This depends on the UART used. For the 16550 there is a bit called STICK
PARITY which allows you to set the parity value. Check the 16550 data
sheet for more info. If I remeber correctly WinNT (possible Win32 in
general) allows the user to set the parity bit.If not you would have to
write a serial port driver in order to handle the 9-bit protcol. For DOS &
Win31 you can probably just fiddle with the bits in the UART register.

The 9-bit protocol (correct me if i am wrong) is
Parity = 1 for address
Parity = 0 for everything else

MD

On Tue, 16 Dec 1997, WF AUTOMACAO wrote:

> How to implement a 9-BIT protocol, using the Serial PC port?
>
>         Miguel.
>