> It should be latched, at least on modern 16550-like UARTs. From > a PC16550D datasheet:
Keep in mind that com(4) is intended to support 16450 chips, which have no FIFO. I believe that the current ordering of the operations is needed to correctly support them, so you might want to decide at runtime where to unmask this based upon whether the chip has a working FIFO or not.
