Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!harpo!seismo!hao!hplabs!sri-unix!gwyn@brl-vld From: gwyn%brl-vld@sri-unix.UUCP Newsgroups: net.unix-wizards Subject: Re: Levels of UNIX, an opinion, a question Message-ID: <16704@sri-arpa.UUCP> Date: Thu, 9-Feb-84 15:58:16 EST Article-I.D.: sri-arpa.16704 Posted: Thu Feb 9 15:58:16 1984 Date-Received: Mon, 20-Feb-84 01:07:59 EST Lines: 9 From: Doug Gwyn (VLD/VMB)The early UNIXes for memory-managed (KT11) PDP-11s were available for the PDP-11/40 as well as the PDP-11/45. The /40 architecture was similar to the more familiar /34 in that it had Kernel & User modes but not separate Instruction & Data spaces. Two "modes" are both necessary and sufficient for controlled resource sharing with the typical memory manager architecture.