(12C/11C) Changing the firmware

[NazarK]

Heyo,

So I got a used 11C and had a really hard time figuring anything out. Trigonometric functions weren't working properly and buttons seemed to be remapped. I ran the keyboard test and display test (ON+divide and ON+mulptiply) which worked fine except at the end of the keyboard test, the calculator showed "12" instead of "11".

This led me to believe that somewhere down the line, somebody swapped the motherboard with an HP 12C instead

I looked at some keymappings on the 12C (such as 1/x) and sure enough those worked. Now is there a way to reprogram the ROM to an 11C or do any modifications? I could probably make stickers and turn it into a 12C but honestly I wanted scientific functions.