this routine is used to send a secondary address to an I/O device after a call to the LISTEN routine is made and the device commanded to LISTEN. The routine cannot be used to send a secondary address after a call to the TALK routine. A secondary address is usually used to give set-up information to a device before I/O operations begin. When a secondary address is to be sent to a device on the serial bus the address must first be ORed with $60.