Tutorial:Hacking a CASIO fx-500MS calculator

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If you own a CASIO fx-500MS calculator, then it means you are having a source of fun. Here are some "funs" to play with your calculator.

Upgrading to fx-570MS[edit]

A CASIO fx-500MS calculator, and any other electronic calculator, contains a ROM, which stores the instructions for the calculator to work. But what is special about fx-500MS is beside the ROM for its model, it also has a ROM for fx-570MS, which is a higher model. And good news, you can upgrade the calculator to fx-570MS without actually buying it.

Enter Standard Deviation (SD) mode[edit]

  • Turn on your calculator.
  • Press MODE then 2.

It should now enter the Standard Deviation mode.


The overall goal of this stage is to overflow the memory of the calculator, making it produce bugs and then access the fx-570MS ROM.

  • Press 1.
  • Press M+ 82 times until it shows two options: EditOFF (1) and Esc (2). Press 2 to escape.
  • Press up button to show Freq80 value.
  • Enter 13131313... until the expression editor fills and you can no longer enter any more number.
  • Press = twice to show the two options again.
  • Press 0 then 1. You should now see a weird screen.
  • Press =. It shows Syntax ERROR.
  • Press AC. You can browse the menu by pressing MODE and... what happened? Are there new modes in the calculator? That's the sign of your calculator turning to fx-570MS. You should realize the key mapping is also different.

Rolling back[edit]

To go back to the boring, original CASIO fx-500MS, simply press ON.

Obfuscating the right edge of the screen[edit]

Using this you can make about 1/4 screen to the right to be obfuscated: every pixel flashes randomly.

Entering REG mode[edit]

Press MODE, 3 then 1.


  • Insert "n" by pressing buttons in sequence: SHIFT 1 3.
  • Press M+ exactly 40 times so that the screen displays "n=40".
  • Press up button to display "Freq40" then fill the expression editor with 30303030...
  • Press = twice. It should show two options to either turn editing off (1) or escape (2). Press 4 first then 1.
  • Press left arrow button. Check the screen.
    • If it shows 303030..., press DEL repeatedly until it displays "Freq40" again. Go back to the previous step.
    • If it shows weird characters, proceed to the next step.
  • Press SHIFT then DEL to turn the cursor to insert mode.
  • Press left arrow button slowly until it is right behind the 3030303 text.
  • Repeatedly press the DEL button until the text is erased. It will appear not erasing the characters but in fact it is still working.
  • Press SHIFT then DEL to turn the cursor back to overwrite mode. Press DEL twice more. You can notice the cursor jump to the second or third character.
  • Press left arrow button once to move the cursor to the left. Press 0 twice.
  • Press nCr button then . (dot). Repeat that 40 times.
  • Press left arrow button until it is right behind the "00" at the beginning.
  • Press SHIFT, DEL, finally 0. You can now enjoy the obfuscated right part of the screen.

In this state, the calculator will no longer respond to any key except ON, which escapes this mess to turn the calculator back to normal.

(To be continued.)