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From: williams@umaxc.weeg.uiowa.edu (Kent Williams)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: How to set serial port to 115k baud?
Message-ID: <3817@ns-mx.uiowa.edu>
Date: 7 Jan 91 21:02:08 GMT
References: <3815@ns-mx.uiowa.edu> <1991Jan5.034731.15478@d.cs.okstate.edu> <1839@gold.gvg.tek.com> <3345@mentor.cc.purdue.edu>
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In article <3345@mentor.cc.purdue.edu> wilker@descartes.math.purdue.edu (Clarence Wilkerson) writes:
>Actually, some of the file transport pograms from laptops to pc's, etc
>use the 115k mode. With error catching protocols, perhaps the 1% error rate
>plus retries is better than 57.5 kbaud ?
>Clarence Wilkerson

No they do some sort of hard-poll bit-banging.

Plus, 1% error rate is fatal for any kind of transfer protocol -- 1
out of every hundred characters is garbage, so if you have 100
character packets, you can get into a situation where you get an error
in every packet.  So if you lower the packet size to 50 then you
double the # of acks you need, and the acks get garbled too, so one
out of every hundred acks gets nuked.  Add that all up and your
throughput approaches zero.  Believe me -- I spent about 48 hours
straight trying to get divide-by-one to work, and it don't.

--
             Kent Williams --- williams@umaxc.weeg.uiowa.edu 
"'Is this heaven?' --- 'No, this is Iowa'" - from the movie "Field of Dreams"
"This isn't heaven, ... this is Cleveland" - Harry Allard, in "The Stupids Die"