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.
