[comp.dcom.modems] 9600 HST

dnelson@ddsw1.UUCP (Douglas Nelson) (01/28/88)

Keep in mind that when using the USRobotics HST during data compression
(MNP Level 5) you have your high speed througput going only though one 
channel, whomever is sending the most data, sender or reciever, gets the
high speed line.  The other side is a 300 baud transmission.  This is noted
when using protocols such as Xmodem or even god forbid, Kermit at those high
speeds because only small 128 byte or so blocks are sent, and then it must
wait for acknowledgement.  Well, when the time for the ACK comes, the modem
switches the recieving/sending high speed line, which takes merely a fraction
of a second, but if you follow your effiency much, you will surely notice it.

For example, recently I did a file transfer of a source listing and was in
a position where Xmodem was the only available protocol.  I completed the
transfer with a 17% efficency, when the norm is around 90%.

The best thing to do is use a streaming protocol, like Zmodem.  Very effective,
since it does not need the acknowledgement unless there was a bad block, as
the checksum is sent in the stream.


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Douglas Nelson
dnelson@ddsw1.UUCP
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