my HP 28S with RPN

I don’t get too terribly attached nor nostalgic about most technology. It’s true that, now having owned an iPhone for a month or so, I can’t see life without it. And, I love the smell of a new computer as it’s unpackaged and the clear plastic is peeled from its perfect plane of glass screen. But I know these items will come and go. Bright and shiny, innovative and invigorating, but in a couple of years some other technology will replace them as I grow weary of what they cannot do, what speeds they cannot attain, what connections they will not make.

img_0173-2011-12-11-17-11.jpgBut my calculator is altogether different. I bought it, used, in 1990, for $100. It was then, and still is, a bargain. It’s an HP 28S sporting two keypads, four lines on its display, an ability to graph and program. These are all much more than I need; in fact my phone can do much more numerical crunching than this calculator, much faster and with much more to offer in terms of the display. But this calculator offers two things that I can’t upgrade with a newer device. The first is what we call “RPN,” otherwise known as “reverse Polish notation.” If you know what this is, then you care deeply about the feature. If you don’t, then you don’t. Essentially, it means that you punch in the numbers and operations in the reverse order that you’re used to. So, to add 3 to 2 you’d enter 3, then 2, then command the calculator to add. Numbers are retained in the “stack,” the list of numbers that will scroll upwards on the screen as I enter them. You’d never guess it, but this actually makes calculations easier. I resent all other calculators without this feature, but more and more this is nearly impossible to find.

It turns out that you can get a fine RPN calculator for a couple of dollars that will work on the iPhone or another device. I use these regularly, but they still miss the really vital feature of this calculator. It’s the keys themselves. They depress with a very specific and perfect feel, clicking just so. It’s a relatively heavy depression — much more substantial than most computer keyboards and far more than most calculators that I come across. There’s a feel to the calculator, as though you’re doing something substantial. Not burdensome, but not trivial, either. It’s like biting into the perfect fruit. As I finish grading a 5 page exam and need to add the scores of the 5 pages I look forward to pulling out this grand machine so that I can tap in the numbers with that satisfying feel. 25. Enter. 32. Plus. 35. Plus. 14. Plus. 28. Plus. “134” reveals the screen, having summed each number to the compilation already remembered with each “plus”.

Because most things that I do with a calculator nowadays are fairly minor — a cosine here, a sum of some numbers there — I only use a fraction of the abilities of this device. It calculates as fast as I can enter in numbers, and it gives me firm results and response. It’s dependable but obscure. No one will steal it unless they’re looking for an antique or, more likely, they’re looking specifically for an HP 28S. (The price these demand now are the same as what they were 30 years ago.) My students look at it as though it should be hand cranked, or perhaps spit out a roll of paper with a typed transcript of operations. And yet I imagine that I’ll hang on to this device for the duration of my career. I don’t think I can say the same of any other piece of technology.

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