Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!gargoyle!ddsw1!karl
From: karl@ddsw1.UUCP (Karl Denninger)
Newsgroups: comp.dcom.modems
Subject: Telebit Rev 4.0 reverse channel (was: Trailblazer working on tty000?)
Summary: So that's why there's no delay on interactive use...
Message-ID: <718@ddsw1.UUCP>
Date: 10 Feb 88 18:14:55 GMT
References: <995@neoucom.UUCP>
Reply-To: karl@ddsw1.UUCP (Karl Denninger)
Organization: Macro Computer Solutions, Inc., Mundelein, IL
Lines: 42

In article <995@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes:
>
>I've yet to get a chance to try the additional features of the 4.0
>firmware.  Most interesting is the additon of a low speed reverse
>channel that is supposed to get rid of the need to ping-pong the
>connection when you're using the TB Plus for dial-up data entry,
>packet ACKs, etc.  One of the other sites in the area is supposed
>to be getting a 4.0 version soon (I hope).

So that's what they added!  Well, now I understand why there is nearly no
delay in what I would expect to be the 'turn around' when I'm using it
interactively.... and it also explains why this nicety doesn't work when I
call a Rev 3 Telebit.

>Today's SYSLOG entries at my machine, impulse, show that it was
>getting about 900 - 950 char/sec on messages between 2000 and 4000
>char.  I didn't have any long traffic today.  That is quite a bit
>better than previous figures.  I plan to investigate the Plus more
>rigorously next week.

We're hitting 950 cps some uucp transactions going to another Trailblazer/host 
at 9600.  Occasionally we even get >11kbaud, but this is on very short 
messages (which fit into the buffer of the modem).  Our local connection 
to the modem is at 19.2K

Unfortunately, we don't have anyone to talk to at 19.2k yet (on both ends);
I'd like to see what kind of throughput is achievable in this case...

>I'm planning to  pit the Plus against a Microcom 9624AX, US
>Robotics, and Racal.  Of the four modems above, the construction
>quality is best in the Plus.  The Microcom is second, with the USR
>a close third.  The Racal has quite a few fix-up jumpers inside.
>Of the four, the Plus is the only modem not using the Rockwell
>chipset for 0-2400 baud; Telebit uses an AMD "Worldchip".

I would be quite interested in the results of this (I have a feeling the USR
HST will be disappointing, though)

-----
Karl Denninger		       |  Data: +1 312 566-8912
Macro Computer Solutions, Inc. | Voice: +1 312 566-8910
...ihnp4!ddsw1!karl	       | "Quality solutions for work or play"