mlord@bwdls58.bnr.ca (Mark Lord) (01/01/70)
<In article <Ns53w6w163w@mimas.UUCP>, vcl@mimas.UUCP (Victor C. Limary) <writes... <> I have a 16MHz 386 computer with 2 megs of mixed 80ns and 100ns SIMMS. <>I am thinking of buying 4 1meg x 9 SIMMS, but I'm not sure about what <>speed memory I should get. Most likely, I will be getting at least 80ns, <>but lately, I've seen lots of 70ns and 60ns RAM. Is there a big <>difference in speed with each 10ns? Prices are about $5-$15 more for <>every 10ns speed increase with the memory. Is getting 70ns or even 60ns <>SIMMs worth the extra money with a 16MHz computer? Buying SIMMS capable of faster speeds does not speed up the memory subsystem of your computer. Your motherboard has to be capable of faster accesses to memory (via programmable wait states or whatever) in order for "faster" SIMMS to be of any use. Buy the cheapest ones you can get which are no slower than the ones your copmuter came with. In your case, play it safe at get 80ns SIMMS. -- ___Mark S. Lord__________________________________________ | ..uunet!bnrgate!mlord%bmerh724 | Climb Free Or Die (NH) | | MLORD@BNR.CA Ottawa, Ontario | Personal views only. | |________________________________|________________________|
garlange@mentor.cc.purdue.edu (Mark Garlanger) (11/20/90)
Is there any problem with running 2 memory simms rated at different speeds? ie some rated at 120ns and some rated at 100ns. Note 120ns is plenty fast enough for my 8mhz 286, but I can get a couple used 110ns or 100ns for fairly cheap. Thanks, Mark
rharrie@ac.dal.ca (11/21/90)
In article <16892@mentor.cc.purdue.edu>, garlange@mentor.cc.purdue.edu (Mark Garlanger) writes: > > Is there any problem with running 2 memory simms rated at different > speeds? ie some rated at 120ns and some rated at 100ns. Note 120ns is > plenty fast enough for my 8mhz 286, but I can get a couple used 110ns > or 100ns for fairly cheap. Thanks, > > Mark If 120ns chips are fast enough for your machine, then any combination of chips with speeds of <=120ns will function OK. The speed on the chip is just the maximum speed that the chip is certified for, not the speed at which it functions. R.
poffen@sj.ate.slb.com (Russ Poffenberger) (11/22/90)
In article <16892@mentor.cc.purdue.edu> garlange@mentor.cc.purdue.edu (Mark Garlanger) writes: > > Is there any problem with running 2 memory simms rated at different >speeds? ie some rated at 120ns and some rated at 100ns. Note 120ns is >plenty fast enough for my 8mhz 286, but I can get a couple used 110ns >or 100ns for fairly cheap. Thanks, > > Mark Mixing speeds is perfectly acceptable as long as they are all fast enough for the computer. Russ Poffenberger DOMAIN: poffen@sj.ate.slb.com Schlumberger Technologies UUCP: {uunet,decwrl,amdahl}!sjsca4!poffen 1601 Technology Drive CIS: 72401,276 San Jose, Ca. 95110 (408)437-5254
mir@opera.chorus.fr (Adam Mirowski) (02/11/91)
In article <Ns53w6w163w@mimas.UUCP>, vcl@mimas.UUCP (Victor C. Limary) writes:
%%
%% I have a 16MHz 386 computer with 2 megs of mixed 80ns and 100ns SIMMS.
%% I am thinking of buying 4 1meg x 9 SIMMS, but I'm not sure about what
%% speed memory I should get. Most likely, I will be getting at least 80ns,
%% but lately, I've seen lots of 70ns and 60ns RAM. Is there a big
%% difference in speed with each 10ns? Prices are about $5-$15 more for
%% every 10ns speed increase with the memory. Is getting 70ns or even 60ns
%% SIMMs worth the extra money with a 16MHz computer?
%% Thanks in advance.
RAM chips cannot tell the motherboard that they are faster or slower.
Also, the motherboard can't by itself tell the speed of the installed
chips... It must be told, either by configuration switches, or
by the setup data stored in backed CMOS memory. If you don't tell
your motherboard that the new SIMMs are faster than the old ones,
it won't tighten the timings and speed the operation.
So if your motherboard isn't configurable for faster chips, all you
need is 100ns SIMMs (as you already have some and that works).
On a 20Mhz 386 I have seen two switches (for reading and writing) that
enabled 100ns, 80 and 70ns operation.
On my 33Mhz, the built-in setup program lets me choose between 0 and 3
wait states for reading and 0-1 wait states for writing. The board
manual shows the correct settings depending on the chip speed.
I should warn you that if you change your 8 256K chips (I suppose) against
4 of 1M capacity, you will loose the memory interleaving possibility
(if you have a DX) until you have 8 chips (2 banks) again. That will
certainly drop your processing speed.
Of course, if your 386 is a SX, the bus is only 16 bits wide so even with
4 chips, or 32 bits of memory access, interleave is possible.
--
Adam Mirowski, mir@chorus.fr (FRANCE), tel. +33 (1) 30-64-82-00 or 74
Chorus systemes, 6, av.Gustave Eiffel, 78182 Saint-Quentin-en-Yvelines CEDEXv119l94u@ubvmsd.cc.buffalo.edu (Dennis G Crawford) (02/11/91)
In article <Ns53w6w163w@mimas.UUCP>, vcl@mimas.UUCP (Victor C. Limary) writes... > I have a 16MHz 386 computer with 2 megs of mixed 80ns and 100ns SIMMS. Persumably, you mean 386 SX. (That's what I personally use...) >I am thinking of buying 4 1meg x 9 SIMMS, but I'm not sure about what >speed memory I should get. Most likely, I will be getting at least 80ns, >but lately, I've seen lots of 70ns and 60ns RAM. Is there a big >difference in speed with each 10ns? Prices are about $5-$15 more for >every 10ns speed increase with the memory. Is getting 70ns or even 60ns >SIMMs worth the extra money with a 16MHz computer? Well.. I had 80 ns 256x9 chips in my CPU, but... when I upgraded to 4megs in 1mbx4 chips, I used 100ns. They were cheaper, and it's what I had more of!! Anything below 100ns in an SX computer is really a waste of memory... For the most part, you're not going to get a really significant change in speed with that computer. You're better off buying 100ns or 80ns at best... )_Dennis_( ---- ... D-Man! -=- "What's a Solvay?" -=- Dennis G. Crawford -=- SUNY Buffalo . .. V119L94U@UBVMS.CC.BUFFALO.EDU -=- CRAWFORD@AUTARCH.ACSU.BUFFALO.EDU .. . UUNET!UBVMSC.CC.BUFFALO.EDU!V119L94U@UUNET.UU.NET -=- DGCRAWF@UMASS ... "How did we get here!? Where are we going!?" -- J. Satriani ....
poffen@sj.ate.slb.com (Russ Poffenberger) (02/14/91)
In article <emR9w1w163w@mimas.UUCP> vcl@mimas.UUCP (Victor C. Limary) writes: >v119l94u@ubvmsd.cc.buffalo.edu (Dennis G Crawford) writes: > > >Actually, I have a 386DX, not an SX. I got a 16MHz one because it was a >DX, and it was cheaper than the SX's that I could find at the time (about >2 years ago). I understand that I won't be getting any significant >increase in speed with anything better than 80ns SIMMS, though. I'll >probably end up getting 80ns ones. Thanks for your help. > Unless you can select how many wait states are used for memory access, putting faster chips in will NOT make your system go any faster. The speed of memory access is fixed by the number of wait states, and putting in memory chips faster than is required by the number of wait states is a waste of money. You can probably get away with 100ns chips in a 16 Mhz system. Check the manufacturers recommendation. Russ Poffenberger DOMAIN: poffen@sj.ate.slb.com Schlumberger Technologies UUCP: {uunet,decwrl,amdahl}!sjsca4!poffen 1601 Technology Drive CIS: 72401,276 San Jose, Ca. 95110 (408)437-5254
ebergman@isis.cs.du.edu (Eric Bergman-Terrell) (02/14/91)
Be careful not to waste your money buying memory that's faster than your CPU. Get memory fast enough to make your computer have zero wait states. Buying memory faster than that will NOT make your system run faster. However, if you're planning on upgrading to a faster machine in the future, you might want to plan ahead and get fast enough memory (but the RAM prices tend to decrease anyway). Sorry I can't give you the exact speed of memory that your system needs to be zero wait state. I have 80ns memory in my 16MHz 386SX and I believe that the machine doesn't have a wait state... Terrell
vcl@mimas.UUCP (Victor C. Limary) (02/15/91)
> Be careful not to waste your money buying memory that's faster than your > CPU. Get memory fast enough to make your computer have zero wait states. > Buying memory faster than that will NOT make your system run faster. > > However, if you're planning on upgrading to a faster machine in the future, > you might want to plan ahead and get fast enough memory (but the RAM > prices tend to decrease anyway). > > > Sorry I can't give you the exact speed of memory that your system needs > to be zero wait state. I have 80ns memory in my 16MHz 386SX and I believe > that the machine doesn't have a wait state... I talked with the dealer a bit, and although I wouldn't trust that guy very much, I think that I can believe him when he says that 100ns is fast enough to keep my machine from running without wait states. I did some testing, and found that 80ns chips gave me an increase of .01 mips. Hardly worth the extra money. I may just get 80ns though, since I may upgrade within the next couple of years. Thanks for your input. _______ / \ | O O | Victor Limary <| < |> mimas!vcl@bbx.basis.com | _____ | \ U / "-----"