what is the name of virtual machine that the mainframe called had
VM (operating system) 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.[1] The current version, z/VM, is still widely used as one of the main full virtualization solutions for the mainframe market.[citation needed]