Leon Presser

Linkers and Loaders

This is a tutorial paper on the linking and loading stages of the language transformation process First, loaders are classffied and discussed Next, the hnking process is treated in terms of the various times at whmh it may occur (i e , binding to logical space). Finally, the hnking and loading functmns are explained m detail through a careful examination of their implementation m the IBM System/360 Examples are presented, and a number of possible system trade-offs are pointed out.

Multiprogramming Coordination

This is a tutorial paper on the coordination of parallel activities It commences with an overview of multiprogrammed operating systems that uncovers an architecture consisting of cooperating, but competing processes working in parallel This is followed by a formal treatment of processes, and an analysis of the fundamental coordination needs of concomitant processes. The analysm leads to a set of two coordination primitives originally defined by Dijkstra. In the rest of the paper, an evolutionary series of examples of increasing coordination complexity is formulated and solved. As the various examples are discussed, cumulative extenmons to the original set of coordination primitives are justified and formally defined.

An Algorithm for the Design of Simple Precedence Grammars

A practical incremental algorithm for transforming an arbitrary context-free grammar into an equivalent grammar with unique precedence relations between any two symbols in its vocabulary is presented, illustrated, and proved. The algorithm has been employed as a tool in the design and implementation of programming languages. It has also served as an effective instructional aid. It is assumed that the reader is familiar with basic concepts in formal language theory.

Structured languages

A design process is a highly creative undertaking that has been generally guided by personal experiences and gross rules of design. This fact has been made explicit and at present the essence of the process of design is under investigation. This important problem is receiving attention in Computer Science. In particular, disciplined program design and development is the center of much discussion.

A tool for enforcing system structure

Reliability considerations had little influence in the design of the first generation of computers. Notable exceptions being, on the hardware side, some circuitry incorporated into the UNIVAC I for checking purposes, and on the software side, the frequency counts employed by von Neumann and Goldstine for measurement purposes. The second generation of computers witnessed a wider interest in hardware reliability while essentially ignoring the software reliability problem. Current computer systems (e.g., IBM/370) incorporate elaborate hardware reliability considerations in their design while continuing to ignore reliable software design.

Dynamic memory repacking

A probabilistic model of a multiprogramming system is exercised in order to determine the conditions under which the dynamic repacking of main memory is beneficial. An expression is derived for the maximum interference that a repacking process may introduce before the original performance of the system is degraded. Alternative approaches to repacking are discussed, and the operating conditions that lead to improved system throughput through repacking are delineated.

Comments on a Paper by Gaver

In a 1967 publication, D. P. Gaver studied a probabilistic model of a multiprogramming computer system. His results have been utilized recently by a number of authors. However, we have observed that Gavers results contain inconsistencies. These inconsistencies are discussed in detail and a correction suggested and verified through an independent derivation.