Daniel L. Murphy

TENEX, a paged time sharing system for the PDP - 10

TENEX is a new time sharing system implemented on a DEC PDP-10 augmented by special paging hardware developed at BBN. This report specifies a set of goals which are important for any time sharing system. It describes how the TENEX design and implementation achieve these goals. These include specifications for a powerful multiprocess large memory virtual machine, intimate terminal interaction, comprehensive uniform file and I/O capabilities, and clean flexible system structure. Although the implementation described here required some compromise to achieve a system operational within six months of hardware checkout, TENEX has met its major goals and provided reliable service at several sites and through the ARPA network.

Structure of a LISP system using two-level storage

In an ideal list-processing system there would be enough core memory to contain all the data and programs. Described in this paper are a number of techniques that have been used to build a LISP system utilizing a drum for its principal storage medium, with a surprisingly low time penalty for use of this slow storage device. The techniques include careful segmentation of system programs, allocation of virtual memory to allow address arithmetic for type determination, and a special algorithm for building reasonably linearized lists. A scheme for binding variables is described which is good in this environment and allows for complete compatibility between compiled and interpreted programs with no special declarations.

Storage organization and management in TENEX

In early 1969, BBN began an effort aimed at developing a new time-shared operating system. It was felt at the time that none of the commercially available systems could meet the needs of the research planned and in progress at BBN. The foremost requirement of the desired operating system was that it support a directly addressed process memory in which large list-processing computations could be performed. The cost of core storage prohibited the acquisition of sufficient memory for even one such process, and the problems of swapping such very large processes in a time-sharing environment made that solution technically infeasible as well.

TENEX, a paged time sharing system for the PDP-10

This paper appears in the March, 1972, issue of the Communications of the ACM. Its abstract is reproduced below. TENEX is a new time sharing system implemented on a DEC PDP-10 augmented by special paging hardware developed at BBN. This report specified a set of goals which are important for any time sharing system. It describes how the TENEX design and implementation achieve these goals. These include specifications for a powerful multiprocess large memory virtual machine, intimate terminal interaction, comprehensive uniform file and I/O capabilities, and clean flexible system structure. Although the implementation described here required some compromise to achieve a system operational within six months of hardware checkout, TENEX has met its major goals and provided reliable service at several sites and through the ARPA network.

A note on the efficiency of a LISP computation in a paged machine

The problem of the use of two levels of storage for programs is explored in the context of a LISP system which uses core memory as a buffer for a large virtual memory stored on a drum. Details of timing are given for one particular problem.

Applications and extensions of the TENEX operating system

The TENEX system was developed in 1969 to serve as a powerful, flexible, yet inexpensive research facility. It provides virtual memory, a hierarchy of processes within each job, a pseudointerrupt system for interprocess communication, and a highly human-engineered command language. This system has become such a popular research tool that there are (as of January 1974) 12 TENEX systems in operation. Ten of these TENEX systems are hosts on the ARPANET, a national computer resource sharing network developed by the D.O.D. Advanced Research Projects Agency.