This paper describes analysis and simulation for understanding of large Ada-83 real-time software. Ada real-time software is frequently very large in size and very complex. The objective is to describe: (1) discovery of the architecture of the software by decomposing the software into a hierarchical structure, (2) generation of state machines that preserve the real-time properties of the hierarchically organized units, and (3) simulation of the software represented by the state machines. Because of the severe limitation of space, these capabilities are only briefly described, without an example. The first two items above have been exercised in processing over 100,000 lines of Ada-83 code. The third item is still being developed.

Business process reengineering is generating considerable interest in the business community because of its demonstrated capacity to reduce costs and increase an organization's responsiveness to competitive challenges and opportunities. The software crisis, as evidence by escalating costs and sluggish responsiveness to changing requirements, is similar to the business problems now being addressed through the application of business process reengineering principles. This article applies three of these same principles to the software crisis: (1) the surfacing of tacit assumptions and an examination of them for error, obsolescence, or irrelevance; (2) a radical redefinition of processes; and (3) the use of technology as a process enabler. After applying these principles to the problems of software development, maintenance, and reengineering, we derived a radical redefinition of the software process. The capabilities of three integrated multitool CASE environments are proposed as an enabling technological infrastructure for the reengineered software process. These are the software specification, software engineering, and software reengineering environments. The reengineered software process and integrated environments are shown to leverage human resources from three sources: legacy software, domain architectures, and reuse libraries.

Concurrent systems are typically large and complex, requiring long, development time and much labor. They are, therefore, prime candidates for simplification and automation of the design and programming process. Their major application areas include real time systems, operating systems and cooperative computation. New applications are emerging with the trends towards wide usage of personal computers connected in a network and towards use of parallel processing in supercomputer architectures.

The use of an assertive specification language for real-time software development and maintenance is considered. The language is used for asserting the acts or relations inherent in the problem to be solved; this is in contrast to conventional programming languages, which are used to express the computer solution. Expressing a problem in Model consists of declaring array variables and defining their relationships through equations. This is different from conventional programming, which relates the problem in terms of computer operations. The language is supported by an automatic system which interacts with the user in soliciting missing definitions or correcting inconsistencies, and which translates the specification into a near-optimal computer solution. The main advantages of this approach are indicated. The use of Model in real-time software development and maintenance is reviewed. Differences from conventional programming are stressed through an example, which also illustrates the use of the three automatic components of the Model system.

An efficient algorithm for synchronized termination of iterative solution of simultaneous equations in a distributed message passing system is presented.The algorithm is based on an assumption that distributed processors are connected via unidirectional channels into a strongly connected network, in which no central controller exists.The number of processors and the network configuration are not known a priori.

An efficient decentralized algorithm for synchronized termination of a distributed computation is presented. It is assumed that distributed processes are connected via unidirectional channels into a strongly connected network, in which no central controller exists. The number of processes and the network configuration are not known a priori. The number of steps required to terminate distributed computation after all processes met their local termination conditions is proportional to the diameter D of the network (D + 1 steps).

The introduction of very high level languages (VHLL) and automatic program generation are expected to reduce significantly the needed programming skills and considerably increase software development productivity. The paper explores the hypothesis that the preferred mode of developing management systems will be for the management professional to directly specify, generate, and debug the needed software without involvement of professional programmers. The investigation is experimental, by having an accountant develop an accounting system, using the equational type MODEL VHLL and program generator, and by monitoring carefully the times that it takes to perform certain steps or debug certain types of errors. The investigation consisted of progressive development of an accounting system in three stages: first a general ledger, extended for inventory management, and concluding with a major modification to incorporate reporting for the effects of changing prices in accordance with Financial Accounting Standard 33 (FAS 33). In this way the work pattern in modifying and maintaining a system was investigated as well. The developer was an M.B.A. candidate majoring in accounting with a limited computer background who determined the requirements of the accounting system and used MODEL to generate the programs, along with their extensions and modifications. A description of the accounting system design is presented first. Next, a sample MODEL specification is discussed in order to communicate generally the style of specifying computations in MODEL. This sample is used also to demonstrate the incorporation of FAS 33.

Describes the use of a very high-level equational language and distributed processing in a methodology for the development of large-scale systems in natural and social sciences, or engineering. The methodology denoted as cooperative computation, consists of dividing the labour among a number of organizationally and geographically dispersed groups, with each responsible for a respective local area, and the integration of the local areas into a global system. With an equational language, the user is able to express computations in terms of equations that are commonly used in science and engineering, without the detail required in programming computers. Object programs are then produced automatically through the use of a program generator and a configurator. The methodology is discussed primarily through an example, using the model language applied in environment of Project Link.

The paper describes the compilation of a program specification, written in the very high level nonprocedural MODEL language, into an object, PL/1 or Cobol, procedural language program. Nonprocedural programming languages are descriptive and devoid of procedural controls. They are therefore easier to use and require less programming skills than procedural languages. The MODEL language is briefly presented and illustrated followed by a description of the compilation process. An important early phase in the compilation is the representation of the specification by a dependency graph, denoted as array graph, which expresses the data flow interdependencies between statements. Two classes of algorithms which utilize this graph are next described. The first class checks various completeness, nonambiguity, and consistency aspects of the specification. Upon detecting any problems, the system attempts some automatic correcting measures which are reported to the user, or alternately, when no corrections appear as reasonable, it reports the error and solicits a modification from the user. The second class of algorithms produces an intermediate design of an object program in a language independent form. Finally, PL/1 or Cobol code is generated.

The Model II language and the associated program generator are used to explain and illustrate the use of very high level nonprocedural languages for computer programming. The effect of a very high level language is obtained in Model II through the elimination of procedural and control facilities that exist in high level programming languages such as PL/I or Cobol. In particular, the statements may be given in any order and there are no control constructs such as input/output, iterations, and memory allocation. The task of ordering the statements for execution and providing control statements is performed by the automatic program generator. The specification of a program is therefore much shorter (approximately one-fifth) than the equivalent high level procedural language program. Most important, a user need not regard the task of specifying a program as defining a process but rather as describing data and relations. This point of view greatly reduces the computer programming proficiency required of a user. The paper focuses on an example of the use of the language in business data processing, its advantages, and its novelty. It only briefly reviews the methodology incorporated in the existing program generator, a detailed description of which may be found in the references.

In recent years, the design of computer circuits has become a thorough and complex job. Factors such as logical design, behavior of components, manufacturing techniques, and life tests are playing an even more important role in the design of an efficient circuit. This paper will discuss how circuit optimization techniques and use of the UNIVAC® I computing system aided in reducing cost and avoiding many of the pitfalls in the design and production of efficient high-speed circuitry for UNIVAC-LARC.

Shift registers using magnetic cores have been conventionally designed with diodes to provide isolation between stages. It is possible to use transfluxors in a two-core-per-bit fashion so as to provide isolation between stages by magnetic means rather than with diodes. A design procedure for doing so is discussed.

A three, and a two winding per core, high-speed, current driven, one core per bit shift register is presented together with an analysis of the basic circuit involved. An intermediate storage capacitor is used between successive logical elements. The charge and discharge of this capacitor are controlled in a positive manner by voltage blocking pulses. The undesired feedback of energy from one stage to earlier stages is thereby prevented, giving high efficiency of operation. The three winding per core register described is reversible and capable of operating in the megacycle range. The application of the basic shift register element to computer logic applications is described.