![]() ![]() Without the necessary hardware (or patience) for the former, the only remaining option was to investigate the firmware updater.įrom the main web page for the CASIO fx-CP400, a firmware updater ZIP file containing an EXE installer can be downloaded. Two options presented themselves - extract the firmware from the NAND flash chip on the device (a complicated, tedious and error prone process) or reverse engineer the Windows firmware update application. With some initial research completed, the next goal was to get the firmware that runs on the calculator. Without this, hacking the device would have been exponentially harder. ![]() The most important resource I found during the research process, though, was CASIO's web page for the fx-CP400 which offered a firmware update tool. (Don't worry if you're confused - I'll discuss these later). But I didn't find much, if any, discussion of the firmware - only one mention of the existence of the 30 resources, and not much else. Though initially exploring the debug menus didn't expose too much new information, their presence was helpful later when decompiling and investigating the firmware. Quickly, I found a forum post with pictures of the internals of the device and revealing some key sequences which could open hidden debugging menus. Researchīefore blindly jumping into reverse engineering the calculator, I made sure to do a bit of research into what others might have already discovered about the device. But that's only half the potential I think this device possesses. Full USB connectivity for data transferįor a student, it was great to use and made many tedious exercises much easier.(Very) limited programmability in a BASIC-like language.Spreadsheets and statistical calculation.Symbolic calculation, including integration and differentiation, and algebraic expression expansion and simplification.Full physical numeric and operator keypad.Touch screen, supporting up to two touch points.The calculatorįor those who've never used one, the CASIO fx-CP400 is quite a well-featured graphing calculator. These posts certainly won't be a tutorial, but more of a tour through my thought processes whilst undertaking work like this. This short series of blog posts will go into some detail about my investigation of the device and its firmware, and hopefully act as an insight into the reverse engineering process and maybe even demystify reverse engineering for those who are just beginning. ![]() In the past 6 months or so, I've spent a bit of time investigating the firmware and making sense of the mess that is the fx-CP400. Sadly, overcome with a fear of bricking the over $200 AUD calculator I absolutely needed for school, I didn't put much effort into hacking at the device. ![]() The 4.8 inch, 310 by 401 pixel color LCD, touch screen, and full physical number and operator keypad prompted many ideas of emulators and various fun pieces of software. When I began Year 11 in 2016 and was asked to buy a CASIO fx-CP400 graphics calculator, the hacker part of my brain immediately started wondering what mischief I could get up to by modifying the firmware. ![]()
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