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000256_news@newsmaster….columbia.edu _Wed Aug 27 18:21:06 1997.msg
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From: jonathan@DSG.Stanford.EDU (Jonathan Stone)
Newsgroups: comp.protocols.kermit.misc,comp.unix.questions,comp.unix.admin,comp.unix.misc,comp.unix.ultrix,comp.unix.shell
Subject: Re: Do not get connected at 33.6K
Date: 27 Aug 1997 22:04:29 GMT
Organization: Stanford Distributed Systems Group
Lines: 54
Sender: jonathan@Cup.DSG.Stanford.EDU (Jonathan Stone)
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References: <5tsn5b$o9q@newslink.runet.edu> <5tupoe$gra$1@apakabar.cc.columbia.edu> <5u0g7d$f6o@newslink.runet.edu> <5u1fh6$n39$1@apakabar.cc.columbia.edu> <5u1mrf$il7@usenet.srv.cis.pitt.edu>
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Xref: news.columbia.edu comp.protocols.kermit.misc:7572 comp.unix.questions:116074 comp.unix.admin:70237 comp.unix.misc:35282 comp.unix.ultrix:31801 comp.unix.shell:54283
In article <5u1mrf$il7@usenet.srv.cis.pitt.edu>, geest3+@pitt.edu (Gregg E Economou) writes:
> In article <5u1fh6$n39$1@apakabar.cc.columbia.edu>,
> Frank da Cruz <fdc@watsun.cc.columbia.edu> wrote:
> >RTS/CTS is the only kind of flow control that really works on a high-speed
> >modem connection, but Ultrix does not support it. Therefore you have to use
>
> the hardware doesent support it on a DS2100-3100 but afaik ultrix supports
> it. Now, depending on the hardware, you dont have support for 38400
> baud connections. Also, if this is on a DS5000/xxx then you should check
> the 19200-38400 high speed external clock generation setting,
> because speeds above 9600 are supported by an external clock supplying
> timing to the two "serial" lines going out of the DZ.
Sorry, this is *still* not quite right.
* The four-port dz-11 clone chip on 2100s and 3100s doesn't
support RTS/CTS at all.
* The 5000/200 supports full modem control on both RS-232
DB-25 bulkheads.
* The dc7085 chip does *NOT*, repeat *NOT* do 19200 baud.
It acutally does 19600 or thereabouts. (The exta/extb clock
is not quite right, perhaps for bug compatiblity with DZ-11s).
This doesn't always work with true 19200 devices.
* Ultrix does *NOT* support 38400 on the dz-clone ports on
the 5000/240. Switching between 19200 and 38400 is done
by toggling a bit on the system-control chip on the motherboard.
That changes the meaning of the `19200' speed setting for
all DC ports, so that they do 38400 when 19200 is selected.
The only way to get 38400 on a 5000/200 with Ultrix is to frob
the system interrupt controller-register bit from the PROM
before booting, and then hope that Ultrix never sets it back:)
The preferred Ultrix software interface for ttys is POSIX-compatible
termios. I have no idea what C-Kermit uses.
However -- I suspect that the original poster has a
5000/{20,25,33,50}, 5000/{120,125,133,150}, or a 5000/{240,260}.
These machines have standard Zilog 8530 SCC chips (or clones), and can
do up to 57.6 before the BRG clock gets too low to reliably sample bits.
Ultrix supports up to 38.4.
NetBSD, OTOH, supports up to 230.6, but you need synch clocking.
(DECstation 5000s can output asynch up to 115.2 perfectly, but cannot
reliably unframe RS-232 at speeds above 57600, because the SCC clock
multiplier is too low to reliably sample the start bits at that
speed.)