(1) See voicemail.
(2) (Virtual Machine) One instance of an operating system and applications in a virtualized environment. See virtual machine.
(3) (Virtual Machine) A runtime engine for a development platform. Examples are the Java Virtual Machine and the .NET Common Language Runtime (CLR). See runtime engine.
(4) (Virtual Machine) The first virtualized OS for IBM mainframes. VM runs multiple IBM operating systems of any type, each with their own applications. Originally developed by a separate research arm of the company, VM later became mainstream in the 1970s. In 2000, IBM introduced z/VM for the 64-bit z/Architecture. VM-CP and CMS VM-Control Program (VM-CP) is the "hypervisor" that provides the virtual machine functionality. Conversational Monitor System (CMS) is a compact guest operating system that is widely used with VM to provide interaction for one user. Each user communicates with CMS in a separate virtual machine in the computer. For more information, visit www.vm.ibm.com. See CP/CMS and virtual machine.