SPUG: On clocks, synchronous packets, and trains

[Bill Campbell]

On Thu, Jun 21, 2007, Michael R. Wolf wrote:
>> I would think that they would have figured out how to meet a schedule 
>> after a hundred years or so.
>
>Trains were, in fact, the driver of coordinated time, and chronographs
>(expensive watches) were the cutting edge in the high tech of the era.  
>
>Without any other means of communication (i.e. before radios), reliance on
>schedules was critical to prevent half-duplex resource contention (i.e. two
>trains on the same track in opposite directions).  

While I understand the idea, I don't think it was that important with rail
roads in the U.S. South as trains tended to stop at practically every cow
pasture.

...
>Another big push toward creating a universal time was the digital telephone
>networks.  Timing bits in asynchronous communications represented lost
>bandwidth since they were transmitted in-band.  Creating an out-of-band time
>reference allowed synchronous communications across long distances (i.e. New
>York to Washington) to prevent packet collision.  Not nearly as spectacular
>as locomotive collisions, but important, nevertheless!!!

My grandmother always claimed that the wreck of the Old 97 occurred on our
family's farm near Danville, Virginia which may be why stewed tomatoes at
our house were always called ``train wreck''.

Bill
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