Published: 07/26/68


MSPM - General Information

F. J. Corbató, A. L. Dean, P. G. Neumann, M. A. Padlipsky

The Multics System-Programmers' Manual (MSPM) has two basic functions: (1) during the design and implementation of the Multics (Multiplexed Information and Computing Service) system, it serves as the place in which to record current design plans, so that all those working on the project may be aware of these plans; and (2) when Multics has passed the initial implementation phase, it is to serve as a reference manual for the use of those charged with maintaining and expanding Multics systems at various sites. It is important to note, however, that the first of these functions must precede the second, in a very real, temporal sense. That is, it is a stated objective of Multics system development that sound engineering practice be applied to system design; as one of the dominant factors in such practice is the notion of iterative design, the MSPM of necessity cannot offer a totally accurate, up-to-date picture of the system while the design and implementation efforts are still in progress. Therefore, the MSPM must be viewed as an internal working document, for use of the three organizations (Project MAC, General Electric Corporation, and Bell Telephone Laboratories) jointly working on the Multics project, until such time as it is specifically released to the general public as being in "final" form -- where final is to be taken as meaning that it presents a consistent picture of the system at a particular, specified stage of development, and is not meant to imply that Multics is envisioned as ever becoming a static entity. (Indeed, the evolutionary quality of Multics, the ease of adding commands for example, is one of the primary design goals of the system.)

It is not intended that the above comments be taken to imply that the MSPM is to be treated as a "Confidential" document. Rather, they are to be taken as a warning to readers of the MSPM, both within and outside of the active membership of the project, that it is at present an evolving depiction of an evolving system. As such, it should not be employed as an absolute authority for deciding what Multics is: the specific discussion of any given area may have become outmoded a week or two ago, and may be replaced a week or two from now. As a matter of fact, it is a stated policy that documentation of modules which are known to be obsolete will be retained in the Manual until replacements are available; this is done on the grounds that somewhat outmoded information is better than no information at all. To put it another way, the MSPM is, after all, a manual for system-programmers.

Still the MSPM is intended to be as up-to-date as possible. Also it will eventually be released for more general distribution to serve the functions of a Multics reference manual and as technical documentation of the system design.