Problems when running from SRAM

Hi again, just after writing the post I realized that the memory tests I was doing to the sram were not correct at all. All the values written to memory had a '1' in the less significant bit. I have tested writting values with a '0' at the LSB and it does not work (there is always a '1' in the LSB). So pin sram_data[0] is not connected (I remove it from the pin assigment list because the conflict with the ~DATA0~ signal) or it is asserted to '1'.