#### Research from 1982

A Rigorous Approach to Building Formal System Requirements

Gruia-Catalin Roman

Technical Report

**Abstract:**

This paper reports the author's experience in the use of formal specifications and presents a step by step approach to developing functional requirements for computer-based systems. A simple model of system requirements is introduced first. A systematic approach to developing requirements by starting with the general model and adapting it to the needs to the problem at hand is described and illustrated by means of the simple but realistic example. A basic knowledge of predicate calculus and set theory is assumed on the part of the reader. The presentation is**... Read More**

Functional Specification of Distributed Systems

Gruia-Catalin Roman

Technical Report

**Abstract:**

A formal Distributed Systems Design Language (DSDL) is described. In DSDL, systems are described as nets of communicating processes. A net is defined by its processes, by the logical communications links between processes, and by the communications protocols. Each process in the net has its own local data, procedures that specify primitive operations over the data, and possesses the ability to exchange messages with other processes in the net. Some of these processes are used to model the system environment. The links identify the logical connections between processes. The way**... Read More**

On Reducing Ambiguities in Methodology Definitions

Gruia-Catalin Roman

Technical Report

**Abstract:**

The paper describes a proposal for a methodology definition language and illustrates it on a variant of a well-known methodology, top-down program design. The language describes: (1) the structure of and the relations between various products of the design process (they are referred to here as configuration items and may include such things as system requirements, program specifications, module design, code, etc.); (2) changes in the state of these configuration items and consistency constraints between their states; and (3) the sequencing of design activities permitted by the methodology. A separate**... Read More**

A Formal Treatment of Distributed Systems Design

Gruia-Catalin Roman and Robert K. Israel

Technical Report

**Abstract:**

The paper reports on a technique for the formal definition of the distributed systems design methodology called the Total System Design (TSD) Methodology. Central to the formalization of the TSD Methodology is the TSD Model, which consists of several information structures and a set of consistency constraints (i.e., acceptance criteria). While the major part of this paper is taken by the model definition, the authors' intent is not simply to justify the model itself. The paper provides convincing evidence that rigorous methodology definitions are both feasible and useful. It offers**... Read More**

The Total System Design (TSD) Framework: An Approach to the Development of Distributed Systems Design Methodologies

Gruia-Catalin Roman, Mishell J. Stucki, William E. Ball, and Will G. Gillett

Technical Report

**Abstract:**

A methodological framework is an abstraction over a class of design methodologies. The framework characteristics the problem solving approach shared by the methodologies belonging to that class: it identifies the nature of their common design concerns and the fundamental logical interdependencies between these concerns. The paper proposes a particular framework called the Total System Design (TSD) Framework. It represents a specification for a class of design methodologies which view computer-based systems as potentially distributed hardware/software aggregates. As such, the TSD Framework consolidates under a unified perspective two traditionally separate concerns:**... Read More**

The Total System Design (TSD) Methodology from Problem Definition to Hardware/Software Requirements

Gruia-Catalin Roman, Mishell J. Stucki, and Will D. Gillett

Technical Report

**Abstract:**

This paper presents an informal description of a methodology called the Total System Design (TSD) Methodology. It consists of two phases that deal with the transformation of a system requirements specification to a processing model (in the architecture design phase) and the subsequent generation of hardware and software requirements (in the binding phase). The proposed design strategy is based primarily on an extension of the concept of abstract machine hierarchies to distributed systems, while the binding strategy could be viewed as a "most constrained first" policy.

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#### Research from 1981

PIN Limitations and VLSI Interconnection Networks

Mark A. Franklin and Donald F. Wann

Technical Report

**Abstract:**

Multiple processor interconnection networks can be characterized as having N' inputs and N' outputs, each B' bits wide. Construction of large networks requires partitioning of the N'*N'*B' network into a collection of N*N switch modules of data size B (B

VLSI Based Interconnection Networks

Mark A. Franklin and Donald F. Wann

Technical Report

**Abstract:**

Interest in tightly coupled multiprocessor computer systems has grown as the possibilities for high performance with such systems have been recognized. Central to their design is the structure of the network over which the processors communicate. Unless properly designed, such networks can be both a cost and performance bottleneck. This paper focuses on the design of VLSI communications networks, this is, on communications network which can be placed on a single VLSI chip. Traditional SSI-based boost and complexity measures for such networks have principally involved switch aggregate counts. In a**... Read More**

Number of Binary Trees

Will D. Gillett

Technical Report

**Abstract:**

A data encoding scheme involving binary tree encodements is presented and analyzed. A closed-form formula for the number of n-bit legal memory configurations is developed. It is shown that the storage capacity loss due the use of this scheme is not significant for large n.

Formal Specifications of ADS, An Abstract Database System

Takayuki D. Kimura and Will D. Gillett

Technical Report

Surface Geometry Acquisition using a Binary-Coded Structured Illumination Technique

Jeffrey L. Posdamer

Technical Report

#### Research from 1980

Design Studies Suggested by an Abstract Model for Medical Information System

Jerome R. Cox Jr., Takayuki D. Kimura, P. Moore, Will D. Gillett, and Mishell J. Stucki

Technical Report

**Abstract:**

We have developed a formal model of a database system that is unusual in that it has the ability to represent information about its own structure and to insure semantic consistency. The model distinguishes general laws from instances of events and objects, but many of its mechanisms serve both categories of information. The model form a substrate upon which an information structure appropriate to neonatology is being developed. Some example queries are shown and a design study for an associative memory suggested by the model is described briefly.

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VLSI Performance Comparison of Banyan and Crossbar Communications Networks

Mark A. Franklin

Technical Report

**Abstract:**

The performance characteristics of banyan and crossbar communications networks are compared in a VLSI environment where it is assumed that the entire network resides on a single VLSI chip. A high level model of the space (area) and time (delay) requirements for these networks is developed and relative performance comparisons are made based on space-time product measure. The results differed significantly from those obtained with more traditional analyses which are usually based on switch aggregate comparisons. These analyses usually lead to the banyan as being the preferable network due to**... Read More**

An Abstract Model of Unstratified Database System

Takayuki D. Kimura, Jerome R. Cox Jr., and Will D. Gillett

Technical Report

**Abstract:**

A semantic data model is introduced with the following capabilities: (1) Abstraction mechanisms for aggregation, generalization and classification, (2) Unstratified control of the database content, (3) Refined control of intentional and extensional information, and (4) Extensive semantic consistency checking. The basic features of the model are illustrated through a scenario of interactions between the user and the database system (using the proposed model) for constructing a simple database on technical publications.

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A VLSI Perspective of Real-Time Hidden Surface Elimination

Gruia-Catalin Roman and Takayuki D. Kimura

Technical Report

**Abstract:**

VLSI technology provides and demands new ways of solving large scale computational problems. In light of this fact, a piplelined version of a real-time hidden surface elimination algorithm is proposed. The approach is tuned to the requirements of the VLSI technology: it is simple and regular, employs only local communciation, and attains a high degree of parallelism. The feasibility of the technique is demonstated for a computer graphics system where objects are defined in terms of planar triangular surface elements. A case is made in terms of the early 1980's**... Read More**

#### Research from 1979

On the Nonquivalence of Shadow Prices and Dual Variables

D. C. Aucamp and D. I, Steinberg

Technical Report

**Abstract:**

The purpose of this paper is to demonstrate that in the event of degeneracy is present in an optimal basic solution to a linear programming problem, the optimal values of the dual variables doe no necessarily correspond to shadow prices. In such instances it will be shown how the actual values of the shadow prices may be determined and the nature of the relationship between shadow prices and dual variables.

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One Dimensional Optimization on Multiprocessor Systems

Mark A. Franklin and N. Soong

Technical Report

**Abstract:**

This paper presents a straightforward approach to determining how best to utilize an MIMD multiprocessor in the solution of one dimensional optimization problems involving continuous unimodal functions and nongradient search techniques. A methodology is presented which allows one to consider a variety of speedup functions which may occur in parallel function and systems evaluation. It is shown how the best of two parallel optimization strategies can be determined for a given accuracy, number of processors and speedup function.

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Interval Maintenance of Dynamically Changing Flow Graphs

Will D. Gillett

Technical Report

**Abstract:**

Many compilers incorporate an optimization phase during the development of the final object code. Most optimization phases utilize a flow graph and partition it into disjoint single entry regions to perform various global flow analyses. The interval is a commonly used single entry region and interval analyses have been developed for performing standard analyses such as live variable analysis, etc. This paper presents a technique for maintaining the interval structure as the underlying flow graph is dynamically modified. The techniques presented preserve the interval order required by many interval analyses**... Read More**

Algebraic Characterization of Petri Nets

Takayuki D. Kimura

Technical Report

**Abstract:**

Let Cn be the direct product of the bicyclic monoid C, taken n times, where n is a positive integer. It is shown that (1) every Petry net with n places can be represented by a finite subset of Cn represents a Petri net with n places, and (3) the firing rule of Petri net with n places, and (3) the firing rule of Petri nets can be defined as a faithful representation of Cn by the inverse hull of additive semigroup N^n is the set of natural numbers. A**... Read More**

Behavioral Abstraction of Communicating Sequential Processes

Takayuki D. Kimura

Technical Report

**Abstract:**

It is shown that behavioral semantics of Hoare's Parallel Commands can be formally specified by an extension of the regular expression, augmented by the shuffle operation and the inverse shuffle operation. As a corollary of the above, it is also shown that the problems of behavioral equivalence and deadlock-detection are solvable for the Parallel Commands.

Gauss-Jordan Elimination By VLSI Mech-Connected Processors

Takayuki D. Kimura

Technical Report

**Abstract:**

It is shown that a mesh-connected n x (n+m) toroidal array of processors can perform Gauss-Jordan elimination without pivoting, on an n x (n+m) matrix, in 4n+m-1 steps, each step involving at most two artithmetic operations for every processor.

Performance Parameters Related to the Synchronization of Clocked Systems

Willie Yaw-Poh Lim

Technical Report

**Abstract:**

The effect of nondeterministic resolution times of flip-flops, used for synchronizing externally generated input events, on the reliability of fixed period and a newly introduced variable period clocked system is investigated. The failure probability of the simplest form of the two system types of compared. It is shown that in general, clocked system failure probability can be expressed as the product of three parameters representing, respectively, the effect of input arrival processes, system structures, and nondeterministic flip-flop resolution times.

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Concurrency Coordination in a Locally Distributed Database System

Gruia-Catalin Roman

Technical Report

**Abstract:**

A pipelined architecture for a locally distributed database system is proposed along with a simple concurrency coordination mechanism. The approach is based on the idea of serializing transaction processing throughout the database. The scheme is shown to require few coordination messages, to be deadlock free, to preserve database consistency, and to support recovery. Several performance related issues are also discussed.

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Total System Development Framework

Gruia-Catalin Roman

Technical Report

**Abstract:**

Building on the fundamental assumption that effective methdologies are problem and environment dependent, a suggestion is made to distinguish between methodologies and the methodological frameworks they instantiate. TSD (Total System Development) is put forth as a candidate framework able to assist in the generation and evaluation of specific system development methodologies, where systems are defined as distributed hardware/software aggregates.

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Verification Procedures Supporting Software Systems Development

Gruia-Catalin Roman

Technical Report

**Abstract:**

A software system development methodology is proposed. Its significance lies in the capacity to support a systematic and well-formalized error detection strategy extending from requirements definition through program implementation. A minimum set of checkpoints is suggested and verification procedures are detailed for each. The significant cost reducing potential of the approach and the way it was implemented in a production environment are also discussed.

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Synchronization Strategies

Mishell J. Stucki and Jerome R. Cox Jr

Technical Report

**Abstract:**

Computing systems are now frequently composed of independently clocked subsystems that cooperate to perform the function desired for the whole. This type of architecture has many advantages and promises to be the standard for the foreseeable future. With the trend towards more and more gates per chip, the number of chips per subsystem gets smaller and smaller, and we can expect to soon see one or more subsystems per chip. This transition will require contributions from disciplines previously outside the field of chip design, and every issue will have to**... Read More**