johnsone@uxh.cso.uiuc.edu (02/10/90)
/* Written 9:08 am Feb 7, 1990 by regan@cs.Buffalo.EDU in */
> Technology Works assured me that the speed difference wouldn't matter, . . .
The people at some of the MacMailOrder places have told me that the speed
doesn't matter, but the dealer here in town said that it might -- as a
practice, the dealer here does not install faster memory (e.g. 80ns) with
memory that is slower (e.g. 100ns).
So what's the correct answer? Does it make a difference?
Erik A. Johnson
Graduate Student, Aero/Astro Engineering
University of Illinois at Urbana-Champaign
johnsone@uxh.cso.uiuc.eduMARCELO@phoenix.princeton.edu (MARCELO) (02/12/90)
In article <88500005@uxh.cso.uiuc.edu> johnsone@uxh.cso.uiuc.edu writes: > The people at some of the MacMailOrder places have told me that the speed > doesn't matter, but the dealer here in town said that it might -- as a > practice, the dealer here does not install faster memory (e.g. 80ns) with > memory that is slower (e.g. 100ns). > > So what's the correct answer? Does it make a difference? > > > Erik A. Johnson When working for an Apple dealer I found that memory hogs (like HyperCard) tend to have problems with simms of different speeds .. I even had some Macs come in with the "Sad Mac" bootups and when running diags on them the problem turned out to be the simms (different speeds) .. Although I'm not sure if the simms went bad because of faulty manufacturing or becasue of the mix of speeds but to stay on the safe side I would recomend keeping the speed the same ..
russ@key.COM (Russell Donnan) (02/14/90)
In article <13800@phoenix.Princeton.EDU> MARCELO@phoenix.princeton.edu (MARCELO) writes: {In article <88500005@uxh.cso.uiuc.edu> johnsone@uxh.cso.uiuc.edu writes: {> The people at some of the MacMailOrder places have told me that the speed {> doesn't matter, but the dealer here in town said that it might -- as a A DEALER told you this??? You have to be kidding! {> {> So what's the correct answer? Does it make a difference? {> {> Erik A. Johnson { { When working for an Apple dealer I found that memory hogs (like {HyperCard) tend to have problems with simms of different speeds .. I even {had some Macs come in with the "Sad Mac" bootups and when running diags on {them the problem turned out to be the simms (different speeds) .. Although {I'm not sure if the simms went bad because of faulty manufacturing or {becasue of the mix of speeds but to stay on the safe side I would recomend {keeping the speed the same .. I was forwarded a thread from rec.audio where people where painting their CD collection green because it made the audio sound better. If this isn't funny, read on: ;-) Lets get one thing straight: The Mac (excluding the IIci) is going to expect to be able to get data from the RAMs in 120ns. The speed quoted on your SIMMs is the worst case data access of the RAMs. Now what that means to you and me is that ANY RAM chips which will have the data available to the Mac by 120ns will work. Putting faster RAMs in won't help you, but it won't hurt you either. Your only real constraint is, that you must put the same SIZE SIMMs in the same RAM bank. Its getting pretty damn hard to find 120ns SIMMs these days, but if you can, they are cheaper. Cheers! -Russ -- Russ Donnan (415) 623-2121 Amdahl Corporation, Key Computer Laboratories, Fremont, CA, USA russ@key.amdahl.com, ...!{pacbell,sgi,amdahl}!key!russ -To capture the essence of an opinion takes but one lawyer.
news@calgary.UUCP (Network News Manager) (02/14/90)
From: sharp@cpsc.ucalgary.ca (Maurice Sharp)
Path: cpsc!sharp
Let us clear this up. Every mac has a certain speed of memory
chip that it requires. This speed depends on the CPU chip that the
mac is running, and perhaps some other hardware, though not usually.
Why does it matter you may ask. The CPU runs along at a certain
speed, and as it does so, it grabs information from memory at a
certain speed. When memory is rated at say 80ns, it means that you
have a gaurenteed access time of 80ns for a any particular part of the
memory. If a processor running very fast (like the IIci 68030) tried
to access slow memory (that is < 80ns), it may not get the
instruction data that it was after. The result of this is anything
from a minor to a major heart attack for the processor.
The bottom line, if your mac requires 80ns memory (like the
IIci), then you had better purchase at least 80ns memory. You can
purchase faster memory (70ns...) if you want, but you should NOT
purchase slower memory. Do so at your own peril, and that of any
applications that you are running. I expect that the mail order
places are mearly trying to sell you what they have.
maurice
Maurice Sharp MSc. Student
University of Calgary Computer Science Department
2500 University Drive N.W. sharp@ksi.cpsc.UCalgary.CA
Calgary, Alberta, T2N 1N4 ...!alberta!calgary!sharp