The Museum of HP Calculators

HP-25 Controlled Coffee Maker

I discovered the HP museum of calculators some time ago and could not stop browsing through all the pages . What a gold mine for information about these wonderful calculators that only HP could build.

I bought my HP25 when I was in my first year of college (well, it was in France and not exactly a college but more a school that lead me to the engineer I am today).At this time , 1978, I had to pay FF800 (about $130.00) for a used HP25 . Not to mention , it was quite a sum for the poor student I was . Anyway I discovered the magic world of programming and was amazed to see that the display of calculator was able to change all the time when the program was running. In my mind, all calculators had a fixed display and did basics operations : plus, minus, multiply, etc..

This calculator was with me during the 4 years of my scholarship and trust me : I used all the programming lines available.I often wished I would have more of them. We used to have competition between the HP-fans and the TEXAS-fans. If I remember correctly the TI57 was a competitor calculator and had almost the same functions as the HP25, except the RPN mode . We frequently tried various calculations using both machines and HP was often a winner (not always...). But the proof came one night when we had both calculators sitting on a table, trying to extract the square root of some huge number. I pulled by mistake both power cords and the 2 calculators fell on the tiles of my small student room. How horrified my friend was to see that his TI57 was memory, while the HP25 was still blinking the long line of red zeros ...

Then in 1981 I had my diploma and went to Morocco to spend my army time. The climate over there is not very friendly for electronic equipment (hot, humid,etc.) but the HP25 never suffered. I even built a programmable coffee maker managed by the HP25. A small wire was connected to the last digit of the display, and I ran a counting program. When the program ended, the display did not move anymore, and this triggered a relay to the AC power for the coffee maker....

Now we are in year 2000 and the HP25 is still in my home office. I would not sell or give it for anything in the world. Needless to say, I bought a new coffee maker with integrated clock since then.

By francis TEYSSIER

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