Partial virtualization I ve added a category of partial virtualization between full virtualization and paravirtualization Although this may not sit well with everybody I think we need a category for a system like IBM M44 44X with virtual machines and multiple address spaces but not full hardware simulation and the ability to boot multiple operating systems There is a fuzzy line between such a system and any OS that provides address space isolation Or rather there really is no such line and all such operating systems could be considered in the same category We wouldn t tend to view them as virtual machine systems today but they were a huge step forward from earlier approaches to multitasking Please feel free to butcher my addition if you see a better way to deal with this I don t think we want to rewrite history based on today s categories however