Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site hocda.UUCP Path: utzoo!watmath!clyde!burl!hou3c!hocda!54394gt From: 54394gt@hocda.UUCP (G.TOMASEVICH) Newsgroups: net.unix-wizards Subject: Levels of UNIX, an opinion, a question Message-ID: <356@hocda.UUCP> Date: Mon, 6-Feb-84 15:54:36 EST Article-I.D.: hocda.356 Posted: Mon Feb 6 15:54:36 1984 Date-Received: Thu, 9-Feb-84 07:36:46 EST Organization: Bell Labs, Holmdel Lines: 10 In the paging-in-somewhere discussion someone asked if UNIX has any levels besides kernel and user. I believe not; it originated on a PDP-11, probably one without supervisor level (I'm not sure). Now the only use of supervisor mode on the PDP-11 is to accommodate a kernel that outgrew the kernel-mode address space. At that point, UNIX already started becoming a pig, and now look where it is! You need a VAX, huge disks, etc. to run everything. The shell was outside the kernel because of the address space limit. The question: where should one draw the line on putting shell, terminal features, editor, etc when the machine has a huge address space? This leads to Rob Pike's discussion.