SHARP EL-W506X scientific calculator from 2011

[jebem]

I got this machine NIB a couple of years ago.
I like the SHARP styling and this model looks nice in any collectors inventory.

This machine uses a similar electronic and mechanical build seen on current CASIO calculators like the fx-991 series for instance. Basically both are cheap and kind of fragile machines using membrane keyboards that still manage to register the keys every single time.
However the SHARP uses a different processor and algorithms giving different calculation results.





The usual forensics test gives a result of: 9.000000098906
So far (Jan-2017), this result is only seen in some SHARP calculators.




Complex numbers. It handles the sqrt(-2).




Integrals. int(0,pi,sin(x)) results in 2.000000001. Not exactly the expected result from a modern calculator these days.

And this machine is slow but understandable considering it is designed to work with solar cells. It took 23 seconds to compute this.



Consulting the user guide I found the reason for the above odd result. We need to specify a higher number of sub-intervals, as by default this calculator will use just 100 intervals.
Trying again but specifying 200 intervals, we got the usual expected result of 2.
To get this answer the machine took 44.5 seconds.




Differentials. diff(3x^3), x=1 results in 9.00000001. Again, this result is odd.




Checking the user guide, we see that for this computation the machine uses a default minute interval of 10^-5.
Trying again but specifying a minute interval of 10^-8 it came out with the usual expected answer for these kind of machines.




Comparing the SHARP to a different school of thought by Casio, for instance trying a fx-991, the above integral and differential gives the expected results of 2 and 9 without the need to specify additional command options.

And this new 2015 ClassWiz generation machines are fast when compared to the 2011 SHARP under the same solar light conditions.
The ClassWiz took just under 2 seconds to compute the integral.

[jebem]

Dismantling.
It uses a single LR44 1.5V cell as backup and auxiliary power for the solar panel.



The solar panel generates 1.8VDC under strong light.




It seems SHARP uses a single internal PCA design for all Colourful Scientific Calculators series.
A table with seven models can be selected by changing the hardware jumpers. I didn't test it.



The solar panel is more sensitive to what can be found on the CASIO fx-991 series.
Under the same conditions, the CASIO machines will not power on, requiring either more light or a battery cell to be able to work.




The keyboard construction is similar to what we see on CASIO machines.
A rubber membrane and discrete plastic keys.