Recent developments in machine-independent job control languages

The paper gives a general survey of recent developments in the field of Job Control Languages. Three high-level portable job control languages (UNIQUE, GCL and ABLE) are presented in outline, and their merits and disadvantages are discussed. The approaches of the MU5 and of single-language machines are discussed together with the question that these pose: ‘Is a JCL as such really necessary?’ In conclusion particular reference is made to the question of standardization and to the continuing work in this field.     

A user-oriented approach to control languages

This paper describes the design approach adopted for SCL which is the control language of System B, the operating system of ICL's new 2900 Series of computers. The design emphasis of SCL is ‘usability’ and the paper sets out to show that SCL provides what users require. The authors both work in the Systems Programming Division of ICL where the majority of their recent work has centred around the design of job management in System B and SCL in particular.     

POP-2 performance on a small 1900 machine

A simple benchmark is described which enables the performance of the programming language POP-2 to be investigated. The benchmark, run using the Multiple On-line Programming (MPO) facilities of the GEORGE 3 operating system, is used to investigate the effects of certain installation controlled running conditions upon terminal response. The results of some of the investigations are presented and an indication of future areas of study is given.     

A general-purpose text editor for OS/360

The IBM 370/165 system at Cambridge provides batch and interactive computing facilities under OS 360/MVT with the Time Sharing Option (TSO). The Cambridge text editor, EDIT, provides comprehensive file manlpulation facilities in a unified manner for both batch and interactive users.     

Development of the ZED text editor

The development process which resulted in a new text editor is described. The reasons for undertaking this development are discussed, and in particular the increased amount of non-interactive use of text editors is stressed. The approach taken to the project is described, including the involvement of users in defining the specification and testing prototypes. Finally the main features of the new editor, ZED, are covered.     

Management implications of job control language standardisation

The brief history of command language standardisation efforts is reviewed: time and cost savings are detailed as reasons for requiring a standard operating system command and response language (OSCRL). A model of an abstract computing machine environment is introduced as a desirable kind of environment and as a way for management to understand the standardisation process. Management involvement is seen as all important, not only to support standardisation but to guide the increased flexibility which standardisation brings. Finally, it is stressed that technical experts must get involved to ensure a competent and comprehensive result - even though an actual standard may be five or more years distant.     

Robust optimal control of regular languages

This paper presents an algorithm for robust optimal control of regular languages under specified uncertainty bounds on the event cost parameters of the language measure that has been recently reported in literature. The performance index for the proposed robust optimal policy is obtained by combining the measure of the supervised plant language with uncertainty. The performance of a controller is represented by the language measure of the supervised plant and is minimized over the given range of event cost uncertainties. Synthesis of the robust optimal supervisory control policy requires at most n iterations, where n is the number of states of the deterministic finite-state automaton (DFSA) model, generated from the regular language of the unsupervised plant behavior. The computational complexity of the control synthesis method is polynomial in n.     

A differential evolution approach for the common due date early/tardy job scheduling problem

The problem of scheduling multiple jobs on a single machine so that they are completed by a common specified date is addressed in this paper. This type of scheduling set costs depend on whether a job is finished before (earliness) or after (tardiness) the specified due date. The objective is to minimize a summation of earliness and tardiness penalty costs. Minimizing these costs pushes the completion time of each job as close as possible to the due date. The use of differential evolution as the optimization heuristic to solve this problem is investigated in this paper. Computational experiments over multiple (280 in total) public benchmark problems with up to 1000 jobs to be scheduled show the effectiveness of the proposed approach. The results obtained are of high quality putting new upper bounds to 60% of the benchmark instances.     

Programs as higher level subroutines

The subroutine call is one of the most fundamental of program control constructs. Despite this, it is rarely implemented at the job control or task level in existing commercially available software systems. When the feasibility of adding a general program calling mechanism to an existing system was investigated, it was apparent that there exist constraints on the amount of state information which could be saved on behalf of the calling program. A mechanism with low run-time overhead which saves a minimal amount of state information has proven to be easily integratable into a commercially available operating system. This mechanism has had a significant impact on the ease of development and support of large systems of programs. Examples of the use of the new calling mechanism include a program development system and a recursive directory manager for hierarchical directories.     

Supervisory control using augmented languages in discrete event systems

This paper introduces the concept of an augmented (super) language of a specified language and studies its application to finite state supervisory control. First, we investigate several properties of an augmented language, especially related to controllability of the specified language. We propose an algorithm for the computation of a controllable sublanguage for which a finite state supervisor exists, using an augmented language, and show a sufficient condition for the controllable sublanguage to be supremal. It is shown, however, that such a finite state supervisor is sometimes blocking. Moreover, we discuss the relationship between the Wonham-Ramadge algorithm and our proposed one.     

The evolution of the operating system EMAS 2900

As a result of experiencing problems with manufacturer's software on the early 2900 machines Edinburgh University took the bold step of attempting to move the general purpose timesharing system EMAS from an ICL 4–75 to an ICL 2970 computer. This paper describes the move together with the changes made and includes some preliminary performance figures from the new system. This implementation project has produced a major time-sharing virtual memory operating system with a fraction of the effort required to implement the original system.     

Workers' intrinsic work motivation when job demands are high: The role of need for autonomy and perceived opportunity for blended working

Work overload or work pressure may undermine workers' intrinsic motivation. In the present research, we tested the conditions under which this may (not) occur, including the perceived opportunity to blend on-site and off-site working through the effective use of computers and modern information and communication technology. Our sample consisted of 657 workers (51% female) representing a variety of industries. As hypothesized, it is not high job demands per se, but high demands in combination with a high need for autonomy and a lack of perceived opportunities for blended working that undermines intrinsic work motivation. When workers high in need for autonomy perceived opportunities for blended working, their intrinsic work motivation was not negatively affected by increasing job demands. This main finding suggests that, particularly for workers high in need for autonomy, the perceived opportunity for blended working is an effective, contemporary resource to cope with the increasing job demands typically observed in today's workplace. Theoretically, these findings contribute to the refinement and extension of influential demands-resource models and Person-Job Fit theory. Practically, our findings may show managers how to effectively keep workers intrinsically motivated and productive in their jobs when job demands are high.     

Unconstrained optimal control of regular languages

This paper formulates an unconstrained optimal policy for control of regular languages realized as deterministic finite state automata (DFSA). A signed real measure quantifies the behavior of controlled sublanguages based on a state transition cost matrix and a characteristic vector as reported in an earlier publication. The state-based optimal control policy is obtained by selectively disabling controllable events to maximize the measure of the controlled plant language without any further constraints. Synthesis of the optimal control policy requires at most n iterations, where n is the number of states of the DFSA model. Each iteration solves a set of n simultaneous linear algebraic equations. As such, computational complexity of the control synthesis is polynomial in n.     

Integration of job shop control systems: A state-of-the-art review

This paper reviews important theoretical and practical developments in job shop control. The distinguishing feature of this paper is the identification and summary of important concepts and procedures useful for incorporation into computerized job shop control systems. The first section briefly examines the job shop control problem, and presents a broad outline of commonly used subproblems and methods. A review of the past work done in the areas of scheduling and sequencing, workload balancing, work flow structure analysis, and job shop capability evaluation is then presented. The final section lists important concepts and procedures for developing computer integrated job shop control systems.     

Learning demand and job autonomy of IT personnel: Impact on turnover intention

Information technology jobs require a significant amount of learning to maintain currency and perform expected activities, more so than in many other professions. The sheer volume of learning can increase work exhaustion, with a negative effect on turnover. However, jobs can be designed to provide a large amount of autonomy over pace and process in the hands of the IT employee. According to job demand and control models, the ability of an employee to pace oneself and make task decisions can lessen negative impacts. From another perspective, IT employees differ in their desires to learn as part of personal and career growth. Thus, negative effects of learning demand should be lessened by the IT employee’s motivation to learn, and motivation is a crucial antecedent in turnover models. A model based on the job demand-control model establishes and tests these relationships and finds them to hold in a sample of 306 IT employees. Work exhaustion is reduced by instilling job autonomy in the presence of learning demands and motivation, which then lessens turnover intentions of the IT workers.     

The development of a hybrid hierarchical/heterarchical shop floor control system applying bidding method in job dispatching

Advancement in computer technology has brought shop floor control into a new era. Hierarchical and heterarchical control structures are two of the most popular control frameworks applied by industries and academics. However, the loading on the central controller may be very heavy in a hierarchical control structure, as the number of equipment in the shop floor increases. On the other hand, in a heterarchical configuration, the inter-cell communication will be very busy making control strategies to achieve. In this research, a hybrid hierarchical/heterarchical structure is proposed. This approach reduces the loading on the shop floor controller by empowering each cell controller to determine the production schedules of its corresponding equipment. However, the shop floor controller still is responsible for the global conditions of the shop such as deciding the job finishing time and balancing the utilization rate of equipment. A bidding method based on the required production costs is also proposed and implemented under the developed control structure.     

Development of scheduling strategies in the TITAN operating system

Scheduling strategies are evolved to solve problems of selection in operating systems. Such strategies frequently undergo evolution in time as details of the specification are changed or, more frequently, as inadequacies in them are shown up by use in a heavily loaded system. This paper describes a number of scheduling strategies used in the TITAN system, and their development to meet changing circumstances or to overcome inadequacies.