25 March, 2010

Another calculator, same as the first?

A new purchase

I recently got another calculator for $10 from an online store. I saved $19.95, so I was happy. There was a reason not to be happy, but more about that later. It's still my first honest-to-goodness modern Hewlett Packard calculator—my previous HP was a HP34C and died long ago. But something struck me as soon as I received it in the post. It's another one of these calculators with a display that has two lines, one for the input calculation, the other shows the output from previous calculations. The display's almost exactly like the Casio FX-82MS with the same characters and annunciators, and the HP 10s even has a very similar keypad layout, only the occasional keys have been transposed, and the directional keypad is in a different position.

As well, the internal menu system is exactly like the FX-82MS, to the extent that if I compared the HP documentation and the Casio documentation, I'd find no mistakes on either calculator. Their documentation certainly differs though, even though they've both printed their respective instructions on a single sheet in multiple panels, the Hewlett Packard documentation is separated into distinct pages, and those pages don't take up an entire column as the Casio instructions do. I also found that the self-test on this calculator is almost (but not quite) identical to the FX-82MS. The key combination to start the test off is even the same: Shift-7-On. Once starting the test, keys in the keyboard test are pressed in exactly the same order as they would be on the MS, which makes for a slightly odd order on the HP's keypad. And I still haven't found out what all the numbers mean at the end.

So, is it a clone?

It's not absolutely a clone, and it has the advantage of being solar-powered like the FX-85MS, though I haven't seen one of those in this country. Nice for when you've got some nice bright sunshine, it keeps the watch-cell battery topped up with solar power, and makes the battery life a lot longer as a result. It also has a slide-on case just like the Casio, but slightly differently designed. The fit is tighter, for one, so the top's not quite as likely to fall off inadvertedly. It has exactly the same default ranges too, so if you couldn't find the FX-82MS, this HP 10s would do fine and be literally a drop-in replacement for it.

The LCD display and the colours selected for the fascia and keys mean that everything can be read clearly, and is easier to read than the MS, and it reminds me of the other white calculator body I have from Casio (the FX9750G Plus). However there's a slight anomaly when you look at the M+ key, the DT is supposed to be associated with it, but the way the design was done for that key isn't quite as together as for the 82MS. However, I can certainly live with it. The keys have a good positive travel and don't have a tendency to offset, unlike the keys on the Casio body which can on occasion look a bit higgledy piggledy. All in all, the Hewlett's quite a good calculator, though the lack of programmability is reflected in its price. It seems strange that somewhere in the documentation on the HP web site, there is mention that the calculator has 128 Kilobytes of memory, I'm trying to figure out what on earth uses up all that space, given there's no programmability.

And the reasons for being unhappy?

About the only problem that I had was when I first received the calculator and turned it on, the display wasn't quite right. In that top line of the display, there was a missing line of dots. I'd normally have shrugged this off, but in the case of this calculator, there's little enough font information as it is, as the font on the top line is only six pixels high by five pixels wide, with an additional pixel's worth of space between each character cell. So having every single character missing its second line of pixels was a bit disconcerting. If it wasn't so cheap, I'd have probably returned it to the retailer by now, asking if I could have another one of the same value. But the cost of return is nearly as much as the calculator cost me to begin with, so I probably won't bother. And as it was, using the self-test cured the missing line of pixels, so I don't have to send this back to the company after all. I would have felt like a charlie if they'd slung it back my way saying "It works, deal with it". I was also hoping like anything that this calculator was programmable, but it was not to be. Ah well.


For simple tests, it shows roughly the same degree of accuracy as other models, though there are some differences. For example, this test:

(asin (acos (atan (tan (cos (sin(9)))))))

results in the figure

being displayed, instead of the FX-82MS' result of 8.999998637. So maybe there are differences after all. After taking away the 9.00000000 and then multiplying by 1E9, we get 2.124, which makes me wonder if this calculator has an extra couple of digits of precision up its sleeve. Weird.

17 March, 2010

Where are the corners?

A new toy from the Rubik stable

You’ve heard me talking about my Rubik’s Cube family, not once, but several times and also about the other non-cube members of the puzzle family. Well, today I bought another non-cube puzzle. This one contains three clear spheres that are hooked together with pivots, and if you look through, you can see six little coloured plastic balls, nestling in the centre sphere. The outside one’s got knobs on, and there’s a steel ball bearing on each of the two inner spheres. So not only do you have to fight logic, but now you have gravity to contend with too. It’s called the Rubik’s 360°, and it's not like any other puzzle I've ever played with.

Why another puzzle?

I’d like to use the excuse that I was getting ready for Brain Week, but frankly that’d be a bit pointless after Saturday. No, I simply liked the look of this puzzle, and thought I’d add it to my collection just because I like it. It also happens to be my equivalent to purchasing an Easter egg—except this one will last much much longer, after the chocolate has become a dim and distant memory. It's also better for my waistline, not that I have much of one anyhow. In addition, I would like to add a couple of other puzzles that I don’t already have, the Megaminx and the Holey Megaminx. I suspect the second will be easier to do because there’s no centres to match the rest of the face against, but I could be wrong. I’ve been wrong before... anyhow, they  both have twelve faces, each  face shares its pieces with five other sides, and they do look quite difficult. One variant has six colours, where opposite sides have the same colour, but the other variant has twelve colours, to remove the chance that two pieces with the same colour pairing can get mismatched. No doubt there'll be other puzzles I want to lay my hands on. Not only are there single-layered versions, but there are double-layered Gigaminx, three-layered Tetraminx, and four-layered Petaminx, though I've no idea what the last one looks like. I've also seen online versions of the Megaminx, and it's easy to use but hard to get used to without the real thing in my hands.