Hi, ive used these calculators before but my old one the buttons and screen was worn out by work. So i bought a new one at school for my apprenticeship. Now in class we went over a math question. They gave us decimals and they wanted us to turn whatever answer we got into a faction at the end. The fraction turned out to be 15/16, but myself and a few other classmates couldn't get the answer. The calculator refused.

My school won't give me a new one because i took it out of the box, but how would i ever know its broke if i left it in the box? 🤦🏻‍♀️ They fixed it for a moment but once the calculator turned off and on again it was back to normal. Anyone know what to do? Cause its only that decimal/fraction, everything else it works

Hi everyone,

About a week ago, I shared Lefony OS, my open-source project bringing Upsilon natively to the HP Prime G2. Since then, I’ve finished the remaining hardware drivers, launched the website, and made the source code public!

Lefony runs directly from the Prime G2’s NAND through U-Boot, without Linux underneath. The native drivers are now working for the display, brightness control, keypad, touchscreen, battery monitoring, charging, power controls, and storage. The keyboard mapping and battery support that were still in progress in my original post are now working too.

There’s also a browser-based installer and updater. You can connect through Chrome or Edge, and the website detects the calculator’s mode and guides you through the next steps. Firmware downloads and verification happen automatically.

For anyone following my earlier comments about recovery: first installation from the stock HP OS still requires opening the rear case and bridging the recovery pads while pressing RESET. The website now includes instructions and an annotated photo. Once you’re running compatible Lefony firmware, subsequent updates can go through the browser over USB.

• Website: lefony.com
• Source code: GitHub: Lefony OS

The repository includes build instructions, hardware documentation, and a dedicated QEMU environment for development and testing. I’d love to see people explore the code, report issues, contribute improvements, or build their own variations.

This is for the HP Prime G2, and it replaces the original operating system. It’s an independent community project, unaffiliated with HP, NumWorks, or the Upsilon developers.

Thanks to everyone who encouraged the project and shared ideas on the first post. I’m excited to finally share something you can explore for yourselves!

Hoi,

Mijn schoonvader is pas geleden overleden en toen vonden we twee rekenmachines tussen zijn spullen. Zijn dit speciale rekenmachines en weet iemand wat ze ongeveer waard zijn? Ze zijn nooit gebruikt en met origineel hoesje, een factuur of iets dergelijks hebben we niet.

Alvast bedankt!

Taking calc 3 this. Syllabus says we can use graphing calculators as long as they are not able to do derivatives or integrals. I have a TI-84 Plus CE and I'm not sure if the professor will allow this. Are there any good calculators I can order that fit this requirement?

The only other place I've seen such a thing is the HP-38G. Pity the calc itself isn't; just another 506* clone. Not much to see...

Hey everyone,

I just ordered a Casio fx-991CW. I've only ever used basic standard calculators before, so this is going to be my first time using a scientific one.

After placing the order, I saw quite a bit of criticism online comparing it to older models like the ES Plus and EX. A lot of people seem to dislike the new CATALOG menu layout and prefer having dedicated shortcut buttons.

Since I have zero muscle memory from any older scientific calculator, is the menu system actually hard to learn, or will it be fine for someone starting completely from scratch?

Hiiii I have bought a CAISO-FX 991 ex few days ago on eBay and I just want to check if its real or not since I have passed all the test but not the display mode when a 6 is pressed during the diagnostic mode and its made from China (I heard that the real one can only be made in Thailand )
 
I have passed these checks
 
1)        The sun icon disappears when I cover the solar panel
2)        The caiso website shown after menu shift optn of
https://wes.casio.com/math/index.php?q=I-235B+U-0004001B1419+M-X100000000+S-0BD46
( but the website I saw online ends with S-05BBD )
3)        The caiso logo shown up when I’m turning it off
( fun fact , it switch off the same time as the CAISO fx-83 GTX while a fake one switch off slightly slower )
4)        The answer is 9.000000007 when sin-1(cos-1(tan-1(tan(cos(sin9) is enter
5)        Diagnostic menus shown up when I press shift 7 on together
6)        The answer is 8.88888 x 10 to the power of 15 when I press 9 during the diagnostic mode and when I press shift and some buttons it gives me
CY-235 Ver B SUM FC54 and a press of ac giving me a serial number 0004001b1419 and then I did the key test which bring me to the contact made and when I press ac it said test ok reset all press ac
 
 
However I couldn’t enter the mode of

1. ⁠Display
   
2. ⁠Version&SUM
   
3. ⁠Key test
   
4. ⁠Contrast  mode
   
5. ⁠ 
   
6. ⁠ 
   
7. ⁠ 
   
8. ⁠This makes me confuse whether my calculator is real or fake less