[fa.telecom] TELECOM Digest V4 #205

telecom@ucbvax.ARPA (06/26/85)

From: Moderator <Telecom-REQUEST@MIT-XX.ARPA>

TELECOM Digest                           Tuesday, June 25, 1985 7:57PM
Volume 4, Issue 205

Today's Topics:

                             Penril woes
                   Ven-Tel Modem schematics needed
                       Phone dialers and modems
                   single line dial in/out on Altos
            Re: TELECOM Digest V4 #202 Clicks and Handsets

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Date: Friday, 21 June 1985  07:33-MDT
From: Steven Taylor <decvax!mcnc!ecsvax!taylor@Ucb-Vax.ARPA>
Subject:   Penril woes

There are at least 3 prom sets for the Penril autodialers in question.
The "vanilla" prom set does indeed keep cd high (as best I remember)
in order to keep terminals happy.  (It was designed to be used with
dumb crt's as an outgoing device.)

A second version was designed specifically to work with Develcon
dataswitches in a bidirectional mode.  That is, they could be used on
the switch for outgoing calls or incoming calls on the same port.  I
KNOW that this prom set does not keep cd high, but brings it up in
response to DTR coming high.  (Remember, the dataswitch does not bring
dtr high until it is trying to initiate a call.  This difference may
be the root of the problem mentioned.)  If you need more detailed info
on this, I'll be glad to discuss this firmware in detail.

Finally, there is also, I understand, a "Hayes compatible" firmware
set available now as well.

Your Penril rep should be willing to work with you on getting a prom
that will work, but you may have to get hin to do some investigation
before he will admit that the three version (minimum) really exist.

Steven Taylor
Distributed Networking Associates
Charlottesville, VA 22901
(804) 979-0656

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Date: Saturday, 22 June 1985  22:00-MDT
From: John Ruschmeyer <vax135!petsd!moncol!john@Ucb-Vax.ARPA>
Subject:   Ven-Tel Modem schematics needed

Monmouth College is in need of the schematics (or any other technical
information) for the Ven-Tel MD 212 PLUS modem (specifically, one of
the older models in the black case).

Recent lightning strikes have disabled two such modems. Ven-Tel's only
suggestion is to send the modems to them for service. Based on a
previous dealing with them, however, the repair would cost more than
replacement.

Any pointers to a schematic, therefore, will be appreciated.  Thanks
in advance.....

-- 
Name:		John Ruschmeyer
US Mail:	Monmouth College, W. Long Branch, NJ 07764
Phone:		(201) 222-6600 x366
UUCP:		...!vax135!petsd!moncol!john	...!princeton!moncol!john
						   ...!pesnta!moncol!john

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Date: Monday, 24 June 1985  17:05-MDT
From: sasaki@harvard.ARPA (Marty Sasaki)
Subject:   Phone dialers and modems

I have this cheapie phone that has a last-number-redial button. I
connect the phone to my modem, and the modem to the telephone line.
Everything is fine when I'm using my phone normally. The fun comes in
when I push the "data" button on the modem. This seems to disconnect
the phone from the line. Unfortunately, the memory for the
last-number- redial seems to need power; it forgets when I push the
"data" button.

I've been thinking of getting a better phone (one of Panasonic's
"Easa-phones") that has a bunch of remembered numbers, and was
wondering whether I would have the same problem of forgetting numbers?
Is there some way around this?

I used to have the phone and the modem in parallel and would sometimes
have problems with noise, especially when I hung up the phone.

----------------
  Marty Sasaki				net:   sasaki@harvard.{arpa,uucp}
  Havard University Science Center	phone: 617-495-1270
  One Oxford Street
  Cambridge, MA 02138

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Date: Saturday, 22 June 1985  20:02-MDT
From: Randy Suess <ihnp4!wlcrjs!randy@Ucb-Vax.ARPA>
Subject:   single line dial in/out on Altos

For all you Altos 586 owners out there that have been stymied by your
lack of ability to use a single modem/port for dial in and dial out,
be unhappy no more.  I have finally got it going using the new ARK
2400 baud modem.  The problem has always been that the Altos requires
cd (pin 8) to be always hi for dial out, but to only be hi on carrier
detect for dial in.  On a DCHayes, for instance, you had to have the
switch 6 up for dial in and down for dial out.  The ARK modem uses a
"intelligent" cd pin.  There is a wiring change to be done on the
cable.  Pin 6 on the Altos goes to pin pin 5 on the modem.  You then
of course have to modify the various programs used with the line.  I
use it on my system for uucp dial out and in.  I just replaced
/usr/lib/uucico with a shell script that tests for usage, disables the
port, then calls a renamed uucico.  After uucico finishes, it
re-enables the port for dial in.  I have been receiving news and
polling other sites with it with no problems.

The ARK's are the best 2400 baud modem going for the price.  They have
built in mnp protocol, and list for $595.

Hope this has been of some help.

-- 
.. that's the biz, sweetheart ..
Randy Suess
Chi-Net - Public Access UN*X 
(312) 545 7535 (h) (312) 283 0559 (system)
{ihnp4|ihldt}!wlcrjs!randy

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From: ihnp4!ihopa!riccb!jmc@Berkeley
Date: 25 Jun 85 08:12:49 CDT (Tue)
Subject: Re: TELECOM Digest V4 #202 Clicks and Handsets

In regards to hearing your voice back in your ear via the phone line,
in a 2W circuit this is called TRANSHYBRID LOSS (or lack of it as it were),
in a 4W circuit this is called SIDETONE.  It was orginally there as a 
function of the 2W to 4W hybrid circuit on a two wire line.  People now
associate this with the phone working.  If a 4 wire line terminates in
a handset or headset then a certain portion of voice is bleed back to 
the ear intentionally.
                                     Jeff McQuinn just VAXing around

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End of TELECOM Digest
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