I have got this old Casio fx-92B calculator I am not using any more. I opened it up and found this:

Circuit board from calculator

I am not an electrical engineer. Is there a possibility of tweaking this board to make it run custom code?

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    \$\begingroup\$ Had it been a fx-92 (not B), you could have changed the working mode of the calculator firmware to unlock useful functions such as complex numbers and advanced statistic regression, by re-soldering the CMODE pins. But that feature isn't "available" on the model B, nor on the fx-92 Plus models. But keep in mind that this is indeed a feature of the firmware itself, you're not actually changing any code. Changing the code would require reprogramming the black chip at the middle, and that is probably not possible. \$\endgroup\$ – zdimension Nov 15 '17 at 16:06
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    \$\begingroup\$ also, FWIW, if you're up for some hacking, you can try to re-use the display and/or keyboard (it's not worthwhile IMO, but it's doable). You'd get better results with older stuff, especially pre-1980s calculators, some of them had a couple of useful semi-discrete ICs in them to do the math. \$\endgroup\$ – vaxquis Nov 15 '17 at 16:13
  • \$\begingroup\$ "Twerk" made me laugh. \$\endgroup\$ – user65586 Nov 15 '17 at 16:26
  • \$\begingroup\$ @jdv It's amazing, the features that calculators have these days… \$\endgroup\$ – duskwuff Nov 15 '17 at 18:50

No. Just no.

This is not possible in any sense you mean for your level of knowledge about microcontrollers and that specific product.

Even someone skilled with microcontrollers would need specific information about that product to create any useful custom code. This information is not something easily found by merely inspecting the board, and the manufacturer is very unlikely to release it.

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    \$\begingroup\$ Odds are it's a dedicated calculator IC with a datasheet only available in Chinese. \$\endgroup\$ – Matt Young Nov 15 '17 at 14:19
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    \$\begingroup\$ And also a good chance that even if it is programmable, it's not re-programmable (OTP) \$\endgroup\$ – W5VO Nov 15 '17 at 15:43
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    \$\begingroup\$ @MattYoung More likely Japanese -- it's a Casio product, after all. Also, the datasheet is almost certainly not distributed at all outside the company. \$\endgroup\$ – duskwuff Nov 15 '17 at 18:52

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