The EISA dual-port programmable serial interface (PSI) card provides serial-mode connectivity hardware for building data communication links on HP 9000 Enterprise Business Servers or HP 9000 Workstations.The product consists of a 2-port serial interface, featuring a flexible physical connectivity interface (RS-232C/V24 or X.21/V11 standards) that allows connection to various types of modem equipment. It supports the X.25/LAP-B protocol, allowing HP 9000-to-HP 9000 communication as well as that between the HP 9000 and other systems (HP or non-HP) over packet data networks or leased lines. This is achieved through the use of X.25/9000 software.