Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!thunder.mcrcim.mcgill.edu!snorkelwacker.mit.edu!apple!mauxci!eci386!woods
From: woods@eci386.uucp (Greg A. Woods)
Newsgroups: comp.unix.sysv386
Subject: Re: Equinox question
Message-ID: <1991Feb20.202915.21242@eci386.uucp>
Date: 20 Feb 91 20:29:15 GMT
References: <27B79130.5C72@telly.on.ca> <1991Feb13.170319.13308@virtech.uucp> <1991Feb15.165755.3231@pcserver2.naitc.com>
Reply-To: woods@eci386.UUCP (Greg A. Woods)
Organization: Elegant Communications Inc.
Lines: 50

In article <1991Feb15.165755.3231@pcserver2.naitc.com> kdenning@pcserver2.naitc.com (Karl Denninger) writes:
> In article <1991Feb13.170319.13308@virtech.uucp> cpcahil@virtech.UUCP (Conor P. Cahill) writes:
> >We have a T2500 running full blast on our Equinox 24 port card with
> >no problems.  We get about 1500 bytes/sec on output and 900-1100 bytes/sec
> >on input.
> 
> However, if you turn on XON/XOFF in a Telebit modem and use spoofing
> (S111-30), it is smart enough to disable it when a uucp call comes in or
> out.  Thus, it works for both interactive users AND UUCP calls.
> 
> This is not obvious, but it does work.  I do it that way myself on one
> modem, the other I wired strange for full modem control (CTS/RTS + modem
> control) since it has V.32 capability and you need it there.

I don't feel entirely qualified to say much directly about Equinox
ports boards, or Telebit's, but I do have a great deal of async
experience on a wide variety of hardware.

From what I understand the particular combination of an Equinox card
and a Telebit will work fine when sending files, since the Telebit
properly paces everything such that its buffer's don't over-flow.

However, in certain circumstances when receiving a file via UUCP with
this setup, I can see that the uucico may lose packets if there is no
hardware flow control.  Maybe the uucico is swapped out.  Maybe the
system has a load average of 15.  Remember, UNIX isn't a real time
O/S.  Any lost packets will mean timeouts in the uucico.  That's
probably why Conor is seeing only an average of 1000 cps input.  I'd
be real disappointed if that's all I was seeing on my system.

Now, for any other devices, i.e. non-spoofing modems, hardware flow
control will be required when sending *or* receiving files with UUCP.
In fact I wish our Anchor 2400 modem had working hfc sometimes, since
when our system gets busy, packets get dropped, and because the alarm
timeouts are lengthy, it can do a real number on the over-all
throughput.  On a busy day, our receive throughput may drop from 190
cps to 90 cps at 2400 bps.  All you folks running single user 33 Mhz
386's and 16 Mb RAM won't have to worry, but the rest of us do.

Finally, I don't care how fast that little Equinox card can receive
characters, if I can't get them safely onto my disk, all the speed in
the world won't help.  I.e. can I cat from each port into separate
files, and receive every byte without any flow control?  That's
potentially over 90 Kbytes per second coming into the system.  It just
won't happen on my 386, no matter what O/S I'm running.
-- 
							Greg A. Woods
woods@{eci386,gate,robohack,ontmoh,tmsoft}.UUCP		ECI and UniForum Canada
+1-416-443-1734 [h]  +1-416-595-5425 [w]  VE3TCP	Toronto, Ontario CANADA
Political speech and writing are largely the defense of the indefensible-ORWELL