Layout of arithmetic keys on early calculators  Printable Version + HP Forums (https://archived.hpcalc.org/museumforum) + Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum1.html) + Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum2.html) + Thread: Layout of arithmetic keys on early calculators (/thread256393.html) 
Layout of arithmetic keys on early calculators  Walter B  11192013 We all know the layout of the HP35 of 1972:
While the order of the arithmetic keys on the SR50 follows a simple logic, I can't comprehend the order on the HP35. OTOH, HP kept it until 1981, so there must have been some reason. Anyone of the experts here got an idea? BTW, both pictures show quite well the bad contrast of รท vs. + though that's another story.
d:?
Re: Layout of arithmetic keys on early calculators  Michael de Estrada  11192013 Maybe HP was trying to capture the lefthanded market.
Re: Layout of arithmetic keys on early calculators  Massimo Gnerucci (Italy)  11192013
Massimo Edited: 19 Nov 2013, 4:39 p.m.
Re: Layout of arithmetic keys on early calculators  Walter B  11192013 Repetitio est mater studiorum ;) Mille grazie  I will need some time to read (and hopefully understand) that thread.
d:)
Re: Layout of arithmetic keys on early calculators  Didier Lachieze  11192013 That's an interesting question, I don't know why on the hp35 and the following hp calculators the order of the arithmetic operators from bottom to top was /,*,+, while on the previous and first HP calculator, the hp 9100, it was the same as on the SR50: +, , *, / (but on the left side).
It seems there was a decision to have a different order between the desktops and the handheld calculators, but I can't imagine any reason behind it. It may also be that both types of calculators were designed by two different groups within hp who didn't care about consistency at that level of detail.
Re: Layout of arithmetic keys on early calculators  Dave Shaffer (Arizona)  11192013 The story on the HP35, as I heard it in 1972 or 1973 from Barney Oliver himself (then a VP at HP) was that a readilyalterable keyboard connected to prototype HP35 functionality was made available to HP engineers who could configure it however they wanted (i.e. what key positions and what functions they used). The final HP35 keyboard was then moreorless a vote by actual HP internal users as to what they wanted/used the most.
I used the '35 for a long time from December 1972 onward and never felt constrained or (dis)affected by the keyboard. My personal preference would be to put the + key above the  key though (with +  at the top, rather than multiply and divide).
Re: Layout of arithmetic keys on early calculators  Paul Berger (Canada)  11192013 I guess I never paid that much attention to the layout of the arithmetic keys until reading this thread and the one referenced. But I guess I am most used of the current layout as when I pick up something like one of my 67s it does not feel right. I noticed that the layout on the 97 is the same as the current layout, which must have been fun for people switching between the 67 and 97. My first calculator a Commodore PR100 has the keys in a square with X / above + .
Re: Layout of arithmetic keys on early calculators  htom trites jr  11192013 I've always thought the primary math keys on the 35 keyboard made sense. Put your middle finger on the home (5) key. Closest reaches for right hand index finger are + and *, the more frequent operations. Then  and / are nearest their inverses. Enter is bigger to bring it into an easy reach for the right hand index finger.
Re: Layout of arithmetic keys on early calculators  Kiyoshi Akima  11192013 And then there's the HP10 with divide and multiply horizontally above the digits and the subtract and add vertically to the right, but it's an "adding machine" and not a "calculator."
Re: Layout of arithmetic keys on early calculators  Eric Smith  11192013 Addition and multiplication are more frequently used than subtraction and division, so they're kept close together to reduce necessary finger movement.
Re: Layout of arithmetic keys on early calculators  Jake Schwartz  11202013 Back in 2000, at Richard Nelson's request, I put together a little presentation for the HP Calculator Conference that year (in Los Angeles) which compared and contrasted HP calc numeric keypads. The short paper, along with a chart categorizing all models up to that point (including the Xpander, which was supposedly imminent) is located My two cents,
Jake
