The VM operating system was developed during the mid-1960s in order to create a virtual system that would appear to each user as a dedicated machine.
Requirements vary among organizations of different sizes.
Because of this, there are different variations of VM to better meet these needs. CP is a set of programs which manages the real machine resources and creates the virtual machine environment. CMS is an interactive operating system within VM, that operates under the control of CP to manage the virtual machine environment. Because of its capabilities of CP, VM is often referred to as the perfect host. A myriad of different operating systems can coexist in the same machine under the umbrella of VM's Control Program.