Stan Evans, Maintenance Engineer on LEO I and LEO II, joined LEO 1956
Date of Birth: Born 23/09/26
I never realised that my life was about to dramatically change when l went to Joe Lyons at Cadby Hall in 1956. for an interview for a job as maintenance engineer working on their first computer they had ever made. I was an experienced electronic technician but knew nothing about computer digital technology.
I was interviewed by the computer engineering manager Peter Mann. He asked me many questions but sadly I did not do very well with my answers. To my surprise and pleasure he offered me a job. It later emerged that all the other candidates had the same lack of knowledge that I had.
What was unique about this computer was that it was the first computer “worldwide” that was designed to do commercial type work. The other computers in use were basically scientific machines.
Lyons formed a company called LEO Computers so in fact I joined this company not Lyons.
There were two other chaps who joined me the same day. Les Rabitt and Stan Holwell. Now this is where I go for a wobble trying to remember names. However here goes.
The senior engineers already on site. Frank Walker, Jimmy Wheeler, George Manley and a much older chap Chas. These were the chaps who not only had to mend LEO I but had to teach us rookies.
Although there were detailed schematics of every specific unit in the machine there were no written notes on the logic. ie how the computer worked other than the hand written notes of our tutors . I pause a minute to reflect “You cannot get more basic than that.”
Our work shop was a 12 ft by 12 ft room located across the corridor from the Computer Room. In addition to us engineers there were three other people in this room.
To help fixing computer faults every unit type had a spare unit. I think they were called LCU xx If a fault was traced to specific unit and the fault cleared when replaced by the spare then Hey Ho back to the operators and the machine was up again. In the work shop the faulty unit was put into the Test Rack.
This Test Rack had simulated features to be able to test the unit and find the fault. There was a very clever engineer called Gibson. He maintained this test rack and also was involved in the thinking about the next step LEO II. Also in the workshop were two ladies.
One was a very experienced lady who did all the electric wiring in the units (modifications etc) The other lady was a thermionic valve tester. She had a check list of units that had been operational for a certain time period and checked all the valves and if below the Makers specification replaced them with a new valve.
The huge irony was that a development engineer chap called Lenearts established that new valves were more likely to fail than the comfortable settled in old ones. So this testing of valves did not really do any good. So this procedure was stopped. We were learning all the time.
There were two people we often worked with on the computer. They were David Caminer and Mary Blood. They were in fact the first Business Computer Systems and Programmers in the country and David led a small team of programmers who had written all the LEO I operational jobs since 1952 which was quite impressive.
Programmes were written in machine code format and stored in the main memory. This consisted of a number of special long tubes filled with mercury. They were stored under the false floor together with a number of smaller tubes, registers that contained only one word of 17 binary bits. Note. I am struggling here and hope I have got it right. I would think the main memory had 32 tanks and each tank 32 words.
I seem to recall a D30 digit. Perhaps that was Leo II
Basically a line of machine code had 4 areas. Each area had a specific significant meaning. If the programmer wanted this action to be an ADD he would put a number in binary in the first area because he knew that number told the computer to ADD. The other three areas were locations of the two numbers in the action and where the answer was to go. Clearly this format would not be the same for other instructions.
How about that a programme lecture in one paragraph. The point of this paragraph was to illustrate how basic the programming was. Cobol, Fortran etc was not even a dream in these days.
Mr Caminers team had written several programmes which tested the performance of the machine. When it failed we were given the reason. If it did not fail we used the margins tester. We had over a 1000 wires from the engineers control panel going to the most crucial electronic sections in the machine. These wires sent electronic signals that increased or decreased digital pulse size. Use of variation of threshold often made the performance test programme fail. Using eliminating switches It was a simple matter to find what unit was causing the programme to fail.
In certain difficult faults Mr Caminer was a great help in typing in a simple programme which clearly showed what action was going wrong, the engineers were then able to get moving with the oscilloscopes and find the fault.
I have enclosed a picture of a young engineer all 30 years old Stan Evans himself working at the LEO I engineers control desk. It was here that the engineers and Mr Caminer did our fault diagnostic work. Very often the engineers would do the same for the same reason. A small loop of a failing instruction made oscilloscope work easier.
Interesting to note that the Operators rarely use the engineers panel because at that time operations control was done using Punch Cards. These cards had been successfully used for many years for basic business tasks. They were 3 inches by 7 inches, had numbered columns 1 to 80 with rows numbered 0 to 9. Rectangular holes were punched out in each column.
To start a programme the operator would push a button called BOOT which placed into the computer Order Tank an instruction to read a card into the computer. This card contained the necessary instructions to read the complete pack of cards into the computer. These cards contained sequence of computer instructions ie the programme, and the scheduled commercial programmes was then ready to run. The operators area was dominated by three big heavy card readers, equally heavy printers and a paper tape reader.
The inevitable happened of course the work load had got very heavy so we had to go to three shifts. I hated the night shifts and I think in hindsight we would have preferred One week of nights and two weeks day/evening. However we three new chaps were very rapidly promoted to Shift Leaders because the senior chaps were moved to Minerva Road factory where work on the next generation computer LEO II was moving very rapidly. Oddly enough I cannot remember anything about our junior engineers at that time.
Doing nights did have one advantage and it’s a story I was very fond of telling. The Lyons management who were very highly regarded and so were provided with an “Out of this world” restaurant. Two lady chefs looked after the restaurant at night. I used to chat these ladies up. Most of us, the engineers and operators enjoyed a very basic level of living so a full roast and three veg was a real treat. I was often offered if it was available a Dover Sole. I have never seen such a big Sole since then. A quarter of an inch fish each side of the bone and the fish overlapping the plate. This is how the rich or talented lived. I missed that!!!! when I eventually moved from LEO I So back to the real story.
Very soon the first prototype LEO II was completed and installed in a different but near bye building to Cadby Hall. Both Les and Stan had moved to Minerva Road but in spite of my pleading I was still left in charge of LEO I. Something about good training in Management for me. Eventually LEO II / I was up and operational taking the commercial work off LEO I.
Transfer at last. No training course slot available so straight in as Shift Leader with new trained engineer Tony Talmadge
to help me. (no the name is not right ) I knew LEO I so well that the experience was invaluable when thrust onto LEO II and Tony was good. Hurrah.
The concept was almost the same but the electronic engineering had taken a massive jump forward. Not only was the machine considerably faster it now had magnetic tape which meant good bye to loading programmes and storing data on clumsy punch cards. Delay mercury tubes were still used for the memories. So given time and not too many nasty faults I soon settled in to my new job.
However even then it was “Stan they are in trouble on LEO. I can you go and help them”!! I suppose I took it as a compliment.
I was on LEO II / I for about 18 months when I was asked if I would be willing to move to East London and install a computer LEO.II/9. Consult with family and Yes. I was also able to help commission the machine at Minerva Road with a chap called Peter Ross before taking it out and installing it at Ilford (the photo people). In the following years we became good friends but that is a Honeywell story.
What was unique about LEO II/9 was that the main memory .was now stored in a new device called a Core Memory instead of bulky mercury tubes.
I was now living quite close to Ilford which made a marvellous change not having to travel a long distance to get to work. I soon settled down and with a good crew I had very low down time.
I should have realised with my past LEO career it would not last for long. My friend Stan Holwell had been made Area Manager and I was asked to take up the appointment of Area Supervisor to support him and in particular address myself to problems at LEO II / 5 the in-house LEO machine located in Hartree House London.
There was a piece of new peripheral equipment being installed called Magnetic Drum but with good support from Minerva Road that ceased to be major problem and it soon became fully operation.
This was a Random Access Device (RAD) that enabled a programme to zoom in very quickly for data instead of a long wait going along a magnetic tape. Disc Drives did not arrive on the LEO II’s
Leo II’s were all thermionic valve machines with the inevitable problem of long periods of down time There was still quite a few difficult faults on Leo II / 5 that required me motoring from Ilford to mend them(Always late evening)But it was always satisfying to fix the problem and get back home again.
Reading back my report its interesting to note that the our memories are very selective. I read the Leo Computer Society members list and see that there were many chaps who I worked with and many others who sadly may have gone now who I do not remember.
One thing I do know Leo produced some of the most highly competent, dedicated engineers and regarded as the best in the country.
My career path with LEO finished quite abruptly for Honeywell Controls advertised for engineers to start up a Computer Division. These computers were the equivalent of the LEO III’s No valves fully transistorised. My golly what a nice change.
So after five years very exciting time with LEO I left and installed the first computer Honeywell had sold Bournemouth Town Hall. But that is another story.
To finish my Saga there was a humorous story about LEO II/9.
Many years later all the LEO II were being replaced with LEO.III’s Fully transistor techniques replacing the unreliable thermionic valves. The machines had little value to the Scrap Merchants except for all the mercury in the old memory tubes. One such dealer thought he had bought LEO II/9 for a song! When his gang arrived to remove the machine he found to his horror NO MERCURY it had a core memory. See also version with photos at https://docs.google.com/document/d/1EjtC3VTgqRgZ2HZGUwB4D9gbd2gcUNmm2aPHgMwmMME/edit and at https://www.dropbox.com/s/im70jnacidwe2jq/Stan%20Evans%20LEO%20Maintenance%20Engineer.docx?dl=0