"I want to use the rotate and carry to set the carry flag to 0, to detect which row of the keys was pressed."


Please give this assembler routine.
I'm sure, it can easily be rewritten in C.

Most times there is no need to access the carry flag directly. Also its not suggested to do so, since then the code was no longer portable.

And also most times the ">>" and "<<" operators are sufficient to do what you want.


Peter