Reliability in Computer Systems [chapter]

1999 Design Reliability  
The research and development program to be carried out by Project MAC was characterized in the first proposal as follows* The broad, long-term objective of the program is the evolutionary development of a computer system easily and independently accessible to a large number of people and truly flexible and responsive to individual needs. An essential part of this objective is the d«velopment of improved input, output and display equi£>ment, of programming aids, of public files and subroutines,
more » ... nd of the overall operational organization of the system. A second, concomitant objective is the fuller exploitation of computers as aids to research and education, through the promotion of closer man-machine interaction. The second objective is not only important by itself, but is also essential to the development of the computer system envisioned above, and vice versa-The third objective, which must be part of any university activity, is the long-range development of national manpower assets through education in the pertinent area: of faculty as well as of students, and outside M. I.T. as well as within the confines of the campus-Again, this third objective is inextricably interwoven with the preceding two, because people's approach to problems will have to evolve in parallel with the computer hardware and software. The initial MAC computer system became operational in November 1963. It was a copy of the Compatible Time Sharing System [1], based on a modified IBM 7094 computer, which had been developed in the M. I. T. Computation Center under the leadership of Professor F-J-Corbato. The first version of this pioneering tim«-ahuing system {2], on an IBM 709 computer, had been publicly demonstrated in November 1961 and a much improved version, including disk mass storage, was in daily operation on aa IBM 7094 computer by the summer of 1963. The new MAC system was established to spur the evolution of an on-line research community, and it did not replace the similar computer installation in the M.I.T. Computation [340] PROJECT MAC Center. The latter, which had to provide more traditional batch-processing service to the M.I.T. community, could be operated in a time-sharing mode only part of the time. The original MAC computer system was considerably improved and extended in the following 2 years and remained in operation until July 1973. The goal of developing an on-line research community was achieved within the first 6 months of operation of the MAC eompntpr system, as evidenced by the table of contents of the July 1964 progress report reproduced in Appendix A. By that time the system was serving some 200 users from 10 different academic departments. As many as 24 users could be using the system simultaneously from any one of some 100 teletypewriter terminals connected to the system through the M.I.T. telephone switching plant. Some of these terminals were located in the homes of researchers. Access to the MAC system could also be gained through the telex and TWX telegraph networks; test3 and demonstrations had already been conducted from the West coast and even from European locations. The MAC system included, by then, the initial model of a multiple display system for computer-aided design [3] developed by the M.I.T. Electronics Systems Laboratory. This system included oscilloscope displays with character generator and light pen and also hardware facilities for rotating in three dimensions the image displayed. The MAC system itself was in continuous operation except for the periods of time required for preventive maintenance and for generating back-up copies on magnetic tape of the users' files stored on disks-Software facilities included some 68 system commands and amounted to some half a million words of machine code. Users' private files occupied, by then, most of two disk files with a total capacity of 13 million words. The following quotations from a report on the MAC system 14], presented orally in June 1964, characterize some of the evidence that emerged from the first 6 months of operation. ' "i
doi:10.1201/9781420050141.ch12 fatcat:z6ijr2725fh3rmpv7et2gqs2z4