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Dave Baum
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HP has brought back the 15c calculator. It's specs may not be so impressive today, but when it was released 30 years ago it was amazing... built-in support for matrix operations, numerical solving and integration. Complex number support without equal. Other calculators had basic complex number operations, but the 15c went the extra mile and supported complex numbers throughout almost about all of its functions. For example, it can calculate the arcsin of 2. The amount of effort that went into ensuring the accuracy of the calculator's results would be impressive with today's software, and is downright astounding considering the limited resources of the time.

But probably the best features of the calculator had to do with usability. Convenient size, readable display, great keyboard, all functions well organized and easily accessible. Batteries that lasted years (as in 10 or 20 years). Working in landscape rather than portait mode was also a plus.

This is the calculator that I used through high school and college, and I have always regretted loaning it out a few years later and never getting it back. Now I have a replacement. Sure, by today's standards $100 is pricey for the capabilities of this device. An HP 50g can be bought for just a few dollars more. But the 50g is often "too much" calculator, and the 15c is just right. I'm thrilled that HP revived this classic model.

I just fixed my HP-42S calculator. I have owned numerous calculators over the years, mostly from HP, and the 42S was by far my favorite. From time to time I'd be tempted by something more powerful like the 48G, but for some reason the 42S was the perfect combination of size, features, and display. It was my primary calculator for 15 years until the keyboard started acting flaky.

By then HP had stopped making good calculators. Or rather they put top-notch calculator firmware into awful mechanical designs like the 49G. The 50g finally seems to be worthwhile, but it's just a little too big and too complicated for my tastes.

Last week I could have really used a good calculator at work, which made me think of the 42S again. I checked ebay. Apparently I'm not the only one that thinks these are excellent calculators because they are selling for upwards of $300: absurd for a 20 year old electronic device that originally cost $100 new.

As a last resort I opened up my broken 42S. These things weren't made to be taken apart. I had to peel off the faceplate (which is now bent), drill out some plastic rivets, and pry the thing apart. I found that one of the keyboard traces wasn't making good contact with the PC board. I cleaned everything very thoroughly, used some plastic behind the keyboard connector to put more pressure against it, and put everything back together.

I have a fully functional 42S again!

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Received both The Math Book and The Physics Book for Christmas, and my intention was to finish one before starting the other. But both books are arranged chronologically and given the amount of overlap between the two subjects it has been much more interesting to interleave the books.

I'm amazed at what the ancient Greeks were able to figure out... and saddened by the centuries lost to the Middle Ages.

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Found some time over the holidays to play with Lego...

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I bought The Monster at the End of This Book for iPad while it was on sale. They really did an excellent job converting this book to an app. Jacob had a blast with it.
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