I've also had a Spectra, and after that an 88 weighted keys alesis QS8. had the ZX Spectrum (i'm still using n as default for loop variable) and then got the marvelous commodore 128. good old days. I was born in '71.
Haha! I'm glad I'm not the only one.
And you might learn it indirectly from all the people and code that follow this convention. In my case, it was FORTRAN first, albeit perhaps in the same academic year 1977-8 where I was introduced to i, j, etc. in Algebra II.
Can you recommend any good resources (preferably books available online) to start with, that one could apply in an emulator?
assembly was the only way to do anything on the XZ81,C64. You needed it a little on the Amiga and MS/DOS graphics (with C doing most the work). On Win95 I used it for a hi res timer (only a couple lines). But haven't used it since. If I were to dig in now, I miiiight start with the C++ compiler's assembly listings. Look at your C++, look at the unoptimized assembly the compiler generates and see how they equate. Google will find quite a few sites of people still using 80x86 assembly I think. Good luck to ya.