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Re: Machines

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  Re: Machines Arne Vajhøj <arne@vajhoej.dk> - 2016-08-01 09:13 -0400

#35162 — Re: Machines

On 8/1/2016 8:56 AM, Stefan Ram wrote:
>   What is the difference between:
>
>       - a simulated machine (a simulator),
>       - an emulated machine (an emulator) and
>       - a virtual machine?

I don't think the terms are defined precisely anywhere.

But when I hear the words I would associate like:
- simulation and emulation => simulating guest computer with ISA X
   on host computer with ISA Y, example SIMH
- virtualization => isolation of guest computer with ISA X
   on host computer with ISA X, example VMWare ESXi

>   Do you think that the Oracle Java virtual machine
>   is a virtual machine in the same sense that Oracle
>   VirtualBox is a virtual machine?

JVM, CLR etc. are also VM's, but in a different sense.

They can be considered a computer executing the Java byte code ISA.
But they do not boot up an OS on them - instead they just execute
a program. And they have free access (except with SecurityManager
for Java) to the host OS and host computer.

Per convention they are called VM's.

So go with the stream and call them VM's - not to be confused
with VM's like ESXi.

Arne

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