<s>
Colossus	B-Application
Chess	I-Application
is	O
a	O
series	O
of	O
chess-playing	B-Application
computer	I-Application
programs	I-Application
developed	O
by	O
Martin	O
Bryant	O
,	O
commercially	O
released	O
for	O
various	O
home	O
computers	O
in	O
the	O
1980s	O
.	O
</s>
<s>
Bryant	O
started	O
Colossus	B-Application
Chess	I-Application
in	O
1983	O
,	O
using	O
his	O
White	B-Application
Knight	I-Application
Mk	I-Application
11	I-Application
program	O
,	O
winner	O
of	O
the	O
1983	O
European	O
Microcomputer	O
Chess	B-Application
Championship	O
,	O
as	O
a	O
basis	O
.	O
</s>
<s>
It	O
was	O
developed	O
on	O
an	O
Apple	B-Device
II	I-Device
,	O
but	O
was	O
first	O
commercially	O
released	O
for	O
Commodore	O
64	O
as	O
Colossus	B-Application
Chess	I-Application
2.0	I-Application
(	O
CDS	O
Micro	O
Systems	O
,	O
1984	O
)	O
.	O
</s>
<s>
Version	O
3.0	O
was	O
released	O
in	O
1984	O
for	O
the	O
Atari	B-Device
8-bit	I-Device
family	I-Device
of	O
computers	O
(	O
published	O
by	O
English	O
Software	O
)	O
,	O
followed	O
by	O
4.0	O
in	O
1985	O
which	O
was	O
released	O
on	O
most	O
formats	O
of	O
the	O
day	O
(	O
published	O
by	O
CDS	O
)	O
.	O
</s>
<s>
As	O
other	O
games	O
of	O
the	O
time	O
,	O
the	O
Acorn	B-Device
Electron	I-Device
implementation	O
required	O
that	O
part	O
of	O
the	O
screen	O
memory	O
be	O
used	O
as	O
working	O
space	O
.	O
</s>
<s>
Colossus	B-Application
Chess	I-Application
featured	O
time-controlled	O
play	O
with	O
game	O
clocks	O
,	O
an	O
opening	O
book	O
with	O
3,000	O
positions	O
,	O
and	O
problem-solving	O
mode	O
that	O
could	O
solve	O
normal	O
mates	O
,	O
selfmates	O
and	O
helpmates	O
.	O
</s>
<s>
Pondering	O
on	O
opponent	O
's	O
time	O
and	O
a	O
three-dimensional	O
chessboard	O
were	O
introduced	O
in	O
Colossus	B-Application
Chess	I-Application
4.0	I-Application
.	O
</s>
<s>
All	O
releases	O
were	O
written	O
in	O
the	O
assembly	B-Language
language	I-Language
of	O
the	O
appropriate	O
CPU	B-Device
;	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
version	O
could	O
examine	O
an	O
average	O
of	O
170	O
positions	O
per	O
second	O
.	O
</s>
<s>
Uncommon	O
for	O
microcomputer	O
chess	B-Application
programs	I-Application
of	O
the	O
era	O
,	O
Colossus	O
had	O
a	O
full	O
implementation	O
of	O
the	O
rules	O
of	O
chess	B-Application
,	O
including	O
underpromotion	O
,	O
the	O
fifty-move	O
rule	O
,	O
draw	O
by	O
repetition	O
,	O
and	O
draw	O
by	O
insufficient	O
material	O
.	O
</s>
<s>
Colossus	O
was	O
also	O
able	O
to	O
execute	O
all	O
the	O
basic	O
checkmates	B-Application
,	O
including	O
the	O
difficult	O
bishop	O
and	O
knight	O
checkmate	B-Application
.	O
</s>
<s>
The	O
program	O
was	O
subsequently	O
ported	O
to	O
Atari	B-Device
ST	I-Device
(	O
1988	O
)	O
,	O
Amiga	B-Device
(	O
1989	O
)	O
and	O
IBM	B-Device
PC	I-Device
(	O
1990	O
)	O
under	O
the	O
title	O
Colossus	B-Application
Chess	I-Application
X	I-Application
.	O
</s>
<s>
The	O
new	O
releases	O
featured	O
four	O
chess	B-Application
sets	O
and	O
enhanced	O
graphics	O
developed	O
with	O
the	O
assistance	O
of	O
Gary	O
Thomlinson	O
and	O
Carl	O
Cropley	O
.	O
</s>
<s>
No	O
work	O
was	O
done	O
on	O
Colossus	B-Application
Chess	I-Application
from	O
1991	O
to	O
2005	O
,	O
when	O
Martin	O
Bryant	O
created	O
a	O
completely	O
new	O
and	O
freely	O
available	O
Windows	O
version	O
conforming	O
to	O
the	O
Universal	B-General_Concept
Chess	I-General_Concept
Interface	I-General_Concept
.	O
</s>
<s>
It	O
was	O
written	O
in	O
C#	B-Application
,	O
then	O
converted	O
to	O
C	B-Language
for	O
speed	O
,	O
and	O
was	O
finally	O
publicly	O
released	O
in	O
2006	O
.	O
,	O
the	O
latest	O
version	O
is	O
2008b	O
.	O
</s>
<s>
Info	O
gave	O
Colossus	B-Application
Chess	I-Application
IV	O
for	O
the	O
Commodore	O
64	O
three	O
stars	O
out	O
of	O
five	O
,	O
stating	O
that	O
it	O
was	O
less	O
attractive	O
but	O
"	O
a	O
darn	O
sight	O
more	O
playable	O
"	O
than	O
Chessmaster	B-Application
2000	I-Application
with	O
both	O
keyboard	O
and	O
joystick	O
controls	O
.	O
</s>
