VM/370

The first VM environment was the IBM System/360 Model 40 VM. VM became mainstream until later with a model of System/370. The VMM in VM/370 was called CP (Control Program). The CP design team also developed a single-user OS called CMS (Conversational Management System), mainly to demonstrate the advanatage of modularization for system evolution. The CP/CMS design separates the function of resouce management from the function to provide services to the user. CP and CMS can exist without each other. In fact, CMS was developed on a bare machine before CP exists.