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Working with Hewlett on the HP-35

Posted by Happy Holden on 9 Apr 2003, 2:18 p.m.

As much as everyone loves their HP calculator, it is nothing in comparison to working on the first calculator (35) with Bill Hewlett. This was a labor-of-love by one of the world's consumate engineers. I was a recent ChE. graduate, hired by HP in 1968, to work in printed circuit manufacturing. This was a new technical area that became pivital in many of HP's calculator products. Bill came down the hill to my desk in early 1970 (we were at 3215 Porter Dr., down the hill from 1501 Page Mill Rd.)and described for me his idea of making a hand-held portable version of the 9100 desktop. He drew a flexible circuit that had a tilted up display, flat keyboard and folded back for the logic section and battery connections. Well, I went off to investigate flex circuits and later came back to him to say that what he wanted didn't really exist. But we could use two flat boards with pins to connect together and assemble the display at an angle. Disappointed, but time being of the essense for the project, he went with the rigid boards. This proved usefull when we eventually would parallel-gap weld the gold-plated beryllium keystrip to the thick-gold plated circuit board and the logic board turned into a multilayer. To make a long story short, Hewlett had 4 operating units (but at 1/4 clock frequency)by Dec. of the year for the Board of Directors to see. He was still a non-believer to Marketing's estimate that we would only sell 300 a year of these 'Hand-held calculators'. Soon after introduction, the order rate zoomed to 3000 per day and we all had to scatter to find sub-contractors to build additional parts for us.

Future stories: How in 1975, HP engineers and Steve Wazniak (he worked for the HP Calculator Div) invented the APPLE 1 using calculator technology.

The story of the original ROM board for the 9100 calculator. It would be complex to manufacture even today, but that was 1968!

The story of how I almost lost my HP-35 (in 1972) to Rumanian Agents at a Trade-Show in Helsinki, Finland

The story of Egan Loebner (one of the inventors of the 9100 in HP Labs) and his 3 years as Science Attache'in Moscow in 1976.


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