I can read 8051 assembler.

I can read C.

But when I read code, I can only see what the code does (if, and only if, the code is reasonably readable).

But I can not know what the code was expected to do. If the code works, then expected and actual performance may be the same, in which case you wouldn't post the code here and ask for help.

So the source code comments should explain what the expected outcome is of the code. What problem the code is intended to solve. Then I can compare this problem description with the real code, and notice if the code in reality does something else.

So as Erik has already noted, you shouldn't explain what an OP-code does. You should try to answer "why". Why have you added your code instructions?