Overview of each operating system; hardware (CPU, memory, I/O, networks); system and user interfaces; native TSO and the UNIX shell; ISPF; KornShell; VI the editor; MVS utilities; UNIX utilities; systems performance; compilers; CICS and Online transaction processing; DB2 common server; porting data across platforms (or using the Network); the user environment; job and process control; pros and cons of each platform. Appendix: ASCII to EBCDIC.