Working Things Out Backwards

[krpalmer]

After reading a book about calculators and then a weblog post about a brief slice of their history when pocket electronic machines became available in the early 1970s, I happened on an emulator program for some of the first Hewlett-Packard pocket devices. That got me thinking about their particular method of data entry, and whether I’d brushed by “Reverse Polish Notation” just because of the unfortunate potential for inappropriate smirks. I did get to the point of looking up the manual for the HP-35 calculator, the original “electronic slide rule,” and then I started searching in my phone’s “App Store.” One free application offered the layouts of the HP-35 and two of its immediate successors, the enhanced HP-45 and the cost-reduced HP-21. It did offer “haptic feedback” when you pushed on-screen buttons, but when I realised it didn’t quite offer the multiple memory registers of the HP-45 I started looking at calculator programs you had to pay for. One person offering quite a few programs had a “free sample” ready in the form of the HP-70, a simplified financial calculator, and that was enough of a preview for me to buy an HP-35 program for my phone and a HP-45 program for my iPad.

Once I’d become used to it I could see how “RPN” entry worked with complicated calculations; the question was just how many of those complicated calculations I actually do. I also got to the point of thinking I ought to see if I could still multiply and divide by hand on paper, and found myself prone to errors while multiplying at length. My only hope is that practice would help there.

Comments

[mmcirvin]

The calculators I eventually settled on in college and grad school were HP's RPL line, the 28S and the 48SX (the latter got stolen--it was too expensive to leave lying around). There were several later models. Eventually HP open-sourced the firmware for them, so a lot of free mobile emulators exist--and these were the most powerful calculators they ever released, though RPL subtly changed the way HP's RPN calculation worked in ways that were not to everyone's taste.

But RPL was a great programming language, sort of a strange cross between LISP and FORTH--it gave the stack unlimited depth and allowed putting everything from graphical objects to programs on it, instead of just numbers. In some ways it was a functional programming language. These calculators also introduced some CAS capability: they could do symbolic algebra and calculus to a limited degree, though it was a bit cumbersome compared to what you could get for a computer.

These days, I don't use all of those capabilities on a regular basis, but a 48GX emulator is my go-to calculator.

Those are all much later models than the ones you're looking at, from the late 1980s and early 1990s, with multi-line LCDs and graphing capability.

[mmcirvin]

...Anyway, I did go down a rabbit hole a while back studying the history of scientific calculators, especially programmables. HP's first RPN calculator was the desktop HP 9100A in 1968, which cost as much as a car, but for many scientific and engineering organizations that was mind-blowing because this thing that could perform many of the computation functions of a full-blown computer was now just cheap enough that you could contemplate putting one on an individual engineer's desk. And the prices came down *fast* from there.

Old computing devices fascinate me, including slide rules. I don't have any at the moment but I kind of want to get my hands on one, but I'm afraid it will lead to a collecting bug that will further clutter my house. Fortunately slide rules are fairly portable.

[krpalmer]

I do have my mother's high school slide rule with me. It's a simple model, with only C, D, CI, A, B, L, and K scales, and all on one side only (with instructions and conversion factors printed on the other side). While I was looking up the calculator simulators, though, I did notice there are also "slide rules for the iPhone"; you have to scroll back and forth to see all of the rule, however.

[lovelyangel]

A long time ago I had some HP calculator emulators on my Mac and iPhone. They were pretty cool but had minor flaws. (One was actually Made By HP.) I don’t need anything more than an RPN 4-banger, and I’ve selected PCalc as my virtual calculator of choice across all my devices. PCalc is a great little company.

As for physical calculators, my HP-45 is in storage. My HP-10c died, but I still have an HP-11c, and an HP-12c. The 12c is what I go to in my home office. It does all sorts of fancy financial calculations, such as Net Present Value, that I never use. But balance my checkbook? It’s right there. The tactile feedback is perfect.

I think in RPN, and it would be tough for me to use an algebraic calculator, although I do know how. I’m just way faster with RPN, and I never have to worry about parentheses.

My slide rules are in storage, also. There’s a yellow plastic Pickett slide rule that I used as a freshman in college. There’s also a bamboo Post slide rule that I couldn’t afford as a college student – but I bought when slide rules were being cleared out at the college bookstore, as engineering mandated scientific calculators, and slide rules were instantly obsolete.

[krpalmer]

I'd bought PCalc quite some time ago, and knew it offered an RPN mode (with a caution when activating it for the first time). I suppose I became enticed by the "calculator simulators" through much the same sort of "seeing what things were like back then" feeling that has me poke away at a variety of computer emulators...