reverse engineer calculator to update the constants.

[Lightium]

I have a Casio fx-991H calculator that I've been using for decades now. I've written to Casio about updating constants or producing a version 2 of the calculator to no avail. Does anyone know the make up of these chips, possibly the pin outs of the chip?

 

[crutschow]

They use a custom microprocessor in the calculator, which cannot be updated.

 

[Lightium]

Hello crutschow, I am sure they were custom, but there's no hope for me to poke around?

 

[Papabravo]

Hello crutschow, I am sure they were custom, but there's no hope for me to poke around?

It is exceedingly unlikely you would discover anything interesting or modifiable. Most of those devices have mask programmed read only memories which allowed them to be produced in volume at low cost. My advice is to find a replacement and bin the original, especially if the keyboard is showing signs of flakiness.

ETA: What constants are you talking about?

 

[danadak]

Most manufacturers code lock their code programmed into memory so it cannot be read.

Protect intellectual property.


Regards, Dana.

 

[Papabravo]

Most manufacturers code lock their code programmed into memory so it cannot be read.

Protect intellectual property.


Regards, Dana.

Only if they use chips with erasable memories. With a masked ROM part there is no method for reading the code so no need to lock it.

 

[Lightium]

I think at least I'll start with the blob. Find the power pins. See how many I/O pins. Maybe design one on computer.

 

[Nigel Goodwin]

I think at least I'll start with the blob. Find the power pins. See how many I/O pins. Maybe design one on computer.

If you're designing a calculator from scratch, why look at the 'blob' in the Casio?. Even if the machine code was readable out of the device (which I wouldn't think would be possible) then raw machine code isn't a great lot of use to you.

And as others have said, why do you imagine 'constants' need updating?.

 

[Lightium]

I am just bored and curious. I get this way sometimes. I think I will practice with the Arduino, keypad, and LCD screen to make a calculator, while I search for a micro for the project.

 

[atferrari]

Why you do not say what those constants are?

 

[Papabravo]

Why you do not say what those constants are?

Maybe he believes in the Tau Manifesto which posits that 3.1415926... was the wrong choice for the circle constant. Instead, we should be using τ=6.28318530718... to relate the circumference to the diameter.

No, really, pi is wrong: The Tau Manifesto

For millennia, the circle has been considered the most perfect of shapes, and the circle constant π captured the geometry of the circle in a single number. But π is wrong, and it’s time to set things right.

tauday.com

 

[ZipZapOuch]

All the important constants on mine match up with accepted values on Wikipedia. The idea of Casio getting a letter about a V2.0 of a 30-year-old product is comical. I would love to have the precision femto-second test equipment needed to measure the time it took them to finish reading the request until it ended up in the bin.

Could you help me write Mattel a letter to fix the error when the runner can run right through a goal-line defender on their green version "Classic Football 2" of Electronic Football?

 

[Papabravo]

A fatter chance there has never been!

 

[schmitt trigger]

What constant would require an update? Is Euler’s constant not valid anymore? Is the cosine of 45 degrees equal to 0.707 not true?

 

[ZipZapOuch]

What constant would require an update? Is Euler’s constant not valid anymore? Is the cosine of 45 degrees equal to 0.707 not true?

Nope, now the cosine of 45-degrees is 0.5^0.5

 

[For The Popcorn]

Well, many members of the US republican party want to legislate that Pi = 3.0. Irrational numbers are so messy you know.

Anti-science, anti-education, anti-rational-thinking party.

 

[ZipZapOuch]

Well, many members of the US republican party want to legislate that Pi = 3.0. Irrational numbers are so messy you know.

Anti-science, anti-education, anti-rational-thinking party.

Then just use the "3" button if that's your thing. Much easier than searching for the pi button and no work to re-configure the calculator.

Nice to hear that you have no evidence of errors on the other constants. I have full faith in the good engineers at Casio. You may want to ask the forum leaders to delete your whole misconstrued thread - there are no errors in the constants, right?

 

[crutschow]

Maybe he believes in the Tau Manifesto which posits that 3.1415926... was the wrong choice for the circle constant.

I agree with that.
It makes sense to use Tau since 2π is used in virtually all mathematical equations involving pi.
About the only time pi is used without the 2 is the relationship between a circle's radius and area, or its diameter and circumference.

 

[Papabravo]

I agree with that.
It makes sense to use Tau since 2π is used in virtually all mathematical equations involving pi.
About the only time pi is used without the 2 is the relationship between a circle's radius and area, or its diameter and circumference.

Any angle smaller than τ is an obvious fraction of a revolution.

 

[ZipZapOuch]

Maybe he believes in the Tau Manifesto which posits that 3.1415926... was the wrong choice for the circle constant. Instead, we should be using τ=6.28318530718... to relate the circumference to the diameter.

No, really, pi is wrong: The Tau Manifesto

For millennia, the circle has been considered the most perfect of shapes, and the circle constant π captured the geometry of the circle in a single number. But π is wrong, and it’s time to set things right.

tauday.com

But I always loved when grandma made two pies. I've never eaten a tau. And "tau day" doesn't seem as much fun as Pi Day.