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Mail Archives: opendos/1997/05/15/10:16:36

Message-Id: <199705151413.KAA23868@delorie.com>
Date: Thu, 15 May 1997 09:13:27 -0500
From: "Jonathan E. Brickman" <brickman AT cjnetworks DOT com>
Reply-To: "Jonathan E. Brickman" <brickman AT cjnetworks DOT com>
To: opendos AT delorie DOT com
Subject: 16 vs. 32-bit performance
Mime-Version: 1.0

> It's a myth that 32-bit operating systems or programs are "twice the
> speed" of 16-bit programs. There's usually a slight increase, but it's
> not all that big. The real difference is when the data handled by the
> program is itself larger than 16 bits, for example if a program
> handles numbers over 65 536 (or, usually, 32 768). A 32-bit version of
> a program like PGP is *much* faster than a 16-bit version, because of
> the numbers it handles. That's the exception, though.

No, it's not.  When I was programming regularly, most of the
calculations I had to be prepared for in GUI, image-manipulation,
sound-related, database-related, and almost every other area were
pushing it in 16 bits.  I don't know about you, but most
of the files on my machine are more than 65,536 bytes long,
and my hard disk is considerably larger than that.  Given
this, 32-bit calculation becomes an immense advantage,
because one clock tick on a 32-bit CPU can often replace four
or more clock ticks on a 16-bit CPU.

> We're all still using 16-bit programs and systems, except those of us
> using Linux, Windows NT and OS/2.

Wrong.  Windows 95 uses 32-bit calculation in much of
its processing.  Not all, but much.  And nearly all
of the apps on my machine run on NT 4 as well, which means
they use 32-bit functionality in most cases.  Not all,
but most.  BeOS and apps will probably replace everything
I use now, in a year or two; and then, my CPU
and OS will be 32-bit, and my filesystem 64-bit.

Given a really decent OS for both platforms, the
same amount of RAM, and comparable CPU horsepower,
the 16-bit system will run more or less half as
fast as the 32-bit system.  The problem is,
decent OSes and comparable CPUs don't really
exist to support such a comparison.  I would
be very interested in seeing performance
comparisons between an 8 MHz 80286 and an 8 MHz
386 running Minix.  I'll bet it's about
a 1:3 performance ratio, when Minix is
optimized for each platform.

Jonathan E. Brickman         River City Computing, Inc.            (913) 232-6663
http://www.cjnetworks.com/~rivercity                    brickman AT cjnetworks DOT com
It seems to me that men usually think more about carburetors, and women
think more about doors.  I think the world needs really good carburetors...and
really good doors.

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