Path: utzoo!utgpu!jarvis.csri.toronto.edu!helios.physics.utoronto.ca!ists!yunexus!maccs!cs4g6ag
From: cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn)
Newsgroups: comp.sys.ibm.pc
Subject: Re: 386 < -- > 386SX?
Message-ID: <25CF24C7.12406@maccs.dcss.mcmaster.ca>
Date: 6 Feb 90 19:25:58 GMT
References: <3533@uceng.UC.EDU> <25ccac6d:47.1comp.sys.ibm.pc;1@nstar.UUCP> <959@watserv1.waterloo.edu>
Reply-To: cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn)
Organization: McMaster University, Hamilton, Ontario
Lines: 40

In article <959@watserv1.waterloo.edu> ssingh@watserv1.waterloo.edu ($anjay "lock-on" $ingh - Indy Studies) writes:
$1. I have a DTK 386sx (ppm-1630 is the technical name) with 2 megs of 100
$ns drams. ?) Are these memory chips the same as that used in 386dx chips?

   There's no law that says "all 386DX systems have to use the same
RAM chips".  I'm sure if you look under the hood of 20 different 386DX
boxes, you'll find several different types of RAM chips used.  The most
common will be 1Mx1 DIPs or 1Mx9 SIMMs, with 80 ns or 100 ns access
times.

$2. I have looked at the DTK 33 Mhz system featured on page 333 (aprox.)
$of the latest Byte, and it says that its 64K cache is capable of 
$maintaining zero-wait states with 100 nanosecond DRAMS. Since the 
$boards are made by the same people, could I use them if I decide to
$move to 33 Mhz? It claims 8.17 MIPS. The fastest I have heard of is
$the Mitac with a claimed 8.31 MIPS. Everex has 8.2.

   Well, it can't maintain zero wait states ... I think the figure you
were looking at says that a 64K cache can eliminate 95% of memory accesses
to a 4M main memory.  Close, but not quite the same.

   As for using the same memory, you'd have to find out what DRAMs are
used on their 386DX board.  There are several different ways you could
populate a board with 100 ns DRAMs.

$4. When I upgrade, that is, change mother boards, I would be getting
$the same performance as building the system from scratch, right? By
$this I mean simply buying a 33 Mhz DTK from a shop with the same
$componentry I am using in my present machine.

   Well, you would get the same CPU performance.  Your disk drive, though,
would still be run with a 16-bit controller (unless you upgrade the
controller, too), so your disk performance would be no better, whereas if
you bought a brand new system it would have a 32-bit disk controller.

-- 
Stephen M. Dunn                               cs4g6ag@maccs.dcss.mcmaster.ca
          <std_disclaimer.h> = "\nI'm only an undergraduate!!!\n";
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       "I want to look at life - In the available light" - Neil Peart