Let's explore briefly the history with virtualization and hypervisors. Most suppose that virtualization is a new concept that came about in the 90's and was introduced by VMware. Virtualization is a much older technology, with a lot of interesting advances made in the recent years. The original hypervisors providing complete emulation of the underlying hardware was developed by IBM in the 60's. The IBM System/360-67 was the first production system capable of full virtualization. Virtualization had a resurgence in the 2000's on Linux and UNIX systems. Once virtualization gained ground in x86 systems, VMs became mainstream. In 2005, Intel and AMD added hardware virtualization assistance to their products: Intel VT-x (codenamed Vanderpool) and AMD-V (codenamed Pacifica). These were followed by I/O MMU virtualization and network virtualization (Intel's VT-c). These chip extensions aided in enhancing the throughput of the guest VMs, which previously had to be emulated by the hypervisor. It allows the guests to function natively with the hardware, where previously more of the hardware required to be emulated by the hypervisor.