<s>
PLEX	B-Language
(	O
Programming	B-Language
Language	I-Language
for	I-Language
EXchanges	I-Language
)	O
is	O
a	O
special-purpose	O
,	O
concurrent	O
,	O
real-time	O
programming	O
language	O
.	O
</s>
<s>
The	O
proprietary	B-Application
PLEX	B-Language
language	O
is	O
closely	O
tied	O
to	O
the	O
architecture	O
of	O
Ericsson	O
's	O
AXE	B-Device
telephone	I-Device
exchanges	I-Device
which	O
it	O
was	O
designed	O
to	O
control	O
.	O
</s>
<s>
PLEX	B-Language
was	O
developed	O
by	O
Göran	O
Hemdahl	O
at	O
Ericsson	O
in	O
the	O
1970s	O
,	O
and	O
it	O
has	O
been	O
continuously	O
evolving	O
since	O
then	O
.	O
</s>
<s>
PLEX	B-Language
was	O
described	O
in	O
2008	O
as	O
"	O
a	O
cross	O
between	O
Fortran	B-Application
and	O
a	O
macro	O
assembler.	O
"	O
</s>
<s>
The	O
language	O
has	O
two	O
variants	O
:	O
Plex-C	O
used	O
for	O
the	O
AXE	O
Central	O
Processor	O
(	O
CP	O
)	O
and	O
Plex-M	O
used	O
for	O
Extension	O
Module	O
Regional	O
Processors	O
(	O
EMRP	O
)	O
.	O
</s>
<s>
Ericsson	O
started	O
a	O
project	O
in	O
the	O
mid-1980s	O
to	O
create	O
a	O
successor	O
language	O
which	O
resulted	O
in	O
Erlang	B-Operating_System
.	O
</s>
<s>
According	O
to	O
co-creator	O
Joe	O
Armstrong	O
,	O
"	O
Erlang	B-Operating_System
was	O
heavily	O
influenced	O
by	O
PLEX	B-Language
and	O
the	O
AXE	O
design.	O
"	O
</s>
<s>
Erlang	B-Operating_System
did	O
not	O
replace	O
PLEX	B-Language
,	O
but	O
was	O
used	O
alongside	O
it	O
.	O
</s>
<s>
Several	O
precompilers	B-Application
or	O
code	O
generators	O
exist	O
,	O
to	O
produce	O
source	O
code	O
in	O
Plex-C	O
from	O
higher	B-Language
level	I-Language
languages	O
or	O
graphical	O
models	O
.	O
</s>
<s>
These	O
can	O
generate	O
Plex-C	O
from	O
:	O
</s>
<s>
Source	O
code	O
in	O
Plex-C	O
is	O
compiled	O
into	O
the	O
assembly	O
language	O
ASA210C	O
.	O
</s>
<s>
The	O
binary	O
form	O
of	O
ASA210C	O
is	O
either	O
interpreted	O
by	O
a	O
combination	O
of	O
hardware	O
and	O
microcode	B-Device
,	O
or	O
is	O
compiled	O
by	O
a	O
just-in-time	O
compiler	O
into	O
native	O
machine	B-Language
code	I-Language
for	O
a	O
high-capacity	O
microprocessor	B-Architecture
.	O
</s>
