INTRODUCTION

In an attempt to better understand the functionality and interaction of system components for the STAR Trigger, a behavioral simulation has been developed. The simulation architecture is based on that presented in the documents Trigger Level 0 Architecture and Trigger Level 1 and 2 Architecture by Krista Marks and Volker Lindenstruth , respectively. With this simulation we are able to study the effect upon the trigger system of varying certain parameters, including collision rate and distribution, throttle methodologies, trigger level CPU analysis time, buffer sizes, bandwidth, error conditions, etc.

The object-oriented simulation language MODSIM II has been used exclusively in the development of the model. MODSIM II is a general purpose modular, block structured high level programming language which provides direct support for object-oriented programming and discrete-event simulation. It has built in functions for advancing time, scheduling events, manipulating objects, generating random numbers, collecting statistical data and generating reports.

In MODSIM, simulation time is evolved by performing various WAIT procedures, where some process is simulated merely by WAITING some period of time. For instance, analysis of an event for a Level 1 Cpu is simulated as a WAIT period of a given length which represents the time it takes to process an event in actual hardware. The terminology of WAITING will be utilized throughout this document.

Goals for the simulation include:

• Determine throughput, deadtime, trigger efficiency as affected by the various input parameters mentioned previously.

• Identify potential bottlenecks and how these are affected by bandwidth, buffer sizes, etc.

• Explore the effect of throttle methods on the system.