Path: utzoo!attcan!uunet!dino!ux1.cso.uiuc.edu!brutus.cs.uiuc.edu!apple!uokmax!rmtodd
From: rmtodd@uokmax.uucp (Richard Michael Todd)
Newsgroups: comp.dcom.modems
Subject: Re: T-25500 with Mac A/UX
Message-ID: <1990Jul3.233157.3740@uokmax.uucp>
Date: 3 Jul 90 23:31:57 GMT
References: <1990Jul02.171637.6630@uhura.neoucom.EDU>
Distribution: na
Organization: Engineering Computer Network, University of Oklahoma, Norman, OK
Lines: 32

wtm@uhura.neoucom.EDU (Bill Mayhew) writes:

>The T-2500 has what seems to be about a 32Kbyte or so buffer.  I
>have observed my Trailblazer continuing to dump data into  my
>computer even after the call has actually terminated.
  Hmm, that's strange.  I don't think that's supposed to happen--the sender 
is supposed to wait around until the receiver sends the "file OK" message
("CY" or something like that--I haven't looked at uucp innards in some time..)
Certainly, I've never seen it happen on my T1000 connected to my Mac IIx.
There's a sizable buffer there, but it empties at the end of each file...

>Whether or not you can use hardware flow control with A/UX depends
>on the tty driver.  I can't tell you right now, but could in the
>near future.  I have a II-cx with A/UX on order and expect it to
>arrive any now!
  For practical purposes, you can't use hardware flow control on a Mac with
A/UX, but the reasons have nothing to do with the tty driver.  The problem is
that the Mac serial ports share the same design flaw as the serial ports of
the Encore/Xylogics Annex terminal server (recently discussed in comp.sys.
encore), namely, there aren't enough wires coming out of the serial port. 
Both the Mac and the Annex give you only two control lines, which can be 
used for either flow-control *or* modem-control (carrier detect, hanging up
under DTR control), but not both.  The driver software can't do anything about
it.  You're stuck--either you choose hardware handshaking, or you choose
the ability to hang up the modem under computer control.  
  My experience is that a T1000 (the 9600bps max throughput little brother
of the T2500) works well enough with a Mac IIx without flow control.  Alas, 
I've never had the chance to play with a full-speed Trailblazer on this 
system... 
-- 
Richard Todd   rmtodd@chinet.chi.il.us  or  rmtodd@uokmax.ecn.uoknor.edu  
"MSDOS is a Neanderthal operating system" - Henry Spencer