# Unlocking Casio fx-82ES to Casio fx-991ES



## CA50 (Dec 27, 2011)

This is a guide to unlock your Casio Scientific calculator to a higher version with more features. 
I have tested it with my own fx-82ES and it worked.

This mod will unlock model number fx-82ES/83ES/85ES to fx-991ES
Generally 82ES comes with 249 functions function and when the "setup" button is presses, only 3 functions are listed, whereas 991ES comes with 403 functions and when the "setup" button is presses, only 8 functions are listed, by this you can differentiate between the two 

*
Steps:
1. Check what version you have - on the back, just above the made in China sign, there is a letter in a circle: if it’s a B, unlucky because you can’t do the mod, however if it’s an A you can.

2. Open up your calculator - on the back there are six screws, using a Phillips screw driver, remove these and then lift off the back, revealing the circuit board.

3. Find the P4 jumper - on the circuit board there are six screws, between the middle two is a little white P4, to the right of this is a small split silver circle. Take your graphite pencil and colour this, making sure the whole thing is covered.

4. Put it back together-now put the back, back on and screw the screws into the holes.*

*Original Setup Screen*
*i44.tinypic.com/5popjb.jpg

*After Unlocking*
*i43.tinypic.com/fcs3mt.jpg

Please share your result. Please note that i will not be responsible if your calculator goes kaput.

Source:
Modding an fx-82ES/83ES into a 991ES - YouTube
hackear calculadora casio fx-82es - Taringa!
How to upgrade your fx-82es, fx-83es and fx-85es to a fx991es - The Student Room


----------



## CA50 (Dec 29, 2011)

Anyone tried this trick ??


----------



## MetalheadGautham (Dec 30, 2011)

This works but has some issues. The buttons labeling around number keys for alternate functions does not change so users may be confused. And these days lots of B models are present.

Considering most FX-991ES usage is by engineering students writing their term exams, few 100 rupees to avoid confusion during exam is justified


----------



## CA50 (Dec 30, 2011)

thats definitely true, this is just a trick to unlock. 

If one can live with the unlock then its OK, else one can consider this as a fun stuff


----------

