EEVblog #1159 - World's Most Precise Pocket Calculator

[EEVblog]

One item mailbag!
A look at the Swissmicro DM42, the world's most precise pocket calculator.
A clone and improvement of the famous HP42S, with open source firmware based on the Free42 platform.

https://www.swissmicros.com/dm42.php
http://thomasokken.com/free42/

[dr.diesel]

That is quite nice!  Is the display cover glass or plastic?

[imo]

I think the "most precise pocket calculator" is the WP-34S.
https://sourceforge.net/projects/wp34s/
It uses DecNumber library with up to 50 decimal places precision.

[bsudbrink]

Just so you know, YouTube has this video marked as "unlisted".  I'm not sure what this means, but I don't see it on my YouTube account subscription page.

[darik]

To show the full precision, use shift-decimal (SHOW).

[Dubbie]

I have this calculator, the only issue I have with it is that the button feel is not as nice as it could be. It is my daily driver at work though.

[EEVblog]

To show the full precision, use shift-decimal (SHOW).

Ah, that works, but unfortunately does not show up long enough to read it!
UPDATE: You have to continue to hold down the button to keep it showing

[EEVblog]

Actual Calculator Forensics result:

[imo]

It seems Dave's buttons died
A big pain all these recent attempts to mimic the original HP-clicky buttons. The WP-34s (HP-30b hw) I own still clicks, but mostly because I stopped using it in order to save the buttons
The thin plastic pins (about 2.5mm long 1mm dia) pushing onto the metal dome usually bend/broke when pushing a little harder.

The DM-42 does not use such long pins, it may last a little bit longer. Not sure you get such HP-feel with it, however.
And my HP-25 and HP-48GX is still clicky..

[BrianHG]

Holly cow Dave!  Your enthusiasm shines through to the moon. 

[inOr]

Once I tried to write a DEC Fortran program to solve a quadratic the high school way, the exact formula you know -b+/- sqrt(b^2 ...., I got a ridiculous answer, so I tried a numeric routine from the DEC collection and wow was that wrong!  So I programmed my own numeric routine and that worked.  Meanwhile, I used my HP xx scientific calculator.  I can't remember the precision, but the answer was bang-on.  They do have their uses...

[johnlsenchak]

Years ago,   I had a  real nice  programmable HP scientific    calculator    where I  wrote a programs  to  calculate  A/C   circuits when  it came to inductors and  capacitors   .

[Fungus]

To show the full precision, use shift-decimal (SHOW).

I was shouting that at the screen while the video was running. 

Ah, that works, but unfortunately does not show up long enough to read it!
UPDATE: You have to continue to hold down the button to keep it showing

How many does it show? 12 digits?

[NivagSwerdna]

Nice.  I have a poor man's version WP 34S .  I know 42S is super popular with the fanboys but IMHO it's a bit hard to live with unless you use it every day since the functions are hidden away... I think I prefer the ones that just have lots of functions on the buttons...

I also have a HP35S which is a nice compromise and not bad for a modern device.

[Gribo]

Does anyone knows who manufactures the display? I have been looking for an E-paper display with fast response time for quite a while.

[imo]

LS027B7DH01 from Sharp Microelectronics..

[pauli]

It's off by one in the last digit

Refer: http://www.hpmuseum.org/forum/archive/index.php?thread-10355.html


Pauli

[rsjsouza]

I also have a HP35S which is a nice compromise and not bad for a modern device.

Although a bit more cumbersome to do base conversion when compared to my 48GX, the 35S is quite nice. (I leave my 48GX at home as I am afraid it will be stolen).

[EEVblog]

It's off by one in the last digit
Refer: http://www.hpmuseum.org/forum/archive/index.php?thread-10355.html
Pauli

Hey Pauli, long time no see, welcome to the forum!

[Spirit532]

I believe the display is a Sharp Memory LCD with the model number LS027B7DH01
It's a ridiculously low retention power graphical LCD, but it comes at a hefty price premium.

[3roomlab]

nothing against real physical calculators. but for those who have tablets old or new, install one of those scientific calculator apps on it (there are hundreds in google app store, some are better, I am using one which appears to be done by a viet dev, they basically copied the entire sci-calc into an app. some includes programming features.), there is nothing like a portable scientific calc with a 10" screen and buttons the size of a thumb. I repeat, buttons with the size of a thumb.

there is nothing like using thumbs to press them, the satisfaction (or fun). and there is no printed words to rub off like casios.

[Fungus]

there is nothing like a portable scientific calc with a 10" screen and buttons the size of a thumb. I repeat, buttons with the size of a thumb.

 

Some of us still have good eyesight and a bit of hand-eye coordination.

[floobydust]

All these app-based calculators still suck compared to old tech.
I have a Sharp EL5103-S that rounds results to engineering units (milli, micro, nano, kilo etc.).
It's great instead for EE work, instead of converting exponents.

The pocket calc speed test I did was always 69! (69 factorial), I wonder how long that takes on this calculator. TI-30 LED was 2 seconds lol.

[rsjsouza]

there is nothing like using thumbs to press them, the satisfaction (or fun). and there is no printed words to rub off like casios.

My old Kindle Fire HD still has a beautifully coded HP-12C in voyager style. Although its size and functionality are quite nice, pressing virtual buttons is not the same at all. YMMV, though.

The pocket calc speed test I did was always 69! (69 factorial), I wonder how long that takes on this calculator. TI-30 LED was 2 seconds lol.

Heh, I did the same. My old Casio fx-39 took about 10 seconds! My dad's TI-59 did not have a built-in factorial function, and the best program I could make at the time took somewhere between 10 and 15 seconds.

[Fungus]

My old Kindle Fire HD still has a beautifully coded HP-12C in voyager style. Although its size and functionality are quite nice, pressing virtual buttons is not the same at all. YMMV, though.

12C? Ew! That's a calculator for bankers.

HP does the 15C (scientific) for Android:

https://play.google.com/store/apps/details?id=com.hp.hp15c15&hl=en_US

(it turns into an RPN  four-banger when you rotate to portrait mode, too)