[GreenKeys] Information Requested

[Christian Gauger-Cosgrove]

Jim:

Thanks for the information. I remember you sent it along to me before,
I just couldn't remember the specifics (beyond the fact it could
rewind tape). Also, I really didn't want to run though a giant wall of
e-mails to re-find our previous conversation.


To Greenkeys:

I know the LCXD dual-head reader can be installed into a 28ASR... any
photos of such a configuration?


Cheers,
Christian

On 19 September 2012 13:51, Jim Haynes <jhhaynes at earthlink.net> wrote:
> On Wed, 19 Sep 2012, Nick England wrote:
>
>> So now I'm curious - what does an LFXD actually do? What does "tape
>> pull-back" mean?
>> Nick
>>
> I've told this so many times I should save it in a file for use when
> someone asks.
>
> LFXD is part of an ASR set for the "Developmental Line-Switched
> Teletypewriter System" which was first done for Delta Airlines.
> Delta needed a new message switching system in a hurry because
> the building containing theirs was to be torn down as part of
> expansion of the Atlanta airport.  Instead of a store-and-forward
> system like they had in mind, AT&T proposed a system that would use
> the DDD phone network for switching.  This required a complicated
> ASR set attached to a modem and auto-dialer.  The ASR set used
> five-level code punched into eight-level tape, the other levels being
> used for control purposes.  Messages typically have multiple addressees.
>
> A message in the Delta system is preceded on tape by the phone numbers
> of all the recipient stations.  LFXD reads the first phone number,
> dials it, and if a connection is made skips to the beginning of the
> message and transmits it.  Then it backs up the tape and stabs it to
> mark that phone number as delivered and advances to the next phone
> number and repeats the process until all copies of the message have
> been delivered.  In case a number is busy or does not answer there
> is provision for some retries and then delivery to an intercept position
> for manual handling.  After all copies of the message have been delivered
> the LFXD feeds out the tape to a point where it is no longer retrievable
> and proceeds to handle the next message.
>
> Since the airlines want mnemonic codes for message addresses, such at
> ATLRVDL for Atlanta, reservations, Delta, there was a machine called
> the Codomat containing cards, like a Rolodex file, with tabs for the
> mnemonic codes and punched with the phone number corresponding to the
> code.  The operator would locate the desired mnemonic, pull the card
> sideways into a slot where a crawling-head reader would read the
> perforations and copy them to the message tape being prepared.  This
> would punch both the phone number and the mnemonic code into the tape.
>
> There was also a large collection of equipment used to interchange
> messages with the store-and-forward systems used by other airlines.
>
> The system was used successfully by Delta for several years.  One was
> also made for United Airlines.  All this depended on the WADS - Wide
> Area Data Service proposed tariff, which the FCC rejected and then the
> systems had to be replaced by something else.  Something else by this
> time was a computer technology store-and-forward switch such as the
> Collins C-8400.
>
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