<s>
Core	B-Application
War	I-Application
is	O
a	O
1984	O
programming	B-Language
game	I-Language
created	O
by	O
D	O
.	O
G	O
.	O
Jones	O
and	O
A	O
.	O
K	O
.	O
Dewdney	O
in	O
which	O
two	O
or	O
more	O
battle	O
programs	O
(	O
called	O
"	O
warriors	O
"	O
)	O
compete	O
for	O
control	O
of	O
a	O
virtual	B-Architecture
computer	I-Architecture
.	O
</s>
<s>
These	O
battle	O
programs	O
are	O
written	O
in	O
an	O
abstract	O
assembly	B-Language
language	I-Language
called	O
Redcode	O
.	O
</s>
<s>
The	O
standards	O
for	O
the	O
language	O
and	O
the	O
virtual	B-Architecture
machine	I-Architecture
were	O
initially	O
set	O
by	O
the	O
International	O
Core	B-Application
Wars	I-Application
Society	O
(	O
ICWS	O
)	O
,	O
but	O
later	O
standards	O
were	O
determined	O
by	O
community	O
consensus	O
.	O
</s>
<s>
However	O
,	O
Redcode	O
supports	O
a	O
number	O
of	O
different	O
addressing	B-Language
modes	I-Language
and	O
(	O
starting	O
from	O
the	O
1994	O
draft	O
standard	O
)	O
instruction	O
modifiers	O
which	O
increase	O
the	O
actual	O
number	O
of	O
operations	O
possible	O
to	O
7168	O
.	O
</s>
<s>
The	O
memory	O
space	O
(	O
or	O
core	O
)	O
is	O
of	O
finite	O
size	O
,	O
but	O
only	O
relative	B-General_Concept
addressing	I-General_Concept
is	O
used	O
,	O
that	O
is	O
,	O
address	O
0	O
always	O
refers	O
to	O
the	O
currently	O
executing	O
instruction	O
,	O
address	O
1	O
to	O
the	O
instruction	O
after	O
it	O
,	O
and	O
so	O
on	O
.	O
</s>
<s>
Low	O
level	O
multiprocessing	O
Instead	O
of	O
a	O
single	O
instruction	B-General_Concept
pointer	I-General_Concept
a	O
Redcode	O
simulator	O
has	O
a	O
process	O
queue	O
for	O
each	O
program	O
containing	O
a	O
variable	O
number	O
of	O
instruction	B-General_Concept
pointers	I-General_Concept
which	O
the	O
simulator	O
cycles	O
through	O
.	O
</s>
<s>
The	O
earliest	O
version	O
described	O
by	O
A	O
.	O
K	O
.	O
Dewdney	O
differs	O
in	O
many	O
respects	O
from	O
the	O
later	O
standards	O
established	O
by	O
the	O
International	B-Application
Core	I-Application
War	I-Application
Society	I-Application
,	O
and	O
could	O
be	O
considered	O
a	O
different	O
,	O
albeit	O
related	O
,	O
language	O
.	O
</s>
<s>
Development	O
of	O
Redcode	O
,	O
however	O
,	O
has	O
continued	O
in	O
an	O
informal	O
manner	O
,	O
chiefly	O
via	O
online	O
forums	O
such	O
as	O
the	O
rec.games.corewar	O
newsgroup	B-Application
.	O
</s>
<s>
Imp	O
Imps	O
are	O
named	O
after	O
the	O
first	O
ever	O
published	O
warrior	O
,	O
Imp	O
by	O
A	O
.	O
K	O
.	O
Dewdney	O
,	O
a	O
trivial	O
one-instruction	O
mobile	O
warrior	O
that	O
continually	O
copies	O
its	O
sole	O
instruction	O
just	O
ahead	O
of	O
its	O
instruction	B-General_Concept
pointer	I-General_Concept
.	O
</s>
<s>
With	O
an	O
understanding	O
of	O
Core	B-Application
War	I-Application
strategies	O
,	O
a	O
programmer	O
can	O
create	O
a	O
warrior	O
to	O
achieve	O
certain	O
goals	O
.	O
</s>
<s>
Warriors	O
can	O
also	O
be	O
generated	O
by	O
genetic	B-Algorithm
algorithms	I-Algorithm
or	O
genetic	B-Algorithm
programming	I-Algorithm
.	O
</s>
<s>
Several	O
evolvers	O
were	O
introduced	O
by	O
the	O
Core	B-Application
War	I-Application
community	O
and	O
tend	O
to	O
focus	O
on	O
generating	O
warriors	O
for	O
smaller	O
core	O
settings	O
.	O
</s>
<s>
Core	B-Application
War	I-Application
was	O
inspired	O
by	O
a	O
self-replicating	O
program	O
called	O
Creeper	B-Application
and	O
a	O
subsequent	O
program	O
called	O
Reaper	B-Application
that	O
destroyed	O
copies	O
of	O
Creeper	B-Application
.	O
</s>
<s>
Creeper	B-Application
was	O
created	O
by	O
Bob	B-Application
Thomas	I-Application
at	O
BBN	O
.	O
</s>
<s>
Dewdney	O
was	O
not	O
aware	O
of	O
the	O
origin	O
of	O
Creeper	B-Application
and	I-Application
Reaper	I-Application
and	O
refers	O
to	O
them	O
as	O
a	O
rumor	O
originating	O
from	O
Darwin	O
and	O
the	O
worm	O
experiments	O
of	O
Shoch	O
and	O
Hupp	O
.	O
</s>
<s>
The	O
1984	O
Scientific	O
American	O
article	O
on	O
Core	B-Application
War	I-Application
nevertheless	O
cites	O
the	O
game	O
Darwin	O
,	O
played	O
by	O
Victor	O
A	O
.	O
Vyssotsky	O
,	O
Robert	O
Morris	O
,	O
and	O
Douglas	O
McIlroy	O
at	O
Bell	O
Labs	O
in	O
1961	O
.	O
</s>
<s>
The	O
word	O
"	O
Core	O
"	O
in	O
the	O
name	O
comes	O
from	O
magnetic-core	O
memory	O
,	O
an	O
obsolete	O
random-access	B-Architecture
memory	I-Architecture
technology	O
.	O
</s>
<s>
This	O
term	O
was	O
then	O
,	O
and	O
still	O
today	O
,	O
typically	O
in	O
use	O
as	O
the	O
term	O
for	O
working	O
memory	O
in	O
working	O
memory	B-Error_Name
dumps	I-Error_Name
,	O
called	O
core	B-Error_Name
dumps	I-Error_Name
,	O
on	O
Unix	O
and	O
most	O
Unix-like	O
systems	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
default	O
filename	O
used	O
for	O
core	B-Error_Name
dumps	I-Error_Name
on	O
such	O
systems	O
is	O
usually	O
"	O
core	O
"	O
or	O
contains	O
the	O
word	O
core	O
.	O
</s>
<s>
The	O
first	O
description	O
of	O
the	O
Redcode	O
language	O
was	O
published	O
in	O
March	O
1984	O
,	O
in	O
Core	B-Application
War	I-Application
Guidelines	O
by	O
D	O
.	O
G	O
.	O
Jones	O
and	O
A	O
.	O
K	O
.	O
Dewdney	O
.	O
</s>
<s>
Dewdney	O
revisited	O
Core	B-Application
War	I-Application
in	O
his	O
"	O
Computer	O
Recreations	O
"	O
column	O
in	O
March	O
1985	O
,	O
and	O
again	O
in	O
January	O
1987	O
.	O
</s>
<s>
The	O
International	O
Core	B-Application
Wars	I-Application
Society	O
(	O
ICWS	O
)	O
was	O
founded	O
in	O
1985	O
,	O
one	O
year	O
after	O
Dewdney	O
's	O
original	O
article	O
.	O
</s>
<s>
Redcode	O
is	O
the	O
programming	O
language	O
used	O
in	O
Core	B-Application
War	I-Application
.	O
</s>
<s>
It	O
is	O
executed	O
by	O
a	O
virtual	B-Architecture
machine	I-Architecture
known	O
as	O
a	O
Memory	O
Array	O
Redcode	O
Simulator	O
,	O
or	O
MARS	O
.	O
</s>
<s>
The	O
design	O
of	O
Redcode	O
is	O
loosely	O
based	O
on	O
actual	O
CISC	B-Architecture
assembly	B-Language
languages	I-Language
of	O
the	O
early	O
1980s	O
,	O
but	O
contains	O
several	O
features	O
not	O
usually	O
found	O
in	O
actual	O
computer	O
systems	O
.	O
</s>
<s>
next	B-General_Concept
instruction	I-General_Concept
.	O
</s>
<s>
jump	O
to	O
location	O
B	O
;	O
otherwise	O
continue	O
with	O
next	B-General_Concept
instruction	I-General_Concept
.	O
</s>
<s>
instruction	O
;	O
otherwise	O
execute	O
next	B-General_Concept
instruction	I-General_Concept
.	O
</s>
<s>
the	O
ICWS	O
'	O
94	O
standard	O
draft	O
added	O
more	O
addressing	B-Language
modes	I-Language
,	O
mostly	O
to	O
deal	O
with	O
A-field	O
indirection	O
,	O
to	O
give	O
a	O
total	O
of	O
8	O
address	B-Language
modes	I-Language
:	O
</s>
<s>
For	O
instance	O
pMARS	O
which	O
is	O
open	B-Application
source	I-Application
software	I-Application
with	O
source	O
code	O
on	O
SourceForge	B-Application
,	O
or	O
the	O
SDL	B-Operating_System
based	O
SDL	B-Operating_System
pMARS	O
for	O
Windows	O
.	O
</s>
<s>
The	O
common	O
implementation	O
pMars	O
was	O
downloaded	O
over	O
35,000	O
times	O
between	O
2000	O
and	O
2021	O
from	O
SourceForge	B-Application
.	O
</s>
