<s>
General	O
Purpose	O
Simulation	B-Language
System	O
(	O
GPSS	B-Language
)	O
is	O
a	O
discrete	O
time	O
simulation	B-Language
general-purpose	B-Language
programming	I-Language
language	I-Language
,	O
where	O
a	O
simulation	B-Language
clock	O
advances	O
in	O
discrete	O
steps	O
.	O
</s>
<s>
It	O
is	O
used	O
primarily	O
as	O
a	O
process	O
flow	O
oriented	O
simulation	B-Language
language	I-Language
;	O
this	O
is	O
particularly	O
well-suited	O
for	O
problems	O
such	O
as	O
a	O
factory	O
.	O
</s>
<s>
GPSS	B-Language
was	O
developed	O
by	O
IBM	O
's	O
Geoffrey	O
Gordon	O
at	O
the	O
beginning	O
of	O
the	O
1960s	O
.	O
</s>
<s>
He	O
named	O
it	O
Gordon	B-Language
's	I-Language
Programmable	I-Language
Simulation	I-Language
System	I-Language
.	O
</s>
<s>
The	O
original	O
releases	O
were	O
for	O
IBM	O
's	O
7044	B-Device
&	O
7090	B-Device
mainframes	O
.	O
</s>
<s>
there	O
were	O
releases	O
for	O
IBM	B-Application
360	I-Application
,	O
</s>
<s>
Over	O
time	O
,	O
other	O
implementations	O
,	O
in	O
other	O
languages	O
and	O
targeted	O
at	O
different	O
size	O
systems	O
,	O
were	O
developed	O
,	O
including	O
DEC	O
's	O
VAX	O
,	O
a	O
specialized	O
APL	B-Language
version	O
for	O
large-scale	O
Univac	O
systems	O
,	O
and	O
Macintosh	B-Device
,	O
among	O
others	O
.	O
</s>
<s>
GPSS	B-Language
(	O
Java	B-Language
General	O
Purpose	O
Simulation	B-Language
System	O
)	O
is	O
a	O
Java-based	O
tool	O
that	O
was	O
developed	O
to	O
teach	O
the	O
GPSS	B-Language
simulation	B-Language
language	I-Language
.	O
</s>
<s>
GPSS	B-Language
resembles	O
a	O
LEGO	B-Language
structure	O
where	O
blocks	O
are	O
chosen	O
by	O
the	O
modeller	O
for	O
specific	O
functions	O
to	O
imitate	O
a	O
particular	O
system	O
.	O
</s>
<s>
GPSS	B-Language
automatically	O
keep	O
track	O
of	O
statistics	O
which	O
brings	O
in	O
fixed	O
form	O
at	O
the	O
end	O
of	O
a	O
simulation	B-Language
as	O
standard	O
report	O
.	O
</s>
<s>
GPSS	B-Language
is	O
one	O
of	O
the	O
oldest	O
language	O
candidate	O
of	O
first	O
object-oriented	O
approach	O
because	O
while	O
transactions	O
are	O
truly	O
instances	O
of	O
model	O
objects	O
,	O
blocks	O
are	O
methods	O
in	O
the	O
modern	O
concept	O
of	O
OOP	O
.	O
</s>
<s>
The	O
following	O
example	O
,	O
taken	O
from	O
Simulation	B-Language
using	O
GPSS	B-Language
,	O
is	O
the	O
"	O
Hello	O
world	O
!	O
"	O
</s>
<s>
of	O
GPSS	B-Language
and	O
will	O
illustrate	O
the	O
main	O
concepts	O
.	O
</s>
<s>
In	O
the	O
example	O
,	O
it	O
materialize	O
a	O
line	O
of	O
chairs	O
and	O
,	O
at	O
the	O
end	O
of	O
the	O
simulation	B-Language
,	O
we	O
will	O
know	O
,	O
among	O
other	O
things	O
,	O
the	O
maximum	O
queue	O
size	O
(	O
how	O
many	O
chairs	O
are	O
needed	O
)	O
and	O
the	O
average	O
waiting	O
time	O
.	O
</s>
<s>
GPSS	B-Language
remembers	O
which	O
transactions	O
are	O
in	O
the	O
queue	O
,	O
so	O
that	O
it	O
possible	O
to	O
know	O
the	O
average	O
time	O
spent	O
,	O
and	O
to	O
check	O
that	O
no	O
buggy	O
transaction	O
is	O
leaving	O
a	O
queue	O
without	O
previously	O
entering	O
in	O
it	O
.	O
</s>
<s>
To	O
simulate	O
multiple	O
parallel	O
servers	O
,	O
like	O
a	O
team	O
of	O
five	O
barbers	O
,	O
or	O
an	O
oven	O
with	O
a	O
capacity	O
of	O
10	O
,	O
GPSS	B-Language
uses	O
entities	O
named	O
STORAGEs	O
.	O
</s>
<s>
Other	O
service	O
time	O
distributions	O
are	O
available	O
through	O
GPSS	B-Language
FUNCTION	O
(	O
a	O
somehow	O
different	O
notion	O
than	O
function	O
in	O
other	O
programming	O
languages	O
)	O
.	O
</s>
<s>
To	O
select	O
the	O
"	O
next	O
"	O
transaction	O
,	O
GPSS	B-Language
uses	O
the	O
first-come	O
first-served	O
basis	O
,	O
with	O
priority	O
.	O
</s>
<s>
In	O
the	O
example	O
,	O
it	O
is	O
set	O
to	O
one	O
,	O
thus	O
the	O
simulation	B-Language
will	O
finish	O
after	O
one	O
run	O
of	O
480	O
mn	O
in	O
simulated	O
time	O
.	O
</s>
<s>
Incidentally	O
,	O
Joe	O
was	O
cutting	O
the	O
hair	O
of	O
customer	O
number	O
26	O
when	O
the	O
simulation	B-Language
was	O
closed	O
.	O
</s>
