"I will be using VM/SP Release 1 in my examples"
"VM (often: VM/CMS) is a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers.
The first version, released in 1972, was VM/370, or officially Virtual Machine Facility/370. This was a System/370 reimplementation of earlier CP/CMS operating system. Milestone versions included VM/SP."
From the right side column in the Wikipedia article:
From that paper:
Creasy and Comeau spent the last week of 1964 joyfully brainstorming the design of CP-40, a new kind of operating system, a system that would provide not only virtual memory, but also virtual machines. [Footnote 25]
[Footnote 25] - Creasy had decided to build CP-40 while riding on the MTA. "I launched the effort between Xmas 1964 and year’s end, after making the decision while on an MTA bus from Arlington to Cambridge. It was a Tuesday, I believe."
I love seeing an anecdote like that about such an influential technology!
Creasy couldn't have made the decision riding an MTA bus in December, 1964! The MTA had been succeeded by the MBTA in August, 1964. (Too pedantic?)
Still it was an amusing pedantic comment.
"One of the other perils of SHUTDOWN is simply that it is so buggy. In fact, the whole SHUTDOWN/WARM START/CKPT START subsystem is just full of bugs, especially in I/O error recovery. The VM community is subjected to altogether too many cold starts as a result. The bugs stay there because IBM provides us with no means of diagnosing problems in this subsystem. When there is a failure in shutting down or starting up, CP is too sick to take a dump of itself. IBM doesn’t provide its VM customers with a standalone dump facility, so it gets very few dumps of shutdown and startup failures. If you begin seeing failures of this subsystem, I urge you to get hold of a standalone dump program from one of the other SCPs and take dumps and report the problems to IBM."
It's worth considering that this was one of the most common ways people would do large scale computing well into the era of UNIX and PCs.
VM Virtual Memory
VM Voice Mail
VM Voice Message