Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site watmath.UUCP Path: utzoo!watmath!idallen From: idallen@watmath.UUCP Newsgroups: net.unix-wizards Subject: Re: unix & real time -- is a rewritten UNIX still UNIX? Message-ID: <9785@watmath.UUCP> Date: Fri, 9-Nov-84 19:12:51 EST Article-I.D.: watmath.9785 Posted: Fri Nov 9 19:12:51 1984 Date-Received: Sat, 10-Nov-84 09:25:18 EST References: <39@uwvax.UUCP>, <5633@brl-tgr.ARPA> Organization: U of Waterloo, Ontario Lines: 32 > From: gwyn@brl-tgr.ARPA (Doug Gwyn ) > > [That UNIX does not do real-time stuff well] is an old myth based partly > on fact. > > [List of drawbacks was here.] > > All these drawbacks can be overcome by a competent UNIX system programmer. But is what you get after all those hacks still UNIX? Someone posted a simple "fix" to a "bug" in Berkeley Pascal involving a missing "default" in the CASE statement, and the cries went up that the resulting language was no longer "Pascal". Interesting point. How much UNIX can you hack up and still call it UNIX? An interesting question, but not the central point I want to make. UNIX can do anything if you just rewrite this or that. The same applies to any piece of software -- if you rewrite it, it can do anything. I guess people who pose questions about what UNIX can do have to be more explicit when they ask. For example (hypothetical): I have a binary multi-user UNIX 4.2bsd. Can *my* UNIX do real time stuff nicely? (Answer: No.) I now have an old V6 UNIX with source code. Can *my* UNIX support virtual memory? (Answer: Yes. Just have a competent UNIX system programmer overcome this drawback by modifying the kernel.) When one says X supports Y after {one,six,twenty} man-months of rewriting, is that a fair answer? I think not. I think a fair answer would say "No, X doesn't support Y, but if you want to spend N weeks changing X, *you* can create *your own* version of X that supports Y." -- -IAN! (Ian! D. Allen) University of Waterloo