Linked by Thom Holwerda on Tue 13th Feb 2007 15:37 UTC, submitted by liquidat
"Almost a month ago InnoTek, the co-developer of VirtualPC, released their Virtual Machine as Open Source. The software was formerly not targetted at desktop users, but that changed when it was released under the GPL. This review tries to shed some light on the question if VirtualBox can get some market share between Vmware and Qemu."
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Member since:
2006-07-14
An emulator is an implementation of the entire hardware of a machine (eg a PC) in software. Every single feature of the "guest" machine has to be written on code (in C, for example). This allows for maximum portability, since porting to a different machine is no different to porting any other C program. Unfortunately due to the complexity of most CPUs, and the x86 in particular, emulators tend to be quite slow.
Rather than implementing the x86 CPU in software, a virtual machine takes advantage of the physical x86 CPU to directly execute guest instructions. This gives a considerable performance increase, but at the expense of tying the virtual machine to the x86 architecture. Whilst it could be ported between OSs, an x86 virtual machine could not be ported to run on a physical machine with, for example, a PowerPC CPU. Other than the different approaches to the CPU, a virtual machine emulates other hardware (the video card etc) in exactly the same way as an emulator.