test si, 01h \n je even_number
perform si & 01h discarding the result but set the zero flag to 1 if the least significant but of si is 0, even set the zero flag to 0 if the and operation between the leas singificant bit of si and 01h is zero, while set the zero flag = 1 if the and operation result is 1. if the si == 0 go to even_number label ese go to odd_number label