Postion of + - x / keys


From my deep & extensive research of about half an hour, it would appear that the HP35 in 1972 and all subsequent handhelds up until the HP10C in 1981 had their four function keys in the order / x + -. Suddenly there's a switch to + - x /.

1) Where did this "odd" / x + - come from? It seems natural, to me, to have the + at the lower corner since it's the most likely to be used.

2) The desktops before, during & after these nine years all had + - x /.

3) Surely there must have been a hoo-har in '81 when, after nearly a decade, a fundamental and, by now, "standard" layout was completely altered? Something akin, I'd imagine, to suddenly having a little piddly enter key hidden away somewhere. What? They have? Oh sorry, didn't notice!

I cannot find any reference to this in any history. Any info, reminiscences, comments?



Don't forget, that not only did the "order" change, but the keys themselves moved from one side of the number keys to the other. From my desktop survey today:

HP 97: Keys on right side, /x-+

HP 41: Keys on left side, -+x/

HP 42S: Keys on right side, /x-+

This really bugs me when I try to do calculator math without looking, and I get used to one machine, then use one of the others.

From my earlier research into the matter, nobody knows why the "switch" was made or whatever. There is some history of key position dating back to manual or electro-mechanical calculators that I don't recall in enough detail to report on. Anyway, if anybody knows more, please enlighten all us curious users.

Dan M.


Where is the "equals" key relative to those?



Couldn't tell you. All my HP calcs seem to have a factory fault and are missing their equals key!


Have a closer look!

It hides on:

the 2 key in a 41

the 0 key on a 48GX (and probably on 48S, 48SX, 48G, and 48G+)

*somewhere* on a 6

And umm, the 38G has one too, but it's called enter!



It's right out in the open on my HP-28S (on the keyboard on the left side). But it doesn't work right! When I try to do 2+2= (and expect to get 4) it says "+ Error: Too Few Arguments" (Dang!) ;-)


As Chris points out, (almost) all the desktops have
the +-x/ order, and (almost) all the calculators have
either +-x/ on the right, or /x+- on the left. Note
that for 'matching' pairs of models like the HP67 and HP97,
the handheld has /x+- and the desktop has +-x/.

Most non-HP calculators I've seen have had the
right-side +-x/ layout. (A few old ones have the keys in
a square, or some other odd variation.) I think this
makes sense from the point of view of the evolution of
adding machines, beginning with a large "+" on the right,
and adding new operations above in the order of ease of
mechanical implementation. I assume HP switched their
handhelds to this layout to be consistent with everyone

As for the /x+- layout, last time this came up I speculated
that HP put the most 'important' operation, "+", on the 'home'
row of the keyboard, that is, across from "5", and the rest
of the layout follows: /x should go together, so they're together where they fit,
below "+" , and "x" is adjacent to "+" since multiplication
is more important and 'closer' to addition than is division.

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