Message-Id: <199705152319.TAA06599@mail.storm.ca>
Comments: Authenticated sender is <yan AT mail DOT storm DOT ca>
From: "Yves Bellefeuille" <an448 AT freenet DOT carleton DOT ca>
To: opendos AT delorie DOT com
Date: Thu, 15 May 1997 19:19:11 -0400
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Subject: Re: 16 vs. 32-bit performance
Reply-to: an448 AT freenet DOT carleton DOT ca
In-reply-to: <199705151413.KAA23868@delorie.com>
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> 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.

First, 32 bits refers to the size of the data, not to the speed of the
calculations. Saying it's "twice as fast" is a complete misconception. 
It's like saying that if you make a door twice as wide, you can move 
through it twice as fast. Sometimes you can, but not always! ;-)

Here are some real-world examples. Higher scores are better.


                        PKUnzip     PGP	

DOS programs under
DOS 6.2                 1,00        1,00


This is the basemark. I've run PKUnzip (from PKZip for DOS) and PGP for
DOS (16-bit) on my system.


                        Unzip       PGP

OS/2 programs under
DOS/2 Warp 3            0,76        1,65


Now I'm using Info-Zip for OS/2 instead of PKZip for DOS, and PGP for
OS/2 instead of PGP for DOS. Unzip is actually slower than before.
This may be because Info-Zip isn't programmed as efficiently as PKZip,
or because the compiler used wasn't efficient. Even though I'm now
using a 32-bit program, real life variations are completely cancelling
any theoretical advantages and giving me a slower result. PGP, on the
other hand, is much faster than before.


                        Unzip       PGP

Linux programs under
Linux 2                 1,02        2,39


Now I'm using Info-Zip for Linux and PGP for Linux. Unzip is very
slightly faster than under DOS. PGP is much faster than under DOS and
even faster than under OS/2. 

So although 32-bit systems and programs are usually somewhat faster 
than 16-bit systems and programs, real-life results vary quite a bit, 
depending on the application, the skill of the programmer, and the 
quality of the compiler. 

Experiment on your own system with 16-bit and 32-bit programs. For
example, compare the speed of PKZip for DOS with the speed of WinZip
for Windows 95. Or choose any other application with 16-bit and 32-bit
versions.

The real advantage of 32-bit systems is portability. Only Inter CPUs
run in 16-bit mode; all other processors will only run in 32-bit mode.
That's another story, though.

Regards,

--
Yves Bellefeuille  See homepage for best freeware for DOS and Win 3.1x
Ottawa, Canada              Finger, homepage or key-server for PGP key
an448 AT freenet DOT carleton DOT ca               Francais / English / Esperanto
http://www.ncf.carleton.ca/~an448/