In the early 1970’s I was project managing a UK wide computer network development really pushing the then available technologies. We were using these new-fangled modems with synchronous transmission and reliant on a “polling” technique to acquire data from remote terminals. The modems were expensive (and in very short supply), and the line rentals (at the magic speed of 1200bps) were also eye-watering. To optimize the costs, and match the required data throughput was a nightmare, requiring multiple “branching points” to establish a viable network. The essential basis of the design was a circle some 120 miles from the mainframe computer site, at which individual lines would branch into multiple lines to the remote sites.
It worked well.
I was then involved in a series of lectures and presentations to various interested audiences, and described the network design as based on the “CJ Principle”.
Nobody ever questioned this description, and it went down in several follow-up sales proposals and even in a number of published technical papers…
Until years later, at a retirement party I was approached by a researcher looking at the early computer networking attempts, and he asked me straight what was the CJ Principle?
Trying to keep a straight face I told him – we were working on balancing the line utilization of many different configurations, with different branching points, and I was getting fed up.
I had a map of the UK on my desk, reached out for the ever-present Coffee Jug, placed it on the map, and drew a pencil around it – the CJ Principle was born.


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Well, now that the money has run out... - Roger Dawson June 16, 2026, 10:48:43
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