Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!lll-crg!lll-lcc!unisoft!mtxinu!ed From: ed@mtxinu.UUCP (Ed Gould) Newsgroups: net.arch Subject: Re: Paging Message-ID: <78@mtxinu.UUCP> Date: Mon, 8-Sep-86 13:29:23 EDT Article-I.D.: mtxinu.78 Posted: Mon Sep 8 13:29:23 1986 Date-Received: Tue, 9-Sep-86 02:27:34 EDT References: <8494@duke.duke.UUCP> <147@eneevax.UUCP> <536@cubsvax.UUCP> <654@hropus.UUCP> <7092@utzoo.UUCP> Reply-To: ed@mtxinu.UUCP (Ed Gould) Organization: mt Xinu, Berkeley, CA Lines: 22 Henry Spencer: >"Virtual memory", strictly speaking, refers to memory that acts like it's >always there but sometimes isn't. I would quibble slightly. To me, virtual memory refers to a memory space that is different than the physical memory of the machine. A PDP-11 has a virtual memory space of 2^16 bytes, or perhaps 2*2^16 bytes. But some models of the machine have a physical memory space of nearly 2^22 bytes. This is not what most people - including me - usually mean when casually talking about virtual memory. Then, it does refer to a virtual space that is larger than the available physical space (available either because the remainder is allocated to other uses, or not physically present), and is managed by some technique like demand paging that allows partly- resident processes to execute. -- Ed Gould mt Xinu, 2560 Ninth St., Berkeley, CA 94710 USA {ucbvax,decvax}!mtxinu!ed +1 415 644 0146 "A man of quality is not threatened by a woman of equality."