Finite State Machine Model Research Articles

A Method for Expressing the Functional Requirements of Real-Time Systems

One of the most difficult phases of software development is the definition of functional requirements -- generating a clear, concise statement of the system’s task and the constraints under which it must operate. This paper describes current research at GTE Laboratories aimed at developing a methodology and tool for expressing the functional requirements of general real-time systems. The requirements methodology is based on the so-called “constructive” specification technique. It provides facilities for describing an abstract machine that captures the behavior of the real-time system as a classic finite-state machine. The finite-state machine model is general enough to describe a broad range of systems, and is well founded both in theory and in practice. In addition, the methodology has special support for the specification of large real-time systems: large systems can be decomposed into more manageable sections called “features,” which can be developed in isolation and merged by a compiler. The research described in this paper is aimed at understanding the nature of real-time functional requirements, and providing tools to aid the requirements writer.

A method for expressing the functional requirements of real-time systems

One of the most difficult phases of software development is the definition of functional requirements — generating a clear, concise statement of the system's task and the constraints under which it must operate. This paper describes current research at GTE Laboratories aimed at developing a methodology and tool for expressing the functional requirements of general real-time systems. The requirements methodology is based on the so-called “constructive” specification technique. It provides facilities for describing an abstract machine that captures the behavior of the real-time system as a classic finite-state machine. The finite-state machine model is general enough to describe a broad range of systems, and is well founded both in theory and in practice. In addition, the methodology has special support for the specification of large real-time systems: large systems can be decomposed into more manageable sections called “features,” which can be developed in isolation and merged by a compiler. The research described in this paper is aimed at understanding the nature of real-time functional requirements, and providing tools to aid the requirements writer.

Performance evaluation of communicating processes

This paper concerns the performance evaluation of an operating system based on communicating processes. Processes communicate via messages and there is no shared data. Execution of a program is abstracted as a sequence of events to denote significant computational steps. A finite state machine model of computation is used for the specifications of abstract computational properties and, thereafter, for the selective analysis of measurement data. A set of conventions is developed to characterize the performance of communicating processes. A hierarchical layering technique is used to concisely describe the characteristics of large systems. A performance monitoring system was implemented and applied to the analysis of RIG, a message-based operating system.

Performance evaluation of communicating processes

This paper concerns the performance evaluation of an operating system based on communicating processes. Processes communicate via messages and there is no shared data. Execution of a program is abstracted as a sequence of events to denote significant computational steps. A finite state machine model of computation is used for the specifications of abstract computational properties and, thereafter, for the selective analysis of measurement data. A set of conventions is developed to characterize the performance of communicating processes. A hierarchical layering technique is used to concisely describe the characteristics of large systems. A performance monitoring system was implemented and applied to the analysis of RIG, a message-based operating system.

A model of timing characteristics in computer control

In this paper, a finite state machine model of timing characteristics in computer control is presented. This model allows for a clear categorization of fundamental transient control mechanisms. The three fundamental categories are: synchronous control with constant cycle time, synchronous control with variable cycle time, and asynchronous control. Each category can be defined into subcategories by which a very wide range of particular timing characteristics can be modelled, e.g., machine subcycles, alternative synchronization mechanisms, etc. The subcategorise are defined by characteristic parameters which can easily be determined for a given microarchitecture. The model is envisioned on a basis for the incorporation of hardware timing characteristics into models of microinstruction semantics as used in the specification and artification as well as the construction and optimization of firmware.

On Future-Dependent Block Coding for Input-Restricted Channels

Consider a restricted channel whose constraints may be characterized by a finite state machine model. Conventional coding techniques for such channels result in codes where the choice of a word to be transmitted is only a function of the current state and the information to be represented by this word. This paper develops techniques for constructing codes where the code word choice may also depend on future information to be transmitted. It is shown that such future-dependent codes exist for channels and coding rates where no conventional code may be constructed.

Spectra of Block Coded Digital Signals

Block codes are multilevel codes of constant length whose codewords are the channel encodings of binary sequences of constant length. The spectral density calculation of pulse trains resulting from the use of these codes is dealt with. Under the assumption that the encoding be represented by a finite-state synchronous sequential machine, by means of homogenous Markov chain theory, the spectral density is evaluated in closed form. Both the continuous and the discrete spectral components are easily obtained as soon as the encoder functions are specified. The result obtained is particularly attractive since the finite-state machine model can be used to represent a broad class of encoding schemes of engineering interest. As an example, the spectral density is calculated in the case of the Franaszek MS-43 code.

Enforcement Policies for Parking Regulations

Effective enforcement of no-parking regulations is essential in urban areas. A probabilistic finite-state machine model that relates enforcement to expected levels of compliance is developed, and its simulation results are shown to agree with experimental data. The effects of deterministic and random enforcement policies are described, and a class of implementable policies that yield satisfactory results is analyzed. Finally, these results are used to determine schedules and routes for enforcement officers that increase their effectiveness.