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From:	Brian Inglis <Brian DOT Inglis AT SystematicSW DOT Invalid>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: why inportb and outportb are so time expensive ?
Organization:	Systematic Software
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Date:	Sun, 12 Dec 2004 00:19:20 GMT
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On Sat, 11 Dec 2004 14:55:08 GMT in comp.os.msdos.djgpp, Carlo
<mail AT bo DOT uf> wrote:

>Eli Zaretskii wrote:
>> 
>> 
>> On what OS?
>> 
>> Also, can you give more details, like how much time each call to
>> inportb/outportb takes?
>My application runs on a dos machine (MS-Dos 6.0) with a i386sx 
>processor @ 33 Mhz clock, with cwsdpmi r5.
>One program loop takes about 1 mSec, 75% of this millisecond spent for 
>inportb and outportb (with an average of 30/40 calls to that functions). 
>Without any of these calls the program runs up to 10 times faster.

The instructions themselves probably aren't slow, but they talk to I/O
device interfaces, which talk to I/O devices, which can take a while.
How long do the I/O interface and device specifications say they will
take to respond to various commands or requests? 

-- 
Thanks. Take care, Brian Inglis 	Calgary, Alberta, Canada

Brian DOT Inglis AT CSi DOT com 	(Brian[dot]Inglis{at}SystematicSW[dot]ab[dot]ca)
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