Inmos and the Transputer

This is an edited version of part of the talk given by Iann Barron to the Computer Conservation Society of the British Computer Society in 1998.

It's the story of the UK's attempt to become a force in the emerging microprocessor industry of the 1970s, told by the man who was the driving force behind it.

In the first part Iann Barron describes how Inmos came into being and the thinking behind the revolutionary transputer.
In the second part, which starts at the point when Inmos had just secured its second slice of Government funding, Iann Barron charts the company's decline and fall.

Part 1

My story starts before Inmos. After working on the Modular One computer, I retired gracefully when I was 37. That was in 1974. I stayed retired for four weeks before I decided that I ought to do something else. I set myself three objectives.

The first was fairly ambitious. I didn't think much of the team at the Department of Industry and I decided it would be nice to get a new one.

The second was even more ambitious; I decided that what we really needed was a Minister for Information Technology, so I went around advocating this vociferously for several years. We did eventually get one, although it proved to be just the one - Kenneth Baker was our only Minister for Information Technology. Fortunately he was around at just about the right time for Inmos. I don't know what he did for the rest of the world, but he was quite helpful to me.

Thirdly, it seemed clear to me that microprocessors were the future, so I wanted to become an expert in that field. I eventually ended up doing consultancy for Intel, Motorola and Texas Instruments, which fairly well covered the waterfront.

At the same time, I became interested in parallel processing and models of parallel processing. I spent some time at Queen Mary College and other places looking at how one might split up computations and implement them more effectively.

It was out of that work that the idea of the transputer grew, so the transputer was around before Inmos. I'm going to move backwards and forwards between the transputer and Inmos because it is necessary to take the two together in order to understand what happened.

Inmos was a complete accident, as far as I was concerned. It started when I was asked to organise a session on the future of computing for a conference in Toronto in 1977. I decided to ask experts from each of several different areas of computing to give their vision of the future.

I realised I needed someone to talk about semiconductors, which were clearly the driving force for computing at the time. I found a man called Petritz who had been at Texas Instruments and who had subsequently written a series of what I thought were very good papers looking at how the technology might develop. So I invited him to come along and talk.

Much to my embarrassment he never responded to my increasingly frantic communications. By the time I told the organising committee, it was a serious problem - they had already printed the programmes with his name among the speakers. Right up to the conference Petritz never made contact with me.

Just before the conference started, there was an air traffic controllers' strike in Canada. So I got to Canada, as did many other people, by a devious route; I flew to Buffalo and was bussed from there to Toronto. I arrived at 3.30 in the morning.

The conference was due to start at 12 o'clock that day. None of my speakers had arrived - it was complete chaos - and by this time I'd been on my feet for some 30 hours. The conference had opened before my speakers eventually arrived, but they did include this man Petritz, whom I'd asked to lecture and who had never contacted me.

My session was immediately after the opening ceremony and was really exciting. I had never managed such a large audience before - there were some 7,000 people. The hall was packed, the aisles were packed, the seats were packed - there were people everywhere. And then Edsger Dijkstra made some very provocative comments about microprocessors; there was pandemonium; people were fighting in the aisles trying to get to the microphones.

Afterwards, I invited my speakers for a drink. We went out, found a darkened bar and settled down. I just wanted to go to sleep. Petritz sat next to me and after a few minutes he said "Pssst! Want to start a new semiconductor company?"

Petritz explained that he was planning to start a semiconductor company. He had hired someone to handle the memory side of the business, and he wanted me to handle the microprocessor side. I never said anything - after 36 hours without sleep, I was dead.

I did not see Petritz again for the rest of the conference. When it was time to leave Canada, the planes were flying again - the air traffic controllers' strike had been declared illegal by the Government.

I wanted to go to Austin, Texas. Now, the way US Customs are handled in Canada, you have to go through US Customs in Toronto or Montreal, rather than when you reach your US destination. I was dressed fairly casually, and the US Customs people wouldn't let me through. They asked for evidence that I was going to Austin, and I didn't have any because it was in my case and my case was on the plane.

So they refused to let me on the plane. Impasse! Then Petritz turned up and said "I know him! You let him on the plane". So we got on the plane and sat down together, and he explained his idea for a semiconductor company. I said no, I wasn't all that interested, because I didn't want to leave the UK. His parting line was "If you can raise the money in the UK you can have part of the company there". I thought, "Maybe I can". That is how Inmos started.

In the UK I had been consulting for the National Enterprise Board (NEB). This was the vehicle set up by the Labour government to improve industrial performance. I'd done various jobs for them. They had asked me to look at reorganising the minicomputer industry and I told them it was a waste of time. They had also asked me to look at reorganising the semiconductor industry.

When I got back to the UK I told them, "Maybe I do have an idea how you can do something for the semiconductor industry. We could set up an operation in the US. We could acquire the technology, bring it back to the UK and, hey presto, you've got a semiconductor company." That idea turned into a two hour presentation two days after I had come back from the US. The Chairman of the NEB said, "Fine! Produce a credible business plan and we'll back you". So that was a pretty good start.

However, I had difficulty in producing a business plan. I had to go back to Dick Petritz, because he had the basic understanding of the costs of the business. And again, he went incommunicado - I couldn't get any information out of him. It wasn't until the end of November that I eventually made contact and he started to take an intelligent interest. He sent over a business plan, but it wasn't terribly good.

He was asking for $12,500,000, which didn't seem to be enough. So on the general principle that you need twice as much as you think, I doubled his figure; I also turned it into pounds for good luck. So, when I went to the NEB I asked for £25 million. They looked at me and said "No, people always get it wrong, you should ask for twice as much".

If you start off with a plan for $12.5 million and have to convert it into a plan for £50 million, it's quite difficult to find a way to spend all that additional money. Fortunately, just before I produced the plan a new piece of equipment had been announced called a wafer-stepper, which replaced the original technique for exposing the photographic patterns on wafers. The merit of a wafer-stepper, as far as I was concerned, was that it cost a million dollars as opposed to $50,000, so I put them into the plan.

It proved a great technical decision. That was the way the industry went, and we were there first. We not only had wafer-steppers, we actually cornered the market. When the other companies realised they wanted them, our orders filled the world's production capacity, so they couldn't get them.

So a $12.5 million business plan was escalated into a £50 million plan, which I happily constructed over Christmas while playing Monopoly with my children. The NEB read the plan and agreed to back it.

There was still the minor problem of convincing the Labour Government that they ought to back the idea, because it was obviously politically very sensitive. It took three months to square the system. The person who objected most was Tony Benn, the MP for Bristol - a bit ironic in view of what happened subsequently. He objected to Americans getting rich out of the British Government. Eventually what happened was simply that Jim Callaghan said "We'll do it". And they did.

So the funding arrived just a year after the original discussions in August 1977. The first thing that happened was that I was given a £5,000,000 cheque to put into the bank. I went home with it, and my kids rifled my wallet that night and found the cheque inside. They assumed it was my money; sadly, it wasn't.

That was how Inmos started, completely by accident, although there was a clear rationale about what we were trying to do.

Now, one of main the elements of the Inmos plan was the transputer. As I have said, this concept had arisen out of the work that I had been doing on parallel processing. It was an attempt to create a thoroughly modern microprocessor.

Strategically, I was trying to sidestep the two principal competitors in the market: Motorola and Intel. I knew that if we went head-on with them we wouldn't have a hope because the market dynamics favoured de facto standards.

At that time both Intel and Motorola operated in a very predictable way. They each had two microprocessor development teams; it took four years to develop a microprocessor chip; so there was a new generation microprocessor every two years. Everybody knew pretty much what the performance would be because the progress of the technology was so well understood. I also knew what the microprocessors were going to be like because both Intel and Motorola were locked into supporting machine code and they didn't have any manoeuvrability to change the underlying architecture or instruction set.

So I knew exactly what was the competition would do. What I was aiming to do with the transputer was to find new markets which would straddle the market that Intel and Motorola controlled, so that when we got ourselves properly established we could swing back in and attack them in their established market.

I aimed to compete in two areas. One was embedded applications, the second was parallel processing. These have a common theme because they both require a chip which is concerned with interacting with things outside itself. What I was trying to do was to find better ways to make chips that could interact with external events, and particularly to try to do this more consistently and more formally, so there would be fewer errors in the programs that were written.

The intention with the transputer was to make improvements on all fronts. We didn't intend to do anything revolutionary. Instead we wanted to get the odd 10%-20% gain from many different areas, although we probably went a good deal further than 20% in a number of areas.

The first thing that we decided, which was at that time revolutionary, was to use CMOS technology. Microprocessors had originally been implemented using p-channel technology and then using n-channel technology.

CMOS gave us a number of advantages. It gave us an important power advantage - chips at that time were getting pretty hot and power management was important. It gave us much easier design methods, and it gave us much greater predictability of the way the circuits worked. (The n-channel circuits of the day were pretty analogue in their behaviour, whereas CMOS contained real digital circuits which behaved in a predictable and controllable fashion, so you could put lots together without getting electrical problems).

The second thing we decided was to use a formal design process. People were having a great deal of difficulty in designing microprocessors and getting them correct. Most microprocessors did not work as intended, while a lot of them had serious design flaws. That meant that the development process had a lot of iterations. We figured that if we went to a formal design process we could get a useful development cycle advantage over the competition.

The third decision was to use a proper CAD system to design microprocessors. The way it was done at the time was largely using a circuit analysis tool which only did the analogue design. It didn't tell you anything about large scale digital circuitry. The only trouble was that there were no commercial design tools available.

So one of things Inmos did, which has never been visible to the outside world, was to develop a major suite of CAD software which designed everything down to the transistor level. That was the fundamental thing that enabled us to deliver our microprocessors.

We had to do even more than this because, at the time, workstations were not available. So, we had to design our own around the Motorola 68000 to provide us with the necessary computing power to put on the desk of the designer and deliver each aspect of the design process.

Sadly, about two years after we started, CAD workstations emerged in the marketplace. Had they been there earlier we would have been delighted to buy them. By the time they came out, we were locked into our own custom systems which we had to stick with for several years thereafter.

We were worried about clock speeds, so we employed a system where we generated clocks internally on a free-running oscillator. That was synched into an internal clock which ran at a much slower speed. This was an essential part of the design concept; if there are a large number of interconnected chips disseminated across multiple boards, we had somehow or other to design a system which was coherent in spite of the fact that we could not fully synchronise the clocks.

We also decided to do something about microcode. Typical microcode, which was the way that control systems and microprocessors were implemented at the time, was very sparse and essentially had a set of wires going one way saying "this is an event" and another set going at right angles saying "this is a control signal". This meant that the microcode was mostly space with nothing useful in it. We devised a method of compacting the microcode so that we could make a microcode ROM which was about a fifth the size of any of our competitors. That was a big space advantage.

Also, because the transputer was a computer on a chip, it was going to have a processor and memory, and so we had the enormous advantage that we had an internal memory interface. If you look at a microprocessor system, the thing that slows it down is moving information off the chip and into the memory system and then from the memory back onto the chip. If you can get the memory system onto the same chip as the microprocessor, you can run the two at a very much higher speed. So we were able to go a lot faster than anyone else because we put as much memory as we could onto the chip itself.

The last technical thing we did was to go to the idea of a Reduced Instruction Set (Risc), though it wasn't called that at the time. We went away from the Complex Instruction Sets (Cisc) that were in microprocessors at the time to something very much simpler and therefore very much faster and very much cheaper to implement. This also had the advantage that it reduced the size of the chip.

Essentially all of those techniques worked and we were successful in what we were trying to do.

There was a similarly well thought out strategy for the memory business.

Our first objective was to make static RAM, the high performance memory which made the computers of the time and subsequent microprocessors really work. This was an interesting market because there was only one company, Intel, making static RAMs. Intel controlled the market, and made an enormous amount of money out of their 4K devices. There were a number of Japanese companies looking at the market. We thought we could get in there and do a good job. Another factor was that it was much easier to design a static RAM, and required less process development, so that we could get to market more quickly. So our fundamental aim was to hit the 16K static RAM market first, before Intel or the Japanese. We thought the static RAM market was going to grow enormously with the computer business, as indeed it did.

Subsequently we intended to introduce specialised high performance dynamic RAMs, and then to have a third round of products based on innovative non-volatile memory technology.

However, as a business, what we were trying to do was severely misunderstood. At that time the next 'great challenge' was the 64K dynamic RAM. So everyone, particularly the UK press, assumed the objective of Inmos was to make 64K dynamic RAMs. Then, as now, this wasn't regarded as a very profitable sort of business so everybody wondered what the hell we were doing. We had the problem that we were being slated in the UK for our stupid policy, and yet we did not want to reveal what we were actually doing.

Our overall business strategy was to introduce a sequence of memory products and finally some five years out to introduce a microprocessor. Five years, because that is the length of time it really takes to produce a microprocessor, I'm afraid. It was a pretty good business plan which convinced everyone.

The intention was to build a pilot plant in the US, develop the process technology there, and then build a large-scale plant in the UK, transfer the process technology across, and build the UK expertise in a viable way thereafter. I inadvisedly described this as a technology pump from the US to the UK - that got me into a lot of trouble with a lot of Americans.

Good as the business plan might be, it had weaknesses that were to cause Inmos continuing grief over the years. The problems were to do with motivation and human nature. What we were trying to create was not one but two start up companies, one in the US for memory products, and one in the UK for microprocessor products. Starting one company is hard enough, starting two which need to be integrated in terms of management, technology and objectives is virtually impossible.

It might not be obvious to an outsider, but there is very little commonality between a memory business and a microprocessor business. The process technology is different, the design philosophy is different (one involves analogue circuit design, the other involves the management of complexity), and the marketing is different (memory is sold to the purchasing organisation, microprocessors are sold to the design group). Even in well established companies like Intel, there were continual conflicts between the memory and the microprocessor businesses; so you can imagine what it was like for Inmos.

Then there are the cultural differences between the US and the UK. Two nations divided by a common language is an understatement. These cultural differences affected Inmos in all sorts of ways. The most serious was the matter of expectation. Americans are taught to be positive, they sell themselves and their achievements, often talking about what is intended to happen as though it is already achieved. The British, by contrast, tend to be cautious, identifying all the potential problems and not making claims until they are entirely certain these are justified. This meant that the Americans continually underestimated the achievements of the British, and the British continually overestimated the achievements of the Americans.

There was enormous conflict between the US and UK. It was an underlying structural problem that went on for years. My US partners regarded the UK company as a tax on the investment capital they had received, and they wanted to lose the UK company as fast as they could. Clearly my motivation was somewhat different.

Now you would think that the motivation of the UK shareholders would have been the same as mine. Unfortunately both the NEB and the Government took the view that the Americans knew best, that the British didn't know anything about semiconductors and that we had to defer to them in every respect. That made my life extremely difficult. I had a continuing battle to stop production, resources and money moving from the UK to the US, and I wasn't getting any support from my seniors. This was made more difficult because the microprocessor business was much longer term than the memory business, so there was a natural tendency to direct the available resources to the memory business, which meant to the US.

Initially there was a big debate about where Inmos should go in the UK and there was lots of political in-fighting about this. My basic management position was that it had to be somewhere near Heathrow because we were going to go backwards and forwards to the US every week. The political view was that the north-east or Scotland or somewhere like that would be better.

By the time the first recruitment advertisement was due to go out it had been agreed, very reluctantly, that we should locate in Bristol. I had been authorised to put the advertisement out, but on the evening before it was due to appear, I received a call from the Chairman of the NEB telling me the agreement had been withdrawn. I explained that the advertisement was already going out, so the Government machine went in motion and stopped the publication of the newspapers. The advertisement had been due to go into three or four newspapers; new copies were printed with a blank space where the advertisement should have been.

Unfortunately, the good old Guardian didn't quite receive the instruction properly and they printed some papers containing the advertisement. Even more unfortunately, those papers were distributed in Newcastle and the surrounding areas. All hell was let loose! The cat was really out of the bag, but the company did end up in Bristol.

The advertisement headline was "Go West young man", which led to further problems. Firstly, the sex equality people came along and said I should not be using the word "man". Secondly, we had asked for "computer architects"; the Royal Institute of British Architects pointed out that the word "architect" was controlled by an Act of Parliament passed in 1933, which specified that architects could design houses, landscapes or ships, but not computers.

We had a thousand replies to that advertisement. There were just three of us to sort them out, and that's how we got our original nucleus of 10 people.

But we really built the company on new graduates. I had done the same with Computer Technology previously; it's the best way to build a company because new graduates are keen and enthusiastic, and they do not know what is impossible. You can ask them to do anything and they just go away and do it.

The plan had been to set up a prototype semiconductor plant in the US which was due to cost $12,500,000 (you might recognise that number!). The same thing happened; it turned into £12,500,000, and before you knew it there was £25,000,000 going into this US facility.

Well, that was not too bad. Sadly, something else happened during this time. We'd set the company up in 1978; within six months the Labour Government which had funded us was no more and Mrs Thatcher was in control. Mrs Thatcher took a very dim view of Inmos. It was an embarrassment and a nuisance to her and she didn't want to know anything about it.

I need to go back slightly to explain a detail of our funding. When it had been agreed that £50,000,000 was the sum of money which should be invested in Inmos, the NEB put in a clause which they explained was perfectly reasonable ... "Look, we know that it has no effect, but we are going to split the investment into two tranches of £25,000,000 because it would look more prudent to the Government if we had control over the second £25,000,000. We, the NEB, understand very well that there will be no measurable results after the expenditure of the first £25,000,000 so we will have really no discretion but to give you that second £25,000,000. However it will look good politically." We agreed quite happily.

We were not so happy when the Government changed. We hadn't received the second £25,000,000 by then, and the Thatcher Government immediately said "We're not going to provide it", which left poor Inmos with rather a nice US operation, some people in the UK thinking about microprocessors, but no other benefits or assets in the UK.

It took something like 18 months of very high profile argument before we got our second £25,000,000, and that severely damaged the UK aspect of Inmos because it delayed its progress by over a year while its US company was up, running and doing good things. However, we did eventually get the money.

Part 2

We then had to build a semiconductor plant in the UK. The Thatcher Government said "We're hands off. We don't involve ourselves with industry at all. We certainly wouldn't want to involve ourselves in any conflicts about where you locate the plant, but it had better be in South Wales"! So that's where it went.

We got the facility up, we got the process in, and then we hit trouble. We couldn't make the process work. We could make integrated circuits but they were unreliable and when we did tests on them we found they suffered from metal fatigue, and a small proportion didn't function correctly.

We identified a particular piece of process equipment which we didn't think worked very well. However the American company insisted that the fault must lie with the management of the operation - no problem with their process - it was the people who were running it in the UK.

Then, three or four months later, at Christmas 1982, we had a severe disaster. A semiconductor plant depends upon using copious quantities of very pure water and has enormous de-ionising facilities for the water to get to absolute, or very near absolute purity. I was rung up on Christmas Day with news that the water was anything but pure and was getting worse.

Even though we were now almost in full production, we had to close the whole plant down. It was not at all clear what had gone wrong. Eventually, after about three days, we identified that the problem lay with the resins which were used for the de-ionisation process - basically chemicals in huge 'tin cans'. The tin cans were about three metres in diameter and eight metres high. Something had gone wrong with them.

What we had to do - and this was all across the holiday period - was to physically dig out all this resin and get another lot trucked in and loaded. Virtually everybody in the company, including me, had shovels, and was standing in these great big tin cans shovelling resin.

The result was that the Americans said, "These Brits don't know what they're doing. Get rid of them!". The semiconductor facility was taken away and put under the control of the Americans who were deemed to understand these things.

What had actually happened, as we found out three months later, was that on Christmas Eve the engineers at the local reservoir decided to celebrate. They were supposed to stay on site, so what they did was to dump 100 times the standard level of chlorine into the water supply, then go off and have a Christmas party. That chlorine totally ruined our semiconductor plant.

We had many further problems. One was with money, because the pound collapsed and so my original £50 million had halved in value by the time we got around to spending the second half of it. So we ran out of money. We then had another highly protracted and visible round of arguments with the Government before we managed to extract another £15 million which was necessary to compensate for the fact that the second £25 million had been delayed.

We had just one staunch ally in the Thatcher Government - Keith Joseph. He consistently supported Inmos, consistently argued our case, and went to the Cabinet three times to get this money. While he was doing this he was being slated in the UK press for his lack of support for Inmos. A sad thing.

We eventually got our money. We got our process up. We got our SRAM out and Inmos became very successful. We were making a lot of money, and we had very good prospects. But Mrs Thatcher decided she didn't want Inmos, so it was politically unacceptable to recognise that we had been successful.

We suffered a succession of press and parliamentary statements about how unsatisfactory Inmos was. We also had the requirement placed upon us as management that we try to buy the company. I can tell you that it is extremely difficult to find a buyer for a company when your major shareholder is the Government and is saying that you're no good.

Our American partners did actually find an American company, which offered to take Inmos off the Government's hands for a fee of £15 million. Incredibly, this was agreed. So I went to the then chairman of Inmos and said, "Look this is totally wrong. We have a company that is doing extremely well and we have a deal which is being stitched up between an American company and our American partners to take it off the UK Government. For this they want to be paid - and then they are proposing to make a lot of money out of the US company."

My chairman said "Yes, I understand all that but I can't do anything about it. If you want to do something I will treat this conversation as privileged". So I went to see Mrs Thatcher and I told her that if the deal went through, in six months there would be so much mud on the face of the Tory Government that it would do them no good. That stopped it!

Back at the ranch, we were still trying to develop the transputer. I had the problem that I was trying both to direct the technical development of the transputer and to cope with my American partners and an unsatisfactory political environment. It was not a very pleasant time in many ways.

Going back to the transputer itself, we had two technical gurus, David May and Robert Milne. They were just like chalk and cheese - completely different in their approaches.

Robert was substantially more clever than David, and David's quite clever enough. When Robert wrote his PhD thesis in Edinburgh his supervisor Robin Milner, who was not lacking academically, said he couldn't understand a word of, it but seeing that Robert had written it, it must be right.

Unfortunately Robert did have the problem that he could not communicate very well with mere mortals. I spent my life trying to understand what it was he was saying. So we had a high level conflict between two people who were both very clear on their views on parallelism, one of whom had a simple vision and one of whom had a far more complicated vision.

Eventually I had to decide between the two. I had no hesitation, because David's position was basically where I had been some time before, but it was very painful at the time. Robert contributed a great deal to the underlying ideas and architecture of the transputer and he deserves recognition for that. Another thing he contributed, ironically, was the name Occam for our programming language.

In terms of process technology we had Peter Cavill from Marconi and Jonathan Edwards from Plessey. The depth of knowledge in the UK on process technology fundamentals was far better than in the United States, and most of the process ideas which were eventually developed came out of the UK company's microprocessor activities.

The CAD system and workstations were developed by Colin Whitby- Strevens and the actual detailed implementation and layout of the transputer was done by a team under Miles Chesney.

We made an experimental microprocessor to prove the technique, to prove the design system, and to prove the process. We had to test a lot of the novel logical techniques that were being used inside. We made a cut-down version of the final transputer, without the on-chip memory and many of the more complicated instructions that relate to processes. We built a second chip to go with it which enabled us to take the outputs and display them; this drove a CRT display.

It all worked! Just like that! Bingo! I think we had one minor revision, but essentially we had produced a complex microprocessor which worked first time.

Essentially a transputer allows a set of programs or processes which are independent of one another to run concurrently, so that the processor is shared between a set of processes. The processors communicate with one another by a simple channel which passes messages and provides synchronisation.

We built the instruction set hardware so that what the programmer saw was effectively a set of parallel processes. The microprocessor implemented them and scheduled them. It did the scheduling in an optimally efficient way in terms of the number of times one swaps from one process to another. Again it all worked!

The trick was that we made sure that the communication between the processes that were running on a transputer was identical from a programmer point of view, whether it was done within one transputer or between multiple transputers. This meant it was invisible to the programmer whether he was using one transputer or several. The program was the same; it was just compiled in a different way depending how many transputers were being used.

Of course there was a performance overhead, and we put a lot of effort into ensuring that the overhead for going from one process to another was as small as possible. It was equivalent to something like three basic instructions, so we could have lightweight processes running very short programs with a negligible overhead. Some transputer applications were written with processes as small as 10 instructions.

The other thing we did was to create the Occam programming language, which directly mirrored the structure within the transputer. Occam was not a one-for-one assembly language; it was a high-level language built with predictability in terms of the length of time taken to execute any bit of compiled program.

All that was great. Everything worked just as the theory said it should. There was just one thing that went wrong - and that was the compilers.

It was quite clear that we were moving to a situation where we were going to have a programming language for our own internal purposes that effectively replaced an assembly language, but we expected that customers would want to program transputers in high-level languages.

That was a fundamental strategic goal from the beginning. It was obvious that people could not go on programming microprocessors in assembly language. There had to be a change.

We thought that if we had a chip which was designed properly to support high level programming languages, we would then be in a very strong position when that change occurred, compared to our competitor companies who were locked into architectures designed for hand-coding, because for them it would be extremely difficult to exploit compilers. We were right about that.

Unfortunately we had a problem - money! We had no money to develop the compilers we needed. Our funds had all been used up in the US. We tried to get away with using a cheap untried UK solution in which we were going to get three compilers generated from one basic piece of code - and it didn't work!

So by the time the transputer came to market everything was there, everything was right, except that we didn't have the compilers necessary to exploit the capability we had created. We never did get those compilers.

Reverting to the original business plan, the proposition that went to the NEB was to make an investment in a semiconductor company, to get it up and running, and establish a viable semiconductor business in the UK. Then the intention was to sell it off, doing away with the need for the NEB by refinancing Inmos in the UK as a UK company.

The plan said that this would happen in 1984. I had forecast that in that year Inmos would have a turnover of £150 million - which it did - that it would have a profitability of £12 million - I think we actually made £15 million - that the NEB would exit during the year, and that the company would be valued at £125 million. That is exactly what happened.

I bet nobody's ever produced a business plan and got it as right as that. I have to admit that if you look at the forecast for any one of the preceding years, they were totally and utterly wrong. But 1984 I got exactly right!

The Government was desperate for us to be privatised in some way, but they had no takers. I devised something I called the white pawn strategy. You've heard of white knights - white pawns are the poor man's version. There was no company in the UK that looked like a white knight, but I did think there were perhaps half a dozen companies that we might persuade to invest in Inmos to provide an underlying resource to support their businesses.

One of these was Thorn EMI. Come the middle of 1984, the then Chairman of Thorn EMI, Peter Laister, started to get ambitious and wanted to acquire something significant. He bid for British Aerospace, failed, and attracted a lot of criticism. One bright young man in his private office said to him "Why don't you buy Inmos instead?", and so he did, in less than a week.

He paid £125 million for Inmos. It was quite sudden, totally unexpected and, from my point of view, very surprising. I was called up one day and told "There's this company that wants to buy you". I went to various meetings, the last of them at the Department of Industry offices in Victoria Street. It started about midday and went on until midnight at which point the deal was done.

I was excluded from most of the meeting. I had no direct involvement, and I was told, "Just go down the corridor and find somewhere to sit". So I did. I sat down in an office and after about 10 minutes I started to look round and realised it was rather a grand office. I looked a bit more and realised there were papers on the desk. I was actually sitting at the Minister's desk. That's security for you!

Eventually I was called back into the meeting and was told the deal had been done. Peter Laister produced a transputer chip from his pocket, waved it at the assembled audience, which consisted of one person from the NEB, one from the Government and 50 lawyers and said, "Look, I've paid £125 million for this".

There was one flaw. The business plan said that in 1984 not only would the company be sold, but that it would be refinanced, because we knew at that stage we would want money put in to expand our business further. But there was no refinancing, and no money went into Inmos. The £125 million went straight to the Treasury.

So from that moment on we had no cash to do anything. We couldn't advance the technology in any way. We couldn't develop our memory products. It was not really Thorn's fault. They shouldn't have bought Inmos - it was a really stupid thing to do, and Peter Laister was ousted from that company within three months. Thorn did try their best to look after us. It was just that they didn't have the kind of cash that was necessary to fund and run a large-scale semiconductor company.

We had been doing very well. Our static RAM products, in spite of the technical problems, had knocked Intel out of the market. We had something like a 60% share of the world's market for them and our only competitors were Japanese companies. We had dynamic RAMs of high performance, and we had transputers just about coming to market. So we were in a very good technical position. We just didn't have the money to exploit it.

There was one other unfortunate occurrence at this stage. Almost immediately after selling the company, it started to become apparent that some of our customers were having failures in their static RAM memory chips. This problem escalated, and after about six months it became clear that we had a serious reliability problem.

The problem was due to a faulty piece of equipment. Inmos was not the only company to suffer at that time and two or three semiconductor companies actually went under as a result. Which piece of equipment was it? Yes, you've guessed it; it was the problem we had identified in the UK factory when we started to manufacture the static RAM in 1982. At that time, not only had the US taken over control and management of the UK factory, but they had also transferred production of the static RAM back to the US - it was a highly profitable product, and the company making the static RAM automatically had the better balance sheet. Heads rolled, and much of the US management was dismissed.

So we had to cut back the company and lost half our transputer design team. We tried to retrench in an appropriate management fashion and to create something valuable out of it, so we actually hived off some of our best people into a new company which then went into business making parallel computers.

The story got worse. Eventually I had the ironic situation where I was in the US running the US company and I had to sell it off. It was actually sold to Seymour Cray, whom I had spent quite a long time trying to convince of the value of the transputer.

It wasn't all doom and gloom because we had, as I have said, good technology. We had developed fundamental patents for static RAMs, for dynamic RAMs and for microprocessors, to the extent that every static RAM or dynamic RAM made involved a significant patent from Inmos. IBM was so concerned about our patent position in microprocessors they gave us rights to all their patents in return for rights in our patents.

Eventually dear old Thorn made something like £150 million to £200 million out of the Inmos patents, which is hardly ever mentioned. They got their money back all right.

There were two other money spinners. Our dynamic RAM technology was very good, and we were able to licence it to a Japanese company and set up an automated manufacturing facility in Japan. The other product was the second test chip we had made for the transputer. We persuaded IBM to use this as their next generation graphic chip, and it became embedded in the PC as the SVGA standard. Some of the oddities in the present Windows operating system stem directly from the way this chip was designed to work with the transputer.

But from the point of view of the transputer we did not have the resources to do what was necessary. We did do one clever thing which was to add a floating-point unit to the existing microprocessor. We exploited the improved process technology to be able to put on board a floating-point unit and again we used formal techniques. We were able to prove what we were doing and we were able to design a floating-point unit better than anything else on the market by a very long chalk. That gave us another couple of years lease of life.

The end came in 1989 when Inmos was sold to SGS Thompson. SGS Thompson was essentially a semiconductor company set up by the French and Italian Governments to do what Inmos had planned to do in the UK.

The Managing Director, Pasquale Pistorio, was very enthusiastic about the transputer. He thought it was an extremely good product and wanted to revive it. He was prepared to put a substantial amount of money in this. But there was a fundamental problem. No work had been done on the transputer in terms of implementation and design since about 1985, and this was 1989.

There were two routes that we could go down. One was to take the existing design and just re-implement it again in the latest process technology, taking advantage of various tricks and getting more memory on the chip and things like that. The most favourable view was that this could be done by 1991; my personal belief was that it would take at least a year or two years longer and would not be competitive.

The alternative was to start from scratch and design a new transputer, keeping the concept and making sure it was software-compatible and connectable and things like that, but changing the instruction set and being quite radical.

The quite radical thing was to put four transputers onto a chip. You could say that we were doing much the same thing as the very long instruction word microprocessors. We were going to produce a system with a full 64-bit internal bus with 32-bit addressing, four address units, four arithmetic units, and two 64-bit floating-point units. We were going to put a 50 Mbps link between the transputers and everything was absolutely divine. The trouble is that this would take a long time to do, and it wouldn't have been available until 1992 or 1993.

So there was no real way for the company to survive. A decision was made to go the route of re-implementing the existing design in the latest technology, and it was a failure as expected. That was the T9000 - it never really saw the light of day. That was the last of the transputer and very recently ST Microelectronics, as SGS Thompson has become, announced that there will be no more transputers, which is sad.

If we look back now, it is clear that Inmos was a glorious failure. It had enormous technical successes. The static RAM technology design is the way that the world now designs static RAM. The same thing is true for dynamic RAM technology. We had the transputer which was a unique design, and we had, as I have said, this very strong patent base. Our problem was the corporate failures.

The underlying issue was the control of the company. There were conflicts between the US and UK, which led to extreme mistrust. We had an antagonistic shareholder. Originally there were difficulties within the Labour Government, because there was one minister who objected - Tony Benn. Later our antagonistic shareholder was Margaret Thatcher.

I had a number of discussions with her aides about the problem. Mrs Thatcher continually said her aim was to support sunrise industries, and that she wanted to compete with the Japanese, and Inmos, of course, was doing all of those things. I was told that she had a very simplistic view towards life and liked to get things down to one basic idea. Her one basic idea about Inmos could not be changed, and that was that Inmos had been started by Tony Benn. Madam didn't like him very much.

At a management level we had the quality failures. There was also the underlying issue, which hits UK companies time and time again, that you can get the money to start, but when you get market success you really need more and you cannot raise it. What went wrong with Inmos more than anything else was the failure to get that second round of finance.

I think you will find that microprocessors in the future look more and more like transputers. You won't see it from the outside but it will be embedded in the way that they actually do their operations.

For all the problems, though, it was great fun, and I'm glad I did it.

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