Newsgroups: comp.sys.att
Path: utzoo!telly!robohack!woods
From: woods@robohack.UUCP (Greg A. Woods)
Subject: Re: 3B2/310 & TB+
Organization: R. H. Lathwell Associates:  Elegant Communications, Inc.
Date: Sat, 28 Jul 90 19:20:42 GMT
Message-ID: <1990Jul28.192042.2741@robohack.UUCP>
Summary: 3b2 port cards
Keywords: Hardware Flow
References: <3580@sactoh0.UUCP> <1990Jul25.062920.12777@robohack.UUCP> <16192@ucsd.Edu> <470@mtndew.UUCP>
Lines: 71

In article <470@mtndew.UUCP> friedl@mtndew.UUCP (Stephen J. Friedl) writes:
> All 3B2s have console and contty ports, and these ports are on the
> motherboard and serviced by the main CPU (by the DUART driver).  They
> can handle quite a good data rate -- sustained full 19200 bps output --
> but they degrade quickly when the system gets busy.  We tell our customers
> to stick a 2400bps modem on the contty port because that's a pretty slow
> speed and is likely to be working even if the other serial cards go down
> (so we can dial in and fix stuff).

Even sustained UUCP at 2400 on contty can be a significant load on a
system.  However, it is true that contty will likely be one of the
last ports on a system to die.

> moving the cursor back.  It can be maddening, so I "fixed" it by
> define the cursor-left character in terminfo as ESC[D.  Sending
> three characters is MUCH faster than waiting on the delays.

I've never seen this.  I know it is possible to put backspace delays
on a port inside the termio driver.  Perhaps the default on PORTS was
to use this delay (for those old 33's you know).  I would hope you
could turn off the delay with an ioctl() though.

> PORTS HPP is purported to be a high-performance version, but I
> don't know much about it (others are welcome to chime in here).
> I have heard that this was originally developed with the military
> in mind, but that very well could be idle gossip.  I don't know
> if it has the same backspace delay bug.

This one does seem to work just fine, though it lacks hardware flow
control.  I ran two 2400 bps modems, and my dmd at 19200 on it for
quite some time with no problems.

> They support CTS/RTS flow control, but it is done in a way that
> makes them not very helpful for many of us.  The big bug is that
> CTS/RTS is mutually exclusive of XON/XOFF -- you can never run
> both at the same time.

This is a serious design flaw in the EPORTS driver and firmware!

> data rates this time can be significant.  I'm told that "skid" of
> 32 or 64 characters is not uncommon, and all the HP LaserJets
> that I've seen can't deal with this.  You gotta either slow it down,
> use hardware flow control, or use a parallel port.

It's too bad you can't set the port priorities in order to close the
window.

> Finally, the EPORTS have had >tremendous< problems in the past
> with bugs.  I have had several customers ready to throw their
> computers out the window due to EPORTS problems, and only in the
> last year or year and a half has it been better (with the 1.3
> driver).  I understand that the EPORTS folks in Lisle had a very
> miserable summer of 1988.

The still do.  Well, maybe not quite as bad.  I seriously wonder if
any of the drones at AT&T can write firmware (the 705 MT's I've been
testing have serious firmware problems, even at rev.1.2).  The EPORTS
with 1.3 drivers still hangs occasionally on every modem except the
AT&T 2224B.  I've put my 1200 on the PORTS/HPP card, but the Microcom
I had for a while required HFC, and was a real pain in the butt.  I've
seen reference (in the newest 3.2.2 docs) to a new command (relport)
(though I've not tried it yet), which the documentation purports to be
able to release a port from a hang without re-pumping the card (and
dropping all connections).

It is a real screamer though!
-- 
						Greg A. Woods

woods@{robohack,gate,eci386,tmsoft,ontmoh}.UUCP
+1 416 443-1734 [h]   +1 416 595-5425 [w]   VE3-TCP   Toronto, Ontario; CANADA