<s>
The	O
Portable	B-Application
C	I-Application
Compiler	I-Application
(	O
also	O
known	O
as	O
pcc	O
or	O
sometimes	O
pccm	O
-	O
portable	B-Application
C	I-Application
compiler	I-Application
machine	O
)	O
is	O
an	O
early	O
compiler	B-Language
for	O
the	O
C	B-Language
programming	I-Language
language	I-Language
written	O
by	O
Stephen	O
C	B-Language
.	O
Johnson	O
of	O
Bell	O
Labs	O
in	O
the	O
mid-1970s	O
,	O
based	O
in	O
part	O
on	O
ideas	O
proposed	O
by	O
Alan	O
Snyder	O
in	O
1973	O
,	O
</s>
<s>
and	O
"	O
distributed	O
as	O
the	O
C	B-Language
compiler	B-Language
by	O
Bell	O
Labs	O
...	O
with	O
the	O
blessing	O
of	O
Dennis	O
Ritchie.	O
"	O
</s>
<s>
Being	O
one	O
of	O
the	O
first	O
compilers	B-Language
that	O
could	O
easily	O
be	O
adapted	O
to	O
output	O
code	O
for	O
different	O
computer	O
architectures	O
,	O
the	O
compiler	B-Language
had	O
a	O
long	O
life	O
span	O
.	O
</s>
<s>
It	O
debuted	O
in	O
Seventh	B-Operating_System
Edition	I-Operating_System
Unix	I-Operating_System
and	O
shipped	O
with	O
BSD	B-Operating_System
Unix	I-Operating_System
until	O
the	O
release	O
of	O
4.4BSD	O
in	O
1994	O
,	O
when	O
it	O
was	O
replaced	O
by	O
the	O
GNU	B-Application
C	I-Application
Compiler	I-Application
.	O
</s>
<s>
It	O
was	O
very	O
influential	O
in	O
its	O
day	O
,	O
so	O
much	O
so	O
that	O
at	O
the	O
beginning	O
of	O
the	O
1980s	O
,	O
the	O
majority	O
of	O
C	B-Language
compilers	B-Language
were	O
based	O
on	O
it	O
.	O
</s>
<s>
Anders	O
Magnusson	O
and	O
Peter	O
A	O
Jonsson	O
restarted	O
development	O
of	O
pcc	O
in	O
2007	O
,	O
rewriting	O
it	O
extensively	O
to	O
support	O
the	O
C99	B-Language
standard	I-Language
.	O
</s>
<s>
Key	O
features	O
of	O
pcc	O
are	O
its	O
portability	B-Architecture
and	O
improved	O
diagnostic	O
capabilities	O
.	O
</s>
<s>
The	O
compiler	B-Language
was	O
designed	O
so	O
that	O
only	O
a	O
few	O
of	O
its	O
source	O
files	O
are	O
machine-dependent	B-Architecture
.	O
</s>
<s>
It	O
is	O
relatively	O
robust	O
to	O
syntax	B-Application
errors	I-Application
and	O
performs	O
more	O
thorough	O
validity	O
checks	O
than	O
its	O
contemporaries	O
.	O
</s>
<s>
The	O
first	O
C	B-Language
compiler	B-Language
,	O
written	O
by	O
Dennis	O
Ritchie	O
,	O
used	O
a	O
recursive	B-Application
descent	I-Application
parser	I-Application
,	O
incorporated	O
specific	O
knowledge	O
about	O
the	O
PDP-11	B-Device
,	O
and	O
relied	O
on	O
an	O
optional	O
machine-specific	O
optimizer	O
to	O
improve	O
the	O
assembly	O
language	O
code	O
it	O
generated	O
.	O
</s>
<s>
In	O
contrast	O
,	O
Johnson	O
's	O
pccm	O
was	O
based	O
on	O
a	O
yacc-generated	O
parser	O
and	O
used	O
a	O
more	O
general	O
target	O
machine	O
model	O
.	O
</s>
<s>
Both	O
compilers	B-Language
produced	O
target-specific	O
assembly	O
language	O
code	O
which	O
they	O
then	O
assembled	O
to	O
produce	O
linkable	O
object	O
modules	O
.	O
</s>
<s>
The	O
language	O
that	O
PCC	O
implements	O
is	O
an	O
extended	O
version	O
of	O
K&R	O
C	B-Language
that	O
Bjarne	O
Stroustrup	O
has	O
called	O
"	O
Classic	O
C	B-Language
"	O
,	O
incorporating	O
the	O
void	O
return	O
type	O
(	O
for	O
functions	O
that	O
do	O
n't	O
return	O
any	O
value	O
)	O
,	O
enumerations	O
and	O
structure	O
assignment	O
.	O
</s>
<s>
The	O
compiler	B-Language
is	O
provided	O
under	O
the	O
BSD	B-Operating_System
licence	I-Operating_System
and	O
its	O
development	O
is	O
funded	O
by	O
a	O
non-profit	O
organization	O
called	O
BSD	B-Operating_System
Fund	O
.	O
</s>
<s>
This	O
new	O
version	O
was	O
added	O
to	O
the	O
NetBSD	B-Device
pkgsrc	B-Application
and	O
OpenBSD	B-Operating_System
source	O
trees	O
in	O
September	O
2007	O
,	O
and	O
later	O
into	O
the	O
main	O
NetBSD	B-Device
source	O
tree	O
.	O
</s>
<s>
There	O
had	O
been	O
some	O
speculation	O
that	O
it	O
might	O
eventually	O
be	O
used	O
to	O
supplant	O
the	O
GNU	B-Application
C	I-Application
Compiler	I-Application
on	O
BSD-based	O
operating	O
systems	O
,	O
though	O
FreeBSD	B-Operating_System
and	O
NetBSD	B-Device
are	O
both	O
looking	O
to	O
Clang	B-Application
as	O
a	O
potential	O
replacement	O
,	O
and	O
Theo	O
de	O
Raadt	O
of	O
OpenBSD	B-Operating_System
asserts	O
that	O
pcc	O
is	O
not	O
ready	O
yet	O
to	O
be	O
a	O
gcc	B-Application
replacement	O
,	O
and	O
the	O
disposal	O
of	O
gcc	B-Application
is	O
not	O
top	O
priority	O
.	O
</s>
<s>
On	O
December	O
29	O
,	O
2009	O
,	O
pcc	O
became	O
capable	O
of	O
building	O
a	O
functional	O
x86	B-Operating_System
OpenBSD	B-Operating_System
kernel	O
image	O
.	O
</s>
<s>
As	O
of	O
this	O
release	O
,	O
the	O
compiler	B-Language
supports	O
x86	B-Operating_System
and	O
x64	B-Device
processor	O
architectures	O
and	O
runs	O
on	O
NetBSD	B-Device
,	O
OpenBSD	B-Operating_System
,	O
FreeBSD	B-Operating_System
,	O
various	O
Linux	B-Application
distributions	O
,	O
and	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
Further	O
development	O
,	O
including	O
support	O
for	O
more	O
architectures	O
,	O
and	O
FORTRAN	O
77	O
and	O
C++	B-Language
front	O
ends	O
,	O
is	O
continuing	O
as	O
of	O
2022	O
.	O
</s>
<s>
PCC	O
was	O
removed	O
from	O
the	O
OpenBSD	B-Operating_System
source	O
tree	O
in	O
2012	O
.	O
</s>
<s>
Development	O
on	O
it	O
had	O
stalled	O
and	O
no	O
maintainer	O
had	O
stepped	O
up	O
to	O
develop	O
it	O
into	O
something	O
that	O
could	O
make	O
a	O
practical	O
alternative	O
to	O
GNU	B-Application
Compiler	I-Application
Collection	I-Application
.	O
</s>
