JT> I call some bbs's, and download at full clapper cps rates
 JT> for anything up to an hour at a time and have no problems.

 RS> Says nothing useful about errors at all,
 RS> clearly not many are occurring with those calls.

 RS> Its also possible to call systems where the download is nothing
 RS> like full cps rates, and the modem is showing that the EC is
 RS> correcting errors, AND you dont ever see a single error at the
 RS> Zmodem level and THAT proves very conclusively that the errors
 RS> aint getting past the modems to be fixed at the Zmodem error level.

 Yes, that's true, I know it corrects *many* errors without either side
knowing how bad it is.
 
 JT> Yet on a bad day when I call a particular bbs, I
 JT> might get several errors over the whole download.

 RS> The usual cause of that is because something is dropping chars
 RS> on the serial line between the modem and the PC, at either end.

 RS> Usually due to interrupt latency on the receiving end
 RS> and a flow control problem on the transmitting end.
 
 I'll put this issue forward to the sysop in question and see if it's a
particular type of modem that's on the bad line.  It may just be a
compatibility issue.

 JT> On the same line, it tends to drop out more
 JT> often, but it sometimes stays on with errors.

 RS> You shouldnt be getting drop outs at all on normal calls.

 I have a banksia 28.8.  I don't know what a normal call is.  NSE.

 RS> On calls that do drop out most likely the modems are retraining
 RS> because the line is shithouse and you can certainly Zmodem errors
 RS> in those circumstance, tho usually they are timeouts, not line errors.

 RS> When they cant even retrain successfully the line drops right out.

 Yes, I've seen this.

 RS> But on a line thats not so bad that they need to retrain, you
 RS> shouldnt be seeing errors at the line level that get past the
 RS> EC between the modems, to be caught by the Zmodem error check.

 I'm just repeating what I experience with this system.  ZModem sees errors,
and there is an associated drop in cps rate.  From the commands and setup I
have fed the modem, I believe that EC is enabled.  What my spastic modem
does behind my back is beyond my control.
 
 JT> And yes I'm sure I have EC turned on, I've tried it
 JT> turned off once, sheez it was bad. IMO, EC *improves* the
 JT> situation, but does not always completely eliminate errors.

 RS> Yes, if the line is so grossly bad that the
 RS> modems retrain, you can THEN see Zmodem errors.

 RS> And the line must be that grossly bad if it drops out at all.

 Out of the 10 odd lines going to the same place, one is by far the worst.
I remember asking ages ago if he had any problem reports by other users, but
there were none.  Most likely it is a compatibility issue.

 RS> Its even possible that the flow control in the transmitting
 RS> modem has some deficiencys in the retrain situation.

 Maybe, I think it is just my modem that is intolerant of bad lines.
 
 RS> If line errors are getting past the
 RS> modems EC you have a problem somewhere.
 
 JT> I wish I knew where,

 RS> Most likely an obscene line if it drops out at all. It shouldnt,
 RS> just fall back speed wise to a speed that isnt too bad error wise.
 
 Given a choice of slow, or dropped line, I'd take slow any day.  With slow,
the data still gets across whatever way.

 JT> I have also noticed this with my older system that
 JT> I used to use, a different pc, modem altogether.

 RS> Which points the finger at the line and/or the BBS modem.

 Either way, fuck all I can do about it except not call that line.
 
 JT> If I call late at night (er, morning), it tends to
 JT> be better, but at peak hour (evening) it's a mess.

 RS> That could either mean that the line is lousy due to crosstalk
 RS> from other calls or its what Telstra calls an HR joint, high
 RS> resistance. Tends to be moister at might so conducts better.

 May very well be, I'll ask again on reports on that particular line, last
time I asked, he said there were no problems.  It must be just bad line
noise, on certain systems, i CAN'T get over 24,000 odd, yet I've called
interstate at 28.8 without even a hint of a glitch.

 In today's mail, there was a message from a guy that downgraded from an
Avtek 28 to a banksia 34.  He *used* to get 28.8 all the time, now he says
he's lucky to get over 24 odd.

 I'm believing more and more that a modem change will make all my problems
disappear.  The only thing that is stopping me, is the adaptive answering
works ok most of the time, and I use it.  Even if the data is reliable on 
a new modem, if the fax don't work, it's no good to me.


John Tserkezis, Sydney, Oz. Fidonet: 3:712/610  Internet: jt{at}suburbia.com.au

... Dip me in Ice magic and throw me to the bisexuals
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