!rutgers!njin!princeton!udel!mmdf
From: MROBINSON@wash-vax.bbn.com
Newsgroups: comp.sys.amiga
Subject: AmigaOS is real-time?
Message-ID: <16100@louie.udel.EDU>
Date: 23 May 89 18:23:45 GMT
Sender: mmdf@udel.EDU
Lines: 26


Is AmigaOS truly a real-time OS?  I mean, I know it doesn't have much
overhead for context switches, and I know the message passing is designed
to be as lean as possible, but real-time?  I'm not entirely clear on what
Forbid() and Permit() do (if I find a case where I feel I need some
synchronization, semaphores will be my first choice, and only in the
direst emergency would I ever use these bad boys), but I don't think they
automagically create a real-time OS.

To me, real-time means that each system call is guaranteed to complete
within a *defined* amount of time (which should be small).  Like, if the
time limit comes along and the call is not done, it unwinds and fails,
and still manages to finish trying within the defined time limit.  Does
AmigaOS have these defined durations for the system calls?  Where do I
find the durations in print?

If AmigaOS is only nearly-realtime, or "real-time if one surrounds the
system call that needs to be completed in a stated amount of time with
Forbid() and Permit()", please don't call it real-time.  That would be
as bad as calling MacOS multi-tasking (yes, I know, MultiFinger IS
non-preemptively multi-tasking, but that means that sometimes the Mac
won't act like its multi-tasking, just like a nearly real-time OS will
sometimes not act like its real-time).  How about NRT for nearly real-time?
Un*x and such are of course NRT (not real-time) -- maybe surreal-time :)

--Max Robinson mrobinson@wash-vax.bbn.com