Thanks for these links. What a superb level of detail! I don't suppose there's an equally detailed book about the 80C320 is there? I find it difficult having to read some data from the 80C320 User Guide, some from 8052 data and some from 8051, and not knowing exactly which bits of each apply to the 80C320.

From the information given in Chapter 3 page 11 and Figure 13, I conclude:

• Reading SBUF has no effect on the UART section of the chip. If I'm not interested in the value, don't have to read it.
  
• Clearing RI has no effect on the UART section of the chip. Characters will be received even if I don't clear it, although this will of course make it difficult to tell when a new character has arrived.
  
• I don't see shifting data in SBUF. I can continue to read the previous character from SBUF while the following character is being received, but as soon as the new character is complete it will move into SBUF overwriting the previous value.

Thanks - Rowan