Designed to solve problems in combining and using major components of computer systems, virtual machine technologies play a key role in many disciplines, including operating systems, programming languages and computer architecture. At the system level, they support the operating system environment on the same hardware platform and in servers. Historically, individual virtual machine techniques have been developed in specific disciplines that employ them (in some cases they are not even referred to as "virtual machines"), making it difficult to see their common underlying relationships in a cohesive manner. Topics include instruction set emulation, dynamic program translation and optimization, high level virtual machines (including Java and CLI), and system virtual machines for both single user and server systems. * Checking virtual machine technology in all disciplines who use their operating systems, programming languages and computer architecture-defining a new and unified discipline. * Judging by the principle researchers at Microsoft, HP, and other research industry groups. * Written by two authors who combine several decades of expertise in research and development of computer systems, both in academia and industry.