[GreenKeys] FAA Teletypewriter Network 1959

[Jim Cooper]

On 3 Oct 2020 at 19:16, Harold Hallikainen wrote:

> Your description of what they went
> through for message routing is
> amazing. The invention of packet
> switching (and computers to handle
> it) sure simplified things! But I can
> imagine electromechanical switching
> with paper tape buffer where the
> entire message is a "packet" and
> routed based on the address in the
> header. Sure easier to do in
> software! 

I may have mentioned this previously, 
but it fits the comment above ... 

Way back in my "early days" when i worked 
for ITT World Communications (Mackay Radio)
in downtown NYC, I designed and supervised
the installation of a world-wide M28 switching 
system that took up an entire floor of the old 
Pan Am building in NYC.  

This system was designed by me with the 
giant schematic attached on the wall of my office! 

All switching was done using stuntbox switches, 
and connections between networks were all done 
using M28 R/T sets -- which are very large cabinets 
with incoming reperf and outgoing LAXD 'climbing 
head' transmitters...  usually two sets in each R/T 
cabinet, one for each direction. 

Some of the R/T worked also as speed changers; 
either from 60wpm to 100wpm (or 67wpm, 50 baud
for European circuits) ... or in a clever arrangement 
where WorldComm sold "half speed" and "quarter 
speed" overseas circuits.  The XD in the R/T set 
would be 'paced' to send a character at channel 
speed, but only every other character or every 
fourth character.  These channels were then time-
division multiplexed onto the full-speed undersea 
cable channel. 

When fully operational, you can imagine that the 
PanAm switching center was not a very quiet place! 

Jim  W2JC   (ex W2BVE)