
The HP-35 Design: A Case Study in Innovation (2011) [pdf] - keenerd
http://archive.computerhistory.org/resources/access/text/2011/12/102746048-05-01-acc.pdf?
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jdblair
My dad had this calculator in the 70s. He was an engineer for the local power
utility and told me that before getting the HP-35 he would submit calculations
at the computer center and get his results back about a week later. With the
calculator he could run his computations immediately, at his desk. It was life
changing, at least in the context of his work.

It was one of the more expensive small things he owned so he never left it at
his desk, carrying it around in his jacket pocket (engineers wore suits to
work in the 70s). He told me he also got a reputation for this, since it was
such a unique thing to be carrying around.

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throwaway7645
Same thing with my dad, but at university level as he could write engineering
programs to help with homework and avoid booking time on the mainframe.

Btw: Would you please ask your father what type of calculations he ran on his
calc as a power systems engineer? Fortran would've been around for state-
estimation and contingency analysis by that time if he was in transmission.
For distribution I could see him doing fault analysis or calculating line
parameters. If he was on the generation side I'm not really sure what he'd be
calculating (not my area). Of course utilities were fully vertically
integrated during that time frame, so he could have done a mixture.

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jdblair
I'll ask the next time I talk to him. I know he worked on high voltage
transmission.

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throwaway7645
Awesome...same as me. I'd love to hear how they did things in more resource
constrained times.

I also have a hobby interest in HP calcs (own a 15-c), so double interest
here. Not sure if you're a blogger, but that is some legitimate history with
the early usage of handheld computing to aid science & engineering. A blog
post would be great, but I'd settle on a reply here.

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jdblair
I'm a past blogger, but I haven't kept up with it for a while.

Here's what my dad wrote when I asked him:

The work often involved transmission line impedance calculations. These and
other power calculations required a great many translations of rectangular to
polar coordinates and back again. We had an Oliveti vacuum tube machine in the
office that would only do this one operation in one direction or the other.
Otherwise it was back to slide rule, pencil and paper. We had an IBM 360 in
the basement that would do grid system power modeling. These calculations
required 24 hours to get an answer.

Mom got me an HP-35 for Christmas. It was like touching an alien spacecraft
technology.

Later on around 1976, I operated a consulting and substation design business.
In this activity I needed to do hand calculations of short circuit current for
industrial customers again using the HP-35. The HP-35 was an important tool
and a real game changer for electrical engineering work.

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throwaway7645
Thanks for the reply! It was a very interesting read for sure. The
polar->rectangular conversions can be done with an $15 Casio FX-115ES from
Walmart pretty easily although RPN is much nicer than scrolling around a bunch
when the equations get long. He might already know that, or find it
interesting. I've never heard of an Oliveti vacuum tube machine, but will look
it up. The IBM 360 machine he mentioned is probably not that different to what
we do today (I bet the software has only changed in minor placed). The biggest
difference is it's moved to Nix or Windows and off the mainframe and we can
simulate massive scale problems in seconds. Of course that means we steadily
increase the scope of the problem until you get a process that takes 24 hours
;). I'm impressed with anyone who can use a slide-rule for anything more
complex than multiplication. Props to your dad btw. I love my job and it's
fascinating to see how past engineers managed to essentially do the same
things with tools that seem archaic today. I guess this is similar to modern
day software engineers on HN getting really excited bout the Xerox Alto
Smalltalk machine & the Symbolics Lisp Machines. The past is neat.

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dingo_bat
Very well written and makes me realize what a pioneer company HP was at that
time. It was the Apple of its time. Best anecdote:

> Stanford Engineering Dean Fred Terman, the person responsible for bringing
> Bill Hewlett and Dave Packard together to start HP was one of the first. He
> was overwhelmed, looking for an umbilical cord connected to a big computer
> doing the precision calculations.

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tabtab
I bought a used one in the 80's and found it an amazing device: simple yet
powerful. A Turing Complete pocket computer. It should be noted that HP did
NOT invent reverse polish notation, and the HP-35 allegedly borrowed a lot of
ideas from the Olivetti Programma 101 computer, arguably the first desktop
computer.

Still, the HP-35 was an amazing packaging of existing but relatively new ideas
(at least as actual products). This kind of thing is what made Apple big: take
different new but existing ideas and combine and package them well by keeping
the good and tossing the bad or low-use features. Steve Jobs had a nose for
how to use new ideas invented by others by carefully picking, choosing, and
associating features. What you leave out is often more important than what you
put in.

I've also read that HP was hesitant to advertise such devices as "computers"
because that carried export restrictions per military concerns. Calling it a
"calculator" got around that. The convention of defining "computer" as
something Turing Complete came later I believe.

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tolger
Very interesting article. My dad, an engineer, had the successor to this
model, the HP-45. It was an amazing machine for it's time. Because of it, I
fell in love with RPN and refused to use anything else. When I went to college
I got an HP-48sx. I think it was the zenith of scientific calculators with so
much functionality crammed into it.

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santoshalper
Really enjoyed that.

