Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!yale!babss!wadswort
From: wadswort@babss.UUCP (John H. Wadsworth)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: SUMMARY: 386 configuration tradeoffs (~200 lines)
Keywords: summary 386 cache performance
Message-ID: <1336@b1.babss.UUCP>
Date: 25 Mar 91 17:36:42 GMT
Reply-To: uunet!wadswort@babss.UUCP ()
Followup-To: comp.sys.ibm.pc.hardware
Organization: Bell Atlantic Business Systems Service Branford, Ct.
Lines: 193
Recently I asked about configuration tradeoffs in a 386 system to
be used to run *nix,X11,GNU etc. Below is a summary with the question
and the replies. The names have been deleted to protect everyone from
conflict of opinion flamewars. Thanks to all who responed. I hope others
can find this info as enlightening as I did!
The quick summary: Buy a 386/33 with at leat 64k cache and >4M with SVGA
Original message starts with >
Replies split by *******
In article <1335@b1.babss.UUCP> you write:
>I'm considering purchasing a system for home use. I will run
>*nix,X11,GNU etc. With this in mind, I'd like to hear your
>opinion about which tradoffs I should make to get a reasonable
>configuration at a reasonable price.
>
>386 33mhz or 25 mhz?
>Is the 25 _that_ much slower?
>
Yes...though 25MHz is pretty reasonable for home use.
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Well, 33MHz is 30% faster.
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25 / 33 = 0.76. Provided you have either cache or fast memory (in
order to have 0 wait states), you really see this difference.
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Well, I own a no cache 25 mhz, and it irritates me. My system has 2 meg of
memory and 80 MB HD. For a couple hundred bucks more ($300 somethin') I
could have own a more powerful 33Mhz 80 MB HD, 64K Cache, 4 M memory, etc.
My suggestion, by 386-33 if what you want is a 386. Among the 386, surely
386 is the most powerful, and the performance to price ratio of 386-33
is better too (from PC Magazine).
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A reminder. You are buying a 387 (which is a good idea for X)
have a look at 486 prices. A 486 motherboard can be a better deal than
386/33 + Coprocessor.
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>Extra cache or extra main memory?
>Given the choice would you rather have more cache or more main memory?
More main memory. Remeber first of all the "more cache" != "more speed"
for every job mix, especially under Unix. Secondly, the cost of paging
from insufficient main memory is orders of magnatude greater than the
cost of taking a cache miss.
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4MB of main memory is not really enough to run X (2MB is not
even close). The system swaps itself to death. I'm pretty
happy round here with a 386/25, 64k cache, 8MB, 344MB disk, and
800x600 VGA running SCO Unix (ODT). Oh, and a tape drive is a
*really big* win (I have a 60MB Archive Viper).
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About cache, 64K or 128K is sufficient. Remember the rule of the-bigger-the-
number-the-better-the-system don't apply to cache. A very large cache would
ussually lies there useless, because you put many junks in there.
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Overall performance will suffer without enough main memory....immediate
performance will suffer due to lack of cache. Get a 64K cache at least,
especially at 33 mhz.
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As I said in my earlier reply, under Unix (and other multitasking
OSes), more cache does *not* mean better performance for any given job
mix. The optimal amount of cache you need can only be determined
empiricly by close examination of what you do on the box...
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Get 8MB for UNIX. Period. SCO Open Desktop requires 6MB just to LOAD...
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This is absolutely not true. ODT will load and run just fine in 4MB
of RAM, although slowly due to excessive paging if you are running X.
It will not load in 2MB...I've never tried 3MB. I *think* the
ISC/ESIX/Microport crowd can load and run a basic system in 2MB, but
someone else will have to confirm this. Something like Xenix will
certainly run in 2MB.
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32Kb cache gets hit rates over 90% for typical applications; 64Kb
cache gets 95%; 256Kb cache gets 97%. My interpretation of these
figures is that 256Kb is not worthwhile. Most mainboards do not let
you choose between 32 and 64 -- they support one or the other.
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Main memory, if the cache upgrade is to 256Kb from either 32 or 64.
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You should get 8Meg RAM, and cache should help a lot. Remember, Unix and X11
require a lot of power.
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>Svga or vga?
>I think I know the answer to this one. I recently read some advice
>that said "Don't skimp on the monitor. Your eyes will suffer" I'd
>rather not have to replace either my monitor or my eyes because
>one was no longer suitable so I suspect I want the SVGA (color too!).
>Are there any problems with this, ie. X11 wont run in Svga anyway?
>
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For monitor, go for SVGA (800x600) at least. If you want sharper image
get the 1024x768 which is now not very expensive.
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And yes...get a quality monitor. You'll be glad you did.
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Definitely SVGA. Looking at your applications, you should get a decent video
card, not the $100 cheap ones.
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Svga. X is terribly cramped (I say useless, but thats just me) with
less than 800x600.
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Svga is a complicated business for XWin. You have to consider if the
X-server you will be running supports your graphics board. The best
vga X-server around is freeware -- X386. It supports best Tseng Labs
(T400) based cards. It will go up to 1024x768 non-interlaced if your
monitor goes along with it.
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the difference in cost is only $100 for card and monitor (plain VGA
cards can hardly be found any more, anyway). But monitor quality
varies widely, even for the same rated specs. Shop carefully.
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Roell's X server supports most major SVGA, with support for the rest on
the way. Beware that not all SVGA chipsets are created equal. Tseng
ET4000 is best; next come several including Trident which is usually
the price leader in this group. Avoid the low-end ones such as Oak.
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>
>Lastly, do you think the prices for a '386 are stable or are
>they expected to drop sharply in the next 6-8 months?
>
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6-8 months down the road there will *always* be something
bigger, faster, cheaper, stronger. Decide what you want and can
afford to buy now. If you keep looking ahead, you'll never actually
buy anything...
[ TRUE! Thanks!] -jhw
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I also heard rumor (again rumor) that once the 486-50 hit the market in 6-8
months, the price of the lower class computer (386 included) will drop.
True or false, you decide.
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