Off by a couple of decades there. IBM's VM OS traces its roots to the 1960s. The original work was done at IBM's Cambridge Labs (which developed the Cambridge Monitor System, CMS) on a modified System/360 Model 40. CP-67 debuted as the first commercial virtual OS a few years later.
A repackaged version for the then-new System/370 machines was released as VM/370 in the early 1970s. All open-source, of course, (long before anyone thought in those terms) since back then software was viewed as a freebie to help sell hardware.
“IBM’s VM OS traces its roots to the 1960s”
Thanks for the update. Could we call VM OS the great-granddaddy of VM?
I was doing PDP-11 work in a predominantly mainframe shop in NYC in 1980 and they treated the introduction of VM/CMS as a virus. I was just slime.