Re: HP-35 Message #3 Posted by Jeff O. on 6 Mar 2006, 8:46 a.m., in response to message #1 by David
Quote:
Is there anything else that i should check for to see if this unit is special?
It is an HP-35, the world's first handheld calculator with transcendental functions. It is quite special! Granted, it might be a little more special if it were a red-dot, but it is a version 2, and has the earliest possible serial number prefix. Following-up on something Karl mentioned, early units had a few "bugs" where they did not provide absolutely correct answers to some very specific arguments in some of the functions. As Karl mentioned, taking the natural logarithm of 2.02 and then the antilog of the result returned 2., rather than 2.02. There was also a bug in the trigonometric functions for certain inputs. Some examples were:
Function Buggy Correct
ARC SIN 0.0002 5.729577893 x 10E-3 0.01145916
ARC COS 0.0002 89.99427042 89.98854
ARC TAN 0.0002 5.729577893 x 10E-3 0.01145916
ARC TAN 1.00020002 45 45.00573
So checking for the above anomalies will tell you if your unit was sent back to HP for repair. If it has the bugs, you have an original, pristine, untouched unit with its “quirks” still intact. If not, you have a unit that the owner went to the trouble to send back, and HP repaired a problem that in the present day would be ignored. Either way, it is special.
Approximate value based on eBay sales would be $40 to $100 (assuming it is not essentially "mint-in-box"). Unless you really need $40 to $100, you should by all means keep it.
Quote:
Maybe I have found myself a new hobby.
If so, be prepared for quizzical looks from friends and family. Also, beware the slippery slope from hobby to, ...obsession. You will obviously need a version 2 with or without bugs as required to complement the unit you have. Versions 3 and 4 are also a necessity, and a version 1 would be really, really nice. One each of the 45, 55, 65, 70 and 80 to fill out the classic series would also be nice. But wait, the 45 comes in at least three versions, so you’ll need one of each of those.......
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