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# How to upgrade your fx-82es, fx-83es and fx-85es to a fx991es

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1. This is going to sound really geeky but, if you own an fx-82es, fx-83es or fx-85es, you can upgrade it to a fx911es, which is soo much better. It allows you to integrate/differentiate/solve quadratic equation etc.

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.

This procedure basically makes the calculator confuse itself about which model it is; models only differ at the jumps. Casio did this to make the calculator suitable for all exams, as in China, you can't use an fx-991es in an exam.
2. Wow...

I think I kinda like this.

It's a little bit cheating though, as over here 991 are banned in exams too.
3. over here 991 are banned
Where are you? By the way all but two of the buttons stay exactly the same and the only two that change are X^3 which can be substituted with the X^y button. The other button is Abs which is rather useless.
4. (Original post by ZakArden)
Where are you? By the way all but two of the buttons stay exactly the same and the only two that change are X^3 which can be substituted with the X^y button. The other button is Abs which is rather useless.
Leeds Uni. They banned the 991. Well, they have in maths, physics and engineering.
5. (Original post by ShinyApple)
Leeds Uni. They banned the 991. Well, they have in maths, physics and engineering.
That's odd, it's allowed for A-level Maths.

And thanks for posting OP, I was going to buy a FX-991 but I might see if I can find a version A FX-82, 83 or 85 as they're quite a bit cheaper.
6. I'm guessing the Ti89 is banned also? It's my main calculator and can basically do anything symbolically. I don't see why it's banned, when it just means that you can quickly do simple calculations and integrations, that long hand would take much longer. It's silly really as in the work place,you'd use a calculator.
7. (Original post by ZakArden)
I'm guessing the Ti89 is banned also? It's my main calculator and can basically do anything symbolically. I don't see why it's banned, when it just means that you can quickly do simple calculations and integrations, that long hand would take much longer. It's silly really as in the work place,you'd use a calculator.
Meh!

Basically they've banned everything that isn't on this very short list. They recommend the fx-85.

I guess they banned it because in the right hands it's easy to cheat. You can do more than just the intergration etc with it. You can program lots of formulas, set up tables etc. The 991 is a very powerful tool.
8. Program formulae? I've never heard of that. But certainly, it has a lot of useful features which make certain calculations a lot easier.

The TI-89 though is a different story. Symbolic algebra and calculus, linear algebra, graphing, custom programs...
10. Research. Some guy found out in Russia or China.
11. Hmm, my fx-85ES has neither an A nor a B on the back above the "Made in China" and I can't find any P4 jumper on the circuit board. I did buy it a long time ago, though, so they may have changed slightly since then. (I cannot remember the fx-991ES being out when I bought my 85ES.)
12. Could you post a photo of your circuit board?
13. I've attached a pic of the lower-half (including where you said the P4 would be).
Attached Images

14. well the source of this knowledge was from http://www.casiocalc.org/?showtopic=2483 .it is in russian you can use google translate to translate it. i searched the relevant terms in google chinese using chinese. and i found the idea of using a pencil. unfortunately i can't find out who was the first person to discover this. In this webpage (http://zhidao.baidu.com/question/39587295.html?fr=qrl) somebody claimed that casio's repairman have told him that fx-82es version b is modifiable too but it is hard. the calculator is likely to be damaged.

aparantly in china some maths teachers told the whole class to modify their calculator to cheat in the exam. so the department of education banned fx-82es's version A in the exam. casio provided free version B replacement for the student who owned version A.
15. Worked for me.
I have a 991 that I use most of the time and an 83-es that I save for exams. My school buys loads of the 83s and sells them to the students for £4.50 because they're an educational institute and don't have to pay tax (or something).
16. Good. Do they sell version As or Bs?
17. The one I've got is a version A, and I bought it in Sept. The one my best friend's got (she bought it 3 weeks ago) is a version B. So I really have no idea, although they probably got a new batch after all the new year 7s arrived and wanted calculators!
18. I still love my 991MS and Ti89. For some uni exams they only let you use an Fx85ES, so what I will do is drill a whole in the case, just above the jumper. Then in the exam colour the jumper in.
19. Well, I tried it - and it works perfectly. Rep would be given.. had I enough posts. I would post a picture of which bit to 'colour in', but unfortunately I managed to burr a screw so badly it won't unwind again .

Attached, however, is a picture of all the little bits of paper I stuck on the calculator so that I didn't have to remember all the positions from my 991.

In case you can't read what they are:
Spoiler:
Show

(from left to right, beginning from the top)

NORMAL/SHIFT/ALPHA/BASE-N/CMPLX

CALC / SOLVE / =
INTEGRAL / d/dx / :
SIGMA
x^3 / DEC
Nth ROOT / HEX
10^x / BIN
e^x / OCT
(complex argument)
Abs
arccos / E
arctan / F
left arrow (reverse ENG) / i
CONST
CONV
MATRIX
VECTOR
CMPLX
BASE

Hope it helps.
Attached Images

20. So, does this affect the functions already on my FX-83ES, other than adding all of those new ones? I want to make sure I don't screw up my calculator before I do this mod.
Out of curiosity... how would you program, say ? Obviously I wouldn't actually use the calculator for that, just wanted an example.

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