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.