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'''[[Main Page|Home]] * [[Engines]] * Atlas'''
[[FILE:Singer Sargent, John - Atlas and the Hesperides - 1925.jpg|border|right|thumb|[https://en.wikipedia.org/wiki/Atlas_%28mythology%29 Atlas] and the [https://en.wikipedia.org/wiki/Hesperides Hesperides] <ref>[https://commons.wikimedia.org/wiki/File:Singer_Sargent,_John_-_Atlas_and_the_Hesperides_-_1925.jpg Atlas and the Hesperides] by [[Arts#JohnSingerSargent|John Singer Sargent]], between circa 1922 and circa 1925, current location: [https://en.wikipedia.org/wiki/Museum_of_Fine_Arts,_Boston Museum of Fine Arts, Boston], [https://en.wikipedia.org/wiki/Wikimedia_Commons Wikimedia Commons]</ref> ]]
'''Atlas''',
an early chess program written in 1967 by [[Alex Bell]] at [[Atlas Computer Laboratory]], [https://en.wikipedia.org/wiki/Chilton,_Oxfordshire Chilton]. It was basically a resurrected, cleaned up [[Algol]] version of Bell's and [[Nils Barricelli|Barricelli's]] old program from the early 60s to test evolutionary theories, which had an [[Evaluation function|evaluation function]] based purely on [[Mobility|mobility]] - at that time the first fully legal chess program to run in England <ref>[http://www.chilton-computing.org.uk/acl/applications/cocoa/p008.htm MASTER at IFIPS]. Excerpt from [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?''. [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], hosted by [[Atlas Computer Laboratory]] from [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>, and likely also the base of Barricelli's [[WCCC 1974]] entry [[Freedom]].
Atlas, running on an [https://en.wikipedia.org/wiki/International_Computers_Limited ICL] [https://en.wikipedia.org/wiki/Atlas_%28computer%29 Atlas] computer <ref>[http://www.chilton-computing.org.uk/acl/literature/acl/p004.htm Atlas Computer Laboratory], hosted by [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>, looked three [[Ply|plies]] ahead with [[Alpha-Beta|alpha-beta]], and would accept almost any [[Captures|captures]] in that [[Depth|depth]] with weighting on swaps of the more powerful pieces, i.e. it would always swap a queen for a queen. If no captures were present it prepared to [[Castling|castle]] or [[Minimax|mini-maximised]] its mobility. A slight modification prevented it from moving its queen in the first 5 moves <ref>[http://www.chilton-computing.org.uk/acl/applications/cocoa/p008.htm MASTER at IFIPS]. Excerpt from [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?''. [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], hosted by [[Atlas Computer Laboratory]] from [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>. Atlas played a few sparring games against [[Lancaster]] <ref>[[John J. Scott]] ('''1969'''). ''Lancaster vs. Mac Hack''. [[ACM#SIG|ACM SIGART Bulletin]], Vol. 16</ref>, [[John J. Scott|John Scott's]] program, then dubbed "Scott" <ref>[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/p005.htm#index22 Chess programs: Scott] from [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin]</ref>, and largely suffered from [[Horizon Effect|horizon effect]].
<span id="MoveGeneration"></span>
=Move Generation=
A description of Atlas' [[Move Generation|move generation]] techniques along with a mate-in-two solver is given with Algol source code listing in ''Games Playing with Computers'', 3.1 Chess <ref>[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/p003.htm Games Playing with Computers | Chapter 3: Board Games], in [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin]</ref>. Atlas uses two distinct [[8x8 Board|8x8 boards]] [1:65] and [[Piece-Lists|piece lists]] [O:16] for white and black man with identical [[Pieces#PieceCoding|piece coding]], passing the boards per reference as 'mymanin' or 'opponents' dependent on [[Side to move|side to move]]. Pre-calculated rook and bishop tables contain one vector of [[Direction|direction]] increments, i.e. east (+1), west (-1), north (+8), and south (-8) for rooks, and further for each square a vector of ray-direction terminal [[Target Square|destination squares]]. The embedded routine 'rookorbishopmove' in scope of the outer move generation routine loops over all four directions, gets increment and terminal target square from the rook or bishop table, and iterates the destination along the ray. Inside the ray-loop it tests whether the target is occupied by an own man, to terminate the ray-loop, otherwise it stores the move, and then tests to break after a capture or even an illegal king capture with an extra exit 'cutoff'.
<pre>
procedure rookorbishopmove(rookorbishop);
integer array rookorbishop;
begin
for j := 0 step 1 until 3 do
begin
k := rookorbishop[j]; k is increment:
l := rookorbishop[4 * square + j]; l is terminal square
for i := square + k step k until l do
begin
if mymanin[i] ≠ 0 then goto newdirection;
c := c+1;
moves[c] := i;
if opponents[i] ≠ 0 then
begin
if opponents[i] = 6 then goto cutoff else goto newdirection
end
end;
newdirection:
end
end of rookorbishopmove;
</pre>
=Master=
In the early 70s, Atlas evolved to [[Master]] in collaboration with [[Peter Kent]], and later with [[John Birmingham]] and chess expert [[John Waldron]], while Alex Bell finally left Chilton.
=Namesake=
* [[Atlas (ESP)|Atlas]] by [[Andrés Manzanares Campillo]]
=See also=
* [[Various Classifications#Astronomy|Astronomy]]
* [[Various Classifications#Geography|Geography]]
* [[Master]]
* [[Various Classifications#Mythology|Mythology]]
=Publications=
* [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin], [http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/index.htm index]
* [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?'' [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], [http://www.amazon.com/Machine-Plays-Chess-Pergamon/dp/0080212220 amazon]
=External Links=
==Chess Program==
* [http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/p003.htm Games Playing with Computers | Chapter 3: Board Games], in [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin]
* [http://www.chilton-computing.org.uk/acl/applications/cocoa/p008.htm MASTER at IFIPS]. Excerpt from [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?''. [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], hosted by [[Atlas Computer Laboratory]] from [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]
==Misc==
* [https://en.wikipedia.org/wiki/Atlas_%28computer%29 Atlas (computer) from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28disambiguation%29 Atlas (disambiguation) from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas Atlas from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_Mountains Atlas Mountains from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28mythology%29 Atlas (mythology) from Wikipedia]
: [https://en.wikipedia.org/wiki/Calypso_%28mythology%29 Calypso (mythology) from Wikipedia]
* [https://en.wikipedia.org/wiki/Farnese_Atlas Farnese Atlas from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28rocket_family%29 Atlas (rocket family) from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28star%29 Atlas (star) from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28moon%29 Atlas (moon) from Wikipedia]
* [https://en.wikipedia.org/wiki/Colossochelys_atlas Colossochelys atlas from Wikipedia]
* [[Videos#YounSunNah|Youn Sun Nah]] & [[Videos#UlfWakenius|Ulf Wakenius]] - Calypso Blues @ [https://fr.wikipedia.org/wiki/Jazz_sous_les_pommiers Jazz sous les pommiers], May 28, 2011, [https://en.wikipedia.org/wiki/YouTube YouTube] Video
: {{#evu:https://www.youtube.com/watch?v=Tw0XAggrigQ|alignment=left|valignment=top}}
=References=
<references />
'''[[Engines|Up one Level]]'''
[[FILE:Singer Sargent, John - Atlas and the Hesperides - 1925.jpg|border|right|thumb|[https://en.wikipedia.org/wiki/Atlas_%28mythology%29 Atlas] and the [https://en.wikipedia.org/wiki/Hesperides Hesperides] <ref>[https://commons.wikimedia.org/wiki/File:Singer_Sargent,_John_-_Atlas_and_the_Hesperides_-_1925.jpg Atlas and the Hesperides] by [[Arts#JohnSingerSargent|John Singer Sargent]], between circa 1922 and circa 1925, current location: [https://en.wikipedia.org/wiki/Museum_of_Fine_Arts,_Boston Museum of Fine Arts, Boston], [https://en.wikipedia.org/wiki/Wikimedia_Commons Wikimedia Commons]</ref> ]]
'''Atlas''',
an early chess program written in 1967 by [[Alex Bell]] at [[Atlas Computer Laboratory]], [https://en.wikipedia.org/wiki/Chilton,_Oxfordshire Chilton]. It was basically a resurrected, cleaned up [[Algol]] version of Bell's and [[Nils Barricelli|Barricelli's]] old program from the early 60s to test evolutionary theories, which had an [[Evaluation function|evaluation function]] based purely on [[Mobility|mobility]] - at that time the first fully legal chess program to run in England <ref>[http://www.chilton-computing.org.uk/acl/applications/cocoa/p008.htm MASTER at IFIPS]. Excerpt from [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?''. [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], hosted by [[Atlas Computer Laboratory]] from [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>, and likely also the base of Barricelli's [[WCCC 1974]] entry [[Freedom]].
Atlas, running on an [https://en.wikipedia.org/wiki/International_Computers_Limited ICL] [https://en.wikipedia.org/wiki/Atlas_%28computer%29 Atlas] computer <ref>[http://www.chilton-computing.org.uk/acl/literature/acl/p004.htm Atlas Computer Laboratory], hosted by [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>, looked three [[Ply|plies]] ahead with [[Alpha-Beta|alpha-beta]], and would accept almost any [[Captures|captures]] in that [[Depth|depth]] with weighting on swaps of the more powerful pieces, i.e. it would always swap a queen for a queen. If no captures were present it prepared to [[Castling|castle]] or [[Minimax|mini-maximised]] its mobility. A slight modification prevented it from moving its queen in the first 5 moves <ref>[http://www.chilton-computing.org.uk/acl/applications/cocoa/p008.htm MASTER at IFIPS]. Excerpt from [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?''. [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], hosted by [[Atlas Computer Laboratory]] from [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]</ref>. Atlas played a few sparring games against [[Lancaster]] <ref>[[John J. Scott]] ('''1969'''). ''Lancaster vs. Mac Hack''. [[ACM#SIG|ACM SIGART Bulletin]], Vol. 16</ref>, [[John J. Scott|John Scott's]] program, then dubbed "Scott" <ref>[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/p005.htm#index22 Chess programs: Scott] from [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin]</ref>, and largely suffered from [[Horizon Effect|horizon effect]].
<span id="MoveGeneration"></span>
=Move Generation=
A description of Atlas' [[Move Generation|move generation]] techniques along with a mate-in-two solver is given with Algol source code listing in ''Games Playing with Computers'', 3.1 Chess <ref>[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/p003.htm Games Playing with Computers | Chapter 3: Board Games], in [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin]</ref>. Atlas uses two distinct [[8x8 Board|8x8 boards]] [1:65] and [[Piece-Lists|piece lists]] [O:16] for white and black man with identical [[Pieces#PieceCoding|piece coding]], passing the boards per reference as 'mymanin' or 'opponents' dependent on [[Side to move|side to move]]. Pre-calculated rook and bishop tables contain one vector of [[Direction|direction]] increments, i.e. east (+1), west (-1), north (+8), and south (-8) for rooks, and further for each square a vector of ray-direction terminal [[Target Square|destination squares]]. The embedded routine 'rookorbishopmove' in scope of the outer move generation routine loops over all four directions, gets increment and terminal target square from the rook or bishop table, and iterates the destination along the ray. Inside the ray-loop it tests whether the target is occupied by an own man, to terminate the ray-loop, otherwise it stores the move, and then tests to break after a capture or even an illegal king capture with an extra exit 'cutoff'.
<pre>
procedure rookorbishopmove(rookorbishop);
integer array rookorbishop;
begin
for j := 0 step 1 until 3 do
begin
k := rookorbishop[j]; k is increment:
l := rookorbishop[4 * square + j]; l is terminal square
for i := square + k step k until l do
begin
if mymanin[i] ≠ 0 then goto newdirection;
c := c+1;
moves[c] := i;
if opponents[i] ≠ 0 then
begin
if opponents[i] = 6 then goto cutoff else goto newdirection
end
end;
newdirection:
end
end of rookorbishopmove;
</pre>
=Master=
In the early 70s, Atlas evolved to [[Master]] in collaboration with [[Peter Kent]], and later with [[John Birmingham]] and chess expert [[John Waldron]], while Alex Bell finally left Chilton.
=Namesake=
* [[Atlas (ESP)|Atlas]] by [[Andrés Manzanares Campillo]]
=See also=
* [[Various Classifications#Astronomy|Astronomy]]
* [[Various Classifications#Geography|Geography]]
* [[Master]]
* [[Various Classifications#Mythology|Mythology]]
=Publications=
* [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin], [http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/index.htm index]
* [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?'' [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], [http://www.amazon.com/Machine-Plays-Chess-Pergamon/dp/0080212220 amazon]
=External Links=
==Chess Program==
* [http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/p003.htm Games Playing with Computers | Chapter 3: Board Games], in [[Alex Bell]] ('''1972'''). ''[http://www.chilton-computing.org.uk/acl/literature/books/gamesplaying/overview.htm Games Playing with Computers]''. [https://en.wikipedia.org/wiki/Allen_%26_Unwin Allen & Unwin]
* [http://www.chilton-computing.org.uk/acl/applications/cocoa/p008.htm MASTER at IFIPS]. Excerpt from [[Alex Bell]] ('''1978'''). ''The Machine Plays Chess?''. [https://en.wikipedia.org/wiki/Pergamon_Press Pergamon Press], hosted by [[Atlas Computer Laboratory]] from [https://en.wikipedia.org/wiki/Rutherford_Appleton_Laboratory Rutherford Appleton Laboratory (RAL)]
==Misc==
* [https://en.wikipedia.org/wiki/Atlas_%28computer%29 Atlas (computer) from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28disambiguation%29 Atlas (disambiguation) from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas Atlas from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_Mountains Atlas Mountains from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28mythology%29 Atlas (mythology) from Wikipedia]
: [https://en.wikipedia.org/wiki/Calypso_%28mythology%29 Calypso (mythology) from Wikipedia]
* [https://en.wikipedia.org/wiki/Farnese_Atlas Farnese Atlas from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28rocket_family%29 Atlas (rocket family) from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28star%29 Atlas (star) from Wikipedia]
* [https://en.wikipedia.org/wiki/Atlas_%28moon%29 Atlas (moon) from Wikipedia]
* [https://en.wikipedia.org/wiki/Colossochelys_atlas Colossochelys atlas from Wikipedia]
* [[Videos#YounSunNah|Youn Sun Nah]] & [[Videos#UlfWakenius|Ulf Wakenius]] - Calypso Blues @ [https://fr.wikipedia.org/wiki/Jazz_sous_les_pommiers Jazz sous les pommiers], May 28, 2011, [https://en.wikipedia.org/wiki/YouTube YouTube] Video
: {{#evu:https://www.youtube.com/watch?v=Tw0XAggrigQ|alignment=left|valignment=top}}
=References=
<references />
'''[[Engines|Up one Level]]'''
