A mechanism provided for controlling a transmission enable (TX_ENA)
signal. The mechanism generates a queue of bits to track a sequence of
commands and provides the transmit enable signal if the queue is empty.
If an entry at a top of the queue indicates a write command, the
mechanism provides the transmit enable signal for a predetermined number
of cycles before the transmit enable signal is needed and until write
data associated with the entry is transmitted, whereupon the entry is
removed from the queue. If the entry at the top of the queue does not
indicate a write command, the mechanism discontinues the transmit enable
signal and removing the entry from the queue.