Path: utzoo!attcan!uunet!wuarchive!usc!apple!agate!shelby!msi.umn.edu!cs.umn.edu!uc!norge.unet.umn.edu!fin
From: fin@norge.unet.umn.edu (Craig A. Finseth)
Newsgroups: comp.emacs
Subject: Re: Flow control
Message-ID: <2977@uc.msc.umn.edu>
Date: 19 Nov 90 16:44:02 GMT
References: <1990Nov17.203241.16722@athena.mit.edu>
Sender: news@uc.msc.umn.edu
Organization: Univ Netw Serv, Univ of Minn
Lines: 48

In article <1990Nov17.203241.16722@athena.mit.edu> chuck@mitlns.mit.edu writes:
>	[Asking about padding vs. XON/XOFF flow control]
>
>  If this is true I don't see how RMS can reasonably claim that
>it is better than Xon/Xoff processing. 

It is better because (1) it doesn't take 2 of the 33 (yes, 33)
available control characters and (2) it is completely out of band, and
hence doesn't interfere with applications that need all 256 characters
(e.g., xmodem).

>  Padding seems to be a miserable solution.  A computer and 
>serial driver are wasting time sending lots of nothing. And

Actually, it is quite reasonable.  Any computer whose performance you
care about will be using DMA and hence no CPU time is wasted.

>it can't reasonbly handle variable speed transmission, such
>as data compressing modems or internet. Most people like having there

Actually, modem compression is irrelevant as it is only the speed of
the final link to the display that is relevant.  Network connections
are a problem, though.

>modems used for sending useful information, since thats one place
>where time=$. Also the computer requires lots of data for every terminal,
>which is a system maintenence burden.

As it turns out, this is a wash.  You will spend the time sending NULs
or waiting for an XON, but you will spend the same time nonetheless.

I don't understand the "system maintenance burden."  These devices
don't wear out by sending data.

>  Someone care to set me straight? Is that really the typical way
>flow control is handled on Unix systems? Should I keep search
>bound to control s or should I change it? While I'm all for
>configurable editors I also think a standard interface is a very
>valuable thing.

Unfortunately, XON/XOFF is more typical (:-(.  Personally, I keep
search on ^S and campaign against XON/XOFF at every opportunity.

Craig A. Finseth			fin@unet.umn.edu [CAF13]
University Networking Services		+1 612 624 3375 desk
University of Minnesota			+1 612 625 0006 problems
130 Lind Hall, 207 Church St SE		+1 612 626 1002 FAX
Minneapolis MN 55455-0134, U.S.A.