
The early history of HP calculators - ohjeez
https://insights.hpe.com/articles/the-early-history-of-hp-calculators-1709.html
======
waynecochran
When I started college in 1985, every Physics student had an HP41C. You were
at a distinct disadvantage on an exam if you had an infix calculator. I still
have my HP41CX that my dad bought me in 1985.

Now I don't see any of the students using them. What happened? When I used to
teach, I would write a large expression on the board and challenge students to
a calculator duel -- me using my 1985 HP41CX and them using their lumbering
infix calculator. I would always win.

The magic is the automatic saving of subexpressions on a stack. Once you got
the hang of it, you would never want to go back to an infix calculator.

I have the HP41C app on my iPhone, but you miss the beautiful haptic feedback
keys that the HP calc's had.

Actually, the very first programming course I ever took was a 2 credit course
called "Programming Calculators" and we learned to program to the HP41. When a
program was running, a little "bird" glyph would "fly" flom left to right
across the LCD screen. I remember writing a program to get the bird to fly
backwards. Silly, but fun.

Of course I had the Math Module that you could plug in and the magnet card
reader. Anyway, I always wondered what happened in the intervening time that
no one seems to use them anymore.

~~~
jhbadger
Basically after the merger with Compaq in 2001, HP lost interest in their
calculators. They still technically sell them, but they aren't advertised to
any degree. Obviously since the advent of the smartphone the need for
dedicated calculators is lessened, but as you say, the haptic feedback is nice
and TI seems to be still selling a lot of calculators.

~~~
keenerd
They were dying long before smartphones. Cheap Casio calculators happened. I
have a little $15 Casio scientific calculator and it has been all that I've
needed for college and professional work. But it can take integrals,
derivatives and has a general newtonian solver. It covers everything except
matrices. Those are miserable to do on any calculator so I'm not missing much.

In all my life I've only ever seen two HP RPN calculators. One belonged to my
high-school chem teacher, the other to a real estate agent. If there were a
$30 RPN calculator with similar functions, I would use it.

Edit: 18 years later and they still make it,
[https://www.casio.com/products/calculators/fraction-and-
scie...](https://www.casio.com/products/calculators/fraction-and-
scientific/fx-115msplus)

Edit2: Looks like the most readily available RPN calculators are the HP 35S
($55) and HP 12C ($50).

~~~
tragomaskhalos
Yup - among us maths geeks at school in the 80s the HPs - especially the 41 -
were the Rolls Royce of calculators, beautiful machines that few could afford,
although even the high end programmable Casio that I settled for was pretty
pricey.

------
raminf
My dad hired me when I was 14 to help with an engineering project that
required calculating thousands of structural tolerances. The job was pretty
repetitive once I figured out how to run the formulae using a slide-rule. At
some point a relative who was also an engineer was moving out of the country
and was selling off his extra stuff. Dad bought what turned out to be an HP-65
programmable calculator, thinking it might come handy for something. He never
opened the box and it sat in his office for weeks.

One day I came across it and started noodling. Pretty soon figured out you
could program the calculator to do the main calculations for my job. What was
supposed to be an all-Summer project ended up finished in less than two weeks!
(I still got paid for the whole work. Thanks Dad!)

That was my first taste of how programming machines can save time.

A few years later I bought myself an HP-41C with a card-reader attachment and
then discovered 'synthetic programming' (one of the earliest versions of
'jailbreaking').

These were all gateway drugs. Have been hooked on programming ever since.

Thanks for bringing back all kinds of fond memories.

------
dm319
Getting good condition HP calculators can be quite expensive second hand.
People interested in buying a new one should check out swissmicros [1]. They
are bringing out an HP42s clone with quad precision decimal accuracy, which
I'm looking forward to! [2]

[1] [http://www.swissmicros.com/](http://www.swissmicros.com/)

[2]
[https://www.youtube.com/watch?v=8LatjXPgLI8](https://www.youtube.com/watch?v=8LatjXPgLI8)

EDIT: I don't have any involvement with swissmicros apart from anticipating
their new calculator

~~~
zokier
One thing that has always befuddled me with HP calcs is their model numbers
that don't seem to follow any rhyme or reason. How does the functionality of
DM42 compare to for example WP34? And how does -48 compare, besides the
relatively useless graphing capability? I see lots of people also preferring
some other models (15, 16, 35, 41 etc), which I would have imagined to be
strict subsets of these "juggernauts", but maybe that is not the case?

~~~
dm319
The 48 was quite a bit bigger than the 42s, which I think is the main
downside. A bit of googling suggests the 48 contains similar features to the
42s, and probably more. It can also show the full 4 level stack - the 42s
showed 2.

However, you're looking for the best all-round scientific calculator (form
factor restricted!) the 42s probably wins. The voyager series (including the
15 and 16) were well-made and in landscape format, which is nice for using on-
the-go with both thumbs. They are more simplistic though - you see one line of
the stack, and there aren't menus - hence several variations to cater for
different markets.

The HP41 was an impressive programmable calculator for its time, and seems to
be more expandable than the 42s. However, the 42s is programmable, has a few
more features and a more modern display.

Not sure about the WP34, though if you look at the cost of a second hand 42s,
you'll see that many people rate it much higher than more modern HP
calculators. I think what puts me off more recent calculators and even some
other HPs, is the ambivalence about RPN. I really like RPN, and don't like
when the UI is compromised to please both.

[1] [http://www.hpmuseum.org/cgi-
sys/cgiwrap/hpmuseum/archv005.cg...](http://www.hpmuseum.org/cgi-
sys/cgiwrap/hpmuseum/archv005.cgi?read=9278)

~~~
zokier
How's the menu interface in HP calcs, is it strictly better than non-menu
ones, or is it more of a usability compromise to allow packing more features?
In other words, are the non-menu ones better for the subset of features they
have?

~~~
dm319
I'd say the way the menus are implemented in the HP42s is more useable than
trying to cram things onto buttons. For example, on the HP12c you have to
remember which registers the sum and mean of x and y are - usefully it tells
you on the back. The HP42s is more explicit with its soft menus.

------
userbinator
Notice the distinct lack of an '=' button --- HP's calculators have been
almost exclusively RPN-based.

It's funny to watch other (newer) developers reactions when they ask to borrow
the calculator that's usually on my desk (a 42S) and then give it back several
minutes later, with a puzzled look on their faces.

~~~
agumonkey
"you've been stacked"

\-- HP calc owner

Last year I finally read the whole manual (as a teen I only used the symbolic
differentiator, most useful and magical to my brain at the time). Since I
learned about Lisp, so RPN programming features appealed to me. I realized
that:

1) RPN has lambda << 2 + >> means (lambda (...) (+ 2 ...))

2) RPN has a short syntax for them << a -> a 2 + >>

Yes, 1990 HP RPN had arrow notation out of the box. Take that ES6 !

~~~
mschaef
> 2) RPN has a short syntax for them << a -> a 2 + >>

The syntax is slightly different. What it should be is this

<< -> a << a 2 + >> >>

The arrow introduces a binding form that captures the top n levels of the
stack into n named local variables. (There's also a lower level implementation
that forgoes the names in favor of a lookup-by-ordinal scheme that's a lot
faster.)

The other notable difference from what you might expect is that the lexical
environment is not captured:

Consider this function:

<< -> a << << a 2 + >> >> >>

What it returns is a function object that looks like this, except that 'a' is
a local variable reference rather than the global variable reference it looks
like:

<< a 2 + >>

Evaluating this results in an error, because while 'a' is represented as a
local variable reference, the environment containing the local binding for 'a'
is no longer available.

~~~
agumonkey
You're totally right. I already forgot the deails.

I just put out my hp49.. god how I love these things.

ps: I just found out the latest attempt I did last years was a var called REC
= << -> U << U U EVAL >> >> .. pretty sure I was trying a fixpoint CPS
factorial in RPN

------
jaclaz
Probably I will sound like a dinosaur, but I actually remember a time where
the HP-97 was a daily used tool at work.

256 steps of program!

I could write small programs that calculated coordinates for road topography,
circular curves and even (with a very little approximation) clothoids.

And you will have to pry out from my cold, dead hands my HP 28C[0][1], I
bought it right when it came out in 1987 (yes, that is exactly 30 years ago)
and it still goes strong.

But to give you a data point, I payed for it (in 1987) around 650,000 Lire,
something like the equivalent to 330 Euro that nowadays would be roughly 750
Euro.

[0]
[https://en.wikipedia.org/wiki/HP-28_series](https://en.wikipedia.org/wiki/HP-28_series)

[1] [http://www.hpmuseum.org/hp28c.htm](http://www.hpmuseum.org/hp28c.htm)

------
tzs
I never personally saw this, but I've been told by people that the HP-41 could
be massively overclocked at the cost of heavy loss of battery life. Supposedly
they could be overclocked sufficiently to handily beat common minicomputers,
such as the PDP-11, at floating point.

Allegedly some people hacked interfaces between their PDP-11 and their
overclocked HP-41 that allowed the PDP-11 to use the calculator as a floating
point coprocessor.

~~~
hota_mazi
Correct.

The HP 41 had something called "synthetic programming", a flaw that someone
once found in the calculator that allowed access to a lot of its internals,
including brand new opcodes and capabilities (even graphics, which the HP 41
didn't officially support).

The downside was that doing the wrong thing could cause the calculator to shut
down sometimes for days in a row. I once did that to my father's calculator
and these were the longest days in my life, dreading that I might have broken
his $300+ purchase for silly programming antics.

------
KGIII
I am pretty old. The first computer I touched was an HP. They called it a
calculator, my understanding is that this decision was based on the fears
people had of computers back then.

Hmm... I don't recall if it was the A or B. But, here is a video that is more
than you wanted to know:

[https://m.youtube.com/watch?v=JmTyrS-
jfi0](https://m.youtube.com/watch?v=JmTyrS-jfi0)

If you're curious, I hated it. In retrospect, it was pretty awesome. At the
time, I hated it. I basically hated computers up until the mid-90s. I didn't
really like them for another ten years. Now, the relationship is like that of
old adversaries that are too tired to fight any longer.

------
paraplegic
My introduction to programming was a 49 step programmable HP-25 which I
borrowed from a friend in residence back in 1978, and subsequently just had to
have one ... RPN got me interested in taking a FORTRAN course, and the
following year I became an undergrad tutor and computer room assistant ...
From lunar lander, to star trek on a mainframe, to a career in software
development ... funny how career trajectories work ...

------
siberianbear
Wow, this is bringing up some memories of my childhood.

One of my childhood friends had a father who was a licensed surveyor and civil
engineer. He showed me how to write programs one one of these calculators. I
was fascinated with it, and started writing simple programs to do obscure
calculations. After I showed him what I had figured out, he showed me how to
remove the faceplate and access a special test mode by pushing some hidden
buttons near the . key at the bottom.

In retrospect, I can't figure out how some civil engineer in a rural area knew
how to access and use these test functions. Probably, he had a friend from the
university who worked at HP or something.

I remember that these calculators use something called RPN (Reverse Polish
Notation). To do "3+4" you enter 3 <enter> 4 <enter> \+ <enter>. I had a
university professor ask once, what's the opposite of RPN: when you enter "\+
3 4"? One other student answered "Reverse Italian notation?" And everyone in
the class laughed so hard...

~~~
MegaDeKay
Actually, to do "3+4" you enter 3 <enter> 4 +

That's it. Note that this is one keystroke less than the regular calculators
used by mere mortals, and that is why RPN rules.

Source: my daily driver HP-15C that I've had since around 1985. Works
perfectly and has only gone through two or three sets of batteries. I'd swear
it was solar powered.

~~~
ZenoArrow
Isn't that the same number of keystrokes?

[3] [+] [4] [=]

[3] [Enter] [4] [+]

Both use four keystrokes.

~~~
jaclaz
Yes, bad example.

See here:

[http://calculatorauthority.com/why-use-a-reverse-polish-
nota...](http://calculatorauthority.com/why-use-a-reverse-polish-notation-
calculator-over-an-algebraic-calculator/)

>For example, we want to compute “(13+3)÷(4×2)” using a calculator of
algebraic notation (not a scientific one) then we have to do many steps to
reach the answer. Firstly, we have to compute “(13+3)” and then we will save
the answer to the memory of the calculator. Then we have to compute the
calculation in the denominator i.e. “(4×2)” and we have to save this answer
too to the memory of the calculator. In the end, we will bring both the
answers and will perform the last operation of division. This procedure has
taken a reasonable amount of time. This thing can be avoided by using RPN
calculator. In RPN calculator, we have to insert just a single line expression
as “13 Enter 3 + 4 Enter 2 × ÷” and the answer will be computed instantly.

More generally the use of a stack (in the case of some calculators an actually
visible stack) helps a lot with complex formulas.

~~~
carussell
[1 3 Enter 3 + 4 Enter 2 × ÷] is 10 button presses for RPN.

[1 3 + 3 = ÷ 4 ÷ 2 =] is also 10 button presses, and how I would have entered
it on an infix $10 TI-30XA during an exam. (At least, it's how I would have
entered it if the figures weren't so small.) You could argue that it's
cheating to "cook" the input beforehand so that the '4×2' divisor becomes two
'4' and '2' divisors, but then you would have to ignore that RPN requires its
own pre-cooked input (and that of the two, the RPN form is the one that relies
on a more extensive cook).

~~~
jaclaz
Yes, you replaced (correctly) a x with a /, and this does require some
(little) effort.

There is no "cooking" in the RPN input, the way you input is a little more
similar to how you do manually operations, and in the order numbers are
written from left to right, but of course beauty is only in the eye of the
beholder.

A (as well small) advantage is that on RPN you "see" that you are dividing 16
by 8, particularly - as hinted previously - when you have a RPN calculator
that allows you to visualize the stack you can see better "partial" results.

Now be nice, and do (13+3)/(3x(SQR(4+2))).

[1 3 Enter 3 + 3 Enter 4 Enter 2 + SQR * /]

~~~
carussell
> There is no "cooking" in the RPN input, the way you input is a little more
> similar to how you do manually operations

You do your pen and paper algebra in RPN?

The point of my "cooked" input comment wasn't to say that the mental overhead
to convert to RPN is complicated or cannot come naturally after some time
getting used to it; it was a defense of my swapping the division operation to
multiply by the reciprocal. The idea is that if I hadn't pre-emptively
addressed this in my first comment, I expected for someone to claim that I was
cheating and feeding in "cooked" input for the infix case. My point is that if
you recognize that converting to RPN is trivial and want to count that as a
zero-cost operation when scoring the efficiency of RPN, then you have to
recognize that converting the divisor to a reciprocal factor is just as
trivial (moreso, really) and should be scored as a zero-cost operation, too.

Otherwise, what you have is an inconsistent standard where the infix
conversion gets arbitrarily counted against the infix case, but the RPN
conversion is somehow "free".

> Now be nice, and do (13+3)/(3x(SQR(4+2)))

I got 15 button presses, compared to your 14. I can live with that, given this
is a calculator that can be picked up for $10. And that's the biggest savings,
considering that the other things I had to worry about as a student were being
gouged by mandatory meal plans and expensive, low-quality, on-campus housing.

FWIW, I actually like postfix notation.[1]

1\.
[https://news.ycombinator.com/item?id=2213066](https://news.ycombinator.com/item?id=2213066)

------
bfirsh
My favourite HP calculator stories: Woz sold his to fund the development of
the Apple I, and they were used in the later Apollo missions as a backup
computer.

[http://www.foundersatwork.com/steve-
wozniak.html](http://www.foundersatwork.com/steve-wozniak.html)

[https://hpinspace.wordpress.com/2009/07/16/hp-65-and-
apollo-...](https://hpinspace.wordpress.com/2009/07/16/hp-65-and-apollo-
soyuz/)

------
ufmace
I just sold my two HP48s a year or so ago. IMHO, can't beat 'em for doing
anything more than single operations on a calculator. I was willing to sell
them partly because I found a nice Android app that emulates one well [0]
enough that it seems like a hassle to keep the actual hardware around.

[0]
[https://play.google.com/store/apps/details?id=org.ab.x48](https://play.google.com/store/apps/details?id=org.ab.x48)

------
gaius
Still got and use my 12C, and 48gx, unfortunately sold my 28 to buy the
latter. When you look at the quality of what HP used to produce versus now,
it's very sad.

~~~
mschaef
> When you look at the quality of what HP used to produce versus now

I was always impressed that the keys used two color injection molding for the
primary labels. There was almost literally no way to wear the label off the
keys, since the label was built into the plastic.

------
wslh
I just bought a new HP 12C to replace the calculator app. I love the form
factor, mainly the keyboard, but they could improve the product adding more
memory for programming. It is odd they have an emulator in place to run the
original ROM!

BTW I have also a HP 48GX but some buttons become unusable. What is the best
shop to repair it?

------
jeff6845
I remember rushing to purchase a HP calculator at employee discount while
interning at HP. Most of us did so. A few who had a relative in the medical
field, or a spouse going to med school, bought the stethoscope at employee
discount.

Those two items were status symbol back then.

------
jimnotgym
I'm too young to remember, but it seems the UK calculator of choice was the
Sinclair
[http://www.vintagecalculators.com/html/sinclair1.html](http://www.vintagecalculators.com/html/sinclair1.html)

~~~
b5
My dad, who went to Uni in the '70s to do maths and physics, has a Sinclair
scientific that looks very similar except has blue LED digits. I don't know
the exact model.

------
ScottBurson
If you're an RPN fan and have an Android phone, you might like RealCalc [0]. I
use it a lot.

[0] [https://www.quartic-software.co.uk/](https://www.quartic-software.co.uk/)

------
pmoriarty
I've never used an HP calculator, but I've recently been getting interested in
emacs' calc, which is also RPN.

Could someone who's used both talk a bit about how they compare? Are calc and
emacs missing something that made HP great?

~~~
mschaef
Interesting you ask.... Emacs Calc was inspired by the HP-28.

[https://www.gnu.org/software/emacs/manual/html_mono/calc.htm...](https://www.gnu.org/software/emacs/manual/html_mono/calc.html)

It's not the same, but having used both, they are very similar in overall
feel.

> Are calc and emacs missing something that made HP great?

A couple things:

First, having specific hardware is (was?) a nice thing.

Secondly, the HP28/48 programming model was very, very orthogonal. It was a
more impoverished Lisp than even elisp is today, but it pervaded the entire
software stack. While people referred to 'RPL' and 'System RPL' with two
different names, the truth is that there was no real distinction between the
programming language you used as a user and the programming language used by
HP to build the machine in the first place. This kind of solidity and general
'gestalt' pervaded the operation of the machine and made them joys to use.

------
noonespecial
I'm a young-un in the HP world. 48g was my first and still only.

But you can pry it from my cold dead hand because the snap of those lovely
keys under your fingers and that stack scrolling up that screen is the
visceral feeling of _math_.

------
throwaway7645
I have one of the new HP 15c's they created 6-7 years ago. It is the exact
same as my dad's from ~1985, but much faster due to the new chip. As great as
it is, the Voyage-200 (TI-89 with more RAM, more buttons..etc) would run
circles around it for usability. A HP might be able to get the answer first,
but with my Voyage the full equation was pretty-printed on the screen and i
could adjust each variable without retyping everything.

------
aryehof
I had a HP-67, then a 41CV which I loved. Then I moved on to the 95LX, 100LX
and 12C. Today it's a 12C emulator on my iPhone that I mostly use.

I grew up on RPN, and have always considered knowing it as a "strategic"
advantage.

------
protomyth
I miss the HP-16C. It was an amazing thing to have something with hex. It was
pretty useful when I was doing assembly.

~~~
paraplegic
A GREAT calculator. I wrote a portable forth which I use for hex conversion
which I still use frequently.

