HISTORY OF HISTORY OF SIMULATION SIMULATION SOFTWARESOFTWARE

• History of simulation software is based on Nance[1995].

• Breaks the years 1955 to 1986 in to 5 periods.

• 1955-60 : The Period of Search • 1961-65 : The Advent • 1966-70 :The Formative Period • 1971-78 : The Expansion Period• 1979-86 : The period of Consolidation

and Regeneration

• Later one more period is added which is most recent period:

• 1987-Present:The Period of

Integrated Environment

The Period Of Search (1955-The Period Of Search (1955-60)60)

• Much effort was expended in the search of :

• Unifying concepts and• Developments of reusable routines to

facilitate simulation.

The Advent (1961-65)The Advent (1961-65)• The simulation programming lang. in

use today appeared in this period.• In the beginning there were:• FORTRAN: Based on packages such

as SIMSCRIPT & GASP (General Activity Simulation program )

• ALGOL : Descendent of SIMULA • GPSS (General Purpose Simulation

System )

• The first process interaction SPLs:• GPSS (General Purpose Simulation

System )• It is used for quick simulation of

communication and computer systems.

• GPSS got popularity due to easy in use.

• It based on block diagram representation similar to process flow diagram and is suited for queuing models of all kind.

• SIMSCRIPT(1963) which is influenced by FORTRAN but later it uses its own SPL.

• It is based on event scheduling.

• GASP(1961) based on ALGOL but later it based on FORTRAN.

• GASP also used flow chart symbols • It is not a language proper but a

collection of FORTRAN ROUTINES

The Formative PeriodThe Formative Period(1966-70 )(1966-70 )

• Concepts are reviewed and refined to promote a more consistent representation of each language’s world view.

• In this period due to rapid H/W advancement and user demands forced GPSS to undergo major revision:

• GPSS/360:Extension to earlier version of GPSS.

• Emerged for the IBM 360 computer.

• SIMSCRIPT II: it having adv in SPLs with its free from English-like language and forgiving compiler.

• ECSL, descendent of CSL was developed.

The Expansion Period (1971-The Expansion Period (1971-78)78)

• Effort were made this period to attempt to simplify the modeling process.

• GPSS/NORDEN: a pioneering effort that offered an interactive, visual online environment.

• GPSS/H(1977): for IBM Mainframes, later for minicomputers and PC.

• It compiled and reportedly 5-30 times faster than standard GPSS with interactive debugging.

• GASP –IV(1971): It uses state events in addition to time event.

Consolidation and Consolidation and Regeneration(1979-86) Regeneration(1979-86)

• It is beginning of SPL ,written for, or adapted to desktop computers and the microcomputers.

• GASP appeared:1)SLAM II2)SIMAN

• SLAM (Simulation Language for Alternative Modeling ) provide multiple modeling perspectives and combined modeling capabilities.

• SIMAN (SImulation ANalysis ) proposed a general modeling capability found in SPLs such as GPSP-IV,but it also had a block diagram component similar in some respect to SLAM and GPSS.

• It run under MS-DOS constraints.

The Present PeriodThe Present Period(1987-Present)(1987-Present)

• For the growth of SPLs on personal computer and the emergence of simulation environments with graphical user interfaces, animation and other visualization tools.

• Many of these environment also contain input data and output data analyzer.