|Re: DM-15CC launched|
Message #33 Posted by RedGlyph on 12 Feb 2012, 6:09 a.m.,
in response to message #32 by Juergen Keller
I have received a production unit on Friday, so here are my first impressions.
Admittedly the size makes it more difficult to punch the keys than a full-sized calculator, but the idea was to build a small calculator from the start. For me the size of the keyboard doesn't make it difficult to use the calculator though, I think it has the right dimensions to be both small and not too small as to be impractical - key spacing makes it more comfortable than a BlackBerry for example.
However, I confirm the keys are hard to press and don't always register, which makes this calculator a bit awkward to use. Add to that a curved surface due to too few screws (four, one in each corner) that makes the calculator bend and sometimes produce a little crushing sound when you press some of the keys, and you get a general impression of something that will not last and is not so pleasant to manipulate.
It is faster than the original HP-15C, although not as fast as the HP-15LE. For example, integration of sin^2(x) from 0 to 45 degrees takes about 30 seconds on an HP-15C, about 5 seconds on the HP-15CC, and less than one second on the HP-15LE. I'd say it more than enough for a calculator.
EDIT: A simple loop with 2000 iterations (LBL A, 1 STO- 0, RCL 0, TEST 1, GTO A) takes
- 19'27" on HP-15C
- 6" on HP-15LE, about 194 times faster
- 2'12" on HP-15CC, about 8.8 times faster. Some complex operations may be faster though.
The ON-x self-test works, the ON-/ one doesn't, however. It displays the first symbols on the screen but pressing any key doesn't make it progress. The only way out is pressing the ON key which produces an "Error 9". Not a big deal I suppose, and it doesn't work on the HP-15LE either, but I think this calculator should have a keyboard test at some point, given this is a weak point of the design.
Unfortunately I could not test the mini-USB connection because I don't have a compatible cable, it looks like a mini-B type like those used on the Motorola smartphone. Not the most common type...
The display is fine, the large numbers are visible enough. While it doesn't offer the same contrast ratio as an original or an LE model, it shouldn't cause any problem in normal conditions. My display was slightly scratched when I received the calculator, it looks like it's prone to being scratched if not taken care of, for instance if stored in a bag without protection. I suppose the units were stacked together after production, that's when it must have happened.
The calculator comes with a protection sleeve that can be seen on the site photos. What is not rendered is its nasty synthetic smell though ;-) It tends to pervade quite a bit.
So in conclusion, this is an interesting gadget for HP-15 enthusiasts, but definitely not something you want to use on a daily basis, or if you must depend on it for an exam or in the field. It could use a better keyboard design, and a more robust case, I expect either to be the weakest feature and to break down first. But you have to look at this as a DIY-grade design, and as such this isn't bad at all!
Edited: 12 Feb 2012, 7:26 a.m.