Disclaimer

Operate your own devices at your own knowledge, responsibility and risk.

Brief

The thing is, the system (OS, I think, ) of Casio fx-9860GII could be installed ("flashed") on fx-9750GII. As a result, the flashed fx-9750GII would have some new functions, among which I consider "natural display" to be of the greatest significance. This article tries to describe the process as succinctly as possible.

Tools needed
  • A Windows PC, and
  • FA-124 from Casio installed, in order for your PC to have the drivers needed, and
  • The flashing tool "pfxRecovery" or "fxRemote", depending on the version of your fx-9750GII, and
  • Well, a MicroUSB cable.
Identifying the version of your fx-9750GII

Find your version number under MENU->system->version.

Those starting with 02.00 or 02.01 should use the older tools and images, which is pfxRecovery and .fls files with filenames starting with corresponding numbers;
Those starting with 02.02 should use the new tools and image, which comes with fxRemote.

Operation steps

Check that the driver from FA-124 is correctly installed, e.g. by fiddling with FA-124.

Make sure that your calculator's batteries aren't run out - at least not too poorly run out.

Turn off your calculator, and have the cable unplugged. Use this key combination on the calculator:

"+" means press and hold, "-" means release, brackets means at the same time, space means wait for half a second or so:

+RESET+F2+4+AC-RESET-(F2+4+AC)+×   -×+9   -9

Now the screen should have a contrast error, and show the words “OS error. \Please update OS.” Now plug the cable and open pfxRecovery/fxRemote.

Try to backup your calculator - this ensures that the tool is working, and also to get an image of your stock system. Try restoring your stock image - this ensures that the restore function is working. At last, restore an fx-9860GII image that comes with the tool and has a filename that corresponds with your version.

Any time later, you can restore the image that you initially created (and which you must have kept in a safe place just in case) to reach the state before you started flashing your fx-9750GII.