Path: utzoo!mnetor!uunet!cbmvax!daveh From: daveh@cbmvax.UUCP (Dave Haynie) Newsgroups: comp.sys.amiga Subject: Re: Amiga UNIX Message-ID: <3663@cbmvax.UUCP> Date: 20 Apr 88 18:43:35 GMT References: <211@laic.UUCP> Organization: Commodore Technology, West Chester, PA Lines: 69 in article <211@laic.UUCP>, darin@laic.UUCP (Darin Johnson) says: > Has anyone bothered to think about writing a non-VM unix for the Amiga? > Buying a 68020/851 card for the 2000 just to run unix seems like a waste > to me. Also, if it indeed requires 100Meg disk (and can't be pruned down > to say... 10Meg) it will indeed be out of my league (I have no problem > leaving find/uucp/vi/uncompress/etc. on floppy). You don't absolutely have to have virtual memory in a UNIX system, though you'll probably find, given the typical size of the more useful UNIX applications, that lots of stuff won't run without it, unless you've got gobs of real memory. What you must have, however, for a modern UNIX, is some form of memory relocation, paging, whatever you'd like to call it. This gives you things like fork() which don't exist in the AmigaOS, and basically require that each process run at the same address. While the 80286 machines that Xenix run on are pretty brain damaged from an architectural point of view, their segmentation scheme works as well as paging to make each process appear to run at the same location in memory. So you can just drop Xenix into an AT[Clone] and go. The plain old 68000 doesn't support anything like that. Which leaves you with three choices: [1] Don't worry about paging. Or the fork() function. Thus also not worrying about running any standard UNIX OS. [2] Don't page in hardware, which leaves your task swap overhead as probably the largest task in your OS, and make the not- overly-efficient-UNIX-OS such a pig as to make it useless. [3] Add some expensive hardware, like an MMU for paging, VM, and protection. Also add a faster CPU that'll handle VM as well and give you the power to run UNIX at an acceptable speed too. > I don't think (could be wrong) that Xenix requires any sort of special > hardware (or gobs of file space). Therefore, why is Commodore writing > a version that will be so expensive to use? It would be real smart of > them to write a version that will work with or without the > extra card. The UNIX port for the Amiga is a real, AT&T System V.3, same thing that runs on VAXen around the world. Xenix is something rather strange; I'm not sure that kludge is the right word, but the fact that it's running on AT[Clones] leads me to believe that kludge may not be the wrong word. What I do know is that any real UNIX OS on a 68020 system is going to be inherently better than any UNIX OS on an AT[Clone] system, and especially so if you're used to VAXen or Suns rather than PDP-11s (well, some folks still use PDP-11s). > And again, I my just wait for someone to port MINIX and then I'll be halfway > there... Naa. What's Minix, something like Version 7. With no memory protection. So what you get can be mathematically calculated as: Version 7 ----------------------------- = 28% of the way there. 22 (V is the 22nd letter) + 3 And that doesn't even take into account the memory protection. > Darin Johnson (...lll-lcc.arpa!leadsv!laic!darin) > (...ucbvax!sun!sunncal!leadsv!laic!darin) > All aboard the DOOMED express! -- Dave Haynie "The B2000 Guy" Commodore-Amiga "The Crew That Never Rests" {ihnp4|uunet|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy "I can't relax, 'cause I'm a Boinger!"