Search results
Results from the WOW.Com Content Network
In computing, a virtual machine (VM) is the virtualization or emulation of a computer system.Virtual machines are based on computer architectures and provide the functionality of a physical computer.
In some respects, a system virtual machine can be considered a generalization of the concept of virtual memory that historically preceded it. IBM's CP/CMS , the first systems to allow full virtualization , implemented time sharing by providing each user with a single-user operating system, the CMS .
The VM hypervisor can simulate several types of console terminals for the guest operating system, such as the hardcopy line-mode 3215, the graphical 3270 family, and the integrated console on newer System/390 and System Z machines. Other users can then access running virtual machines using the DIAL command at the logon screen, which will ...
A virtual machine implements functionality of a (physical) computer with an operating system. The software or firmware that creates a virtual machine on the host hardware is called a hypervisor or virtual machine monitor. [2] Software executed on these virtual machines is separated from the underlying hardware resources.
These hypervisors run on a conventional operating system (OS) just as other computer programs do. A virtual machine monitor runs as a process on the host, such as VirtualBox. Type-2 hypervisors abstract guest operating systems from the host operating system, effectively creating an isolated system that can be interacted with by the host.
A hypervisor is an operating system that runs a virtual machine. The virtual machine is unaware that it is an application and operates as if it had its own hardware. [14] [29] Virtual machines can be paused, saved, and resumed, making them useful for operating systems research, development, [30] and debugging. [31]
The term "virtualization" was coined in the 1960s to refer to a virtual machine (sometimes called "pseudo machine"), a term which itself dates from the experimental IBM M44/44X system. [1] The creation and management of virtual machines has also been called "platform virtualization", or "server virtualization", more recently.
Operating-system-level virtualization usually imposes less overhead than full virtualization because programs in OS-level virtual partitions use the operating system's normal system call interface and do not need to be subjected to emulation or be run in an intermediate virtual machine, as is the case with full virtualization (such as VMware ...