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From: davidsen@steinmetz.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Which 80386 system to buy?
Message-ID: <7393@steinmetz.steinmetz.UUCP>
Date: Thu, 17-Sep-87 14:57:37 EDT
Article-I.D.: steinmet.7393
Posted: Thu Sep 17 14:57:37 1987
Date-Received: Sat, 19-Sep-87 10:07:59 EDT
References: <133@ncrcpx.UUCP> <3320054@hpsrlc.HP.COM>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 43

In article <3320054@hpsrlc.HP.COM> waynec@hpsrlc.HP.COM (Wayne Cannon) writes:
|Has anyone any experience with the Tandy 4000?  Currently the Tandy and
|Wyse machines both appear attractive.  Wyse says that they will support
|both the 287 and 387 coprocessors, while Tandy supports only the 287.

It's good to have the choice. While the 387 delivers more performance,
it may be desirable to have a boost at lower cost. The 387 is about
twice as costly as the 287, and seems to deliver about four times the
performance (from published figures, don't flame me).

|Both support true zero wait-state RAM access via a two-plane memory
|interleave over the entire 32-bit memory space while some competitors
|achieve their memory speed only via memory caching in a smaller
|high-speed memory (cost savings?!) and run the bulk of their 32-bit RAM
|at a slower pace.

This is a more complex topic than you imply.  The cost savings is in not
using cache.  The 45ns static memory used in most caches makes the
manufacturer's cost for a 1MB machine about the same.  The addition of
caching logic probably makes it cost more (the new Intel cache
controller may change that).  However, unless you use real static memory
for main memory, the cache is a win.  If you use 16 bit memory to save
money, the performance hit is 40% without cache, 15% with (that *is* my
measurement).  The cache gives about 18-22% improvement for 100ns 1MB
chips (my measurement). 

Note that Compaq has added cache to their new motherboard with the 387
on it.  I suspect that cache with interleaved memory will become the
most cost effective method as speeds increase. 

When I bought my PC Designs machine I got some benchmarks from friends
at COMDEX, who found it was 20% faster than the (original) Compaq386. At
some point I will want to get a revised motherboard with a 20MHz 386 and
387, but I am pretty happy for now.

Hope this clarifies the tradeoffs involved. I'm looking at getting a
VESTA 386, and will let you know what results I have if I buy it. I want
to run a BBS on it, using VAT, but doubt that their serial drivers are
strong enough.
-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me