Fernando J. Corbató

Introduction and overview of the multics system

Multics (Multiplexed Information and Computing Service) is a comprehensive, general-purpose programming system which is being developed as a research project. The initial Multics system will be implemented on the GE 645 computer. One of the overall design goals is to create a computing system which is capable of meeting almost all of the present and near-future requirements of a large computer utility. Such systems must run continuously and reliably 7 days a week, 24 hours a day in a way similar to telephone or power systems, and must be capable of meeting wide service demands: from multiple man-machine interaction to the sequential processing of absentee-user jobs; from the use of the system with dedicated languages and subsystems to the programming of the system itself; and from centralized bulk card, tape, and printer facilities to remotely located terminals. Such information processing and communication systems are believed to be essential for the future growth of computer use in business, in industry, in government and in scientific laboratories as well as stimulating applications which would be otherwise undone.

An experimental time-sharing system

It is the purpose of this paper to discuss briefly the need for time-sharing, some of the implementation problems, an experimental timesharing system which has been developed for the contemporary IBM 7090, and finally a scheduling algorithm of one of us (FJC) that illustrates some of the techniques which may be employed to enhance and be analyzed for the performance limits of such a time-sharing system.

Multics: the first seven years

In 1964, following implementation of the Compatible Time-Sharing System (CTSS) serious planning began on the development of a new computer system specifically organized as a prototype of a computer utility. The plans and aspirations for this system, called Multics (for Multiplexed Information and Computing Service), were described in a set of six papers presented at the 1965 Fall Joint Computer Conference. The development of the system was undertaken as a cooperative effort involving the Bell Telephone Laboratories (from 1965 to 1969), the computer department of the General Electric Company, and Project MAC of M.I.T.

Structure of the multics supervisor

This paper is a preliminary report on a system which has not yet been implemented. Of necessity, it therefore reports on status and objectives rather than on performance. We are impelled to produce such a prospectus by two considerations. First, time-sharing and multiprogramming are currently of great interest to many groups in the computing fraternity; a number of time-sharing systems are now being developed. Discussion of the issues and presentation of goals and techniques is valuable only if it is timely, and the appropriate time is now. Second, every large project undergoes a subtle alteration of goals as it proceeds, extending its aims in some areas, retracting them in others. We believe it will prove valuable to us and others to have on record our intentions of 1965, so that in 1966 and 1967 an unambiguous evaluation of our successes and failures can be made.

Generation of Spherical Bessel Functions in Digital Computers

A method of computation for spherical Bessel functions of real and imaginary argument is given which is especially suitable for high speed digital computers. The accuracy and convergence are examined and criterion formulas are given. A procedure based on the Wronskian is used to simplify the final normalization.

On building systems that will fail

for his work in organizing the concepts and leading the development of the general-purpose large-scale time-sharing and resource-sharing computer systems CTSS and MULTICS

The Project MAC interviews

On the day following the Celebration of the 25th anniversary of Project MAC held in Cambridge on October 16 and 17, 1988, two small groups of participants in the developments of CTSS and Project MAC met to exchange recollections about their activities. These interviews are separated into two parts, concentrating on each of the two developmental stages of time-sharing, although it was impossible to strictly maintain the separation since the discussions naturally overlapped the time periods. By choice, the interviewers guided the discussion to concentrate on the more personal and background aspects of this history, since the technological history has been well documented in the open literature.

On computer system challenges

When one considers open problems in Computer Science, it is important to recognize that, in contrast to the neat well-defined problems of the theoretical side of Computer Science, Computer Systems deal with engineering systems that meet societal needs. Solutions often change with time and frequently require evolution and adaptation. As computers have become ubiquitous in our society over the last fifty years, they have become more and more interconnected, culminating in the Internet and the World Wide Web. Not surprisingly, these changes have had great social and political impact and seem likely to evolve at a rapid pace for many decades. Nevertheless, even though today we are far from a stationary computer and network infrastructure, it is possible to identify a few fundamental challenges that should be addressed. All of these problems have been identified before by others, and indeed there is a great deal of current activity in both research and development, but I believe it is useful to spotlight these central challenges. First, there is a problem of trustworthiness and authentication. Even within an isolated computer, one cannot be sure that the system behavior will be correct if the programs and system are not potentially open for inspection and verification. In particular, black-box systems are a major difficulty because they require blind faith. For example, we see this playing out in criticisms of electronic voting systems with proprietary software. But trustworthiness is especially a problem when interacting over the Internet. Today, every user must make assumptions about the identity of those he or she is interacting with since the network infrastructure and protocols in use allow header information to be forged. One egregious problem arising from the current loose framework of authentication is the near-exponential rise of spam (i.e., junk mail). It seems clear that within a few years unless some major engineering changes are made, the convenient use of electronic mail will be destroyed by irresponsible spammers drowning out meaningful communication. Second, there is the challenge of governance of international information exchange. Today’s Internet is governed in a de facto sense by the control of the domain name server machinery and by the agreed-upon protocols of network messages. At present, managing the Internet is like governing without a constitution. This challenge may appear entirely political, but effective solutions require good technical support such as the development of the Open Source movement, the infrastructure of anonymous servers, and cryptographic tools to avoid tyrannical control over the free flow of information. A third challenge is the need to create permanent information that is capable of being retained indefinitely for millennium after millennium. What makes this problem critical is that most records and documents today are stored digitally without any paper records. There are projects addressing this problem but the difficulties are daunting. Electronic media are fragile: magnetic tapes have lifetimes measured in decades at most and CDs are only good at best for a few centuries; there is no

Project MAC (time-sharing computing project)

The history of Project MAC from its inception is reviewed. It is noted that the story of Project MAC is a continuation of that of CTSS (Compatible Time-Sharing System), marking the transfer of an experimental system into the practical academic field and thence into the commercial field. Two men were key to this recognition of the value of the work by Corbato et al.-J.C.R. Licklider and R.M. Fano. Lickliders early concepts of man-computer symbiosis were identified as being supportive of the ideas which led to the development of CTSS, and his relocation to the Advanced Research Projects Agency (ARPA) puts him in a position to do something about his aspirations. Excerpts from reports dealing with Project MAC are presented.<<ETX>>

CTSS-the compatible time-sharing system

Excerpts are presented from a 1962 paper by Fernando Corbato, M. Merwin-Daggett, and R.C. Daley. The selection from the paper, which reported work completed in late 1961, is reprinted from Proc. Spring Joint Computer Conf., vol.21, 1962. In this system, the time-sharing occurs among four users, three of whom are online each at a typewriter in a foreground system, and a fourth passive user of the background FAP-MAD-MADTRAN-BSS Monitor System used by most of the MIT Computation Center programmers and by many other 7090 installations.<<ETX>>