Helmut K. Berg

Data structure architectures - a major operational principle

Computer architectures may be characterized by their operational principle and their physical structure. The paper defines these two characteristics for the novel concept of data structure architectures (DSAs). The representation and processing of arbitrary data structures in such a DSA is demonstrated by examples. It is shown how the functional requirements of a DSA can be satisfied by the specific information structure and the physical structure of the STARLET architecture introduced in preceding publications.

Correctness of Firmware -An Overview-

Similar to the developments in the area of software engineering, microprogram verification evolved into one of the fundamental notions of firmware engineering. In a general sense, program verification is the task of systematically demonstrating that a program achieves its intended purpose, i. e., the task of proving the absence of errors from a program. This task may be considered as a backward mapping from a given program to a statement of the functional requirements for that program. There exist two fundamental approaches to establish such mappings. A program may be exercised for a specific set of input values; the successful completion of program execution constitutes a necessary condition for the correctness of that program. A more rigorous approach is to provide an argument that a program satisfies its functional requirements which is independent of specific input values thus constituting a necessary and sufficient condition for the correctness of that program. In this paper, we investigate both approaches to the verification of firmware.

Hierarchical Specification of Abstract Data Types

We introduce a hierarchical specification technique for abstract data types (ADT) in which the data objects of an ADT are represented by other, simpler ADTs and in which the functional behavior of an ADT is specified in terms of an input/output specification employing applications of the functions of the representing ADTs. By introducing instances of abstract data structures as fundamental representations, the danger is avoided that such representations might imply particular implementations. We will prove that a minimum and complete fundamental representation for hierarchical ADT specification can be established. It will be demonstrated that our technique provides a straight-forward approach to the specification of arbitrarily complex ADTs (e.g. a relational data base system).

An Approach to the Specification of Distributed Software

In this paper we first characterize distributed systems. Next we survey recently proposed programming constructs designed to facilitate communication amongst software elements of a distributed system. We then give the basis of a methodology for the formal specification of distributed systems, and follow with an example to clarify the technique. We close with a discussion of necessary extensions to the methodology and a review of the objectives of specification.

Correctness of Software - An Overview

During the late sixties and early seventies it became obvious that the design, coding, testing, and maintenance of large programs had become an unmanagable endeavor. Such large programs, particularly operating systems, were prone to unexpected collapse, causing severe outages of service to a community of users dependent upon them for the preparation and execution of their application programs. Large application programs too, e. g. compilers, sort-merge packages, etc. suffered from the same propensities. The root cause of the deficiencies exhibited by these programs was easily attributed to the fact that a sound engineering discipline did not exist (or was not used) to guide their development. More specifically a discipline did not exist (or was not followed) to guide program design, and the verification of the correctness of implemented programs.

STARLET: a computer concept based on ordered sets as primitive data types

It is a well-acknowledged fact that the adequate structuring of data is as important as the adequate structuring of a program. The classical von Neumann - machine deals on the hardware level only with scalars and, therefore, provides no hardware support of any sort for the manipulation of more complex data structures. Some more recently developed concepts - all variants of Iliffes Basic Language Machine -- provide some hardware support for structuring data in the form of trees. Contrastingly, in the STARLET concept to be discussed in this paper, the basic data structure is that of ordered sets (as given by strings and arrays). In the paper, the basic notions of this novel concept are introduced and discussed, especially the internal information structure which differs considerably from that of the von Neumann-machine or other concepts. This very idiosyncratic information structure has far-reaching consequences with respect to the hardware structure of the machine. Finally, a number of resulting features will be discussed and an attempt will be made to compare the computing power of STARLET with that of avon Neumann-machine with equally fast hardware.

The Use of Formal Specification of Software

ion and Refinenent in RIM D. L. Boyd, A. Pizzarello, W. T. Wood. 111 Hierarchical Specification of Abstract Data Types H. K. Berg, W. K. Giloi 150 An Approach to the Specification of Distributed Software W. R. Franta, W. E. Boebert, H. K. Berg 197 Correctness of Software An OVerview H. K. Berg, W. R. Franta, T. G. Moher 237 Interactive Design and Verification: A Message Switching Network Example

Towards a Uniform Design Methodology for Software, Firmware, and Hardware

Over the last two decades, drastic changes in computer technologies had an enormous impact on the computer system design scenario. To cope with the implications of these changes, designers must strive for new approaches to computer system design. These approaches must lead to methods for analyzing design tradeoffs in the context of changing technologies and expanding applications as well as to methods for synthesizing application-driven system designs that economically use the multitude of potentials offered by new technologies. Moreover, modern approaches to system design integrate software, firmware, and hardware development into design methodologies which allow these major components of system implementation to be tailored such as to optimize their contribution to the evnisioned application and system performance. In this paper we attempt to indicate how principles and concepts of software, firmware, and hardware design might be integrated into a uniform design methodology. Our considerations are primarily concerned with formal methods. We do not intend to propose the ideas presented in this paper as the ultimate approach to integrated system design.