Functionally Independent Programs in Multitasking Environment

his paper introduces a new concept of information security in respect to multitasking computational systems. According to the proposed definition a multitasking computational system is information secure, if execution of any application cannot negatively influence on other applications. Thus information security is being considered as protection of executing application and system programs from arbitrary actions of other application programs. Information security is provided by the software and hardware architecture, which guarantee information and functional independence of system and application programs and in time resource availability. A program is functionally independent if an execution sequence of program commands and a program itself could not be changed by other programs. This ensures integrity of programs. Compliance with there conditions is ensured by some technological and hardware means including static program and data allocation, separation of configuration and execution stages, special hardware features, minimizing the complexity of system programs. A computational system model is introduced for which functional independence requirements are fulfilled. Implementation of the model needs a new kind of hardware. Execution of some typical algorithms must be performed by hardware. Some computations performing as a rule by operating system are executed on configuration stage. The computational system consists of hardware, system programs and application programs. System programs nomenclature and their configuration do not depend on application programs. System programs and application programs do not depend on each other according to the data. A processor as a part of hardware can execute in addition to commands processor transactions, i.e. standard programs, determining computational process. Implementation of some programs as processor transactions allows to protect the computational system from uncontrolled interference by application programs. The model does not use any hardware means for memory protection. This is implemented using system programs. Planning is carried out by system programs. The scheduling algorithm guarantees the integrity of system and application programs. When scheduling, processing of application-specific data is carried out by processor transactions. This provides information security at the scheduling stage. The proposed hardware and software architecture can be used in information and computing systems for the maintenance of critical objects. Architecture can serve as a conceptual basis for creating systems for which information security requirements are primary, especially for those that function in real time.