by twinslim » 31 Mar 2023, 20:00
I thought it might be good to share my recent experience doing these upgrades to make it easier for others. Some of the info is not quite right or is out of date. First off the 2.04 image listed for the fx-9860g slim is the same as the 2.04 for the fx9750gii so it won't work. The slim has different keyboard mappings. See the info above this post where a valid slim image is provided along with all kinds of good information. That sure made it easy for me to upgrade my slims. I did follow the polyos process and got the 4M images for fx-9750gii's using a command line from a cmd window. Next, for SH3 calcs including the slim, it isn't necessary to put them in OSerror mode. fxrecovery will do that for you and just has a popup to confirm it is in OSerror at some point. There is a warning popup about the image mismatch with the calculator, so you just ok the continuation of the process. For SH4s (I didn't do any of the special date code ones) you can start the recovery and then after a bit it will prompt to do the key codes to get it into OSerror. The codes given by the program popup are correct - you don't hold reset down from the start as stated on the pages here. When you are done, don't forget that the setup may have Lineio selected instead of Mathio for SH4. Regarding drivers from FA-124, you don't have to do anything. Installing FA-124 will give you the drivers for your calculator usb to usb cable that fxrecovery uses. You don't need FA-124 invoked.
If you want to use FA-124 or fxrecovery with old 3-pin serial on Win10 or any new computer which would not have serial ports, then you can get a usb to ttl converter on ebay and connect it to a 2.5mm stereo cable. Note that there are USB to ttl and USB to RS232 UART cables around that use either FTDI or CP2101 chips usually. You need to put in the drivers for those. I had one that popped up as a CP2102 under the Other line in the Device Driver window, so I searched out CP2102 and found the drivers at the Silicon Labs site and put them in and it was working, although it was to RS232 levels not TTL. Note that RS232 is -12v to +12v originally but later uses reduce the voltage. My cable was -6v to 6v. These won't work however since the calculators need TTL style levels of 0 to +5 v (or later ones which probably use 3.3v chips need 0 to +3v). The calculators seem to be tolerant of extra voltage and negative voltages without damage, but the sense of the bits is opposite for RS232 vs TTL so you need adapt to TTL levels or get a converter that does TTL output directly.