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Application of level changing to a multilevel storage organization
A technique for organizing the devices of a computer storage system is described. This technique, called the multilevel store, provides a means for economically satisfying the requirements for very large storage capacities of certain data management and information retrieval systems. The concept of level changing is introduced and its application to the multilevel store is discussed. A possible means for physically organizing the information for efficient use of the multilevel store is presented.
Computer programming deals with an enormous variety of activities and is carried on by people with a great variety of backgrounds. It seems clear that part but not all of this activity is evolving toward a distinct professional field, but that the scope of this emerging profession, and some of its economic, social, and educational characteristics are as yet by no means well defined. In this paper, these issues are examined and some opinions about them are expressed.
On the automatic simplification of source-language programs
Methods of simplification that can be applied automatically to programs written in an ALGOL-like language are discussed. The simplifications are based on the form of the program and the knowledge obtained by a processor, without any understanding of what the program is supposed to do. These methods have been implemented in a processor called SURE that accepts a program written in JOVIAL and outputs an equivalent JOVIAL program that may be shorter and may be executed faster than the original.
SURE is described, some of the problems encountered in automatic improvement at the source-language level are discussed, and further types of automatic program improvement are suggested.
Examples of algorithms that will accomplish automatic storage reservation without the need for explicit array declarations are described.
DITRAN—a compiler emphasizing diagnostics
DITRAN DIagnostic FORTRAN) is an implementation of ASA Basic FORTRAN with rather extensive error checking capabilities both at compilation time and during execution of a program. The need for improved diagnostic capabilities and some objectives to be met by any compiler are discussed. Attention is given to the design and implementation of DITRAN and the particular techniques employed to provide the diagnostic features. The handling of error messages by a general macro approach is described. Special features which provide teaching aids for use by instructors are noted.
System performance evaluation: survey and appraisal
The state of the art of system performance evaluation is reviewed and evaluation goals and problems are examined. Throughput, turnaround, and availability are defined as fundamental measures of performance; overhead and CPU speed are placed in perspective. The appropriateness of instruction mixes, kernels, simulators, and other tools is discussed, as well as pitfalls which may be encountered when using them. Analysis, simulation, and synthesis are presented as three levels of approach to evaluation, requiring successively greater amounts of information. The central role of measurement in performance evaluation and in the development of evaluation methods is explored.
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