Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!decwrl!netcomsv!gandrews
From: gandrews@netcom.COM (Greg Andrews)
Newsgroups: comp.dcom.modems
Subject: Re: Telebit registers
Summary: Not everything is always documented.  For good reason.
Message-ID: <1991Jun12.221820.24046@netcom.COM>
Date: 12 Jun 91 22:18:20 GMT
References: <2081@ssbn.WLK.COM>
Distribution: na
Organization: Netcom - Online Communication Services  UNIX System {408 241-9760 guest}
Lines: 52

In article <2081@ssbn.WLK.COM> bill@ssbn.WLK.COM (Bill Kennedy) writes:
>
>Greg Andrews posted a very useful follow up to Howard Siegel's m'aidez
>for T-1600 result codes (a decode of S59) and this morning I got a
>prompt and helpful reply from Mark at Telebit tech support regarding a
>connect problem I'm having with a cellular phone.  Mark told me to
>experiment with some undocumented register settings to make a PEP
>connection work across a cellular link, I haven't finished experimenting.
>
>What I'm wondering is whether or not a document exists that explains
>what the various registers are and what they mean.  Maybe this is a topic
>for a Nutshell book, but I seem to be out in left field when I encounter
>things like the cellular stuff.  Greg shed light on S59, Mark told me to
>meddle with S36 and S120, none of these are well covered in TFM.  I have
>no interest in dorking around with my Telebit modems for the sheer hell
>of it but I'd like to have some info about what these registers are and
>what they do.  I'd pay some sum for it too, anyone else?
>

Well, we're talking about two very different situations here.  The S59
register in the T1600 is indeed documented - the manual is simply missing
some important information about the various options.  The S120 and J6S36 
registers are only found in PEP modems - not in the T1600.

S120 and J6S36 are undocumented on purpose.  Several years back, when they
were first created, those registers were fully documented as a means to
make PEP handle adverse phone line conditions gracefully.

Suddenly, lots of people people started calling tech support to complain 
that their PEP connections were running slowly.  It turned out these folks
were playing with the registers when they didn't need to.  They thought
it was required to adjust the registers for long distance calls.  In the
process they were affecting their interactive responsiveness.

To solve the problem Telebit removed the registers from the documentation.
If someone is having trouble with their connection, they can call tech
support for help, and they'll get advice on the register adjustments.  
Everyone else won't mess with the registers, and therefore won't shoot 
themselves in the foot.

I'm sure there will be folks who post the S120/J6S36 settings, either
in this newsgroup or in private e-mail.  Some of those settings are
rather old, and may not work as well with newer versions of firmware.


>Bill Kennedy  internet  bill@ssbn.WLK.COM or ssbn!bill@attmail.COM

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