Thanks Erik,

I am going to leave iic out as I have little time logged with this protocol/architecture, but I'm thinking rs485.

Baby steps to begin...no semaphores no shared memory (really aimed at m. Smith), just looking to establish communications between the master and slave. Later? small inexpensive data loggers or dumb (really smart when you really think about it) controllers. I'm thinking of a system where a master pings a slave and then cuts the need for polling and lets the slave do it's dedicated task.

One thing I did notice in reading the bible (section More About Modes 2 and 3). I can't seem to resolve the 2nd sentence in the 2nd paragraph - "The receive portion is exactly the same as in Mode 1" (?) If the data word in 9 bits how are they defining 'exact'?

Thanks both of you for your feedback.

Carl