Path: utzoo!utgpu!cunews!bnrgate!bwdls58!mlord
From: mlord@bwdls58.bnr.ca (Mark Lord)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Comparing 486 to 386 Systems
Message-ID: <6440@bwdls58.bnr.ca>
Date: 11 Apr 91 13:40:36 GMT
References: <40409@netnews.upenn.edu> <1991Apr4.062503.1325@agate.berkeley.edu> <27865@neptune.inf.ethz.ch> <1991Apr6.191106.5863@cc.helsinki.fi> <27899@neptune.inf.ethz.ch>
Sender: mlord@bwdls58.bnr.ca
Reply-To: mlord@bwdls58.bnr.ca (Mark Lord)
Organization: Bell-Northern Research, Ottawa, Canada
Lines: 45

In article <> brandis@inf.ethz.ch (Marc Brandis) writes:
<That was exactly my point. As far as I remember the original question was about
<a system to run DOS. With Windows you get the benefits of VM86 and of the 
<paging unit, but not of the 32-bit architecture (and I do not think that the
<advantage of Windows in enhanced (speak 386) mode vs. Windows in standard
<(speak 286) mode is as large as the advantage of Windows in standard mode vs.
<Windows in real (speak 8086) mode.

The 32-bit architecture of a 386 provides immediate performance benefits
to MS-DOS users in *at least* the following significant ways:

	1) PKZIP takes full advantage of the 32-bit regs/instructions
	so as to gain maximum performance on a 386.  Not that any of
	us actually use .ZIP files regularly.   :)

	2) The motherboard BIOS typically takes great advantage of the
	32-bit regs/instructions to aid performance.

	3) Extended memory managers (QEMM,386^MAX etc), which are among
	the most popular commercial software, also take full advantage of
	the 32-bit archictecture to maximize performance, especially when
	performing copies to/from extended memory via the XMS interface.

	4) Disk caching programs, such as HYPERDISK, take full advantage
	of the 32-bit instructions and registers for maximum performance.

	5) The Windows 3.0 386-kernel uses 32-bit registers and instructions
	internally.

	6) *All* code, including the oldest 8/16 bit programs, gain a slight
	increment from automatic use of the 32-bit wide instruction prefetch
	queue of the 386, which can hold up to twice the data of the 16-bit
	queue of the 8086/80286.

That's all I could think of in two minutes.  Of course, others have already 
reminded us all of the *other* benefits of the 386 virtual architecture,
which by itself is enough reason for never again purchasing anything less
than a 386 for a general purpose personal computer.
-- 
MLORD@BNR.CA  Ottawa, Ontario *** Personal views only ***
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