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Mapping a file to memory

Discuss issues related to the Casio Prizm 3rd party development
Senior Member
Posts: 110
Joined: Mon Mar 02, 2015 10:53 am
Calculators: Casio fx-CG 20

Re: Mapping a file to memory

Postby AmazoNKA » Sun Jun 12, 2016 6:44 pm

does it mean we won't be able to downgrade the OS on the newer calculators - that would be bad for when a developer wants to make sure his addin is backward compatible etc...

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Posts: 100
Joined: Sun Mar 24, 2013 12:01 pm
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Re: Mapping a file to memory

Postby TeamFX » Sun Jun 12, 2016 11:10 pm

That is definitely something that should be tested.

When you try to downgrade the OS using the SYSTEM menu, you normally get a "Your OS is up to date" message. When updating via the boot code's updater, the OS version number is set to something like 00.xx.xxxx which allows downgrading.

You can manually invoke this updater as follows:
- Turn the calculator off
- Press the RESTART button on the back and [F2]+[4]+[AC/ON] at the same time
- Release the RESTART button and continue holding the other three keys for two seconds
(As long as you press RESTART, nothing will happen, it just interrupts the power supply)
(After releasing RESTART, the boot code is executed and checks the above keys)
- If you pressed these keys, the display should stay black
- Otherwise, you will see a white display followed by the language screen
- Now press the key [9] for two seconds, then [x] (multiplication) for two seconds, or vice versa
- Finally, you should see the message "OS ERROR Please update OS" on the screen
- You can now connect a USB cable and run the Casio setup program
- When you press RESTART (before updating), your current OS just boots

I have sent you a PM with an older setup file.

Senior Member
Posts: 110
Joined: Mon Mar 02, 2015 10:53 am
Calculators: Casio fx-CG 20

Re: Mapping a file to memory

Postby AmazoNKA » Sun Jun 12, 2016 11:43 pm

TeamFX wrote:After releasing RESTART, the boot code is executed and checks the above keys

are the keys combos checked by bootloader - that would explain why bootloader is different to allow exam mode keys combo but as bootloader is not updated with os that probably disproves my assumption... do you think bootloader combos are for fresh power ups restart pin basically and other combos are just for regular wake up with ACon key? Thanks

Senior Member
Posts: 100
Joined: Sun Mar 24, 2013 12:01 pm
Calculators: None

Re: Mapping a file to memory

Postby TeamFX » Mon Jun 13, 2016 12:26 am

Normal boot code execution is very short. Just two or three pages in IDA or about 1000 bytes with all subroutines. It just sets some hardware bits, checks if the OS is there and then jumps to 0x80020008. There is not even a BIOS interface. There was one only in early ClassPad models.
The rest of the boot code consists of unused routines and the updater which is run when the OS could not be found or some contacts are shorted or some keys pressed.

When you turn off the calculator, the hardware enters standby mode. When you press [AC/ON], no boot code is processed but some OS-specific key codes are checked.

Senior Member
Posts: 100
Joined: Sun Mar 24, 2013 12:01 pm
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Re: Mapping a file to memory

Postby TeamFX » Thu Feb 02, 2017 3:57 pm

Updated OS 2.02 has been released for fx-CG10/20 models.

Version 2.02.xx1x
Matrix calculation capability improvement

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Posts: 110
Joined: Mon Mar 02, 2015 10:53 am
Calculators: Casio fx-CG 20

Re: Mapping a file to memory

Postby AmazoNKA » Fri Jun 15, 2018 7:39 pm

Hi Simon and TeamFX, I wonder for a discussion on tiplanet if it is possible to have a functioning addin for Prizm with a file size larger than 2mb as it seems not to show up in the main menu once it is over that limit. Does it have something to do with the virtualisation constraints mentioned in this thread earlier? Thanks for your insights in advance

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