Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!usc!gem.mps.ohio-state.edu!sunybcs!rutgers!bpa!cbmvax!valentin From: valentin@cbmvax.UUCP (Valentin Pepelea) Newsgroups: comp.realtime Subject: Re: Realtime and UNIX (Re: An opportunity for Commodore (Re: Windows without Front/Back gadgets)) Keywords: unix Message-ID: <8552@cbmvax.UUCP> Date: 14 Nov 89 05:39:14 GMT References: <22175@gryphon.COM> <4537@sugar.hackercorp.com> <788@jc3b21.UUCP> <4679@cbnewsc.ATT.COM> <4532@sugar.hackercorp.com> <104@amix.commodore.com> Reply-To: valentin@cbmvax.UUCP (Valentin Pepelea) Organization: Commodore Technology, West Chester, PA Lines: 68 In article <104@amix.commodore.com> ford@amix.commodore.com (Mike "Ford" Ditto) writes: >In article <4532@sugar.hackercorp.com> peter@sugar.hackercorp.com (Peter da Silva) writes: >>UNIX is not real time. Many of the things we now take for granted would just >>not be possible under UNIX, or would be unbearably slow. It would kill the >>... > >Everything in the above paragraph is false. Peter doesn't seem to >know a trademark from an operating system implementation. There are >many things commonly called "Unix", and even the ones to which the >trademark actually applies are widely varied and evolve over time. >Apparently Peter has never seen one which meets his expectations of a >real-time system, and has concluded that if he has not seen it, it can >not possibly exist. Ever. > >"Unix", as people (except Peter) seem to be using the term here, >refers to a fairly abstract model of multitasking, and a set of >programmer interfaces to it. It typically also implies a set of tools >and user interfaces in the form of a set of programs. None of these >notions have any relation whatsoever to real-time performance. The I think you are a little unfair to Peter here. It is generally accepted by the masses that Unix is not a real-time operating system because most implementations out there do not have any real-time extensions. Whether an OS bearing the Unix name can be easely implemented to support real-time applications is therefore a moot question. >"Unix" and "real-time" are orthogonal concepts. You can have either >one without the other, or neither, or both. For a Unix wizard like you, having ported Unix to our platform this is exact. For a guy like me and Peter, this is fresh news. >With AmigaDos we technically have neither, although we are close enough on >both sides to do some good things. This is highly debatable. I, personally, can guarantee you that any event can be start to be processed under the Amiga's Exec within 200 microseconds, with an average of considerably below that. I can also show you how to break that response time, but then you can do that with any real-time operating system. It's all a question of how you set your priorities. Note though, that there are some on the devellopment team who also think the Exec does not meet precisely the real-time criteria. >>It's possible to build a realtime system that looks like UNIX, but Commodore >>does not have the resources to do this. > >If you mean there aren't enough programmers here to implement a >real-time OS from scratch in this decade, you're probably right. But >Commodore has other resources; for example such a system could be >licensed. The people who came up with OS/9 provide nifty libraries under it that make the OS look like Unix to the programmer. They already have a 680x0 port of OS/9. The problem with licencing another real-time OS is that all the current software would break under it. Another option though is to simply provide a library which runs under AmigaDOS and emulates Unix functions as well as it can. I remember that Deven Cervone had volunteered to do just that. It sound like an interesting university student project. Valentin -- "An operating system without memory is Name: Valentin Pepelea an operating system without virus." Phone: (215) 431-9327 UseNet: cbmvax!valentin@uunet.uu.net - Kodiak Claimer: these are only bad opinions