Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!mailrus!ncar!mephisto!ncsuvx!news
From: ml@ecerl3.ncsu.edu
Newsgroups: comp.sys.amiga
Subject: Re: Dnet
Keywords: Dnet, Telebit Trailblazer
Message-ID: <1990Mar8.231002.21288@ncsuvx.ncsu.edu>
Date: 8 Mar 90 23:10:02 GMT
References: <25358@swrinde.nde.swri.edu> <1990Mar7.000117.6984@ncsuvx.ncsu.edu> <25373@swrinde.nde.swri.edu>
Reply-To: ml@ecerl3.UUCP ()
Distribution: na
Organization: North Carolina State University
Lines: 47

In a previous article, kent@swrinde.UUCP (Kent D. Polk) wrote:
]In article <1990Mar7.000117.6984@ncsuvx.ncsu.edu> ml@ecerl3.UUCP () writes:
]>In a previous article, kent@swrinde.nde.swri.edu (Kent D. Polk) wrote:
]>
]Handshake can be a big problem above 2400 baud.... 
] ... Actually, as I mentioned
]in my original posting, I can get DNET to work fine at 2400 with the
]Trailblazer. The higher speeds are the problem.

Yes, right.  Just in case there's confusion here, note that I said
~600 Cps (characters per second), NOT ~600 Bps (bits/sec).  
2400 bps would be around 240 cps (given that a character takes about 10
bits when you account for stop/start/parity bits).

Even despite the slow result (~600cps) this is still 2 or 3 times faster
than using 2400bps mode; I was just expecting results more on the order
of 900cps or higher (much higher with PEP enabled).

]>The modem does all sorts of data compression techniques to get its speed.
]
]Actually, it gets it's speed by using up to 512 different frequencies,
] ...    The MNP protocol is the one
]which uses data compression to get the higher speeds from what I
]remember (little do I know). PEP can make use of data compression, but
]does not require it for the faster speeds.

OK, I guess I'm laboring under a misconception here.  I thought the
9600 bps rate was achieved using a large symbol set (ie 512 frequencies)
but that the higher rates (up to around 18000 bps -- PEP enabled)
was by adding compression techniques as well.
But I'm no expert here.

My real points in the prior response were:

  1)  It's fast.  Comfortably faster than 2400 bps.
  2)  It wasn't as fast as expected (not really 9600 bps or higher)
  3)  I don't think the modem is the culprit for (2).
  4)  I suspect serial port handshaking IS the culprit.  
      No proof.  I could be way off base here.

I just don't want anyone to misread the prior message and think
I was saying that the modem was doing 600 bps which would indeed
be miserably slow.



             ==[ ml@eceris.ncsu.edu (128.109.135.109) ]==