Other GPSS versions
There are several other GPSS versions available. While IBM no longer supports GPSS, the two most widely used commercial versions are GPSS/H and GPSSWorld.
The main difference between WebGPSS and these commercial versions is
that these versions cater to an existing commercial customer base, often
requiring sophisticated features. They hence aim at being upwards
compatible with earlier GPSS versions, in fact going back to old IBM
versions. This has lead to these versions having many more block
types. Thus while WebGPSS has only 18 block types, GPSS/H has some 70
block types. Many of these block types in GPSS/H do roughly the same kind
of job. Thus LET in WebGPSS does the same job
as ASSIGN, BLET, INITIAL,
LET, PRIORITY, SAVEVALUE
and SELECT of GPSS/H.
WebGPSS on the other hand does not have to bother about an old
commercial customer base. Instead it has been continuously simplified
based on student feedback. When many students have found something
difficult to learn, we have changed the syntax. As an example, if you go
to BYE when then queue at Joe is already 4, we write in
WebGPSS: IF Q$Joe=4,BYE, while one in GPSS/H has to
write TEST NE Q$JoeQ,4,BYE.
Because of this, WebGPSS is much easier to learn. With WebGPSS one has been able to cover the same material in 10 hours that required 22 hours when using a commercial GPSS version.
Yet, WebGPSS is almost as powerful as these other GPSS versions. For example, all of Tom Schriber's famous Red book case studies and 99 percent of other GPSS textbook programs have been rewritten with the same amount of code in WebGPSS. WebGPSS has definitely proved to be powerful enough for student projects.
For the one percent of the cases when WebGPSS is weaker than GPSS/H,
(mainly lack of conditional UNLINK), we provide a software
that can translate the code of a WebGPSS program, so that it can run
under GPSS/H. One can then add specific GPSS/H statements
(like UNLINK) to the translated program.
In this way we believe that it will be easy to proceed from WebGPSS to commercial packages, not only to GPSS/H and GPSSWorld, but also to e.g. SLX and SIMAN/ARENA.
Further information on the history of GPSS and on different GPSS versions is provided in a paper.