[comp.sources.bugs] Zmodem upload problems

garyf@mehlville.ncsa.uiuc.edu (Gary Faulkner) (12/22/89)

In article <80@ucunix.SAN.UC.EDU>, rainwatr@ucunix.san.uc.edu (Don
Rainwater) writes:
> 
> 	I have a VAX 8650 running Ultrix 3.0.  Terminal connections are
> via DECservers.  My port is running at 19.2k, and my "terminal" is a Mac II.
> The Mac is running ZTerm .85, and I have the rzsz package from 5/89
> running on the Ultrix system.
> 
> 	I'm able to download (sometimes very large) files from Ultrix
> without any trouble, but uploads don't even get past the first byte.
> The error I get is "ZRPOS=0".  I have the same problem trying to upload
> from an IBM/PC-AT compatible running DSZ, so I think we can eliminate
> the Mac from the list of suspects.
> 
> 	Has anyone been able to successfully upload files to an Ultrix
> (or other Unix) host?  Any help would be greatly appreciated.  Kermit is
> just too slow.

Yep, we have the same problem with our ultrix and our sun hosts using
rzsz, again for uploads only.  I am taking the liberty of cross posting
this response to comp.sources.bugs to attempt to get a dialog/fix going
in that area.  I don't think anyone has complained (at least not very
loudly) about this yet, and hopefully someone has a fix for the problem.

Gary Faulkner
National Center for Supercomputing Applications - University of Illinois
Internet: garyf@mehlville.ncsa.uiuc.edu
Disclaimer:  I've only stated my opinion, not anyone elses.

dplatt@coherent.com (Dave Platt) (12/22/89)

In article <1989Dec21.200309.17636@ux1.cso.uiuc.edu> garyf@mehlville.ncsa.uiuc.edu (Gary Faulkner) writes:
> In article <80@ucunix.SAN.UC.EDU>, rainwatr@ucunix.san.uc.edu (Don
> Rainwater) writes:
> > > 	I'm able to download (sometimes very large) files from Ultrix
> > without any trouble, but uploads don't even get past the first byte.
> > The error I get is "ZRPOS=0".  I have the same problem trying to upload
> > from an IBM/PC-AT compatible running DSZ, so I think we can eliminate
> > the Mac from the list of suspects.
> > 
> 
> Yep, we have the same problem with our ultrix and our sun hosts using
> rzsz, again for uploads only.  I am taking the liberty of cross posting
> this response to comp.sources.bugs to attempt to get a dialog/fix going
> in that area.  I don't think anyone has complained (at least not very
> loudly) about this yet, and hopefully someone has a fix for the problem.

The ZMODEM protocols requires that the sender->receiver channel be able
to transmit 8-bit-wide data;  the receiver->sender backchannel only
needs to be 7 bits wide.

I suspect that your Ultrix and Sun systems, or perhaps your
terminal-servers, are set up so that they expect to see data arriving
in 7-bit-plus-parity-of-some-gender, and that they are stripping the
parity bit off of the data before passing it on to the receiver (rzsz,
in this case).  This will entirely confuse a ZMODEM transfer;  the
packet CRCs will not match, and the receiver will repeatedly ask the
sender to retransmit the first packet (ZRPOS=0).  Eventually the transfer
will choke and abort.

ZMODEM also transmits control-characters in its data... both as part of
the packet-control sequences, and in the data.  It normally "escapes
out" a limited set of control-characters... XON and XOFF, and a few
others which tend to be "eaten" by network hardware or software.  It's
possible to tell a ZMODEM sender to escape all control characters...
in ZTerm 0.85 this is done in the "ZMODEM Parms..." dialog box.  This
might help...

It is not possible to transmit data using ZMODEM if your sending
channel is only 7 bits wide.  You may be able to configure your
terminal-server so that it will grant you a clean 8-bit-wide input
channel... "8 data bits, no parity, 1 stop bit" is the usual
incantation in telecom programs.  I recall that "tip" hardware could be
persuaded to do this, by giving certain commands during the connection
sequence;  your term'server may have similar capabilities.

If you can't arrange for an 8-bit clear input channel, you won't be able
to use ZMODEM to upload, and will need to fall back and punt... use
MacKermit (or the equivalent).  Recent Kermits can use large packets...
1K bytes or so... and can deliver decent throughput.  You'll lose some
bandwidth because Kermit will be forced to escape all characters whose
8th bit is on... but this is inevitable if you don't have an 8-bit-wide
data channel.

I've used ZTerm (many versions) to upload data to my Sun systems running
rzsz.  As long as I go in through a serial-port configured for 8-bit
input, everything works fine.

I believe that rz attempts to put the tty channel into "raw" mode when it
starts receiving.  This apparently turns off parity checking and enables
8-bit input.  It's possible, I suppose, that this feature isn't effective
if you're logged in over a TELNET-style connection from a terminal
server.
-- 
Dave Platt                                             VOICE: (415) 493-8805
  UUCP: ...!{ames,apple,uunet}!coherent!dplatt   DOMAIN: dplatt@coherent.com
  INTERNET:       coherent!dplatt@ames.arpa,  ...@uunet.uu.net 
  USNAIL: Coherent Thought Inc.  3350 West Bayshore #205  Palo Alto CA 94303

jeff@eniac.seas.upenn.edu (Jeffrey M White) (12/23/89)

In article <1989Dec21.200309.17636@ux1.cso.uiuc.edu> garyf@mehlville.ncsa.uiuc.edu (Gary Faulkner) writes:
>In article <80@ucunix.SAN.UC.EDU>, rainwatr@ucunix.san.uc.edu (Don
>Rainwater) writes:
>> 
>> 	I have a VAX 8650 running Ultrix 3.0.  Terminal connections are
>> via DECservers.  My port is running at 19.2k, and my "terminal" is a Mac II.
>> The Mac is running ZTerm .85, and I have the rzsz package from 5/89
>> running on the Ultrix system.
>> 
>> 	I'm able to download (sometimes very large) files from Ultrix
>> without any trouble, but uploads don't even get past the first byte.
>> The error I get is "ZRPOS=0".  I have the same problem trying to upload
>> from an IBM/PC-AT compatible running DSZ, so I think we can eliminate
>> the Mac from the list of suspects.
>> 
>> 	Has anyone been able to successfully upload files to an Ultrix
>> (or other Unix) host?  Any help would be greatly appreciated.  Kermit is
>> just too slow.
>
>Yep, we have the same problem with our ultrix and our sun hosts using
>rzsz, again for uploads only.  I am taking the liberty of cross posting
>this response to comp.sources.bugs to attempt to get a dialog/fix going
>in that area.  I don't think anyone has complained (at least not very
>loudly) about this yet, and hopefully someone has a fix for the problem.

  Same problem here.  With a connection to a Unix host through an Annex
terminal server, xmodem-based file transfers (which include straight xmodem
and the MacXmodem derivatives) would be fine for transfer from the host to the
PC/Mac, but fail going the other way.  The exception is that file transfers
when dialing up (which is 1200 baud for me) do work fine in both directions.
I never got around to finding how fast a baud rate you could have before
it would start to fail again.  My suspicion is that xmodem doesn't like the
buffering (no matter how slight) that these terminal servers do.

						Jeff White
						University of Pennsylvania
						jeff@eniac.seas.upenn.edu


moran@tron.UUCP (Harvey R Moran) (12/23/89)

In article <1989Dec21.200309.17636@ux1.cso.uiuc.edu> garyf@mehlville.ncsa.uiuc.edu (Gary Faulkner) writes:
>In article <80@ucunix.SAN.UC.EDU>, rainwatr@ucunix.san.uc.edu (Don
>Rainwater) writes:
>> 	I'm able to download (sometimes very large) files from Ultrix
>> without any trouble, but uploads don't even get past the first byte.
>> The error I get is "ZRPOS=0".  I have the same problem trying to upload
>> from an IBM/PC-AT compatible running DSZ, so I think we can eliminate
>> the Mac from the list of suspects.
>> 
>> 	Has anyone been able to successfully upload files to an Ultrix
>> (or other Unix) host?  Any help would be greatly appreciated.  Kermit is
>> just too slow.
>
>Yep, we have the same problem with our ultrix and our sun hosts using
>rzsz, again for uploads only.  I am taking the liberty of cross posting

    sz/rz works fine here for both upload and download.  Points of
comparison:  zmdm1.43, VAX-750, Ultrix 3.1, DECSERVER, IDX line mux,
Vadic modem, 1200 (yeah I know, but that all I've got to work with)
<--> Telebit T1000 modem, Microport System V/AT 2.3, 8 Mhz '286
AT-clone, xcomm PD communications package, zmdm1.43 transport.

   Though I've used it only twice, the same AT up/downloads with a '386
running ISC 2.02, zmdm2.02 and some kind of internal modem, at 2400 baud.

   In both cases, uucp accounts for most of the traffic, zmodem is used
only when file transfer is an afterthought after logging in.

   Perhaps the baud rate is the problem.  Fielding interrupts at
19,200 baud is a tricky business, especially when there are no
required ACK's in the protocol to throttle reception rates down.
While I have no personal experience, everything I've seen in various
newsgroups on the net would lead me to believe that neither VAXen nor
Suns are capable of reliable streamed reception at 19,200 and even
9600 is *really* touchy.

    Of course, in the mentioned case of the VAX 8600, it is getting
LAT packets from the DECSERVER rather than interrupt per byte.  The
machine with the strain is the DECSERVER itself.  I have no knowledge
about its capability to deal with high baudrate incoming data streams.

-- 
# Harvey Moran  moran@tron.UUCP  moran@tron.WEC.COM   ...!uunet!tron!moran
# Westinghouse Electric Corp., Electronic Systems Group, Baltimore, Md.

pel@unhd.UUCP (Paul E. Leclerc) (12/24/89)

>In article <80@ucunix.SAN.UC.EDU>, rainwatr@ucunix.san.uc.edu (Don
>Rainwater) writes:
>> 
>> 	I have a VAX 8650 running Ultrix 3.0.  Terminal connections are
>> via DECservers.  My port is running at 19.2k, and my "terminal" is a Mac II.
>> The Mac is running ZTerm .85, and I have the rzsz package from 5/89
>> running on the Ultrix system.
>> 
>> 	I'm able to download (sometimes very large) files from Ultrix
>> without any trouble, but uploads don't even get past the first byte.
>> The error I get is "ZRPOS=0".  I have the same problem trying to upload
>> from an IBM/PC-AT compatible running DSZ, so I think we can eliminate
>> the Mac from the list of suspects.
>> 
>> 	Has anyone been able to successfully upload files to an Ultrix
>> (or other Unix) host?  Any help would be greatly appreciated.  Kermit is
>> just too slow.

Try doing an sz -e file.    -e says to escape characters that might
be special to things like terminal servers.  I don't use Zterm so
I don't know if that is possible.   It has worked for me when
I have to go through ethernet terminal servers.

          Paul Leclerc
===========================================================================
Paul Leclerc,  Computer Specialist III |Bitnet:    P_LECLERC@UNHH.BITNET
University of NH                       |UUCP:      ...uunet!unh!pel
===========================================================================



-- 
===========================================================================
Paul Leclerc,  Computer Specialist III |Bitnet:    P_LECLERC@UNHH.BITNET
University of NH                       |UUCP:      ...uunet!unh!pel