I do a lot of work with Web sites and people are often talking about using a CMS to make it easier to upload and place content. For them, CMS stands for Content Management System, but I thought it would be fun to revisit Conversational Monitor System – one of the first virtual machines that people really enjoyed using because of its flexibility and functionality.
Our story starts in the mid-1960s at IBM’s Cambridge Scientific Center, where CMS – then called Cambridge Monitor System – first saw the light of day running under CP-40, a VM-like control program, which then developed into CP-67. It provided a way of giving every user the appearance of working on their own computer system. So, every user had their own terminal (the system console for their system) as if they had their own processor, unit record device (what we’d call a printer, card reader, and card punch), and DASD (disk space). The control program looked after the real resources and allocated them, as required, to the users.
In 1972, when IBM released its 370-architecture machine, a new version of VM called VM/370 became available. Unlike CP/CMS, IBM supported VM/370 and CMS retained its initials, but was now known as Conversational Monitor System – highlighting its interactive nature. This commercial product also included RSCS (Remote Spooling Communication Subsystem) and IPCS (Interactive Problem Control System), which ran under CMS.
VM itself was originally not very popular within IBM, but, through quite an interesting story, survived. VM/370 became VM/SE and then VM/SP. There was also a low-end variant called VM/IS. Then there was VM/SP HPO before we had VM/XA SF, VM/XA SP, then VM/ESA, and now z/VM.
But returning to CMS, it was popular because you could do so much with it. You could develop, debug, and run programs, manage data files, communicate with other systems or users, and much more. When you start (IPL CMS) CMS, it loads a profile exec, which sets up your virtual environment in exactly the way that you want it to be.
Two products that made CMS users very happy were PROFS and REXX. PROFS (PRofessional OFfice System) became available in 1981 and was originally developed by IBM in Dallas, in conjunction with Amoco. It provided e-mail, shared calendars, and shared document storage and management. It was so popular that it was renamed OfficeVision and ported to other platforms. OfficeVision/VM was dropped in 2003, with IBM recommending that users migrate to Lotus Notes and Domino, which it had acquired by taking over Lotus.
REXX (Restructured Extended Executor) is an interpreted programming language developed by Mike Cowlishaw and released by IBM in 1982. It is a structured, high-level programming language that's very easy to get the hang of. In fact, it was so popular, that it was ported to most other platforms. REXX programs are often called REXX EXECs because it replaced EXEC and EXEC2 as the command language of choice.
CMS users will remember XEDIT, which is an edit program written by Xavier de Lamberterie that was released in 1980. XEDIT supports automatic line numbers, and many of the commands operate on blocks of lines. The command line allows user to type editor commands. It replaced EDIT SP as the standard editor. Again, XEDIT was very popular and ported to other platforms.
CMS provided a way to maximize the number of people who could concurrently use mainframe facilities at a time when these facilities were fairly restricted. It was a hugely successful environment, spawning tools that themselves were ported to other platforms because they were so successful. I used CMS and VM a lot back in the day, and even wrote two books about VM. Like many users, I have very fond memories of using CMS and what could be achieved by using CMS.