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5. Programming problems and languages and processor design considerations......
5.1.1. Problems of very large programs and of program documentations......
6.2. Batch fabrication and integrated circuits......
6.3. Advanced data storage developments..
6.3.1. Main memories...............
6.3.2. High-speed, special-purpose, and associative or content-addressable
6.3.3. High-density data recording and storage techniques........
7. Debugging, on-line diagnosis, instrumentation, and problems of simulation........ 7.1. Debugging problems.......
7.2. On-line diagnosis and instrumentation.....
List of Figures
Figure 1. A generalized information processing system..
Research and Development in the Computer and Information Sciences
3. Overall System Design Considerations:
A Selective Literature Review
Mary Elizabeth Stevens
This report, the third in a series on research and development efforts and requirements in the computer and information sciences, is concerned with a selective literature review involving overall system design considerations in the planning of information processing systems and networks. Specific topics include but are not limited to: requirements and resources analysis, problems of system networking, input/output and remote terminal design, character sets, programming problems and languages, processor design considerations, advanced hardware developments, debugging and on-line diagnosis or instrumentation, and problems of simulation. Supplemental notes and a bibliography of over 570 cited references are included.
Key words: Data recording; debugging; holography; information control; input-output; integrated
This is the third in a planned series of reports involving selective literature reviews of research and development requirements and areas of continuing R & D concern in the computer and information sciences and technologies. In the first report,* the background considerations and general purposes intended to be served by the series are discussed. In addition, the general plan of attack and certain caveats are outlined.**
In the first two reports in this series, we have been concerned with generalized information processing systems as shown in Figure 1, more particularly these reports were concerned respectively with information acquisition, and sensing, and input operations and with information processing, storage, and output requirements. In this report we will be concerned with some of the overall system design considerations affecting more than one of the processes shown, such as programming languages, remote terminals used both for input and output, and advanced hardware developments generally.
Affecting all of the system design requirements for specific functions of generalized information processing systems are those of hierarchies and interaction of systems, and of effective access-response languages; the client, system-configuration, and system-usage considerations (especially in terms of multiple-access, time-shared systems), and of system evaluation, including such on-going "evaluations" as debugging aids and on-line instrumented checking or monitoring facilities.
Under overall system design requirements, we are concerned with input-output capabilities and terminal display and control equipment, with processor and storage systems design, with advanced technological developments, with programming language requirements, and with problems of online debugging, client protection, instrumentation, and simulation.
First, however, let us consider some of the overall system design considerations involved in requirements and resources analysis and in problems of system networking.
2. Requirements and Resources Analyses
The introduction of automatic data processing techniques has not changed the kind of fact-finding, analysis, forecasting, and evaluation required for
*Information Acquisition, Sensing, and Input: A Selective Literature Review. **Appendix A of this report contains notes and quotations pertinent to the running text. For the convenience of the reader, notes "1.1" and "1.2" recapitulate some of the considerations discussed in the first report. Appendix B provides a bibliography of cited references.
effective systems planning and implementation; it has changed the degree, particularly with respect to extent, comprehensitivity, detail in depth, and questions of multiple possible interrelationships. For example, a "single information flow" concept becomes realizable to an extent not possible before. On the other hand, distributed 2.2 and decentralized
systems also become more practical and efficient because of new possibilities for automatic control of necessary interactions.
A major area of continuing R & D concern with respect to both requirements and resources analysis is that of the development of more adequate methodologies.2.3 Nevertheless, the new business on the agenda of the national information scene - that is, the challenge of system networking-offers new possibilities for a meshing of system design criteria that have to do with where and how the system is to be operated and with where and how it is to be used.
2.1. Requirements Analysis
Requirements analysis, as an operational sine qua non of system design, begins of course with suitable assessment of present and potential user needs. Elsewhere in this series of reports, some embarrassingly critical commentaries with respect to actual or prospective usage are selectively covered.2.4 Assuming, however, that there are definitive needs of some specifiable clientele for processing system services that can be identified, we must first attempt some quantifiable measures of what, who, when, where, and why, the information-processing-systemservice requests are to be honored.2.5 In particular, improved techniques of analysis with respect to clientele requirements, information control requirements, and output and cost/benefit considerations are generally desired.
2.1.1. Clientele Requirements
It is noted first that "lack of communication between the client, that is, the man who will use the system, and the system designer is the first aspect of the brainware problem." (Clapp, 1967, p. 3). Considering the potential clients as individual users of an information processing system or service, the following are among the determinations that need to be made: 2.6
1. Who are the potential users? 2. Where are they located? 2.7
3. If there are many potential users, user groups, and user communities, how do needs for information and for processing services differ among them? 2.8
4. What are the likely patterns and frequencies of usage for different types of potential clients?
5. To what extent are potential clients both motivated and trained to use the type of facilities and services proposed? 2.9
However obvious these and other requirements analysis considerations may be, a present cause of critical concern is the general lack of experimental evidence on user reaction, user behavior, and user effectiveness.2.10
2.1.2. Information Control Requirements Detailed consideration and decision-making with respect to controls over the quality and the quantity
of information input, flow, processing, storage, retrieval, and output are essential to effective system design. Davis in a late 1967 lecture discussed many of the multifacetted problems involved in information control-in both system planning and system use. The varied aspects range from questions of information redundancy in information items to be processed and stored to those of error detection and correction with respect to an individual item record as received, processed, stored, and/or retrieved.
Among these information control requirements are: input and storage filtering and compression; quality control in the sense of the accuracy and reliability of the information to be processed in the system; questions of file integrity and the deliberate introduction of redundancy; problems of formatting, normalization, and standardization, and error detection and error correction techniques.
More particularly, Davis (1967) is concerned with problems of information control in a system with the following characteristics:
"1. It has several groups of users of differing administrative levels.
"2. The information within the system has imposed upon it varying privacy, security and/or confidentiality constraints.
"3. The information entering the system is of varying quality with respect to its substantive content; that is, it may be raw or unevaluated, it may have been subjected to a number of evaluation criteria or it may be invariant (grossly so) as standard reference data. "4. The user audience is both local and remote. "5. Individual users or user groups have individual access to the information contained within the system.
"6. The information within the system is multisource information.”
(Davis, 1967, p. 1-2).
We may note first the problems of controls that will govern the total amount of information that is to be received, processed, and stored in the system. These may consist of input filtering operations 2.11 as in sampling techniques applied to remote data. acquisition processes 2.12 or in checking for duplications and redundancies in the file.2.13
Other information control requirements with respect to the total amount of information in the system relate to problems of physical storage access, withdrawals and replacements of items to and from the store, maintenance problems including questions of whether or not integrity of the files must be provided (i.e., a master copy of each item accessible at all times),2.14 provisions for the periodic purging of obsolete items,2.15 revisions of the file organization in accordance with changing patterns of usage,2.16 response requirements,2.17 and requirements for display of all or part of an item and/or indications of its characteristics prior to physical retrieval.2.18
Another important area of information control is that of identification and authentication of material