GPSS World Reference

Manual

Table of Contents

Preface xvii

Product Description

About This Manual

Chapter 1 - Introduction

1.1. Highlights

1.2. GPSS World Concepts

1.3. Architecture

1.4. The Modeling Language

1.5. Compatibility

Chapter 2 - Operating GPSS World

2.1. File Directories

2.2. Installation

2.3. The GPSS World Environment

Chapter 3 - Model Statements

3.1. Using Model Statements

3.2. GPSS Statements

3.3. Fields

3.4. Expressions

3.5. Names

3.6. Numbers

3.7. Using Strings

Chapter 4 - GPSS Entities

4.1. Transaction Entities

4.2. Block Entities

4.3. Facility Entities

4.4. Function Entities

4.5. Logicswitch Entities

4.6. Matrix Entities

4.7. Queue Entities

4.8. Storage Entities

4.9. Savevalue Entities

4.10. Table Entities

4.11. Userchain Entities

4.12. Variable Entities

4.13. Numeric Group Entities

4.14. Transaction Group Entities

4.15. Random Number Generators

4.16. Data Streams

4.17. Continuous Simulation

Chapter 5 - GPSS World Windows

Chapter 6 - Commands

BVARIABLE

CLEAR

CONTINUE

EQU

EXIT

FUNCTION

FVARIABLE

HALT

INCLUDE

INITIAL

INTEGRATE

MATRIX

QTABLE

REPORT

RESET

RMULT

SHOW

START

STEP

STOP

STORAGE

TABLE

VARIABLE

Chapter 7 - Block Statements

ADOPT

ADVANCE

ALTER

ASSEMBLE

ASSIGN

BUFFER

CLOSE

COUNT

DEPART

DISPLACE

ENTER

EXAMINE

EXECUTE

FAVAIL FUNAVAIL GATE GATHER GENERATE INDEX INTEGRATION JOIN

LEAVE

LINK

LOGIC

LOOP

MARK

MATCH MSAVEVALUE OPEN

PLUS

PREEMPT

PRIORITY

QUEUE

READ

RELEASE

REMOVE

RETURN

SAVAIL

SAVEVALUE

SCAN

SEEK

SEIZE

SELECT

SPLIT

SUNAVAIL

TABULATE

TERMINATE

TEST

TRACE

TRANSFER

UNLINK

UNTRACE

WRITE

Chapter 8 - PLUS

8.1. Defining PLUS Procedures

8.2. The Language

8.3. The Procedure Library

8.3.1. Utility

Procedures

8.3.2. Math

Procedures

8.3.3. Query

Procedures

8.3.4. String

Procedures

8.3.5. Probability

Distributions

Chapter 9 - Advanced Topics

9.1 Transaction Chains

9.2 The Transaction Scheduler

9.3 Synchronization

9.4 Preemption and Displacement

9.5 Interfacing with External Programs Chapter 10 - Performance Tips

10.1 Memory Allocations

10.2 Identifying Congestion Points

10.3 Operating Tips

10.4 Modeling Tips

Chapter 11 - Standard Reports

11.1 Report Management

11.2. Sample Report

11.3 Standard Report Items

Chapter 12 - Statistics

12.1 Collecting Statistics

12.2 Space-Time Products

Chapter 13 - Troubleshooting

13.1. Problems Operating GPSS World

13.2. Debugging

13.3. Error Messages

Appendix

1.1. GPSS Grammar

1.2. PLUS Grammar

Glossary

GPSS WORLD REFERENCE MANUAL

© Copyright 2000 Minuteman Software.

Holly Springs, NC, U.S.A.

All Rights Reserved.

The software described in this manual is furnished under license and may be used or copied only in accordance with the terms of the license agreement.

Minuteman Software

P.O. Box 131

Holly Springs, NC 27540-0131 U.S.A.

GPSS Worldtm is a high powered general purpose computer simulation environment, designed for simulation professionals. It is a comprehensive modeling tool covering both discrete and continuous computer simulation, with an extremely high level of interactivity and visualizability.

Using GPSS World, it is possible to predict the effects of design decisions on extremely complex real world systems.

This manual contains information on the use of the GPSS World application program, and is the primary reference for the version of the GPSS language implemented by GPSS World.

The first part of the manual shows you all you need to know in order to make full use of the features of the GPSS World application program. The last part of the manual contains a detailed description of each GPSS Statement and a variety of information that may be useful as you become experienced with the use of GPSS World. Most of this manual is acessible via the online Help facility of GPSS World.

A companion manual, entitled GPSS World Tutorial, is included in the documentation set. It contains an introduction to simulation with GPSS, followed by suggested sessions involving many different sample models. You may find one or more examples that correspond closely to your own simulation

problems.

How To Get Started

If you are familiar with GPSS and do not wish to go through all the features offered by GPSS World, after you have installed

GPSS World according to the instructions in Chapter 2, you should work through the manual entitled GPSS Worldtm

Tutorial.

Then, as questions arise, refer to the Statement descriptions in

Chapters 6, 7, and 8 of this manual. The Online Help feature can save you the trouble of looking up the details of individual

Statements. You can start the Online Help system by pressing l , by pushing a Help button, or by choosing from the Help menu. You can reach context sensitive help by placing the

menu selection cursor over the menu item, and then pressing

l.

To get the maximum benefit of GPSS World, you need to be aware of all it has to offer. This is best done by working through the GPSS World Tutorial Manual, and then the GPSS World Reference Manual. We suggest that you experiment with new features until you are comfortable with them.

The Parts of This Manual

This manual begins with general information. It then proceeds to material of increasing detail.

∙Chapters 1 and 2 contain introductory material about GPSS World, the manual, and some concepts you will need.

∙Chapters 3 and 4 describe the most important aspects of the GPSS language.

∙Chapter 5 contains the detailed descriptions of the windows of GPSS World.

∙Chapters 6, 7, and 8 comprise the reference section. They contain detailed descriptions of each of the Commands, Block Statements, and PLUS Facilities, respectively.

∙Chapter 9 contains many details of the programming of GPSS World. Generally only experienced GPSS modelers will use the material in this chapter.

∙Chapter 10 contains information on how to get the most from your simulations. It contains performance tips and other information you may find useful.

∙Chapter 11 describes the Report Management

Facilities, and the Standard Reports produced by GPSS World.

∙Chapter 12 discusses the statistics generated automatically by GPSS World.

∙Chapter 13 contains the error messages, explanations, and remedial actions.

∙Finally, the Appendix contains a description of the formal grammar, and a short glossary.

Some readers will appreciate the formal grammar description in the Appendix. Most of the elements of the GPSS dialect used with GPSS World are defined formally there. The forms of an operand which are acceptable are given under the appropriate Statement description in Chapter 6, 7, or 8.

How This Manual Describes Actions

Concepts with meaning specific to GPSS World are capitalized.

For example, the Current Events Chain is a specific construct with a special meaning. When words are used generically, and do not refer to a particular item, they are not capitalized.

Actions you are asked to make immediately, are represented by verbs in uppercase. For example, when you see PRESS, CHOOSE, CLICK, DOUBLE CLICK, SELECT, or TYPE, you are to perform the action, yourself. When actions are referred to, but you are not asked to do them immediately, the verbs are shown in lower case.

Words representing objects or denoting concepts specific to GPSS World, are often shown in italics for emphasis, when first encountered, or capitalized when used frequently. For example, SHOW is an Immediate Command.

Keystrokes you are required to make are indicated by a special font which encloses the name of the key in an outline. For

example, "PRESS e" means that you are to press the key labeled "Enter" on your keyboard.

When more than one key must be used, the key symbols are

separated by a plus. For example, b + a + H means that you

are to press and hold the left key, while you press and release the right ones.

Mouse actions are required when the capitalized phrases

CLICK or DOUBLE CLICK appear. This means that you are to