<s>
Concurrent	B-Language
Pascal	I-Language
is	O
a	O
programming	O
language	O
designed	O
by	O
Per	O
Brinch	O
Hansen	O
for	O
writing	O
concurrent	B-Architecture
computing	I-Architecture
programs	O
such	O
as	O
operating	B-General_Concept
systems	I-General_Concept
and	O
real-time	B-General_Concept
computing	I-General_Concept
monitoring	O
systems	O
on	O
shared	B-Operating_System
memory	I-Operating_System
computers	O
.	O
</s>
<s>
A	O
separate	O
language	O
,	O
Sequential	O
Pascal	B-Application
,	O
is	O
used	O
as	O
the	O
language	O
for	O
applications	O
programs	O
run	O
by	O
the	O
operating	B-General_Concept
systems	I-General_Concept
written	O
in	O
Concurrent	B-Language
Pascal	I-Language
.	O
</s>
<s>
Both	O
languages	O
are	O
extensions	O
of	O
Niklaus	O
Wirth	O
's	O
Pascal	B-Application
,	O
and	O
share	O
a	O
common	O
threaded	O
code	B-Application
interpreter	I-Application
.	O
</s>
<s>
The	O
following	O
describes	O
how	O
Concurrent	B-Language
Pascal	I-Language
differs	O
from	O
Wirth	O
's	O
Pascal	B-Application
.	O
</s>
<s>
Several	O
constructs	O
in	O
Pascal	B-Application
were	O
removed	O
from	O
Concurrent	B-Language
Pascal	I-Language
for	O
simplicity	O
and	O
security	O
:	O
</s>
<s>
Concurrent	B-Language
Pascal	I-Language
includes	O
class	O
,	O
monitor	O
,	O
and	O
process	O
data	O
types	O
.	O
</s>
<s>
Instances	O
of	O
these	O
types	O
are	O
declared	O
as	O
variables	O
,	O
and	O
initialized	O
in	O
an	O
init	B-Operating_System
statement	O
.	O
</s>
<s>
Monitors	O
provide	O
the	O
only	O
mechanism	O
for	O
interprocess	O
communication	O
in	O
a	O
Concurrent	B-Language
Pascal	I-Language
program	O
.	O
</s>
<s>
The	O
configuration	O
of	O
processes	O
,	O
monitors	O
,	O
and	O
classes	O
in	O
a	O
Concurrent	B-Language
Pascal	I-Language
program	O
is	O
normally	O
established	O
at	O
the	O
start	O
of	O
execution	O
,	O
and	O
is	O
not	O
changed	O
thereafter	O
.	O
</s>
<s>
The	O
communication	O
paths	O
between	O
these	O
components	O
are	O
established	O
by	O
variables	O
passed	O
in	O
the	O
init	B-Operating_System
statements	O
,	O
since	O
class	O
and	O
monitor	O
instance	O
variables	O
cannot	O
be	O
used	O
as	O
procedure	O
parameters	O
.	O
</s>
