oldie but goody

Discussion of chess software programming and technical issues.

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Dann Corbit
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Re: oldie but goody

Post by Dann Corbit » Wed Nov 06, 2019 11:03 pm

I would be interested in trying to compile it with gfortran, g95 and the like. Some of them have flags that allow older standards.
I expect that there would be OCR bugs, but those will probably be easy to find.
Taking ideas is not a vice, it is a virtue. We have another word for this. It is called learning.
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Re: oldie but goody

Post by bob » Thu Nov 07, 2019 5:46 pm

I will warn you: they are NOT easy to find. If Fortran only required type declarations for all variables, it would be pretty easy. But with the "implicit" declaration (IE implicit integer a-z) we are pretty much screwed. Each piece will have to be debugged pretty much line by line since it won't produce any errors. I think I have the book stuff (probably in the .zip I sent you). So it would be pretty complete, except for pondering. It has the code, but it doesn't use a unix or windows compatible to check to see if console input is available. Code could probably be stolen from Crafty, but it has to be converted to FORTRAN and the correct system calls would have to be figured out.

When this version was done, it was comparable in speed with chess 4.x, searching about 6 plies normally with occasional dips into 7 plies, until nearing the endgame. Be interesting to see how a basic full-width search does (this WAY before any algorithm-based forward pruning like reductions, WAY before Beal's null-move paper. IE a basic Shannon type-A search.

I believe that program hit around 1800 or so with it's USCF rating back then. Wonder how much higher it would be today. I think it was less than 1K on the xerox. Started at 2-3K on the Cray until it was cleaned up for that architecture a couple of years later.

Edit: actually I suspect that NPS would be closer to 100 in the xerox. After thinking about it. Previous version, highly selective, was 1 NPS on that hardware. This was significantly faster, but also significantly smaller (version 5 was > 100,000 lines of code, this version being under 10K. MUCH easier to work on, improve, and debug...

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