Verbose modems (Re: MORE 6386 UUCP WOES)

[Robert C. White Jr.]

in article <6916 at chinet.chi.il.us>, les at chinet.chi.il.us (Leslie Mikesell) says:
> Xref: nusdhub comp.dcom.modems:1126 comp.sys.att:1681
> Where is the EIA signal to indicate 9600 vs. 4800 vs. 2400 vs. 1200
> baud connection?  Where is the software support for it?  The real

We call the EIA signal to indicate baud "receive detect."  When
this signal lead is examined over time and compared with a known
"base state series"  (you and I call them characters) one can
easily determine baud rate (and other settings).  This procedure is
called "auto-bauding" and has been successfully used for years.

The software support for same can be found in /etc/gettydefs and /etc/gettys
(amoung other places).

> point is that modern microprocessor controlled modems have many more
> features than those available when the EIA signals were defined (although
> it is still reasonable to expect DCD to indicate a connection to a
> remote modem).  ASCII strings are the only way to access the new features,

Wrong!  DCD is *supposed* to indicate connection to a *remote device*  many
peices of software are so broken that they use DCD to detect the
modem.  DSR (Data Set Ready) is intended to detect the presence of a "ready"
"data set" (you know, a modem) and DTR (Data Terminal Ready) the
computer or "terminal"  (e.g. the terminal endpoint on any given leg
of the circut. . . instead of "terminal" in the common usage).

Some old UNIX System implementations were broken in this respect, but
almost all of them have since fixed this.  

> so why hasn't the software support caught up.  Why can't getty be told
> to match the speed of a connection?  (I know something like this has been
> posted.)  Why doesn't uucp's dialer pay attention to the CONNECT message and
> change speeds if necessary? 

getty doesn't need this behavior.  To implement it would needlessly
make a simple opperation much more complex.  Especially when you
consider that the many different "connect messages" produced by the
various types of modems.  I have seen dialers (on UNIX Systems) which
attempt this, and even tried to manage a few of them, but when you get
a hundred or more modems going, the space usage does not justify the
inconvience.  (yes, I meant those words just that way.)

If you cant live through the extra five characters at 9600 baud, you
must really be tense! ;-)

> Les Mikesell

Less, please study the specs of RS-232C and later specs like RS-442
et. al. before complaining to much.  The larger specs contain the
types of direct-wire protocols you want.  They are also quite a lot
more expensive to fully implement.  Not to many companies or
individuals feel the expense is worth the features for the kind of
environment you are talking about.

Remember the KISS principle  "Keep It Simple Stupid"  becuase simple
is often more reliable.

Rob.