Posts: 4,587
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Joined: Jul 2005
I guess they didn't want to bear the tool costs for too many dedicated double-shot keys in the very beginning of the HP-35. Numeric keys and ENTER could be used in other instruments as well, but SIN etc.? Remember it was the very first scientific pocket calculator and they were grossly underestimating its success, so some extra care seemed appropriate - use plain blue keys. At the time of v4, however, they knew scientific pocket calculators were a success story, so the tooling would pay. I'm just guessing, but the thoughts look reasonable to me at least :-)
Posts: 980
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Joined: Aug 2006
Hi there. After using my 45 and 55 again (for the 800th time), yeah, it hit me that perhaps this facelift transitions into the new Classic look.
**UPDATE**
I just got my latest, the HP-35 v4. Now that I see it and have it in person, I can see its resemblance to it 45 and 55 brethren much more obviously.
Edited: 7 July 2012, 5:40 p.m.