Unlocking the additional space on a fx-CG50AU

[MajesticFalcon35 Profile]

As I live in Australia, I have the fx-CG50AU. It's basically identical to the normal CG50, but it has 4MB of storage rather than 16MB, to comply with SACE regulations.
I assumed that the memory was just a smaller chip, but I connected it to my laptop the other day and looked at it through Windows Disk Management, just for kicks. Lo and behold, the additional 12MB was present, but unpartitioned. https://imgur.com/a/UyJ0jmF

Attempting to expand the storage through Windows caused a file system error on the calculator, which was expected. Does anyone have any ideas on how to access this 12 MB of storage for storage?

[critor Profile]

Hi.

First thing to do would be to open your calculator and take a picture of its Flash NAND chip.

The fx-CG10/20/50 are using a 32MiB NAND, a Spansion S99-50272 :

With a 16MiB partition reserved for the operating system (more than 12MiB big), and another 16MiB partition for storage.


The fx-CG50AU might be using a smaller 16MiB NAND, and the reported 16MiB availability would just be a software error.


By the way, any picture/capture of the file system error ? Thanks.

[MajesticFalcon35 Profile]

Hi.

First thing to do would be to open your calculator and take a picture of its Flash NAND chip.

The fx-CG10/20/50 are using a 32MiB NAND, a Spansion S99-50272 :

With a 16MiB partition reserved for the operating system (more than 12MiB big), and another 16MiB partition for storage.


The fx-CG50AU might be using a smaller 16MiB NAND, and the reported 16MiB availability would just be a software error.


By the way, any picture/capture of the file system error ? Thanks.

Sorry that it's been a while, I forgot I ended up making this post. I reformatted my calculator through Windows Disk Management to reproduce the file system error, it's shown here: https://imgur.com/a/vu1EZoi
I pulled the back off to get a look at it's specific internals, shown here: https://imgur.com/a/MFwW16Y
The NAND in the FX-CG50 AU is also a Spanison S99-50272, the same type of chip as seen in the standard FX-CG50. This likely means that there is genuinely another 12MB on the chip that is set to not be available to the user.

I admit that what I'm looking for is probably pretty difficult, but any help at all is appreciated. Thanks!

[critor Profile]

Thank you for your reply.

Could you check the 1st line on the diagnostics menu ?

There is nothing dangerous in this menu. To access it :

• turn off the calculator
• hold the [OPTN][EXP] keys
• without releasing them, hold the [AC/ON] key
• the calculator should turn on and show you a "diagnostic mode / factory use only" popup
• release all keys
• quickly type [F1] and then [9]

The 1st line should report you the model code on the left, and the Q-bits values on the right.
I wonder if there is any difference with the fx-CG50 shown below :

[MajesticFalcon35 Profile]

Hey,

I ran the diagnostic mode, it's shown here.



Most notably, the model code is slightly different. On the standard FX-CG50, the model code is CY810AY. The FX-CG50 AU has a model code of CY810FY instead.

[Goose Profile]

I hope this forum isn't dead, is there any way I could help?

[MajesticFalcon35 Profile]

Haha, I'm still here almost five years later. I never did figure this one out myself, but if you have any leads on where to go with this one, I'd be happy to dig my old calculator back out and give this a shot.