Virtual Machines
A virtual machine is a software computer that, like a physical computer, runs an operating system and applications.
A virtual machine is an emulation of a specific computer system.
Virtual Machines
In order to manage multiple operating systems on the same machine, a program called a hypervisor is used.
The hypervisor manages and allocates the system's processor, memory, and other resources to each OS.
VM 1
VM 2
VM 3
VM 4
Hypervisor
Host Operating System
CPU Disk Memory
Virtual Machines
Examples
Run Windows programs on a Mac with a virtual machine.
Server can provide different virtual functions such as file server, print server, web server
Virtual Machines
Advantages•Multiple OS environments can exist at the same time on the same machine•Only one physical computer required•Easier maintenance and more convenient recovery
Disadvantages•Using virtual machines running simultaneously on the same computer may lead to unstable performance•A virtual machine is not as efficient as a real machine when accessing the computer hardware
EmulatorsAn emulator is a program that enables the computer to behave like another computer or piece of hardware.
Examples:Mobile phoneVideo consoleOlder computer
Mobile DevicesMobile devices are smaller versions of a computer system
Examples are tablets and mobile phones
They use the same basic stored program concept as a full-size computer system but there are some differences due to size:StorageProcessing powerUser interactionSlimmed down OSInterfaces