A secured system for accessing application services from at least one application program where at least one client station having low-level application independent logics stored therein and at least one controller for controlling the low-level application independent logics, the low-level application logics including a user interface logic, a device control logic for controlling devices, a file system logic, and a communication interface logic, and wherein at least one client station has means to restrict access to said application independent logics, at least one application server having high-level application logic stored in a server device for running at least one application program, the server device being coupled to said at least one application server and low-level interface between said at least one client station and said at least one server for connecting said at least one client station to said at least one application server, wherein upon accessing by said at least one client station, said at least one application server runs at least one application program which selectively controls said low-level application independent logics for controlling devices of said at least one client station and accessing data of said at least one client station without permanently storing said at least one client station data in said at least one server. There is also a description of a secure operating system and method and a secured system and method of construction of a computer system as well as description of system and method of how to preserve a running current state of an application program for security and relocation purpose.