Abstract: A method and apparatus for dispatching elevator cars to hall calls in a system where there are two types of elevator controllers (12, 14) in operation, one (12) of which operates using relay logic. The calls are stored in a relay logic memory common to both elevator controllers (12, 14). A first controller reads the call information directly from the memory (18); the second controller reads the memory through a cross cancellation device (10) which multiplexes the information from the memory so that the calls are provided on a serial link (32) to the second controller (14). The second controller (14) is programmed to respond to calls which the first controller (12) has not answered.