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Jailbreak for fx-991 dex


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#1 jakiki6

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Posted 28 September 2020 - 06:26 PM

Hi,

I'm trying to find a jailbreak for my calculator. I already have a way to write data to ram. Does anyone have a dump of the firmware and some technical information about the processor and instruction set?



#2 user202729

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Posted 29 September 2020 - 01:34 PM

...

* no. The software way to dump the ROM is tedious and involves a lot of trial and error.

Do it the hardware way is probably easier, if you figure out how to.

 

* yes, the CPU is nX-U8/100. You can find the instruction manual online.

 

It isn't possible to execute assembly code from RAM, however. (as far as I know -- if you figure out how to then you can post it here -- I'm sure someone will be interested)

 

If you can modify the hardware, why don't you just replace the internal with a new one?


Edited by user202729, 29 September 2020 - 01:34 PM.


#3 jakiki6

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Posted 29 September 2020 - 03:43 PM

Sounds nice :)



#4 jakiki6

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Posted 29 September 2020 - 04:03 PM

Is there an assembler to compile code or at least a manual to the instruction set?



#5 user202729

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Posted 29 September 2020 - 04:23 PM

https://github.com/u...-U8-INST-05.pdf

 

Assembler is in the same repository.



#6 jakiki6

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Posted 30 September 2020 - 06:02 PM

Ok I'm writing my own one



#7 jakiki6

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Posted 19 October 2020 - 01:20 PM

I've started "hacking" my calculator and found some useful information about internal representation of data. I'll post it tomorrow. I'm also working on getting the rom image.

 

Wish me luck






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