Tom Osborne’s Story in His Own Words
In 1994, Dave Packard was writing a book about the world-famous HP way and the founding of HP. Tom Osborne wrote up his recollections concerning his original calculator design (the Green Machine) and the HP 9100 and HP 35 calculator projects in a letter he sent to Barney Oliver, but the technical details in Osborne’s letter didn’t make their way into Packard’s more business-oriented book. Below is the letter that Tom Osborne sent to Barney Oliver in 1994. The letter provides a wonderful record of Osborne’s thoughts and experiences as he made history with the HP 9100 and HP 35 calculators.
The Green Machine had its beginnings in 1962 while I was a student at UC Berkeley. (It is called the Green Machine because of the Cadillac Green Metallic paint I used on it's balsa wood case.) At UCB, I had independently (and belatedly) re-discovered what is now known a Finite State Machine (FSM), but I moved the art from the province of mathematicians into the realm of engineering by discovering a set of transformations that could reduce the description of an FSM directly into very efficient digital circuitry. Later, we at HP called the entire process the Algorithmic State machine procedure.
I first used my transformations to produce digital circuits when I was at UC Berkeley. There I found they produced such elegant circuitry that it took me hours to reverse engineer the results to see why they worked so well. Most of the efficiency comes from the ASM's uncanny ability to perform operations that seem to be redundant (like setting an already set flip-flop) but careful examination shows that these seemingly ineffective actions greatly reduce the gate count required to implement the function as a whole. The technique also produces some actions that at first seem inefficient but in fact set up conditions that greatly simplify later operations.
In 1962, after leaving UCB, I worked for SCM Corp (Smith-Corona Marchant), which was a major manufacturer of mechanical rotary calculators. They were trying to establish an electronics base. It was incredibly frustrating to watch them struggle with electronic digital design. I was a junior employee and totally unable to convince them that there was a better way to design things. In the fall of 1963 I told them that I could no longer help them produce a calculator that, in my opinion, was doomed to failure (it was, and it did). I offered to design a machine for them at no cost if they would give me lab space. Later, if they liked what they saw, they could pay me for the time I had spent in the design and construction. I do not know if they fired me or I quit, but they did get excited about me having not given them the plans for the calculator I must have designed. In their opinion, they could not see how I could so confidently state that I could build a calculator without having designed it. Nothing I could say would convince them that there were more efficient ways to design digital circuits.
In 1963 I was unemployed, miffed, but well armed with good design techniques. Carol [Osborne’s wife] had a good job, so we were not about to starve. We discussed the options and decided to go ahead and build a calculator, but only after having sought legal help to ensure that SCM would not have any claims to my design. I went to one of the biggest law firms in San Francisco who helped me write a crackerjack of a note telling SCM that I had given them everything they had asked for except for the design of calculator, which at that time simply did not exist. The note politely but firmly said that if they wanted anything else they must tell me about it. They did not reply.
In January of 1964 I began the design of a calculator that was going to have several attributes not found in contemporary machines. It was going to be about 100 times faster, take about one tenth of the power, be about a third of the size and weight of the then existing calculators, and have a floating point arithmetic unit that produced 10 significant digits of accuracy over a dynamic range spanning 200 decades. Most of the speed came from a Random Access Memory (everyone else used delay line memory). The savings in power and size came from good engineering.
Things were a bit slow at the start. The calculator would be about 50 times larger than anything I had previously designed. Conventions and standards had to be developed; procedures had to be refined; and more importantly a ferrite-core Random Access Memory had to be designed. Ferrite-core RAMs had been around for a long time, but I had to build one costing several orders of magnitude less than anything then in existence.
Because I had no laboratory equipment my circuit designs relied heavily on good modeling and careful calculations (it would have been nice to have had the calculator being designed to help me with those computations). I used less sophisticated equipment to achieve my goals. I calibrated the on-off periods of the calculator's asymmetric clock oscillator by listening to its fundamental harmonics on a radio. I built a sophisticated digital tester to debug the calculator's algorithms. Without that tester the project would have failed because of the enormous amount of time required to simultaneously monitor the outputs of 40 flip-flops, to set their initial conditions, and to stop processing at a predetermined condition previously set into the tester.
I remember an especially poignant day shortly after my arrival at HP when I was able to see, for the first time, most of the actual waveforms of the circuits I had designed. Once in the early stages of the calculator's design, I visited the UCB engineering lab late one evening to use an oscilloscope to tell me why my RAM sense amplifier responded so well to signals whose polarity was opposite to those I wanted to capture. That time was well spent because I had had stumbled onto a circuit that used the very low impedance of the RAM's sense windings to drive a transistor out of saturation. The circuit had superior noise immunity and performed far better than the one I had initially designed. Later, that same circuit would be used to build the HP 9100's ROM sense amplifiers.
The ASM process and the tester I had designed allowed me to debug the calculator's routines much as one debugs computer programs. Although the first routine I designed was a simple mathematical function (a shift operation), it was obvious that even with the tester, it took an enormous amount of time enter arguments and see the results. I decided to abandon the mathematical routines and concentrate on the keyboard and display routines and their associated hardware. Oddly enough, when the entry and display routines were completed, the calculator looked as if it was complete. However, it was several months before the calculator would be able to perform arithmetic.
Finally, on Christmas Eve afternoon in 1964 the calculator was totally functional. I remember the overwhelming realization that sitting in front of me on a red card table in the corner of our bedroom/ workshop, sat more computing power per unit volume than had ever existed on this planet. I felt more like the discoverer of the object before me than its creator. I thought of things to come. If I could do this alone in my tiny apartment, then there were some big changes in store for the world.
To protect my inventions in the calculator, I wrote up a patent application and spent more money than I thought existed in getting it ready to file with the patent department. I did not file because I wanted the eventual buyer of the inventions to be able to tailor the claims and to redo the patent's specification. I also thought that the un-filed patent was as good as one that was filed (I had up to a year from the date of my first public disclosure to file, and all of the demonstrations I gave were on a confidential basis.)
I never considered manufacturing the calculator myself, so my task was to find a manufacturer for the Green Machine. I had already failed at selling my concept to SCM, but now that I could blow the socks off of anything on the market (and probably anything under development) I had no trouble in getting attention. I had discussions with more than 30 companies, all of which turned me down (HP was among those). Although no one wanted to buy the rights to the machine, I was given some incredibly good job offers.
I remember many humorous events surrounding the disclosures to various companies. The IBM people were not slowed down a bit by their inability to find the apartment's slightly hidden entry. They climbed the fire escape and knocked on the fire exit window. I opened it and they entered by climbing over the hi-fi set which partially blocked their entry. Through it all they retained their composure.
Most of the demonstrations were made in the presence of Richard T. Lacoss, a classmate at UC Berkeley whom I paid $5.00 per demonstration. I had no idea of the impact he had on the people who came to our apartment for a demonstration. Apparently they were not expecting to have any witness at all, and especially one who was a final year PhD candidate. One time while waiting for the Monroe Calculator representative to arrive, Richard told me that he wished he had been named Thad (a contraction of his middle name). When Al Jensen, Monroe's chief engineer, arrived I introduced him to Thad Lacoss. That overloaded Richard's composure gland. He deteriorated one level every time Al called him Thad. One especially deep downturn occurred when Al asked "Thad" where he thought we should go for lunch. I knew Richard had totally missed hearing his new name and was lost in thought having nothing to do with my demonstration. Richard almost used the fire escape exit when I said "Well Thad, Al would like your recommendation on a place for lunch".
Things were pretty low a year later when I was about at my rope's end in trying to market the calculator. Then, I received a phone call from HP's Paul Stoft. Paul told me that Tony Lukes, an HP employee and a co-worker at SCM with me, had told Paul that I was working on a calculator and that I had a reputation for making things that worked. Paul asked me to bring the Green machine down to HP. I showed it to Paul. He then introduced me to Barney Oliver who watched the demo and asked me if I could make it do the transcendental functions and if I had ever heard of the Cordic Algorithm. Yes and No to those. Barney then showed me a 64-bit ROM that needed help, but showed promise. He wanted to know if I could implement things in ROM. Again, I knew I could, but I was a bit worried about increasing its bit capacity by a factor of 500. To me it appeared that each of us thought that there was no reason not to proceed. Barney then asked me if I could come back the next day to meet with Dave and Bill. That was OK with me, but I asked, “Bill and Dave who?” (that was the first time I had heard their first names).
The meeting the next day was memorable. Nothing like it had occurred with the previous companies. It appeared to me that while other companies were looking for a weakness that might preclude them from success, HP was looking for the opportunity to might lead to a success. We discussed the project's good points, its weak points, and the risks involved to both parties. We agreed to give it a try for six weeks during which I would explain my design processes to HP's engineers and perform a total evaluation of the project. The meeting was about over when Mr. Packard said, "Oh Tom, we won't take the project without you coming along with it." I said, "You can't have it without me." In those few words it was clear to me that one of my main tasks was to transfer the information that existed only in my mind into the minds of the people with whom I would be working for a couple of years. It was also clear that I was among people who were open minded and trained to advance the state of the art.
The six week investigation went well. I found the HP employees to be enthusiastic and very competent. I had some difficulty in explaining some of my processes because they had not been named. I had never explained them to anyone except a few people at SCM and the process had been greatly enhanced since I had left them. Although the processes were clear in my mind, I had not given many of them names, so I found that I had to name these processes before I could explain them effectively.
It was a busy time. I spent a few weeks with Dave Cochran (HP) and Malcolm MacMillan, a consulting mathematician who had reduced the Cordic Algorithm into hardware. I did not see his machine, and from all accounts it did not work very well. None the less, Malcolm knew his mathematics, and explained the Cordic algorithm well. It was the basis of the transcendental functions in the calculator we would build. Malcolm had a quality I have not seen in anyone else. Late one evening he told Dave and me that he had perfect pitch. With that Dave hauled out an audio oscillator, shorted the output (we had no speaker, but the short caused the output transformer's laminations to hum enough to be heard). Dave spun the oscillator's dial to some random frequency and looked at Malcolm, who winced and told us that the music world does not recognize the continuous spectrum. It only considers the notes to which a piano is tuned. None-the-less, he would give it a try. He hummed a bit, closed his eyes a lot and absolutely nailed the frequency. I was then, and now am even more, impressed with his performance.
The HP 35 project was just plain fun. We knew it would work (the algorithms were similar to those in the HP 9100) so we spent a lot of time deciding whether the arithmetic keys should be on the right or the left, and whether the “+” key should follow the convention of adding machines and be placed in the lower right corner, or whether it should be located where it is most convenient. As I recall, we did not seem to be the least bit worried about the fact that we were going to be the first people to have non-standard key spacing. After all, if the thing was to fit in a shirt pocket, the keys had to be crunched together.
I was a bit concerned about the stack architecture and RPN notation, but that all went away when I demonstrated one of the first prototypes to my mother-in-law, who is anything but a mathematician. After I had done some fairly complex operations, Fran said, "How many things can you stack up in that machine?" With that comment, my worries disappeared.
Looking back, it seems as if the HP 35 had a life of its own. It simply chose HP as its birthplace. It had no name until we were about to introduce it. I asked Bill if he had any preferences. We had kicked around a few somewhat wild names but none seemed quite right. Bill looked at the machine for a minute or so and said, "Let’s call it the HP 35." It sounded OK to me, but why the 35? He smiled and said, "Well, it has 35 keys".
The HP 35's design-to-production cycle was incredibly short for a product of that complexity. We got the official go ahead on Ground Hog's day (2 Feb) and demonstrated working machines to the Board of Directors in August. I still do not know how it happened in such a short time. I remember being busy, but I do not recall the HP35 having had any major hang-ups.
We had no idea whether the HP 35 would be a success or a dud. (Before it was introduced, a market analysis by a major consulting firm had determined that it would fail because of the tiny keys and the RPN notation. In my opinion, it succeeded for those reasons.) Anyway, we gave it our all and found that it was so well received that overnight, it made the slide rule a relic.
As I said, the slides were greased for the HP 65 (the world's first programmable shirt pocket calculator). That too was a super project. By that time, everyone in the calculator business was aiming at HP. I knew they would be second guessing what we were doing, so at a convention at which I was a speaker, I somewhat intentionally misled the competition by telling them that to just have a programmable calculator was inadequate. The programs had to be easily loaded into the machine. Keying them in once is OK, but successive loadings should come from a magnetic media, like an external tape reader (at the time we were designing an internal card reader into the HP 65). When we introduced the HP 65 with its tiny internal mag reader, I could hear the competitor's projects fall by the wayside.
Both the HP 35 and the HP 65 are on permanent exhibit at the Smithsonian. They changed the world we live in. I am truly honored to have worked with and for a company whose underlying principle and business is that of providing the world with products that allow it to be a better place.
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