[GreenKeys] ebay "Teletype Message Numbering Module"

Sat Jan 11 16:44:39 EST 2014

Dave,

It's odd that ZCZC would be used to start up TTY's that had idle

line motor timeouts. It would only come across as garble as

the motor ramps up...and, possibly, so would the characters

afterwards until the machine synchronizes with the incoming

signal.

Usually, a string of LTRS would "wake up" the machine. The

ZCZC would be read by a stuntbox or other type of controller

to know that a valid message was coming through, or

possibly take a TTY out of "non- print" mode.

Jack K0TTY

From: greenkeys-bounces at mailman.qth.net
[mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of NNN7DXB at aol.com
Sent: Saturday, January 11, 2014 3:36 PM
To: navy.radio at gmail.com; greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] ebay "Teletype Message Numbering Module"

Hi Nick and Group:

No experience with the civilian way of doing things, but in the military,
particularly

in the US Army and during "tape relay" operations, the normal message
numbering

sequence usually started out like this:

ZCZCFMA123

There were No spaces between the ZCZC, the Channel Identifier and the
Channel

or Message Number.

The ZCZC was referred to as the "Start of Message Indicator" or "SOM". This
had

a unique purpose in that is started up, (or "woke up") distant-end teletype
machines

(usually printers) that had an auto shut-off feature which usually kicked in
after about

60 seconds to 3 minutes of idle time (no traffic on the circuit). The ZCZC
served the

same purpose that a "LINE BREAK" function did on some other other types of

machines, and it is said that the ZCZC insured that all followed characters
were

in fact received and not misinterpreted as garble or hash. More in ACP-127,
Tape

Relay Instructions if you do a search on the Internet.

The Channel Identifier more or less identified the specific channel over
which the

traffic was being sent, usually using the last two letters of the sending
stations

Routing Indicator (either the last two, or the last two INVERTED, depending
on

the TAPE RELAY station). Thus, the Major Relay (tape relay) station "RUFM"

in Frankfurt, Germany would use "FM" as the Channel Identifier. The
following

letter "A" signified the specific channel if there were more than one
channel or

circuit going to the same distant station, thus FMA, FMB, etc.

The Message Number, called a Channel Number, was affixed in sequence to

each and every message sent over a channel or circuit. This insured 100%
message

accountability (no lost messages along the way). Any missing Channel Numbers

had to be immediately identified and accounted for via SERVICE message
between

the distant station and the sending relay (or other tributary in the
system).

In later years, ZCZC would be slightly modified to VZCZC, thus VZCZCFMA123,

particularly during the AUTODIN era of the CommCenters in both Mode II and V

operations. Channel Numbers, etc were not used in DATA or Mode I operations,

since these were fully digital and the "computer" kept track of all message

traffic.

In the old days (before 1968), we had the old AN/FGC-35 and AN/FGC-38 tape

relay sets. As mentioned by others, these included a bank of 3 TDs, one of

which was used strictly for Channel Numbering using a pre-made roll of tape

with the channel numbers and channel ID punched into it. An op would have to

press the TD with the channel number ID in order to crank out a channel
number

and after it was transmitted, it stopped, and the TD containing the next
message

in the 1st (or 2nd) TD would then start up by sending the message.

Common practice was that the LEFT-most TD had the Channel Number tape

in it, while TDs 2 and 3 were reserved for message tapes to be transmitted.

In later years, Kleinschmidt AN/TGC-5 and AN/FGC-70s tape relay sets would

perform the Channel Numbering automatically. These numbers were generated

by the machine itself, and there was no need for a separate, dedicated
Channel

Numbering TD on the KLI equipment.

In stations that did not have automatic numbering equipment, the ZCZC

was generally not used. Instead, VV followed by 3 spaces and then the

Channel ID and number were used.

Ex: VV   FMA123

Regardless of what system was used, in most tape relay or torn tape

operations, the next sequence of characters was always 5 spaces, 2

carriage returns and a line feed (5-2-1, or 5 SP, 2 CR, 1 LF). This was

necessary in order to "align" the message with the distant ends printer.

In the military formats, the Channel ID ("Channel Serial", ZCZCFMA123,

etc, was called "Format Line 1).

Hope this clarifies. From an old tape ape of tape relay days!

Dave

CommCenter Group

----------------------------------------------------------------------------
------------------------------------------------

In a message dated 1/11/2014 12:23:38 P.M. Pacific Standard Time,
navy.radio at gmail.com writes:

ZCZC NYWCH 001

Teletype 173520 Message Identification And Numbering Module Assembly

Howdy gang - I identified this eBay item as the message numbering unit used
in 28 Torn Tape Relay equipment, in particular the Transmitter Group which
has two triple-TD trays and 6 of these numbering units. The military version
is TT-333A/UG and you can see photos at

http://www.navy-radio.com/tty-relay-equip.htm

I also got front/rear views from the eBay seller and added them a little
further down the page. 

I have one triple-TD tray and got 3 of these numbering units from the eBay
seller with the intent of creating a "half-size" TT-333A/UG.

As Jim Haynes said, these units generate the header for a tape that you are
going to transmit. The stepper relay connects 15 sequential characters in
5-wire parallel to the distributor on the corresponding TD in the equipment
cabinet. There is also a tandem mode where one numbering unit controls two
TDs in alternating sequence so that you can load one message tape while the
other is being transmitted. Clever lads, those Teletype chaps....

When you load a tape and switch to RUN on a TD, the numbering unit first
generates the following sequence:

(LTR) ZCZC ABCDE (FIG) 123 (LTR) (start_message_tape)

where 123 is from the sequential message number counter,  ABC are
customer-wired characters, and DE are customer-defined characters by two
plug-in code cards (visible in the front photo).

The eBay seller has some more and will post them for sale I presume - I got
3 of them for $60 ea. (yeah, too much but better than the original $950 ea.
listing...)

If you are interested in these things, I will be scanning and posting
description, parts, and wiring diagrams over the next couple of weeks.

Cheers,

Nick England K4NYW

www.navy-radio.com <http://www.navy-radio.com/> 

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