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000015_news@columbia.edu_Wed Jul 26 23:43:33 1995.msg
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From: caf@omen.com (Chuck Forsberg WA7KGX)
Subject: Re: Kermit download from CompuServe.. best setup??
Organization: Omen Technology INC
Date: Wed, 26 Jul 1995 23:43:33 GMT
Message-Id: <DCCKKL.K63@omen.com>
References: <3uidtu$r5c@hpber004.swiss.hp.com> <MpREww8Z7mxH084yn@netcom.com> <DC7oIH.6IA@omen.com> <kwOFww8Z7GDV084yn@netcom.com>
Lines: 76
Apparently-To: kermit.misc@watsun.cc.columbia.edu
In article <kwOFww8Z7GDV084yn@netcom.com>,
Jeffrey Hurwit <jhurwit@netcom.com> wrote:
>In article <DC7oIH.6IA@omen.com>, caf@omen.com (Chuck Forsberg WA7KGX) wrote:
>
>>The complexity of the Kermit protocol with its window management and
>>other features exacts a penalty in CPU resources.
>
> To be perfectly honest, I'm not familiar with zmodem. However,
> there was quite a bit of discussion in one of our ISP-local news
> groups about disconnects at 10 minutes during transfers using sz.
> It was reasoned that 10 minutes indicated the idle daemon kicking
> in and logging out sessions, and the solution was found to be to
> use an sz option to enable windows. Why does sz offer this
> feature, if it's known to be detrimental in some way?
This question isn't relevant to the question of CPU loading.
Controlling the ZMODEM window with the sz -w option is exactly
that! An option. It can be used to enforce a high level flow
control when lower levels of flow control are not set properly.
It cal also be used to generate activity on the reverse channel
to prevent idleout programs from fragging the transfer. It is
not the default because it can reduce throughput in some
situations.
>
>> Let's compare sz
>>(a link to Unix Professional-YAM) and CKermit 5a 190:
>>
>>(38kb direct connect)
>>
>>ls -l *gif
>>-rw-r--r-- 1 caf omen 352650 Feb 8 1992 b17mh.gif
>
> Um, perhaps Frank may comment on the validity of the rest of your
> test, but
>
>>time kermit -s b17mh.gif
>
> tells Kermit to do newline and charset translations, which might
> account for some CPU power. At the least, you'd have a corrupted
> gif file on the other end.
>
> I think the command you wanted was 'kermit -s b17mh.gif -i'.
>
> Also, did you have control character unprefixing set up for
> C-Kermit? Excessive prefixing may also account for some CPU time.
I used the same very aggressively optimized .kermrc file I used
for the Protocol Shootout. It is more aggressive (when sending
to ZCOMM or Professional-YAM) than MSKermit allows. It also
disables Kermit's default file corruption transfer mode.
>
>>The files were received by a 32 bit beta test version of Professional-YAM
>
> Does this software not tell the user whether the file transfer is
> taking place in BINARY or TEXT mode? (If it does Kermit transfers,
> does it not process file attributes packets?) MS-Kermit puts the
> transfer mode right up there on the screen, so if the transfer is
> accidently started in the wrong mode, the user may observe that and
> restart.
The default for Professional-YAM and ZCOMM is to transfer files without
translation. Professional-YAM and ZCOMM Kermit transfers feature
automatic Kermit downloads. In fact these programs are so quick they
often beat MSKermit on downloads from Unix CKermit.
Despite Frank and Joe's expressed enthusiasm for quality Kermit
implmentations, I rather doubt that ZCOMM and Professional-YAM will appear
in any Columbia University list of efficient Kermit programs.
--
Chuck Forsberg WA7KGX caf@omen.COM 503-621-3406 FAX:-3735
Omen Technology Inc "The High Reliability Software"
Author of YMODEM, ZMODEM, Professional-YAM, ZCOMM, GSZ and DSZ
TeleGodzilla BBS: 503-621-3746 FTP: ftp.cs.pdx.edu pub/zmodem