The Simulation of Time sharing Systems The development of new large scale time-sharing systems has raised a number of problems for computation center management. Not only is it necessary to develop an appropriate hardware configuration for these systems, but appropriate software adjustments must be made. Unfortunately, these systems often do not respond to changes in the manner that intuition would suggest, and there are few guides to assist in the analysis of performance characteristics. The development of a comprehensive simulation model to assist in the investigation of these questions is described in this paper. The resulting model has a general purpose design and can be used to study a variety of time-sharing systems. It can also be used to assist in the design and development of new time-sharing algorithms or techniques. For the sake of efficiency and greater applicability, the model was implemented in a limited FORTRAN subset that is compatible with most FORTRAN IV compilers. The use of the simulation is demonstrated by a study of the IBM 360/67 time-sharing system. CACM July, 1967 Nielsen, N. R. CA670701 JB February 28, 1978 9:15 AM 1572 5 1572 1572 5 1572 1572 5 1572 1805 5 1572 1846 5 1572 1892 5 1572 2188 5 1572 2218 5 1572 2317 5 1572 1198 6 1572 1380 6 1572 1380 6 1572 1424 6 1572 1484 6 1572 1518 6 1572 1526 6 1572 1572 6 1572 1572 6 1572 1572 6 1572 1572 6 1572 1572 6 1572 1572 6 1572 1693 6 1572 1728 6 1572 1728 6 1572 1748 6 1572 1749 6 1572 1751 6 1572 1751 6 1572 1753 6 1572 1752 6 1572 1752 6 1572 1781 6 1572 1810 6 1572 1879 6 1572 2095 6 1572 2126 6 1572 2148 6 1572 576 6 1572