>Then the only solution that is avaialbe to >us is to use the transitor. I will try this >method soon, but still before I will try to >see if there is a firmware solution(there >isn't probably). > >BTW. In the TI protocol w/o Ack, there is no >handshaking, so a byte sent away by a calc CAN >be recieved by multiple calcs. And then errors are generated in bytes and the calc has no idea there was an error.