[GreenKeys] Question regarding TWX and Dial TWX...

[Don Robert House]

Yes Bryan,

Those of us that were part of "The System" would agree with you.   
There is much that most people know nothing about.

Each 5 level machine that was set up on the original Teletypewriter  
Exchange Service starting in 1932 was connected
to another machine through a series of telegraph switchboards, more  
correctly, cord boards.  As the service grew so
did the required number of cord boards and operators to handle the  
load.  Starting approximately in 1959 each and
every machine had to be extensively modified so that the -130vdc loop  
could be cut over to a standard telephony loop
with dial tone.  Each machine took about 4 hours to modify.  It was  
not easy since the machine had to work on
the high voltage loop until the cut over.  Every customer was sent a  
letter and yellow stickers were put in the machines
top covers to remind the operator to throw the key on August 31,  
1962.  If they did not the machine would run open
until they did.

There was lots to do besides the modifications to the machines.  The  
dial network had to be set to recognize these
stations as teletypewriter stations and sent through the network on  
trunks designed for the purpose.  In 1963 as the
TWX network started to move to ASCII, another big problem had to be  
worked out.  How would a 5 level machine
communicate with an 8 level machine?  A set of special Area Codes were  
set up. (I have tried to reach Mark Cuccia
to get a copy of the practice I sent to him describing the dial TWX  
network that was created.  I have not heard from
him since I moved back here to Illinois.)  As memory serves I believe  
the codes were 910, 810, and 710.

If a 5 level machine dialed one of these codes the call would be  
routed to one of several convertor exchanges across
the country. The convertor exchanges served as the interface between  
the new 4 row 8 level machines and the
older 5 level machines.  The messages were odd to watch as the 100 wpm  
8 level machines would start and stop
to let the 60 wpm 5 level machines catch up.  During the Christmas  
holiday many customers would call our repair
service and ask that we send them "Christmas tapes"  I sent a couple  
of these, without really thinking, to a couple of
customers that had 5 level machines.  My foreman got a call from the  
supervisor of the convertor exchange that
"Someone from your area is tying up all of our convertors with these  
damn picture messages!" Sorry sir!

Each of the 4 Row 8 level machines, aka M33 and M35 had a private line  
channel to a major city like Chicago that
was equipped with a switch group dedicated to switching dial TWX  
traffic.  In Chicago it was the Congress C.O.  A
couple of us that did most of the TWX installations got to know the  
technician in Congress pretty well.

In the northern and northwestern suburbs of Chicago we maintained over  
600 teletype machines 24/7/364. The
only day no one was called out for trouble was Christmas Day, unless  
it was a state for federal emergency.  At
all other times we were required to repair all business customers in  
less than two hours.  It was quite a challenge.

You or some others might like to know what the orange lamp on dial-up  
M33s and M35s was for. They are
marked REST.  Funny because it stands for Restraint.  A signal from  
the convertor office stopped the 8 level
machine and lighted that lamp.  The operators thought the machine was  
"RESTing."  The white lamp indicated
a BREAK signal from the receiving station to stop the transmitting  
station in case of a paper or tape jam.

A few of the M35s had a set of small indicator lamps under these two  
lamps.  These were set up to monitor the
call to let the operator know how the call was progressing.  The  
service was called WADS D.
Wide Area Data Service - D.  It was tested but never deployed for  
service.

That is all for now.  My fingers are sore and my XYL is calling me to  
go to bed.

Memories, memories.

Don
K9TTY



On 22 Apr 2010, at 9:11 PM, Bryan Brodie wrote:

Ok Don, you've piqued my curiosity.

I searched google regarding the nationwide cutover to dial that took  
place at 8:00 a.m. on August 31, 1962. There's virtually nothing out  
there other than oblique references.

I'd love to know more about this: did other tech change at the same  
time? was this a cost savings measure? did it free up capacity? how  
much central office infrastructure was mothballed when this happened?  
what were the other technical ramifications, besides what you  
mentioned already?

Just curious - Bell System lore fascinates me. To me, the dismantling  
of AT&T ranks with the burning of the library at Alexandria in terms  
of knowledge squandered...

Bryan Brodie

On Thu, Apr 22, 2010 at 7:24 PM, Don Robert House <k9tty at dls.net> wrote:
Rice,

I had one of these in the museum in a M15 TWX machine.  It also still  
has the WECo 101A Dataset
mounted on the side of it with a subset on top.  A real collectors  
item.  All of these M15s, M19s, and
M28s had to be modified with 101A or B Datasets and custom wiring in  
addition to the answer-back
mechanism previous to the nationwide cutover to dial that took place  
at 8:00 a.m. on August 31, 1962.
They also had to put the new W-R-U over the "D" key cap on. Notice  
that you have to open the little
door on the front of the M15 or M19 cover to depress the Here Is key.

See the image below under your photo of the M15 Keyboard.  That is NOT  
a Telephone set.  Notice
there are no letters on the dial.  If you lift the handset there is a  
solid plastic cap where a transmitter
would be on a telephone set.  The receiver is just to monitor call  
progress.  15s and 19s had the
Dataset and subset on the left due to the handset and cord normally  
used by the operators left
hand.  On Model 28s the subset was integrated into the top of the  
Dataset housing on the right of
the machine.  The 28s had a half of a handset with just a receiver and  
a straight non-coiled cord for
listening for call progress.  Thereafter the telephone style sub set  
disappeared as they were slowly
replaced first with M28s and later with Model 33s and Model 35s.

At Ball Brothers in Mundelein, IL I replaced a M19 TWX with a model 33  
TWX... The operator quit.

Don
K9TTY