I'm using the serial ports on a Dallas 80C320 to drive a half-duplex RS485 bus (i.e. the Rx and Tx pins are connected together, and I've got a control pin to switch the driver and receiver (a MAX483) on and off). Do I have to be careful that turning the driver off and receiver on does not make the receiver think that it's received a byte? Presumably it only needs a spike to make the UART think it's seen a start bit, and even if it sees nothing else, it will assume it's just received a NULL character. Do I therefore have to do clr RI and possibly read SBUF after turning off the driver, to make sure there's no spurious byte received?

If the receiver has received a byte (possibly the above spurious byte caused by turning the driver off), what do I have to do to enable it to receive another one? Do I have to clear RI? Do I have to read SBUF? If I don't do these things, and another byte comes along, what happens?
- does the byte get ignored?
- or does the byte overwrite what was in SBUF?
- can I detect that this has happened?

Just trying to be sure I've handled every eventuality so I get reliable communications with no lost bytes, no spurious bytes, no lock-ups etc.

Many thanks - Rowan