Date: Fri, 30 May 1997 08:54:52 -0400 (EDT)
From: "Mike A. Harris" <mharris AT blackwidow DOT saultc DOT on DOT ca>
Reply-To: "Mike A. Harris" <mharris AT blackwidow DOT saultc DOT on DOT ca>
To: OpenDOS discussion list <opendos AT delorie DOT com>
Subject: Re: 16 vs. 32-bit performance
In-Reply-To: <199705151828.OAA00071@delorie.com>
Message-ID: <Pine.LNX.3.95.970530084501.3136Q-100000@capslock.com>
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On Thu, 15 May 1997, Jonathan E. Brickman wrote:

> Most programs still read in files byte-per-byte,

Programs read byte for byte or int for int, but they certainly
don't read it directly from disk sectors, they read them from
disk buffers in the operating system.  The OS reads in
several sectors at a time and buffers them.  It is impossible to
read a single byte from the hard disk.  The interface does not
work that way.

The whole 16/32 bit argument is retarded.  If 16 bit code was
faster than 32 bit code, then all games and other software would
remain 16 bit.  Extending the argument even further - 8 bit would
be faster than 16 bit.  Both are obsurd.

Another point is that in 32bit Pmode 32bit ops and 8 bit ops run
fast, but 16 bit has a penalty.  This makes 16bit code even
slower.  Likewise in Real mode, 32bit registers, etc have the
penalty, but the process of doing 32 bits at a time WITH penalty
is still faster than 2 separate 16 bit operations in almost all
cases.

I refer you to Michael Abrash's "Zen of Assembly Language", and
"Zen of Code Optimization", and "Zen of Graphics Programming"
which go into optimization techniques in much detail.

32bit OS's and programs are in whole much faster than their 16bit
counterparts.

Nuff said.  No reply needed, nor expected.

Mike A. Harris        |             http://blackwidow.saultc.on.ca/~mharris
Computer Consultant   |                  Coming soon: dynamic-IP-freedom...
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URL: Digital Equipment Corp.             http://www.digital.com