Regarding your first question, on a standard 8051, there is a single receiver input pin, RXD, that is typically shared with one of the PIO ports.

On the Triscend E5 device, you have options. The receiver input and output are two separate signals. They can share the same pin, or they can be two separate pins (very helpful for bidirectional SPI).

Regarding your second question, data is transmitted at the baud. The incoming data is asynchronous. You cannot be sure exactly when a data bit starts or ends. Consequently, the UART hardware samples the input data, according to the baud rate, and extracts the valid data.

Furthermore, both ends of the communication path may be communicating at slightly different baud rate frequencies. Because received data is resampled, the UART tolerates about 3% error in the baud rate frequency. This allows you to send and receive data even though the baud rate equation doesn't provide an integer value at your specified operating frequency. You are allowed a bit of wiggle room.

See the following link for additional information.
http://portal.knowledgebase.net/display/1...p?aid=9661