New modem transfer protocol (Long - protocol weenies only)

New modem transfer protocol (Long - protocol weenies only)

Post by Wolfgang Hen » Sun, 29 Mar 1992 13:45:30




: >This morning while I was trying to convince myself to get out of bed, I
: >thought of a new method to transfer files.  We all know that one of the
: >best transfer protocols w/ error correction is zmodem, but with a 2400bps
: >modem the best transfer is only 232cps, not 240cps.  I was wondering why
: >not be able to get 240cps.

Great to experiment with new ideas like this. I wonder if you are aware, though,
that there are different flavors of Zmodem? I often use one which is
internal to Qmodem with 232 cps, but have been advised that DSZ Mobyturbo is
faster, approaching 240 cps. Maybe you can check this one out for some more
ideas?

PS. DSZ Mobyturbo is as fast as half-duplex HSLINK.

--
_______________________________________________________________________________

 
 
 

1. New modem transfer protocol

I'm posting this for a friend of mine who's into programming.  Since
he has no net access, you can send replies to this address with
the subject: to Dan or post to the net.

-------------------------------------

This morning while I was trying to convince myself to get out of bed, I
thought of a new method to transfer files.  We all know that one of the
best transfer protocols w/ error correction is zmodem, but with a 2400bps
modem the best transfer is only 232cps, not 240cps.  I was wondering why
not be able to get 240cps.  Then I came up with something I'm going to
call Tmodem or TransQ (haven't decided yet.)  With this protocol one WILL
be able to transfer at 100% of their modem speed and STILL have error
correction!!!

How do I do this, you ask?  Well... zmodem sends a block of data with a
contained CRC error correction byte and block header.  TransQ has 100%
data & no CRC or header!  And now you ask how I do error correction?
This is the interesting part.  The CRC is created at the receiving end
and sent back to the transmitter.  The transmitting machine then compares
this CRC with the correct value for the block.  If the block is correct,
then no corrections are made.  If the CRC is wrong, the block is re-sent.

Now you ask how I get 100% throughput if I keep the transmitter waiting
for CRC's after every block?  This I do by having it send the next block
before the CRC is received.  It then keeps track of which CRC's were
returned good and only resends the bad blocks.

Well... that's the story.  I'm going to start working on an XPR for the
TransQ protocol and release it as shareware or demoware.  I think people
will switch to TransQ because it is faster and more fault tolerant than
zmodem and the like.  (I didn't get into the full story of how fault
tolerant it is, but it can handle short periods of 100% noise dropout for
long periods of time without barfing.)  Let me know what you think about
this....

                                       Dan Lorusso
post to the net or

subject: To Dan
                  Thanks!

2. Measuring Frequency Variation with SIMULINK

3. how to deploy new zone-transfer protocols

4. GFC For Hot Tub

5. The TELEBIT protocol (was: Modem protocols in BBS lists)

6. Power Pack + PXENGINE + classes

7. Looking for protocol docs for modem protocols

8. /bin/bash for Windows NT(spit)?

9. Source Code for Modem transfer protocol

10. any light on applications of protocol parameter message of V5.2 protocol

11. TLS protocols vs. SET, SSL protocols over networks?

12. Unable to set default network protocol on client machines - Default Protocol checkbox disabled