If there's one person to blame for my addiction to to portable, battery-operated gadgets, it's my uncle, who had access to the latest scientific calculators by HP or Texas Instruments through his job. We're talking here about expensive little computers with memory in the KB range and 10-digit 7-segment red LED displays.
1980 he would show me the HP 41C, which was a break-through device. It sported a alphanumeric display, which allowed to enter commands by its name and hence not limit its functionality by the number of keys on the keyboard. Users could redefine the keyboard and there were expansion modules for adding more scientific and financial functionality. I wanted to have one so badly, but there was no way to justify this kind of expense for a sixth grader.
Fast-forward 30 years. The coolest handheld device is the iPhone with memory in the gigabytes. And there's an awesome HP 41CX emulator (iTunes Store link) available in the iPhone app store for $10. The look is absolutely authentic (the feel, of course, is lacking the characteristic plop of an HP keypad) and, for $5 extra, you even get a virtual dot-matrix printer.
Between the original HP 41C and the iPhone are pretty much 30 years of progress. A 10-character black-and-white LCD display is replaced with a high-res color screen. Kilobytes with Gigabytes, multi-assigned keys with a touch screen and an optional magnet-card writer with high-speed wireless network access. Only the battery life suffered greatly: the 41C was able to operate for a few more days after the low battery warning - with the iPhone you better rush to the next power outlet right away.
One could imagine, if HP engineers in '79 could have dreamed up hardware, they would have ended up with something close to the iPhone: with its touch screen, it perfectly supports the user-definable keyboard without the plastic overlays that were shipped with the 41C. But what do modern calculators look like in 2009? Interestingly the current top model, the HP 50 is a pretty boring piece of technology, with a monochrome low-res graphical display. And the iPhone App Store sports only a few emulators and variations of the build-in calculator. The HP 41CX emulator is the only programmable one (which is technically a violation of the iPhone app agreement - but in this case Apple probably didn't mind too much).
I guess, the top-notch app would be Mathematica. It should be too difficult to port Mathematica to the iPhone, and I'm sure that somebody at Wolfram Research has probably already running it. The main issue with it is probably the $999 price limit in the App Store.
