No
An advantage of using a virtual machine is you can run multiple operating systems under the umbrella of one operating system. Without a virtual machine you have to reboot every time you want to want to change operating systems but with a VM you can simply switch between them.
A virtual machine will provide generic hardware that can be found in many other computers. Having a virtual machine eliminates the need to have either a second system, or to reboot to test their operating system.
types of devices in operating system
That's the "base" operating system. Let's say you have Windows 7, and you need Windows XP for compatibility (for instance, lots of older games no longer work with Windows 7). So you install a virtual machine using a special program such as as VMWare, and you run Windows XP in a window within Windows 7. (It can be full-screen as well.) Or perhaps you want to try out Linux. In this example, the base machine - the real, physical machine - has Windows 7; that's the host operating system, while the virtual machine has Windows XP (or Linux).Note: It is also possible, for example, for the host operating system to be Windows 7, and the virtual machine also Windows 7 - this can help you isolate different installations, and - for example - if you no longer need it, erase the entire virtual machine, which is faster, and often much cleaner, than uninstalling.
A Guest operating system is one that runs on top of another, similar to a program. Guest operating systems are usually run in a "virtual machine", which does not interact directly with the real hardware of the computer.
Operating System level.
An advantage of using a virtual machine is you can run multiple operating systems under the umbrella of one operating system. Without a virtual machine you have to reboot every time you want to want to change operating systems but with a VM you can simply switch between them.
Virtual Layer
Modern machines do not consist of multiple levels of virtual machines; that is a function of the host operating system's virtual machine manager and its guest operating systems, all of which are implemented through software. The operating system's virtual machine manager exposes one or more virtual machines upon which you can host one or more guest operating systems and their applications. In order to execute compiled Java applications upon one of these guest operating systems you will also need to install the Java virtual machine for that specific operating system. Thus you end up with a Java program executing within a Java virtual machine executing within a virtual machine executing within a virtual machine manager executing upon the physical hardware. The physical hardware itself may be optimised to handle virtual machine managers more efficiently, but the virtual machine manager is a software program; it is not part of the physical machine architecture
A virtual machine will provide generic hardware that can be found in many other computers. Having a virtual machine eliminates the need to have either a second system, or to reboot to test their operating system.
types of devices in operating system
Yes, but only one can be in control of the system. When a choice of operating systems exist, you typically choose the controlling operating system via a boot menu at startup. To switch to another operating system, you must restart the system. It is possible to run two or more operating systems at the same time via virtual machines. A virtual machine is a software program that emulates a real computer. However, operating systems within a virtual machine have no direct control over the physical machine which is always under the direct control of the one operating system chosen at startup. Virtual machine operating system calls are routed to the virtual machine software which must translate the call to invoke the appropriate system function of controlling operating system. As a result, virtual machines perform extremely poorly compared to the physical machines within which they operate.
You can't use all of your system memory to run a virtual machine because then there wouldn't be enough memory for the Operating System that's running the virtual machine to function. For instance, if you have 4 GB of system memory total, and your operating system needs at least a quarter of that (1 GB) to function, then your virtual machine maximum memory would be 3 GB.
A Virtual Machine.
Windows, Solaris, Linux, & Apple OSX...
The only virtual machine that currently support USB passthrough to allow a guest operating system to use a USB device connected to the host is VirtualBox.
1.Java virtual machine is required to interpret .class files. 2.JVM makes the java as platform independent.