The IBM mainframe branch of evolution is different from UNIX and Windows. It is unfamiliar for most. I know the first time I sat down with a terminal to a UNIX

The IBM mainframe branch of evolution is different from UNIX and Windows. It is unfamiliar for most. I know the first time I sat down with a terminal to a UNIX machine I found it hostile, unintuitive and perplexing. vi is not easy to use when you know nothing about it to begin with. Yes I fly on UNIX after a few decades but I sill remember my first introduction. z/OS (which is also, but far from only UNIX¹), came out in 2000 and is far more than this article lets on. z/OS supports backwards compatability CICS, COBOL, IMS, PL/I, IBM Db2, RACF, SNA, IBM MQ, REXX, CLIST, SMP/E, JCL, TSO/E, and ISPF, among others. z/OS also ships with a 64-bit Java runtime, C/C++ compiler based on the LLVM open-source Clang infrastructure, z/OS can communicate directly via TCP/IP, including IPv6,[5] and includes standard HTTP servers (one from Lotus, the other Apache-derived) along with other common services such as SSH, FTP, NFS, and CIFS/SMB. ¹ UNIX (Single UNIX Specification) APIs and applications through UNIX System Services – The Open Group certifies z/OS as a compliant UNIX operating system – with UNIX/Linux-style hierarchical file systems.