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Subject: Re: Tiniest chess program ever written?

Author: Dave Kuntzsch

Date: 09:03:18 09/10/02

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On September 10, 2002 at 08:33:48, Eli Liang wrote:

>In 1957, Alex Bernstein created a computer chess program that handled all the
>rules of chess and ran on an IBM 704 with a _total_ of 7K x 36bits of valve
>storage.  His program completed a 4-ply selective search in 8 minutes (but the
>processor speed of those IBM 704 was 0.042Mhz).
>
>In 1983, David Horne created a legendary chess program in 672 bytes of Z80
>assembly language and Basic, but his program didn't handle castling or
>en-passant, had a fixed opening move, only did a 1-ply search, and was unable to
>actually finish a game.
>
>In comparison, last month, Douglas Bagnall created a chess program with a static
>evaluator and a full-width 3-ply search which seems pretty hefty at 4.4K bytes
>of JavaScript since not only was it coded in a HLA, but it is not limited in RAM
>as Horne's and Bernstein's programs were.  (Not to mention that I've tried it
>and unfortunately, it seems buggy.)
>
>Questions:  Was Bernstein's the smallest/tightest/most-memory-efficient _full_
>chess program ever written?  What do you think is the smallest possible full
>chess program with alpha-beta search that could ever be written in Intel x86
>native code, if you disregard how to get moves in and out of it (no UI)?  I know
>the latter question is rather imprecise because of issues concerning complexity
>of static evaluation, depth of search, etc., but I am just looking for some
>imprecise opinions.

In the late 70s and early 80s, I wrote an 18K Z80 assembler program. It followed
all rules including castling on both sides, en passant, and pawn promotion. It
had a small imbedded opening book, all keyboard and display routines,
alpha-beta, mini-max, move ordering and killer move heuristic. The search depth
could be set to any value by the user.  It was inspired by an article in Popular
Science describing game theory. I still have the printed source, but in looking
for it the past month, I haven't been able to find it yet. BTW, the Z80 was an 8
bit machine and ran at 4Mhz. When it finally deveped a memory bug that I was
never able to pinpoint, I bought one of the first IBM PCs (floppy disk, 8080
chip), but never converted the program. The Z80 is still sitting in my basement.

Dave



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