This paper describes firmware and hardware support necessary for constructing easy-to-understand and high performance operating systems including language translators and interpreters. Basic principles are one-to-one correspondence between logical hierarchy and physical hierarchy, and vertical migration. Implementation of monitors in firmware and architectural support for it are discussed, and a sample system is shown. Architectural support for user microprogramming is then discussed and an example is shown. After a total system firmware structure is discussed, an experiment of vertical migration is described. It is shown that a proper selection of modules for migration is extremely important. It is suggested that the direction shown in this paper is one of future directions of computer systems.