<P> However, the distinction between these two types is not necessarily clear . Linux's Kernel - based Virtual Machine (KVM) and FreeBSD's bhyve are kernel modules that effectively convert the host operating system to a type - 1 hypervisor . At the same time, since Linux distributions and FreeBSD are still general - purpose operating systems, with other applications competing for VM resources, KVM and bhyve can also be categorized as type - 2 hypervisors . </P> <P> The first hypervisors providing full virtualization were the test tool SIMMON and IBM's one - off research CP - 40 system, which began production use in January 1967, and became the first version of IBM's CP / CMS operating system . CP - 40 ran on a S / 360 - 40 that was modified at the IBM Cambridge Scientific Center to support Dynamic Address Translation, a key feature that allowed virtualization . Prior to this time, computer hardware had only been virtualized enough to allow multiple user applications to run concurrently (see CTSS and IBM M44 / 44X). With CP - 40, the hardware's supervisor state was virtualized as well, allowing multiple operating systems to run concurrently in separate virtual machine contexts . </P> <P> Programmers soon re-implemented CP - 40 (as CP - 67) for the IBM System / 360 - 67, the first production computer - system capable of full virtualization . IBM first shipped this machine in 1966; it included page - translation - table hardware for virtual memory, and other techniques that allowed a full virtualization of all kernel tasks, including I / O and interrupt handling . (Note that its "official" operating system, the ill - fated TSS / 360, did not employ full virtualization .) Both CP - 40 and CP - 67 began production use in 1967 . CP / CMS was available to IBM customers from 1968 to early 1970s, in source code form without support . </P> <P> CP / CMS formed part of IBM's attempt to build robust time - sharing systems for its mainframe computers . By running multiple operating systems concurrently, the hypervisor increased system robustness and stability: Even if one operating system crashed, the others would continue working without interruption . Indeed, this even allowed beta or experimental versions of operating systems‍--‌or even of new hardware ‍--‌to be deployed and debugged, without jeopardizing the stable main production system, and without requiring costly additional development systems . </P>

Which one of the following virtualization products uses a bare metal implementation