Path: utzoo!attcan!uunet!cs.utexas.edu!ntvaxb!ac08 From: ac08@vaxb.acs.unt.edu Newsgroups: comp.os.misc Subject: Re: Macintosh OS (was: 68000 and Workstations.) Message-ID: <26229.266186ee@vaxb.acs.unt.edu> Date: 28 May 90 20:15:42 GMT References: <30273@ut-emx.UUCP> <76700207@p.cs.uiuc.edu> <1990May24.114553.10301@phri.nyu.edu> <37@voa3.UUCP> <402@newave.UUCP> <26200.265dd7be@vaxb.acs.unt.edu> <6392@scolex.sco.COM> Followup-To: comp.os.misc Lines: 72 In article <6392@scolex.sco.COM>, seanf@sco.COM (Sean Fagan) writes: > > Most people consider that a *true* OS has protection of some sort; that is, > some way of making sure that programs don't step on each other and can live > in peace and harmony. (Sometimes, this is done just to make sure that the > program doesn't step on the OS, true, but it's still nice to be there 8-).) > No- most people consider that a *true* OS lets the machine run, access its peripherals, and not mess on the carpet... :) You're running into the "computer science" viewpoint... 'the ideal system is whatever you happen to like...' ...up until a few years ago, small computers didn't have to sweat protected modes. People were happy to run any programs they wanted without having to submit a job to the queue, and you didn't *need* multitaksing- it was for those multimillion dollar "big iron" mainframes... ;-) > Ask yourself this: using your "OS," following all of the rules, is it > possible to write a program that will lock up the machine? On the Mac, I > think it is, under MSDOS it certainly is. On the Amiga, I don't think it > is, because the rules they laid down were oriented towards multitasking > instead of rapid screen update. Yet the Amiga doesn't have an MMU, just > like the Mac. Which one has the OS, then? Yes, it is- sorta. But it's also possible to lock up any machine under those conditions... [P.S.- Not all Macs have MMUs... As a matter of fact, most don't.] > >>So- for your next trick, are you going to prove black is white, or that >>1 + 1 = 3? > > No, the next trick would be to make sure that people take an OS course > before defining what an OS is. That's going to be very, very hard, though, > I think. > No- the hard part is keeping people from redefining what an operating system is- in defiance of what everybody else calls it... Just because they tell you something in class, it doesn't automatically make it true... The Mac is *not* a top-notch multitasking operating system- but it *is* an operating system. >>[Written with more than a little tongue in cheek... the Mac OS is more of >>an operating "system" than most, since it *does* have a fairly firm set of >>rules, as opposed to most machines, which have few outside of the coding of >>the ROMS and the CPU...] > > Huh? The Mac, last time I checked, had a lot of routines a programmer could > use, some of which were in ROM, others in RAM, but not much else. I have > never, for example, seen something that said "do not modify the Status > Register" (N.B.: It's been a while, I'll admit, and I may have missed it. > If so, I'd be glad to hear about it). > And piles upon piles of manuals on the Mac OS... which makes it hard for a person to know them all. The strongest part of an operating system is the framework it provides for the user and programmer. But if you *really* follow all of the rules in all of your programs, they won't crash. But humans aren't smart enough to do that... :) > -- > -----------------+ > Sean Eric Fagan | "It's a pity the universe doesn't use [a] segmented > seanf@sco.COM | architecture with a protected mode." C Irby ac08@vaxb.acs.unt.edu ac08@untvax