Article View: comp.sys.mac
Article #20261Re: Virtual Memory with the Mac OS
From: Alan Lovejoy
Date: Tue, 13 Oct 1987 13:52
Date: Tue, 13 Oct 1987 13:52
18 lines
1480 bytes
1480 bytes
In article <6453@apple.UUCP> north@apple.UUCP (Donald N. North) writes: >For the record, the HMMU (an Apple custom, not a 68461) adds ONE wait state >to each basic memory access; when it is replaced with a PMMU (68851) TWO wait >states are added to each memory access. Thus it only pays to use the 68851 >when you really need it (ie, for A/UX). It not only costs you $$ but degrades >performance too. >-- > >Don North >Apple Computer, Inc. >Advanced Technology Group It appears my sources were wrong (I've never looked inside a Mac II myself). One of my sources also maintains that two wait-states are necessary for mother-board memory accesses so that NuBus devices can access it. Is there any truth to this (now I doubt everything!)? --alan@pdn
Technical Details
Message-ID:
<1514@pdn.UUCP>Path:
arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!umd5!mimsy!oddjob!gargoyle!ihnp4!homxb!mtuxo!mtune!codas!usfvax2!pdn!alanReferences:
<2653@okstate.UUCP> <2542@batcomputer.tn.cornell.edu> <1478@pdn.UUCP> <6453@apple.UUCP>Show Full Headers
Complete Article Headers
Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!umd5!mimsy!oddjob!gargoyle!ihnp4!homxb!mtuxo!mtune!codas!usfvax2!pdn!alan From: alan@pdn.UUCP (Alan Lovejoy) Newsgroups: comp.sys.mac Subject: Re: Virtual Memory with the Mac OS Message-ID: <1514@pdn.UUCP> Date: Tue, 13-Oct-87 09:52:56 EDT Article-I.D.: pdn.1514 Posted: Tue Oct 13 09:52:56 1987 Date-Received: Thu, 15-Oct-87 06:24:27 EDT References: <2653@okstate.UUCP> <2542@batcomputer.tn.cornell.edu> <1478@pdn.UUCP> <6453@apple.UUCP> Reply-To: alan@pdn.UUCP (0000-Alan Lovejoy) Organization: Paradyne Corporation, Largo, Florida Lines: 18 Keywords: virtual memory 68851 HMMU wait states