Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!uc!nic.MR.NET!hal!ncoast!allbery From: allbery@NCoast.ORG (Brandon S. Allbery) Newsgroups: comp.sys.mac Subject: Re: Nix on mixing memory speeds? Message-ID: <1989Sep23.010904.7650@NCoast.ORG> Date: 23 Sep 89 01:09:04 GMT References: <11979@cit-vax.Caltech.Edu> <4002@phri.UUCP> <2040@leah.Albany.Edu> Reply-To: allbery@ncoast.ORG (Brandon S. Allbery) Followup-To: comp.sys.mac Distribution: usa Organization: North Coast Public Access UN*X, Cleveland, OH Lines: 33 As quoted from <2040@leah.Albany.Edu> by jh0576@leah.Albany.Edu (Joe Houghtaling): +--------------- | In article <4002@phri.UUCP>, roy@phri.UUCP (Roy Smith) writes: | [in response to an inquiry on mixing speeds of memory chips] | > Bullshit. | | Please, if you can't make a constructive addition to the net, at least | don't be insulting. +--------------- He was insulting only to the person who claimed to the original poster that the memory speeds *had* to match. (His dealer, if I remember correctly.) Said dealer may be trying to make him pay more than he has to, or he may simply not know any better, but either way his claim is bogus. (semi-techie explanation; my field is software, but I've dealt with memory) There is, by and large, only *one* case where the memory speeds would have to match: if the memory storage system accesses more than one memory chip at the same time, all of those chips must be the same speed or the memory access hardware will get a severe case of heartburn. Of course, the Mac *does* access more than one chip at the same time; but that's why the constraint is on *banks* of SIMMs. The Mac memory hardware requires speeds to be the same over a bank of memory because a memory access is actually 16 bits (68000) or 32 bits (68020/030); thus, a SIMM bank is two SIMMs on an SE (2 * 8 RAM chips per SIMM) and four (4 * 8) on the II and its descendants. ++Brandon -- Brandon S. Allbery, moderator of comp.sources.misc allbery@NCoast.ORG uunet!hal.cwru.edu!ncoast!allbery ncoast!allbery@hal.cwru.edu bsa@telotech.uucp, 161-7070 BALLBERY (MCI), ALLBERY (Delphi), B.ALLBERY (GEnie) Is that enough addresses for you? no? then: allbery@uunet.UU.NET (c.s.misc)