Ken Johnson

by Ivor Catt, May 2007

Statement about Ken Johnson
Ivor Catt. 21 May 2007

I returned home from abroad and looked at my emails a few hours ago. Time is short before the funeral on Wednesday, so I will put down the key points about Ken that I know of. Like Blair, with an eye to our legacy, they are important. At some future time there may be interest in what happened at the beginning of the computer age. I will welcome any additions sent to me electronically for adding to this web page.

After graduating in engineering at Cambridge in 1959, I was hired by Gordon Scarrott into the Ferranti R&D labs in West Gorton, Manchester, where I stayed for three and a half years, finally leaving to go to the USA for six years. After leaving Gorton, I have had virtually no contact with anyone from those for me formative 3 years.

A few days before leaving for Los Angeles, a one day meeting was organised at West Gorton to discuss the significance for the future of digital computers of the shortly to arrive integrated circuit. (We knew that the then current battle for supremacy between the digital computer and the analogue computer had an inevitable outcome.) Ken Johnson took the stage for a brief while, and drew the then ruling memory circuit, the transistor bistable, on the board. It had around ten components. He pointed out that with a single additional traisistor, a whole column of bistables could be searched for the presence of a "one" by looking for current through a totem pole arrrangement.

I have published somewhere that that was a traumatic experience for me. It meant that the Von Neumann computer would soon be replaced by array processing. However, this did not happen. My own failed (not significantly exploited) attempts were The Kernel Machine and the earlier "Catt Spiral". "The Nub of Computation" gives the underlying ideas. Gordon Scarrott's later team in Stevenage made two other 'failed' attempts.

The problem is that "The separation of storage from the processing unit is implicit in the von Neumann architecture.", see Wikipedia

When finally giving up on hi tech engineering ten years later because nothing was happening , I published my lament in "New Scientist".. It still has not happened today, see my 2003 article , and the computer art remains half strangled, shut off from its massive potential.

I went to Los Angeles, and soon migrated to the new microelectronics industry, which was separate from digital computers. I was taken to Motorola, Phoenix, Arizona, to look into the interconnection of high speed ( 1 nsec ) logic gates. The locals only knew about design and manufacture of the new integrated circuits, not about their use. A key to this use is the question of crosstalk between parallel conductors buried inside a multilayer printed circuit board. I did my experiments, and saw the new flat topped noise, as opposed to the traditional spike of unwanted noise, or interference. That was fine, but a peculiar, small spike appeared at the end of the flat topped noise. Fortunately, Walt Seelbach, deputy head of R&D, told me to continue in my lengthy efforts to get to the bottom of it.

At a crucial point in my work, whom should I see walking down the corridor, many thousands of miles from his proper place in Manchester, but Ken Johnson. I still don't know why he was there.

I grabbed Ken and took him into my office. There, I told him the problem. He replied by saying that there were two modes of propagation, which he probably might have called the Even Mode (EM) and the Odd Mode (OM). He then drew one of them (OM) incorrectly, as going down the active pair and returning up the passive pair. However, he had given me the concept of two modes. The correct OM is a diagonal situation, as I found out very soon after Ken's hint, see my book. . This discovery , already known in microwave theory but inaccessible, and now forgotten again by the computer world, was my biggest achievement up to that time.

After three years of battle with Narud, head of R&D in Motorola, who blocked it, during which he tried to get me fired, I published this key result in 1967, see ref. 15

None of the information above, or the other insights from Ken touched on above, are known to any relevant Professor or text book writer today, 40 years later. None of it is in any college syllabus.

The above is an abrupt story about two important leads given to me by Ken. I may later recollect others than the two key leads he gave me (above). The fact that a ten minute talk by Ken could direct my life and work for decades, and that this happened at least twice, should be recorded. I also cited Ken . (Figure 1) at the time.

Ken was the most talented design and R&D engineer in a very talented lab, Computer R&D in Ferranti, West Gorton, Manchester, 1960, with the late Charlier Portman and other key players directed by the late Gordon Scarrott. It should have taken control of and directed the Computer Art into the future. It is important to work out why the potential of that exceptional team, the finest in all my experience, came to so little.

Ivor. 21 May 3007.

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