The Z53C80 SCSI (Small Computer System Interface) controller is designed to implement the SCSI protocol as defined by the ANSI X3.131-1986 standard, and it is fully compatible with the industry standard 5380. The device is capable of operating both as a Target and as an Initiator. Special high-current open-drain outputs enable it to directly interface to the SCSI bus. The Z53C80 has the necessary interface hook-ups which allow the system CPU to communicate with it as with any other peripheral device. The CPU can read from, or write to, the SCSI registers which are addressed as standard or memory-mapped I/Os.