Mac+Hack

was a chess program, developed in 1966 and 1967 at MIT by Richard Greenblatt assisted by Donald Eastlake for a DEC PDP-6. It was developed entirely in MIDAS, the PDP-6 macro assembler. The Greenblatt Chess Program was the first computer program to play chess in human tournament competitions and be granted a chess rating. || toc =Hash Table= Mac Hack VI was the first chess program which uses a transposition table, but not yet iterative deepening. It regular searched five plies plus quiescence search and a conditional intermediate layer if own pieces were en prise.
 * Home * Engines * Mac Hack VI**
 * [[image:machackdisplay02.jpg width="233" height="252" link="http://ljkrakauer.com/LJK/60s/resign.htm"]] ||~  || **The Greenblatt Chess Program**, also called **Mac Hack VI** or **MacHack VI**
 * Mac Hack GUI, DEC 340 display  ||~   ||^   ||

In his 1970 paper //A New Hashing Method with Application for Game Playing//, where he introduced Zobrist hashing, Albert Zobrist mentions a possible hashing method to obtain an integer which describes the board configuration, and then to [|divide] the integer by the hash table size and use the [|remainder] as hash address and the [|quotient] as key. However, the integer which describes the board may occupy many computer words, and the divide will be complicated and slow. Further the quotient may occupy several words as well, thus most of the transposition table would be occupied by these keys if type 1 errors were to be avoided. While Zobrist mentions Mac Hack VI used a 32K hash table, he does not made it explicit that Mac Hack used this divide technique.  =Type B= Inspired by the Kotok-McCarthy-Program, Greenblatt thought he could do better and he succeeded to do so. Mac Hack VI was Shannon Type B, but was less narrow than Kotok-McCarthy's {4, 3, 2, 2, 1, 1, 1, 1, 0, 0} and used a width of {15, 15, 9, 9, 7, ...} in tournament play. Quote from //Oral History of Richard Greenblatt// :



=Opening book= Mac Hack VI incorporated a table of opening positions with selected replies. The opening book was compiled by two MIT students, Larry Kaufman, a chess master and top rated U. S. Junior player, and Alan Baisley a chess expert. It is noteworthy that Larry Kaufman started his computer chess career over 40 years ago as team member of Mac Hack!

Quote from //Oral History of Richard Greenblatt//: || =Matches=

Robert Q
First tournament game by a computer, Carl Wagner (2190) - Mac Hack VI aka "Robert Q", January 21, 1967

code [Event "Boylston Chess Club Tournament"] [Site "YMCU, Boston"] [Date "1967.01.21"] [Round "1"] [White "Carl Wagner"] [Black "Robert Q"] [Result "1-0"]
 * [[image:RobertQ1967.JPG width="500" link="http://news.google.com/newspapers?nid=1928&dat=19670123&id=O2ggAAAAIBAJ&sjid=1GYFAAAAIBAJ&pg=2308,2313204"]] ||
 * [|Allen Moulton] and R. William Gosper operating "Robert Q" running on a PDP-6 ||
 * [[image:RobertQAlanBaisley1967.JPG width="500" link="http://news.google.com/newspapers?nid=1928&dat=19670123&id=O2ggAAAAIBAJ&sjid=1GYFAAAAIBAJ&pg=2308,2313204"]] ||
 * Carl Wagner and Alan Baisley (right) ||
 * Carl Wagner and Alan Baisley (right) ||

1.g3 e5 2.Nf3 e4 3.Nd4 Bc5 4.Nb3 Bb6 5.Bg2 Nf6 6.c4 d6 7.Nc3 Be6 8.d3 exd3 9.Bxb7 Nbd7 10.exd3 Rb8 11.Bg2 O-O 12.O-O Bg4 13.Qc2 Re8 14.d4 c5 15.Be3 cxd4 16.Nxd4 Ne5 17.h3 Bd7 18.b3 Bc5 19.Rad1 Qc8 20.Kh2 Ng6 21.Bg5 Re5 22.Bxf6 gxf6 23.Ne4 f5 24.Nf6+ Kg7 25.Nxd7 Qxd7 26.Nc6 Rbe8 27.Nxe5 Rxe5 28.Qc3 f6 29.Rd3 Re2 30.Rd2 Rxd2 31.Qxd2 Ne5 32.Rd1 Qc7 33.Bd5 Kg6 34.b4 Bb6 35.Qc2 Nc6 36.Be6 Nd4 37.Rxd4 Bxd4 38.Qxf5+ Kg7 39.Qg4+ Kh6 40.Qxd4 Qe7 41.Qh4+ Kg6 42.Bf5+ Kf7 43.Qxh7+ Kf8 44.Qh8+ Kf7 45.Qa8 Qc7 46.Qd5+ Kg7 47.Kg2 Qe7 48.h4 Kh6 49.g4 Kg7 50.h5 Qe2 51.h6+ Kf8 52.h7 Qxf2+ 53.Kxf2 Ke7 54.h8=Q a6 55.Qe6# 1-0 code 

The Dreyfus Match
In 1967 AI critic Hubert Dreyfus at MIT was challenged by Greenblatt to play a game against his program.

Quote from //Oral History of Richard Greenblatt//:

Herbert Simon, an AI pioneer, watched the match. He said : code [Event "The Dreyfus Match"] [Site "MIT"] [Date "1967.??.??"] [Round "1"] [White "Hubert Dreyfus"] [Black "Mac Hack VI"] [Result "0-1"]

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Nc3 Bc5 5.d3 O-O 6.Ng5 Na5 7.Bd5 c6 8.Bb3 Nxb3 9.cxb3 h6 10.Nh3 d5 11.exd5 Bg4 12.f3 Bxh3 13.gxh3 Nxd5 14.Nxd5 Qxd5 15.Bd2 Qxd3 16.b4 Be7 17.Rg1 e4 18.fxe4 Bh4+ 19.Rg3 Bxg3+ 20.hxg3 Qxg3+ 21.Ke2 Qxh3 22.Qg1 h5 23.Bc3 g6 24.Qf2 h4 25.Qf6 Qg4+ 26.Kd2 Rad8+ 27.Kc2 Qxe4+ 28.Kb3 Qe6+ 29.Qxe6 fxe6 30.Rh1 Rf4 31.Be1 Rf3+ 32.Ka4 h3 33.b5 Rd4+ 34.b4 cxb5+ 35.Kxb5 Ra3 36.Kc5 Rd5+ 37.Kc4 b5# 0-1 code

IFIP Match
In August 1968, at the 4th IFIP conference held in [|Edinburgh], Mac Hack running on a PDP-10 won an exhibition match versus a program written by John J. Scott, running on a ICL 1909/5. The game was analyzed by Jack Good, as published in Donald Michie's //Machine Intelligence 4//.

ETH-MIT Match
In 1968, Gerald Tripard, postdoc at ETH Zurich and co-author of the chess program Charly, asked Richard Greenblatt for a match versus Mac Hack VI. Three games were played in October and November 1968 via [|ham radio], all three won by Mac Hack VI.

The 70s
Mac Hack was ported to a PDP-10 and was the first computer chess program to be widely distributed. It didn't play any ACM or ICCA tournaments, though. In 1977 Mac Hack played three exhibition games against [|Bobby Fischer]. In 1978, Mac Hack (dubbed Machack) played a match versus the readers of the Computerwoche, a German weekly computer magazine affiliated with the [|International Data Group], one move per week  : code [Event "Schach dem Computer"] [Site "Computerwoche"] [Date "1978"] [Round "?"] [White "CW-Leser"] [Black "Machack"] [Result "1-0"]

1.e4 e5 2.Nf3 Nf6 3.Nxe5 d6 4.Nf3 Nxe4 5.d4 d5 6.Bd3 Be7 7.h3 O-O 8.O-O Nc6 9.Nc3 Nxc3 10.bxc3 Be6 11.Bf4 Re8 12.Re1 Qd7 13.Rb1 Rab8 14.Ng5 Bf5 15.Qh5 Bxg5 16.Qxg5 Rxe1+ 17.Rxe1 Be6 18.Qg3 Rc8 19.Bh6 g6 20.Qh4 f5 21.Qf6 Nxd4 22.cxd4 c6 1-0 code

=CHEOPS= //see main article CHEOPS// In the end of the 70s a brute force version of Mac Hack was ported to the Chess-orientated Processing System CHEOPS, one of the first dedicated hardware approaches in computer chess, which original conception and hardware design was instrumented by Edward Fredkin. Unfortunately it never competed against other programs of that time.

=Remark by Bill Gates= Remark by [|Bill Gates] on the [|17. IJCAI 2001], [|Seattle], [|Washington], USA, August 7, 2001 :

=See also=
 * CHEOPS
 * Kotok-McCarthy-Program

=Publications= > Chapter IV. The Greenblatt Chess Program
 * Richard Greenblatt, Donald Eastlake, [|Stephen D. Crocker] (**1967**). //The Greenblatt Chess Program//. Proceedings of the AfiPs Fall Joint Computer Conference, Vol. 31, pp. 801-810. Reprinted (**1988**) in Computer Chess Compendium, [|pdf] from The Computer History Museum or as [|pdf or ps] from [|DSpace] at MIT
 * L. Stephen Coles (**1967**). //Memorandum - Chess at Carnegie Tech//. [|pdf]
 * Paul Rushton, Tony Marsland (**1973**). //Current Chess Programs: A Summary of their Potential and Limitations//. INFOR Journal of the Canadian Information Processing Society Vol. 11, No. 1, [|pdf]
 * Monroe Newborn (**1975**). //Computer Chess//. [|Academic Press], New York, N.Y. ISBN 0-125-17250-8.
 * John Moussouris, Jack Holloway, Richard Greenblatt (**1979**). //[|CHEOPS: A Chess-orientated Processing System]//. [|Machine Intelligence 9] (Jean Hayes Michie, Donald Michie and L.I. Mikulich editors) Ellis Horwood, Chichester, 1979, pp. 351-360. Reprinted (**1988**) in Computer Chess Compendium

=Forum Posts=
 * [|Re: Berliner vs. Botvinnik Some interesting points], post 8 by Bradley C. Kuszmaul, rgcc, November 06, 1996 » Transposition Table in Mac Hack
 * [|Fischer vs. MIT's Greenblatt program, 1978] by Robert Hyatt, rgcc, February 27, 1999
 * [|More Fischer v Greenblatt] by scorsi, rgcc, February 28, 1999
 * [|Re: What Chess programs existed in the '60s?] by David Blackman, CCC, April 13, 2000
 * [|MacHack VI] by kaqs, CCC, August 28, 2005
 * [|MacHack under PDP-10 emulation] by Ian Osgood, CCC, February 03, 2011

=External Links=
 * [|Mac Hack from Wikipedia]
 * [|Opening Moves: Origins of Computer Chess, Getting Going] from [|The Computer History Museum]
 * [|Classic Computer Chess - ... The programs of yesteryear] by Carey, hosted by the [|Internet Archive]
 * [|Mac Hack Attack] by Bill Wall, [|Chess.com], May 13, 2008
 * [|Mac Hack VI competes] by Lawrence J. Krakauer
 * [|Chess stories] by Lawrence J. Krakauer
 * [|I resign] by Lawrence J. Krakauer
 * [|Computer chess via ham radio] by Lawrence J. Krakauer » Mac Hack vs. Charly
 * [|Boylston Chess Club Weblog: Bill Buckner & Ben Landy...All is Forgiven]
 * [|Computer Chess and Canada] by [|David Cohen], 2005 - covers Phil Haley - Dataline PDP-10 (MacHack 7)
 * [|63-chess.mp4] hosted by [|MIT CSAIL]
 * [|PDP-10/its · GitHub] (OCM 470 and accompanying files is a 1980 version of Mac Hack) maintained by [|Lars Brinkhoff] and [|Eric Swenson]

=References= =What links here?= include page="Mac Hack" component="backlinks" limit="100"
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