[ih] early networking

[John Levine]

It appears that John Day via Internet-history <jeanjour at comcast.net> said:
w>Then the light dawned, as the video relates, message switching was analogous to FCFS batch processesing. Packet switching was analogous to
>multiprogramming (timeslicing) round-robin scheduling. (To continue the operating system analogy, long messages take a little longer but the
>completion time for short messages is shorter.) And virtual circuit was round-robin with contiguous memory allocation, and datagrams were a
>tool for exploring the next step,  but because they handled the immediate problem that step was never taken.

I suspect this sort of thing has been invented many times.

In 1956, TAT-1 was the first telephone cable between North America and
Europe (well, Newfoundland to Scotland) using highly reliable vacuum
tube amplifiers* to provide 37 voice channels in each direction. It
was a huge improvement over the former SSB radio and 37 channels
wasn't enough.

In 1960 Bell Labs invented Time Assiged Speech Interpolation (TASI.)
They knew that in a phone conversation each person is only speaking
about 40% of the time, so when someone paused talking, they'd swap
another conversation into the channel, and when they resumed, they'd
put the paused conversation onto a free channel. This smells sort of
like packet multiplexing although done almost entirely with analog
equipment. TASI worked well enough that they could put 74
conversations on the 37 channels with no noticable loss of quality.

Here's some BSTJ articles about TASI:

https://archive.org/details/bitsavers_BellSystemJV41N04196207_12232730/page/1438/mode/2up

R's,
John

* - in the two decades TAT-1 was in use there were zero amplifier
failures. They stopped using it because TAT-6 and -7 each had
thousands of channels making the early cables irrelevant.