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From: mir@opera.chorus.fr (Adam Mirowski)
Newsgroups: comp.windows.ms,comp.sys.ibm.pc.misc
Subject: Re: Unable to unzip files from CICA???
Message-ID: <8044@chorus.fr>
Date: 28 Feb 91 19:19:19 GMT
References: <21774@yunexus.YorkU.CA>
Sender: mir@chorus.fr
Reply-To: mir@opera.chorus.fr (Adam Mirowski)
Organization: Chorus systemes, Saint Quentin en Yvelines, France
Lines: 43

In article <21774@yunexus.YorkU.CA>, frank@nexus.YorkU.CA (Frank Pikelner) writes
%% [...]
%% The files are then transfered via modem to my home IBM compatible computer.
%% [...]
%% To send the files from the SUN to the  IBM I use Zmodem or  KERMIT protocols
%% (both in binary modes).
%% 
%% 	1. My first problem is many files when I attempt to run PKUNZIP
%% 	   I get ZIP file error and to run PKZIPFIX. The PKZIPFIX does
%% 	   not fix my problem and the file it creates can not be decompressed.
%% 
%% 	2. Transfering the files via modem using ZMODEM protocol I get
%% 	   CRC and BAD BLOCK errors after he first 1024K or 2048K for 
%% 	   most files. My CPS after that goes down to 18 or 36 and the
%% 	   transfer gets abandoned after this.

The problem here is probably flow control, either between your PC and your
home modem or between your Sun and its modem.

In the first alternative you send the file to the PC at a higher speed that
it can process it, so that characters get lost. That is the reason for CRC
and BAD BLOCK errors. There is probably a 1K or 2K buffer in your PC that
is filled through the IT routine and emptied by the communication program.

Your program probably signals the overrun in some way, either by emitting
XOFF/XON (^S/^Q) characters, or by rising a physical line. The sender 
visibly ignores that signals or doesn't hear them. Usually zmodem (DSZ)
on Unix uses both hardware and software handshake. Is your modem cable
complete? It should be a straight cable, with pins 2,3,4,5,6,7, 8 and 20
wired.

I had an opposite problem: downloads worked fine, but uploads failed,
precisely because of flow control. My 2400 modem default configuration
was no flow control at all. You probably have a high speed modem and
a slow computer, or work under a environment that introduces interrupt
latencies (Win3, Deskview, QEMM).

In the second alternative, you have the same problem I had. Try to setup
your Unix modem to both local XON/XOFF control and physical handshaking.
You will need the same kind of straight cable as for the PC.
-- 
Adam Mirowski,  mir@chorus.fr (FRANCE),  tel. +33 (1) 30-64-82-00 or 74
Chorus systemes, 6, av.Gustave Eiffel, 78182 Saint-Quentin-en-Yvelines CEDEX