UPDATE 20130111: due to some of my personal data management issues, the skydrive link is indefinitly unavailable. i'll try and fix it soon (as in a month or so...). for the time being, just ask me for the stuff.

UPDATE 20130116: I wrote a more succinct version of the story somewhere.

UPDATE 20130525: I finally bothered to upload the files to box.com.

context:

i bought an fx-9750GII according to school recommendations. i previously had been using th fx-82es, and expected naturla display on any higher class casio calculators. however, casio upset me, because i did  not find any way to show natural display. i did some searches, and found out that it could gain natural display by flashing in an image of the fx-9860GII. so i started learning about it.

the aim is to give fx-9750GII more functions, mainly being natural display.

the idea is to flash in an fx-9860 image.

in my process, i am using windows 7 (ultimate x64).

disclaimer:

this procedure includes flashing a system image into a digital device's ROM. flashing the inappropriate ROM image COULD POTENTIALLY KILL YOUR DEVICE!! with great benefit comes great risk, so do this at your own choice and responsibility. I AM NOT RESPONSIBLE for your consequences. understand the whole process before starting.

here is the procedure:

  1. install the usb driver.

    this step is easy.
    assuming you are using windows, just install the FA-124 from the CD that came out of the box, or find it on the casio official websites. make sure the driver is working well, by pressing WinKey+R then typing in devmgmt.msc , then seeing if there are any yellow exclaimation marks . if there are, then the calculator is plugged in, but the driver is not working properly. if there are not, either the calculator is not plugged in, or (, which is good, ) the calculator is plugged in and the driver is working properly.

  2. check your calculator version

    this step is partially tricky, but the non-tricky part is necessary.
    i suppose that only fx-9750GII will work (whose back & lid is white while the front panel is blue), instead of fx-9750GI (whose back & lid is blue while its front panel is white) or just ~G (which seem to have a completely different shape) to be working as well. there are two types of GII models, and let me just call one of them GII-1, and the other GII-2. the GII-2's would supposedly show "USB Power Graphic 2", though mine is a GII-2 but just showed "USB Power Graphic".
    first look in your system menu of the calculator (by pressing the MENU button), and see the "version". versions 2.00.* and 2.01.* means a GII-1, and version 2.02.* means a GII-2.
    then, for the sake of finding help elsewhere, turn the calculator off and press and hold the key combination[OPTN+EXP+AC] to show a factory menu. press F1, then choose "delete all data" (in fact i don't find anything deleted), then find "version". expect something like
    OS Ver 02.02.0201
    DateO 2011.0801.1932
    DateA 2011.0525.1010
    these numbers can help you identify help on other places e.g. forums.

  3. download the tool

    this step is easy.
    though i have put them in the same zip, slightly different tools are needed for GII-1 and GII-2. the tool for GII-1 is called "pfxRecovery"; the tool for GII-2 is called "fxRemote". both tools are contributions by cfxm and Simon Lothar at casiocalc.org. download the tools from my skydrive box.com .

  4. enter "BIOS" of the calculator

    this step is both tricky and necessary.
    in order to let the tool acccess the flash memory of the calculator which stores the system, sort of a BIOS screen is to be entered. check that the RESET button is functioning before proceeding. turn off the calculator, and press the following key sequence. "+" means press and hold, "-" means release, "()" means at the same time, "     " 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.". this is the "BIOS" screen. with this screen showing, and with the calculator being connected to a computer with the usb driver properly installed, and with the tool run as administrator, the tool can read or write the calculator's flash storage in which the system lies.

  5. flash images

    this step is important, and decides whether your calculator lives or dies. there may be sorts of error prompts.
    enter "BIOS" screen for the calculator; connect the calculator to a PC with the usb driver; better kill the FA_124 process (or close FA-124); run the tool.
    "backup" means saving the current system as a file on your computer, for restoration later. "restore" means to flash a system image into the flash storage of the calculator. i suggest to first backup your current system, then flash your own system image back. if everything goes fine, and your calculator (hopefully - ) did not die, carry on and flash an appropriate fx-9860 system image. choose the .fls file, whose name corresponds with your calculator's version. for example, my calculator has the version 02.02.0701, which starts with 02.02, i simply choose the tool "fxRemote", and eventually flash the "2_02_0201_sh4.fls"

  6. have fun!

    hopefully, your calculator lived, and lives better than before!

  7. notes

    credit should be redirected to cfxm and Simon Lothar.

    related resoures:
    a place to continue learning:
    a highly relevant video: